Biology 103 Chapters 8-12

In recent years, three factors have made organ transplants a viable option for many people:

1) improvements in immunosuppressive drugs, (2) better techniques for cross-matching (or "typing") tissue, and (3) national sharing of information and donor organs through organ-bank systems. The organ-bank system allows patients to receive the best matches possible regardless of where they live.

What diseases cause the spleen to enlarge?

A few diseases, such as infectious mononucleosis and leukemia, cause the spleen to enlarge. The swollen spleen can sometimes be felt as a lump in the upper-left abdomen. A strong blow to the abdomen can rupture the spleen, causing severe internal bleeding. When the spleen ruptures, surgical removal of it may be necessary to prevent a fatal hemorrhage.

Ventricle

A general term for a cavity. In the heart, one of the two chambers that receives blood from an atrium and pumps it into an artery.

The complement system

A group of bloodborne proteins that, when activated, enhance the inflammatory and immune responses and may lead to lysis of pathogens.

major histocompatibility complex (MHC) proteins

A group of proteins on the cell surface that identify an individual's cells as self and normally signal the immune system to bypass the individual's cells.

sinoatrial (SA) node

A group of specialized myocardial cells in the wall of the right atrium that initiates the heartbeat. The SA node is called the pacemaker of the heart. A small mass of cardiac muscle cells located near the junction of the right atrium and the superior vena cava.

What is true about voice production? It occurs during inspiration. The thicker the cords, the higher the pitch. Stretching the cords produces a lower pitch. A husky voice can be due to laryngitis. Vibrations of the glottis accounts for soundwave production. I DON'T KNOW YET

A husky voice can be due to laryngitis. Inflammation of the vocal cords due to laryngitis can cause the voice to become husky and deep. Inflammation causes the vocal cords to swell and become thicker. The pitch of the voice is dependent on how the vocal cords vibrate. The thicker an object, the lower the frequency of vibration and the lower the pitch that is perceived. Voice production occurs during expiration, not during inspiration. While sounds can be made during inspiration, it is not equivalent to normal speech. Stretching the cords produces a higher pitch, not a lower pitch. The pitch of sound depends on the frequency of vibration. Thinner objects vibrate quicker than thicker objects and have a higher pitch. Stretching the cords makes them thinner, and the pitch of the voice goes up. Expired air causes the vocal cords to vibrate, producing sound. The glottis is an open passageway in the larynx that air travels through.

Cytotoxic T cell:

A killer T cell that directly lyses foreign cells, cancer cells, or virus-infected body cells.

graded potentials

A local change in membrane potential that varies directly with the strength of the stimulus. Graded potentials decline with distance form the stimulus.

Virus

A noncellular infectious agent that can replicate only within a host cell. Viruses consist only of one or more pieces of genetic material (DNA or RNA) surrounded by a protein coat.

Inflammation

A nonspecific defensive response of the body to tissue injury characterized by dilation of blood vessels and an increase in vessel permeability. The presence of inflammation is indication by redness, heat, swelling, and pain.

Antibody

A protein molecule released by a B cell or a plasma cell that binds to a specific antigen.

nodes of Ranvier

A short unmyelinated gap between adjacent Schwann cells where the surface of a neuron axon is exposed.

action potential

A brief change in membrane potential of a nerve or muscle cell due to the movement of ion across the plasma membrane. Also called a nerve impulse.

Viruses consist only of one or more pieces of genetic material (DNA or RNA) surrounded by a protein coat. What is the protein coat called?

A capsid

Plasma cells

A cell derived from a B cell lymphocyte specifically to mass-produce and release antibodies.

Diaphragm

A dome-shaped sheet of muscle that separates the thoracic cavity from the abdominal cavity. Also a contraceptive device inserted into the vagina to cover the cervical opening.

The symptoms of HIV infection and the subsequent development of full-blown AIDS progress slowly. The course of the disease falls into three phases (Figure 9.21):

Acute Infection (Phase I) Chronic HIV Infection (Phase II) AIDS (Phase III)

Bronchus

Any one of the larger branching airways of the lungs. The walls of bronchi are reinforced with cartilage. (Plural: Bronchi)

Allergen

Any substance that triggers an allergic response.

Like our own cells, bacteria use ATP as a direct energy source and amino acids for making proteins. They store energy as carbohydrates and fats. Where do they obtain those raw materials?

Anywhere they can. Some bacteria break down raw sewage and cause the decomposition of dead animals and plants, thereby playing an essential role in the recycling of energy and raw materials. Others obtain nutrients from the soil and air.

Atrial Systole

As contraction starts, the heart is already nearly filled with blood that entered the ventricles and atria passively during the previous diastole. Contraction of the heart begins with the atria. During atrial systole, both atria contract, raising blood pressure in the atria and giving the final "kick" that fills the two ventricles to capacity. Atrial systole also momentarily stops further inflow from the veins. Both atrioventricular valves are still open, and both semilunar valves are still closed.

There are several types of neuroglial cells in the central nervous system. What are these cells and their functions?

Astrocytes CNS neuroglial cells that maintain a chemical environment that facilitates neuron function. oligodendrocyte In the central nervous system, protective sheaths of myelin are produced by another type of neuroglial cell called an oligodendrocyte. Two very debilitating diseases are caused by oligodendrocyte dysfunction. In the autoimmune disorder multiple sclerosis (MS), the protective sheaths produced by oligodendrocytes in the CNS become progressively damaged. Eventually, they form hardened (sclerotic) scar tissue that no longer insulates the neurons effectively. As a result, transmission of impulses in CNS neurons is disrupted. Common symptoms of MS include numbness, tingling, muscle weakness, paralysis, visual impairment, and urinary incontinence. The disease usually appears in people between 20 and 40 years of age, and although it can be fatal in the most severe cases, the probability of an almost normal life span (with physical limitations) is fairly high.

carbaminohemoglobin (HbCO2)

Carbon dioxide bound form of hemoglobin

Which statement is true about external respiration? Oxygen diffuses from plasma to alveoli. Carbon dioxide diffuses from cells to blood, and oxygen diffuses from blood to cells. Carbon dioxide diffuses from alveoli to plasma, and oxygen diffuses from plasma to alveoli. It involves systemic capillary beds. Carbon dioxide diffuses from plasma to alveoli. I DON'T KNOW YET

Carbon dioxide diffuses from plasma to alveoli. External respiration involves carbon dioxide diffusion from plasma to alveoli. This question has two aspects to consider. Where is the process occurring, and what is the direction? There are a few different types of respiration: external, internal, and cellular. External respiration involves the lungs. This is the "where." The direction depends on the gas. Oxygen is diffusing from the lungs to the blood. This is because there is a higher concentration of oxygen in the alveoli than the blood entering the pulmonary capillaries; thus oxygen diffuses from the lungs to the blood. On the other hand, carbon dioxide diffuses from the blood to the inside of the alveoli because there is a higher concentration of carbon dioxide in the pulmonary capillaries than in the alveoli. While plasma and alveoli are involved with external respiration (the location is correct), the direction is wrong. There is less oxygen in the plasma than in the alveoli; thus oxygen will go from the alveoli to the plasma, not the other way around. Systemic capillary beds are involved with internal respiration. This question was asking about external respiration, thus will involve the pulmonary capillaries. While carbon dioxide diffuses, from cells to blood is a proper "direction" and oxygen diffuses from blood to cells is also a proper direction, this is occurring at the tissue level and is part of internal respiration. Cells or tissues are key words to indicate internal respiration is occurring. Alveoli are the correct location, but the directions are again wrong for external respiration. Carbon dioxide does not diffuse from the alveoli to the plasma. It goes from the plasma to the alveoli so it can eventually be exhaled out of the body.

acquired immune deficiency syndrome (AIDS)

Disease caused by human immunodeficiency virus (HIV). Symptoms include severe weight loss, night sweats, swollen lymph nodes, and opportunistic infections.

Septum

Divides the right and left chambers of the heart

Cardiovascular disorders are among the most preventable of chronic health conditions. Although some factors are beyond your control—such as sex, race, age, and genetic inheritance—your lifestyle choices can also affect your risk. Things you can do to reduce your risk include:

Don't smoke or, if you do, quit. Smokers have more than twice the risk of heart attack that nonsmokers do, and smokers who suffer a heart attack are nearly four times as likely to die from it. Some researchers think secondhand smoke poses a risk as well. Watch your cholesterol levels. Cardiovascular risk rises with the blood cholesterol level. There is also evidence that high cholesterol increases risk even more when it is combined with other factors such as hypertension and tobacco smoke. Keep moving. Regular, moderate exercise lowers the risk of cardiovascular disease. This is not surprising because the heart is, after all, a muscle. Most physicians recommend exercising for at least 20 to 30 minutes, at least three times per week. Physical activity tends to lower blood pressure and cholesterol and makes it easier to maintain a healthy body weight. Always consult your physician before starting an exercise program If your blood pressure is on the high side, seek treatment. As discussed earlier, untreated hypertension damages blood vessels and increases the workload on the heart.

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During exercise, the metabolic activity of the active skeletal muscles goes up dramatically. As a result, the production of vasodilator waste products increases, and the local concentration of oxygen falls. Both of these contribute to dilation of the blood vessels. Consequently, blood flow through the active skeletal muscles increases. To sustain blood pressure in the face of increased blood flow, the heart must increase its output. From what you know, you might guess that an increase in blood flow to muscle would cause a fall in blood pressure, which in turn would cause a baroreceptor-mediated reflex increase in cardiac output. However, blood pressure doesn't fall very much (if at all) during exercise—if anything, it rises a little. During exercise, the primary cause of increased cardiac output is sensory input from moving muscles and joints. This sensory input signals the cardiovascular center to stimulate the heart and increase cardiac output even before blood pressure can fall very much. In other words, during exercise the body anticipates the need for increased cardiac output and prevents blood pressure from falling in the first place. In nonathletic people, cardiac output reaches a maximum of about 20-25 liters per minute during heavy exercise. However, trained athletes whose heart muscles have hypertrophied as a result of exercise training can reach cardiac outputs of up to 35 liters per minute, or almost seven times their resting cardiac output. The usual guideline for safe but effective training to improve cardiovascular fitness is to perform an activity that raises your heart rate to its "target heart rate" for at least 20 minutes, three times a week or more. Target heart rates are calculated as a percentage of the maximum heart rate, which varies with age (Figure 8.19). The maximum heart rate is calculated by subtracting your age from 220. The target heart rate during moderately intense exercise is 50-70% of the maximum heart rate. This target range is ideal for someone just beginning an exercise program. As their fitness improves, they can gradually build up to the 70-85% target range during vigorous physical activity. There are a variety of wearable fitness trackers that can monitor heart rate during exercise, or the wrist pulse can be checked manually. It is always recommended that an individual check with their physician before beginning an exercise program.

When a person who is initially at rest begins exercising, do you think tidal volume will increase, decrease, or stay the same? How about vital capacity? Explain.

During exercise, tidal volume increases dramatically. Vital capacity remains the same because the vital capacity represents the maximum volume that can ever be exhaled under any circumstances—that is, the lungs do not suddenly grow larger. Exercising just means that each breath is moving more air in and out, using a higher proportion of the vital capacity.

Which disease is characterized by a thick and sticky mucus? Strep throat Bronchitis Cystic fibrosis Pneumonia Emphysema I DON'T KNOW YET

Cystic fibrosis Cystic fibrosis is characterized by a thick and sticky mucus. Cystic fibrosis is a genetic disease that causes an overproduction of mucus in the respiratory and digestive tracts. While mucus serves to trap microbes, the thick mucus actually causes bacterial infections. Cystic fibrosis results in chronic inflammation that cannot be cured. Respiratory treatments serve to alleviate the signs and symptoms of cystic fibrosis. Pneumonia is an infection of the lungs. Viruses, fungi, and bacteria can all cause pneumonia. The infection leads to inflammation, and the edema associated with inflammation causes problems with gas exchange. Pneumonia can be very mild, as in the cases of walking pneumonia, or deadly, depending on the infectious agent and the health of the individual. People with impaired lung function due to years of smoking are much more susceptible to having a case of pneumonia becoming deadly. Emphysema is almost always due to smoking, though it can also be caused by a genetic mutation. Emphysema is characterized by a loss of elasticity of the lungs and destruction of the alveolar walls. Loss of elasticity results in loss of elastic recoil, which causes the use of accessory muscles to exhale. Bronchitis is an inflammation of the bronchi. It can be due to infection and cause a case of acute bronchitis, or smoking can cause chronic bronchitis. Inflammation of the bronchi results in excessive mucus production and an inability to completely exhale. Strep throat is a bacterial infection of the pharynx characterized by fever and inflammated tonsils. Antibiotics can cure it. Each of these disorders, along with cystic fibrosis, results in impaired ventilation and gas exchange.

We only have one tonsil. (True or false)

False. We actually have several tonsils, and some are not readily visible.

Blood pressure is usually the same in all blood vessels (True or false)

False. Blood pressure is not the same in all blood vessels. Figure 8.15 compares the pressures in the various vessel types of the circulatory system.

immunity

Resistance to disease and pathogens.

If a foreign object lodges in the trachea, what happens?

Respiration is interrupted and choking occurs. If the airway is completely blocked, death can occur within minutes. Choking often happens when a person carries on an animated conversation while eating. Beyond good manners, the risk of choking provides a good reason not to eat and talk at the same time. Choking typically stimulates receptors in the throat that trigger the cough reflex. This is a sudden expulsion of air from the lungs in an attempt to dislodge foreign material (Figure 10.5b). If the object blocks the airway completely before the person has finished inhaling, there may not be much air in the lungs. This will make the obstacle more difficult to remove. If the object blocks air flow only partially, it may be possible to dislodge it by inhaling slowly, then coughing.

Pulse

Rhythmic expansion and recoil of arteries resulting from heart contraction that can be felt from the surface of the body.

What is the correct order of the intrinsic conducting system? Purkinje fibers, bundle branches, AV bundle, AV node, SA node AV node, SA node, AV bundle, bundle branches, Purkinje fibers SA node, AV node, AV bundle, bundle branches, intercalated disks Intercalated disks, SA node, AV node, AV bundle, bundle branches, Purkinje fibers SA node, AV node, AV bundle, bundle branches, Purkinje fibers

SA node, AV node, AV bundle, bundle branches, Purkinje fibers SA node, AV node, AV bundle, bundle branches, Purkinje fibers is the correct order for the intrinsic conducting system. The intrinsic conducting system is a built-in electrical system for the heart. It serves to create action potentials that will cause the cells in the myocardium to contract. The first portion is the SA node, which is the pacemaker since it creates action potentials at the highest rate as compared to the rest of the intrinsic conducting system. The SA node is found in the right atrium. The SA node sends signals to the AV node, which electrically connects the atria to the ventricles. The AV node then sends impulses to the AV bundle, which then splits to form the left and right bundle branch. Each branch is going to serve its respective ventricle. The branches then divide into multiple Purkinje fibers that penetrate into each ventricle. AV node stands for atrioventricular node, which electrically connects the atria to ventricles. The SA node precedes the AV node. SA stands for Sinoatrial node. Atrio stands for atrium. Purkinje fibers are last, not first. These are the fibers that penetrate the ventricles. Intercalated discs are associated with the contractile fibers. The intercalated discs contain gap junctions that electrically connect one cardiac fiber to the next. The Purkinje fibers directly excite the contractile fibers, which then transmit the action potential to the next cell using intercalated discs.

Antibodies are classified by size, location, and function, and which one of the following represents the most common type of immunoglobulin? MHC IgA IgM IgG IgD

IgG

The ________ class of immunoglobulins is the most common type and is the only type that can cross the placenta to pass on the mother's acquired immunity to the developing fetus. IgE IgD IgG IgA

IgG

There are five classes of immunoglobulins, each designated by a different letter:

IgG, IgM, IgA, IgD, and IgE.

Which antibody is composed of five individual antibody subunits bonded together? IgM IgE IgA IgD IgG

IgM IgM is composed of five bonded antibody subunits. It is known as a pentamer since it is composed of five antibody subunits. IgM is the main antibody in the primary response. IgA is usually a dimer made of two antibodies bonded together. IgA is found in body secretions; thus it serves as the first line of adaptive defense. IgD, IgE, and IgG are all single antibodies; however, they differ in their functions. IgD is the receptor found on the surface of B cells that binds to a complementary antigen. Upon binding, the B cell is activated and changes into plasma cells and memory cells. IgG is the main antibody associated with the secondary immune response. IgE is the antibody associated with allergic reactions. Thus, a knowledge of the structure and function allows the antibody to be identified.

IgM (5-10%):

IgM antibodies are the first to be released during immune responses. Found in blood and lymph, they activate the complement system and cause foreign cells to agglutinate. Anti-A and Anti-B blood cell antibodies belong to this class.

What is not true about antibody production? Immature B cells engulf an antigen and form fit an antibody to that antigen. Antibodies are mass produced by plasma cells. Antibody production accounts for long-term immunity. Memory cells are also produced. The body has the capability to form antibodies against a variety of antigens. I DON'T KNOW YET

Immature B cells engulf an antigen and form fit an antibody to that antigen. Immature B cells do not engulf an antigen and form fit an antibody to that antigen. Antibodies are produced by a mechanism called clonal selection. Clonal means making exact copies and selection deals with how a particular antibody is made with its own specific shape. A large number of B cells is present, each with slightly different receptors on them. These receptors are really just antibodies attached to the cell membrane. All of the receptors are identical for a particular B cell. Each receptor can only bind to a particular antigen. Binding to the antigen induces the B cell to divide and form plasma cells and memory cells. The plasma cells are genetically programmed to secrete the same antibody that was acting as a receptor on the B cell. Thus, each B cell is predestined to form a particular antibody. It is just a matter of "selecting" the B cell by having the appropriate antigen bind to it. Thus, individuals have large numbers of B cells, each one having the capability to produce a different type of plasma cell, which would secrete its own specific antibody. Adaptive immunity is not only specific but is also long lasting. Activated B cells reproduce and make many identical plasma cells (cloning) and identical memory cells (cloning).

Mast cells

Immune cell that detects foreign substances in the tissue spaces and releases histamine to initiate a local inflammatory response against them. Mast cells typically are clustered deep in an epithelium or along blood vessels.

threshold

In an excitable cell such as a nerve or muscle, the membrane voltage that must be reached to trigger an action potential, or nerve impulse.

AIDS (Phase III)

In phase III, the symptoms of infection become apparent. Once the number of helper T cells falls below 200 per cubic millimeter of blood and the person has an opportunistic infection or type of cancer associated with HIV infection, the person is said to have AIDS. Infections and cancers associated with AIDS include specific types of pneumonia, meningitis, encephalitis, tuberculosis, Kaposi's sarcoma, and non-Hodgkin's lymphoma, among others. Notice that AIDS may not appear until years after initial HIV infection. Untreated AIDS is nearly always fatal.

In the peripheral nervous system, many neuron axons are enclosed and protected by specialized neuroglial cells called

Schwann cells (Figure 11.7a).

What prevents backflow into the ventricles from the main arteries leaving the heart when the heart relaxes?

Semilunar valves

There are three types of neurons in the nervous system, as shown in Figure 11.2.

Sensory neurons Interneurons Motor neurons

Interneurons and motor neurons have numerous dendrites that are fairly short and extend in many directions from the cell body. Why are sensory neurons an exception?

Sensory neurons are an exception because their dendrites connect directly to an axon.

Baroreceptors

Sensory receptor that is stimulated by increases in blood pressure.

What is the muscular partition that separates the right and left sides of the heart?

Septum

Cardiac cycle

Sequence of events encompassing one complete contraction and relaxation cycle of the atria and ventricles of the heart.

Cytokines

Signaling molecules secreted by helper T cells. Cytokines have a variety of functions, including promoting immune cell development, stimulating their activity, and attracting them to an area of infection.

bronchioles

Small airways within the lungs that carry air to the alveoli. The wall of bronchioles are devoid of cartilage.

Lymph nodes

Small masses of tissue and lymphatic vessels that contain macrophages and lymphocytes, which remove microorganisms, cellular debris, and abnormal cells from the lymph before it is returned to the cardiovascular system.

Arteries branch again and again, so the farther blood moves from the heart, the _________ in diameter the arteries become. larger smaller

Smaller

What are vaccines produced from?

Some vaccines are produced from dead or weakened pathogens. Examples include the inactivated polio vaccine, made from inactivated ("dead") poliovirus and the chicken-pox vaccine, a weakened form of the varicella-zoster virus. Other vaccines are simply antigenic components of pathogens, such as the capsid protein of a virus or the outer surface of a bacterium. These vaccines have very few side effects because the vaccine consists of highly purified antigens rather than entire bacterial cells or viruses.

atrioventricular (AV) node

Specialized mass of conducting cells located at the atrioventricular junction in the heart. located between the atria and ventricles The muscle fibers in this area are smaller in diameter, causing a slight delay of approximately 0.1 second, which temporarily slows the rate at which the impulse travels. This delay gives the atria time to contract and empty their blood into the ventricles before the ventricles contract.

Histamine

Substance produced by basophils and mast cells that causes vasodilation and increases vascular permeability.

Lymphatic system

System consisting of lymphatic vessels, lymph nodes, and other lymphoid organs and tissues. The lymphatic system returns excess interstitial fluid to the cardiovascular system and provides a site for immune surveillance.

Inside the spleen are two types of tissue:

Red pulp White pulp

Cell body

Region of a nerve cell that includes the nucleus and most of the cytoplasmic mass, and from which dendrites and axons extend.

Who is responsible for cell-mediated immunity? B or T cells?

T cells.

Which immune system cell must be presented with antigen by an antigen-presenting cell such as a macrophage, in order to become appropriately activated? natural killer cell B lymphocyte macrophage plasma cell T lymphocyte

T lymphocyte

Thymus gland hormones cause

T lymphocytes to mature

What contains lysozyme?

Tears and saliva

The very muscular left ventricle pumps blood through a fourth valve into

body's largest artery, the aorta.

B lymphocytes mature in the ________. liver spleen blood bone marrow

bone marrow

There is a tendency to treat all fevers as if they were a problem. But a modest fever may be beneficial because it makes our internal environment less hospitable to pathogens and enhances the body's ability to fight infections. Fever increases the metabolic rate of body cells, speeding up

both defense mechanisms and tissue-repair processes. When the infection is gone, the process reverses: Macrophages stop releasing pyrogens, the thermostat setting returns to normal, and your fever "breaks."

However, the cardiac pacemaker can be influenced by the ___________ to speed up or slow down

brain

Like other viruses, HIV infects by

entering a cell and using the cell's machinery to reproduce. HIV targets helper T cells, gaining entry by attaching to CD4 receptors.

Diseases caused by different types of viruses range from life threatening—AIDS, hepatitis, encephalitis, rabies—to annoying—colds, warts, or chicken pox. Viral infections can be minor for some people but serious for others. An otherwise healthy person may be ill for only a few days with a viral infection, whereas someone who is very young, very old, or in poor health may die. (True or false)

True.

Trachea

Tube extending from the larynx to the bronchi that is the passageway for air to lungs. Also called the windpipe.

Vocal chords

Two folds of connective tissue that extend across the airway. Audible sounds are heard when the vocal cords vibrate as air passes by. The vocal cords are supported by ligaments and enclosed within a cartilaginous structure nicknamed the Adam's apple.

helper T cell

Type of T lymphocyte that orchestrates cell-mediated immunity by direct contact with other immune cells and by releasing chemicals called lymphokines.

How do digestive and vaginal acids keep pathogens out?

Undiluted digestive acid is strong enough to kill nearly all pathogens that enter the digestive tract on an empty stomach. Only one strain of bacteria, Helicobacter pylori (H. pylori), can thrive in the highly acidic environment of the stomach. H. pylori is now known to contribute to many cases of stomach ulcers. Vaginal secretions are slightly acidic, too, though not nearly as acidic as stomach secretions.

Atrioventricular (AV) valve

Valve located between the atria and their corresponding ventricles that prevents blood from flowing back into the atria when the ventricles contract.

________________ of arterioles and precapillary sphincters reduces their diameter and thus reduces blood flow to the capillaries.

Vasoconstriction

Skeletal Muscles Squeeze

Veins

human immunodeficiency virus (HIV)

Virus that destroys helper T cells, thus depressing cell-mediated immunity. Symptomatic AIDS gradually appears when the helper T cell population is significantly depleted.

tidal volume

Volume of air inhaled and exhaled in a single breath. Normal tidal volume is approximately 500 milliliters, or about a pint.

The activation and clonal expansion of cytotoxic T cells.

When a mature T cell with CD8 receptors meets an APC that displays an antigen and MHC (Figure 9.14), ➊ the T cell is activated and ➋ begins to produce a clone of cytotoxic T cells. This activation also is promoted by cytokines secreted by activated helper T cells. ➌ Activated cytotoxic T cells are the only T cells that directly attack and destroy other cells. ➍ Like helper T cells, some cytotoxic T cells become memory T cells. Once activated, cytotoxic T cells roam throughout the body in search of cells that display recognizable antigens, which indicate that those cells are infected with a virus or are cancerous. When T cells find their target cells, they release chemicals that will destroy those abnormal cells.

With arterial blood pressure held relatively constant, the flow of blood through each precapillary sphincter (and hence each capillary) can be adjusted according to need, just like turning a faucet on or off. How is the flow adjusted?

When a particular tissue is metabolically active, such as when a muscle is contracting, it consumes more oxygen and nutrients. Increased metabolism also raises the production of carbon dioxide and other waste products. One or more of these changes associated with increased metabolism cause precapillary sphincters within the tissue to vasodilate, increasing blood flow (Figure 8.18). Scientists do not yet know the precise mechanisms of this vasodilation or the identity of all the chemical substances that influence the vasodilation.

When health professionals measure your blood pressure, what are they assessing?

When health professionals measure your blood pressure, they are assessing the pressure in your main arteries.

Within hours after second exposure to an antigen, what's activated?

Within hours after second exposure to an antigen, memory cells are activated. New armies of T and plasma cells form, and within a few days, antibody concentrations rise rapidly to much higher levels than in the primary response. Notice that antibody levels remain much higher in the body after the second exposure.

The fact that arteries are constantly under high pressure places them at risk of injury. If the endothelium becomes damaged, blood may seep through the injured area and work its way between the two outer layers, splitting them apart. The result is an

aneurysm

Which blood vessel lacks smooth muscle? vein capillary venule artery arteriole I DON'T KNOW YET

capillary Capillaries lack smooth muscle. Capillaries are the smallest blood vessels and are designed for nutrient and waste exchange. The key for this to occur is to have a very thin vessel in order for diffusion to occur. Thus, capillaries are only composed of an endothelial layer. They lack the muscular layer and the outer connective tissue layer. All other blood vessels contain smooth muscle. The smooth muscle is under sympathetic control. The purpose of the smooth muscle is to control blood pressure. If the pressure is too high, the muscle will relax and the vessel will dilate. However, if the pressure is too low, the muscle will contract and the vessel will constrict. Contraction of the smooth muscle is most pronounced in the arteries and arterioles as noted by the prominent muscle layer. Veins and venules have a much thinner smooth muscle layer

Carbonic anhydrase catalyzes what reaction? bicarbonate ions and hydrogen ions to produce carbonic acid carbon dioxide and bicarbonate ion to produce carbonic acid water and bicarbonate ion to produce carbonic acid water and carbonic acid to produce bicarbonate ion carbon dioxide and water to produce carbonic acid I DON'T KNOW YET

carbon dioxide and water to produce carbonic acid Carbonic anhydrasecatalyzes carbon dioxide and water to produce carbonic acid. Carbon dioxide is a waste produce from cellular respiration. High levels of it cause the pH to drop; thus it needs to be removed from the blood stream. It is somewhat soluble, and some of it combines with hemoglobin. The majority of it travels in the form of the bicarbonate ion. How does carbon dioxide form the bicarbonate ion? By going through a two-step reaction. First, carbon dioxide combines with water to form carbonic acid. This occurs relatively slowly, but carbonic anhydrase speeds up the reaction. Carbonic acid dissociates and releases a hydrogen ion and the bicarbonate ion. Please review acid base chemistry in Chapter 2 if you need help with acids and bases. The formation of carbonic acid occurs as red blood cells encounter carbon dioxide from the tissues. Bicarbonate ion comes from the dissociation of carbonic acid. Water and carbon dioxide combine to form carbonic acid. The reaction is sped up using the enzyme carbonic anhydrase. Bicarbonate ions and hydrogen ions produce carbonic acid, but this doesn't require an enzyme. Carbonic anhydrase also catalyzes carbonic acid, breaking down into carbon dioxide and water. This reaction occurs at the lungs so carbon dioxide can enventually be exhaled.

The two lymph ducts join the subclavian veins near the shoulders, thereby returning the lymph to the

cardiovascular system.

Arrhythmias take many forms. Occasional skipped heartbeats, for example, are fairly common and usually of no consequence. However, a type of rapid irregular ventricular contraction known as ventricular fibrillation (or "V-fib") is very quickly fatal unless treated immediately. Ventricular fibrillation is the leading cause of cardiac death in otherwise healthy people. In a hospital, ventricular fibrillation is treated by

cardioversion, which is designed to restore the normal heart rhythm when a patient has an unstable pulse. This may involve medication (chemical cardioversion) or a strong electrical current applied to the chest (electrical cardioversion). Automatic external defibrillators (AEDs) are now available in many public places with instructions (audio commands and visual instructions) simple enough to be followed by a CPR/AED-trained lay person.

The external nose consists of

cartilage in the front and two nasal bones behind the cartilage.

Action potentials occur because the axon membrane contains voltage-sensitive ion channels that open and close sequentially once threshold has been reached. An action potential occurs as a sequence of three events:

depolarization, repolarization, and reestablishment of the resting potential (Figure 11.5).

The immune system comprises cells, proteins, and the lymphatic system, all working together to

detect and kill particular pathogens and abnormal body cells.

Lung volumes and rates of change of volume are useful in

diagnosing various lung diseases For example, emphysema is a condition in which the smaller airways lose elasticity, causing them to collapse during expiration and impairing the ability to exhale naturally. A spirometer recording of someone with emphysema might show a decreased inspiratory reserve and a prolonged period of expiration after a maximum inspiration because of resistance to air outflow.

Most of the filtered fluid is reabsorbed by __________ back into the last half of the capillary before it joins a _________. The force for this reabsorption is the presence of protein in the blood but not in the interstitial fluid. In other words, fluid diffuses from an area of high water concentration (interstitial fluid) to an area of lower water concentration (blood plasma). However, the diffusional reabsorption of fluid does not quite match the pressure-induced filtration of fluid, so a small amount of filtered fluid remains in the interstitial space as excess interstitial fluid.

diffusion, vein

Natural killer (NK) cells are a group of white blood cells (lymphocytes) that destroy tumor cells and cells infected by viruses. NK cells are able to recognize certain changes that take place in the plasma membranes of tumor cells and virus-infected cells. The name natural killer reflects the fact that NK cells are nonspecific killers, unlike the cytotoxic T cells discussed later in this chapter that target only specific enemies. NK cells are not phagocytes. Instead, they release chemicals that

directly destroy the target cell. One of these chemicals forms a hole in the target cell membrane. Enzymes are then released by the NK cell and enter through the hole into the target cell, digesting and destroying the target cell. NK cells also secrete substances that enhance the inflammatory response.

Pathogens cause

disease

Cellular metabolism in body tissues continuously produces carbon dioxide as a waste product. One of the most important functions of blood (other than the transport of oxygen) is to transport away from tissues and back to the lungs, where it can be removed from the body. Because the partial pressure of is higher in the tissues than it is in blood, readily diffuses from tissues into the bloodstream. Once in the blood, is transported in three ways:

dissolved in blood plasma, bound to hemoglobin, or in the form of bicarbonate (Figure 10.12b).

When is the thymus gland the largest and most active?

during childhood. During adolescence, it stops growing and then slowly starts to shrink. By that time, our defense mechanisms are typically well established. In old age, the thymus gland may disappear entirely, to be replaced by fibrous and fatty tissue.

The mucus in the nasal cavity traps

dust, pathogens, and other particles in the air before they get any further into the respiratory tract.

Oxygen is transported in blood in two ways:

either bound to hemoglobin (Hb) in red blood cells or dissolved in blood plasma (Figure 10.12a).

Electrocardiogram records the heart's _______ ___________

electrical activity

What's the innermost layer of the heart?

endocardium

Hormones play a role in regulation of the cardiovascular system. Hormones are chemical messengers secreted by

endocrine organs or specialized groups of cells into the bloodstream that have specific effects on target organs or cells.

What is the outermost layer of the heart?

epicardium

Which structure covers the larynx during swallowing? epiglottis the Adam's apple alveoli trachea the glottis

epiglottis The epiglottis covers the larynx during swallowing. The epiglottis is a flap-like structure composed of flexible elastic cartilage. The larynx has an opening called the glottis, which provides a path for air to enter and exit the larynx. Food and water can potentially enter the glottis and cause choking, but the epiglottis bends over to cover the glottis during swallowing. Talking and swallowing can lead to choking; thus the protective mechanism doesn't always work. The alveoli, which are involved with gas exchange, are deep within the lungs. The trachea is a tube that connects the larynx with the two primary bronchi. The glottis is the hole that air goes through, while the epiglottis is the flap. The prefix "epi" means above or upon. Thus, the epiglottis is above or goes upon the glottis. The Adam's apple is the name given to the protruding aspect of the larynx typically found in males.

The larynx contains two important structures:

epiglottis and vocal cords

The epicardium consists of a thin layer of

epithelial and connective tissue

Together, the chordae tendineae and papillary muscles prevent the valves from

everting (opening backward) into the atria when the ventricles contract.

Capillary walls consist of a single layer of squamous epithelial cells (Figure 8.3c). Microscopic pores pierce this layer, and the cells are separated by narrow slits. These openings are large enough to allow the

exchange of fluid and other materials between blood and the interstitial fluid (the fluid that surrounds every living cell) yet small enough to retain RBCs and most plasma proteins in the capillary. Some white blood cells (WBCs) can also squeeze between the cells in capillary walls and enter the tissue spaces. In effect, capillaries function as biological strainers that permit selective exchange of substances with the interstitial fluid.

Extensive networks of capillaries, called capillary beds, can be found in all areas of the body, which is why you are likely to bleed no matter where you cut yourself. The branching design of capillaries and their thin, porous walls allow blood to

exchange oxygen, carbon dioxide, nutrients, and waste products with tissue cells.

Finally, the T wave occurs when the electrical activity in the ventricles

ends and the ventricular muscle cells rest in preparation for the next cycle.

Which of the following is associated with the specific defenses of the body? natural killer cells the inflammatory response interferons cell-mediated immunity the complement system

cell-mediated immunity

What does the nervous system include?

central nervous system and peripheral nervous system

Four heart valves enforce the heart's one-way flow pattern and prevent blood from flowing backward. The valves open and shut passively in response to

changes in the pressure of blood on each side of the valve.

Aortic bodies are a ____________ type of receptor. proprioreceptor osmoreceptor thermoreceptor nociceptor chemoreceptor I DON'T KNOW YET

chemoreceptor Aortic bodies are a type of chemoreceptor. Recall from the nervous system that chemoreceptors sense chemicals. It turns out that levels of carbon dioxide, hydrogen ions, and oxygen influence the rate of breathing. The chemoreceptors detect the chemicals and send neural impulses to the breathing centers in the medulla. High levels of carbon dioxide and hydrogen ions will increase ventilation, while low levels of oxygen will also increase ventilation. Nociceptors sense pain, which may increase the breathing rate by turning on the sympathetic nervous system. However, aortic bodies, along with carotid bodies, are types of chemoreceptors. Thermoreceptors sense temperature, and these receptors are associated with the skin. Osmoreceptors sense the solute concentration to determine if a person is dehydrated or not. This does not influence breathing. Proprioreceptors are associated with muscles, synovial joints, and tendons and function to determine body position.

With the exception of the very smallest bronchioles, the bronchi and bronchioles are lined with

ciliated epithelial cells and occasional mucus-secreting cells. The thin, watery mucus produced by the mucus-secreting cells traps dust, bacteria, and other small particles. The ciliated cells then sweep the accumulated mucus and trapped material upward toward the pharynx so that it can be swallowed.

These two organ systems are integral to a functioning human immune system.

circulatory and lymphatic

the amount of the air that we can forcibly exhale beyond the tidal volume (about 1200 ml) is the

expiratory reserve volume

The visible portion of the nose is known as the

external nose

We can live without a spleen because its functions are shared by the lymph nodes, liver, and red bone marrow; however, people who have had their spleen removed are often more vulnerable to

infections.

Which blood vessel has the lowest blood pressure? capillary venule aorta inferior vena cava femoral vein I DON'T KNOW YET

inferior vena cava The inferior vena cava has the lowest blood pressure. As blood travels through a blood vessel, it encounters resistance in the form of friction. A marble rolling on the floor goes slower and slower as resistance slows it down, until it eventually stops. The same is happening with blood. Blood pressure is constantly dropping as the blood travels from one area to the next. The pressure is highest at the aorta, since it is right after the heart. The pressure keeps dropping until it reaches almost zero in the vena cava. Many people incorrectly believe that capillaries have the lowest blood pressure, but blood travels the slowest in them, and they do not have the lowest pressure. Pressure keeps dropping as blood travels; hence blood has lower and lower pressure from capillaries to the venules and lower from the venules to veins, such as the femoral vein. The aorta has the highest pressure since resistance has been minimal due to the fact that the aorta is at the very beginning of the systemic circuit.

Where are papillary muscles located? only the left ventricle left and right ventricles at the beginning of capillary beds left and right atria only the right ventricle

left and right ventricles Papillary muscles are located in the left and right ventricles and work with the chordae tendinae to prevent the atrioventricular (AV) valves from going into the atria. The chordae tendinae (essentially tendon chords) are string-like structures that connect AV valves to nipple-like muscular structures called papillary muscles. During ventricular contraction, the blood needs to leave the ventricles and travel either to the pulmonary or systemic circuits. What stops the blood from pushing its way back through the AV valves and back into the atria? The chordae tendinae prevents this from happening. As the ventricles contract, the papillary muscles also contract, thereby pulling down on the chordae tendinae, and in turn the AV valves are prevented from opening up into the atria. Imagine an umbrella turning inside out when it is windy. This is what would happen if there were no chordae tendinae; the AV valves would enter the atria. The atria lack papillary muscles. If the atria had papillary muscles connected to chordae tendinae, then contraction of the papillary muscles would cause the AV valves to enter the atria and blood would flow from the ventricles to the atria. There are left and right AV valves; hence each ventricle needs papillary muscles to prevent the AV valves from everting into the atria during ventricular systole. Capillary beds have precapillary sphincters that open and close to control blood flow through a capillary. Papillary muscles connect to chordae tendinae and function to ensure that the AV valves do not evert into the atria.

Blood returning from the lungs to the heart enters the

left atrium and then passes through a third valve into the left ventricle.

Local control mechanisms dictate

local blood flows

Where is the thymus gland located?

located in the lower neck, behind the sternum and just above the heart.

Hypotension

low blood pressure

Maintenance of arterial blood pressure is crucial to drive the flow of blood throughout the body and all the way back to the heart. Recall that fluid always flows from a region of high pressure toward a region of

lower pressure. By the time it reaches the capillaries, blood flow is steady rather than pulsatile, and pressure continues to fall as blood flows through venules and veins. The differences in the blood pressure of arteries, capillaries, and veins keep blood moving through the body.

Lymph nodes cleanse the

lymph

The fluid in the lymphatic capillaries is

lymph

What do lymphatic vessels transport?

lymph

Located at intervals along the lymphatic vessels are small organs called

lymph nodes

Antibodies are released into the

lymph, bloodstream, and tissue fluid, where they circulate throughout the body.

The basic components of the lymphatic system are a network of ____________ vessels throughout the body as well as a series of lymphatic organs and tissues, including the lymph nodes, the spleen, ______ bone marrow, the __________ gland, the tonsils, and the adenoids (Figure 9.3).

lymph, red, thymus

What do lymphatic capillaries merge to form?

lymphatic vessels.

Which one of the following is/are located in the tonsils to filter out many of the microorganisms that enter the throat? red blood cells platelets thymus lymphocytes adenoids

lymphocytes

The thymus gland contains

lymphocytes and epithelial cells encased in connective tissue.

The white pulp contains primarily

lymphocytes, searching for foreign pathogens in the blood.

The red pulp contains

macrophages that scavenge and break down microorganisms as well as old and damaged red blood cells and platelets.

Like any cell, human cells also have surface proteins that can act as antigens under the right circumstances. Your cells have a unique set of proteins on their surfaces that your immune system uses to recognize that those cells belong to you. These self markers are known as

major histocompatibility complex (MHC) proteins

Many bacteria live on and within our bodies, particularly in the digestive tract and the vagina, drawing energy from the food we eat in exchange for

manufacturing vitamins or controlling the populations of other, more harmful bacteria.

The tonsils are masses of lymphatic tissue near the entrance to the throat. Lymphocytes in the tonsils gather and filter out

many of the microorganisms that enter the throat in food or air.

Other activated complement proteins bind to bacterial cell membranes, marking them for destruction by phagocytes. Others serve as chemical attractants to draw additional phagocytes to the infection where they destroy bacteria. Still others cause

mast cells, specialized connective tissue cells, to release histamine, a chemical that enhances inflammation.

There is probably no more basic rhythm to which humans respond than the familiar "lub-DUB-lub-DUB" of the heart beating. We probably experience it, at least subconsciously, even before we are born. These heart sounds reflect events that occur during the cardiac cycle—specifically the closing of the heart valves. The "lub" signals the closure of the two AV valves during ventricular systole. The slightly louder "DUB" occurs when the aortic and pulmonary semilunar valves close during ventricular diastole. The sounds are due to vibrations in the heart chambers and blood vessels, which are caused by the closing of the valves. Blood flows silently as long as it flows smoothly. However, if blood encounters an obstruction, the disturbed flow can create unusual heart sounds called

murmurs.

The heart is mostly

muscle

What keeps blood flowing in one direction, especially in regions of low blood pressure? precapillary sphincters smooth muscle endothelium connective tissue found in the outer layer of the blood vessel YOU WERE UNSURE AND CORRECT muscular pump, breathing, and valves I DON'T KNOW YET

muscular pump, breathing, and valves Valves and the muscular pump account for blood flowing in one direction where there is low blood pressure. Use a tube of toothpaste to envision a muscular pump. The toothpaste won't leave the tube until you press on the tube. Pressing on the tube creates pressure within the tube, and this pressure forces the toothpaste out of the tube. Now imagine the blood in your legs as toothpaste. What keeps it flowing? As you move, the skeletal muscles contract and relax, essentially getting wider and thinner. The muscles press against the veins just as you did with the toothpaste. This muscular pump aids in the flow of venous blood since it is under such low pressure. The process of ventilation causes changes in the thoracic volume, which leads to pressure changes. The thoracic pressure goes down, while the abdominal pressure goes up. These changes create a pressure gradient facilitating the return of blood in the inferior vena cava to the right atrium. The veins also have valves to ensure the flow goes toward the heart. Endothelium is simple squamous epithelium that lines all blood vessels and functions to provide a smooth surface for blood flow. The connective tissue found in the outer layer of the vessel holds the vessel in place. It doesn't influence the diameter of the vessel, nor does it effect the direction of blood flow. Smooth muscle can cause constriction or dilation, but this change is minimal in veins. Precapillary sphincters are valves found at the beginning of capillary beds. They are not associated with veins. It is the valves and muscular pumps that account for the one-way flow of blood.

Schwann cells produce a fatty insulating material called

myelin

During development, individual Schwann cells wrap themselves around a short segment of an axon many times as a sort of insulating blanket, creating a shiny white protective layer called a __________ ___________ around the axon (Figure 11.7b).

myelin sheath

Neurons that have axons wrapped in a myelin sheath are called

myelinated neurons.

What is the middle layer of the heart?

myocardium

Because of their specificity, monoclonal antibodies can be prepared that target just the cancer cells or ______ required for cancer cell growth.

proteins

Only about 20% of cells in the human nervous system are neurons. The rest are neuroglial cells. What are neuroglial cell's functions?

provides physical support and protection to neurons and helps maintain healthy concentrations of important chemicals in the fluid surrounding them. Neuroglial cells do not generate or transmit impulses.

Because the electrical impulse travels down the septum to the lower portion of the ventricles and then spreads rapidly upward through the Purkinje fibers, the lower part of the ventricles contract before the upper part. This lower-to-upper squeezing motion pushes blood into the

pulmonary trunk and aorta.

A good place to detect a pulse is the

radial artery (inside your wrist, just below the base of the thumb).

Subsequent exposure to the pathogen elicits a _________ __________ ____________ that is faster, longer lasting, and more effective than the first.

secondary immune response

Second is the QRS complex, representing the spread of the electrical impulse down the

septum and around the two ventricles in the Purkinje fibers, causing ventricular systole.

The stimulus that starts a heartbeat begins in the

sinoatrial (SA) node

The cardiac conduction system consists of four structures:

sinoatrial node, atrioventricular node, atrioventricular bundle and its two branches, and Purkinje fibers.

The heart is composed primarily of cardiac muscle, and like our skeletal muscles, it benefits from regular exercise. During sustained (aerobic) exercise, the heart beats more rapidly and more powerfully to sustain blood pressure in the face of increased blood flow to hardworking skeletal muscles. Over time, this causes the heart to increase in

size (hypertrophy) slightly. However, it is important not to overdo any exercise training regimen. If the heart is overexerted, it may become starved for oxygen, and heart muscle may become damaged.

Between adjacent Schwann cells are short uninsulated gaps called __________ ____ __________________ where the surface of the axon is still exposed.

nodes of Ranvier

The upper respiratory tract comprises the

nose (including the nasal cavity) and pharynx—structures above the Adam's apple.

The respiratory system includes the

nose, pharynx, larynx, trachea, bronchi, and lungs.

Sensory neurons

of the PNS are specialized to respond to a certain type of stimulus, such as pressure or light. They transmit information about this stimulus to the CNS in the form of electrical impulses. In other words, sensory neurons provide input to the CNS.

Motor neurons

of the PNS transmit impulses away from the CNS. They carry the nervous system's output, still in the form of electrical impulses, to all of the tissues and organs of the body.

The AV valves consist of These valves are supported by strands of

of thin connective tissue flaps (cusps) that project into the ventricles. connective tissue called chordae tendineae that connect to muscular extensions of the ventricle walls called papillary muscles.

he lymphatic vessels carry lymph into and out of each node (see Figure 9.3). Valves within these vessels ensure that lymph flows in a. multiple directions b. one direction

one direction Valves within these vessels ensure that lymph flows only in one direction.

Once blood has been pushed toward the heart by skeletal muscles or drained in that direction by gravity, it cannot drain back again because of these The opening and closing of venous valves is strictly dependent on differences in

one-way valves. blood pressure on either side.

T cells do not produce antibodies. Instead, some T cells directly attack foreign cells that display antigens. Other T cells release proteins that help coordinate other aspects of the immune response, including the actions of T cells, B cells, and macrophages. Cell-mediated immunity protects us against

parasites, bacteria, viruses, fungi, cancerous cells, and cells perceived as foreign (including, unfortunately, transplanted tissue—see section 9.8, Tissue Rejection: A Medical Challenge). T cells can identify and kill infected human cells even before those infected cells have a chance to release bacteria or viruses into the blood.

To fight an existing or even anticipated infection, a person can be given antibodies prepared in advance from a human or animal donor with immunity to that illness. Usually this takes the form of a gamma globulin shot (serum containing primarily IgG antibodies). The procedure is called

passive immunization

Pleurisy is an inflammation of the pleural membranes. Where are these membranes located? surrounding the left and right primary bronchi lining the nasal cavity surrounding the trachea surrounding each lung within each lung I DON'T KNOW YET

surrounding each lung The pleural membranes surround each lung. Recall from the first chapter the pleural cavities surround each lung. That concept is restated in this chapter. The pleural membranes are actually two membranes: One membrane covers the cavity wall and the second membrane is part of the surface of the lung. There is pleural fluid between the two membranes. This fluid functions in lubrication and in providing surface tension to keep the lungs attached to the pleural cavity to prevent them from undergoing elastic recoil and collapsing. Mucous membranes are within the bronchi of the lungs. Pleural membranes are found lining the pleural cavity and are a part of the surface of each lung. Connective tissue called adventia is on the outside of the trachea and functions to hold the trachea in place. Mucous membranes line the nasal cavity. These membranes function to trap microbes and to humidify air going to the lungs. Pleural membranes don't surround the left and right primary bronchi; they form the surface of the lungs and line the wall of the pleural cavity.

If hypertension is suspected, your physician will probably measure your blood pressure on at least three different occasions before making a firm diagnosis. True hypertension is a _________ elevation in blood pressure above normal levels—a systolic pressure of 130 mm Hg or greater or a diastolic pressure of 80 mm Hg or greater. Even blood pressure that is consistently just below the hypertensive level (prehypertension) may carry a slightly higher risk of health complications.

sustained

The autonomic division has two subdivisions called the

sympathetic and parasympathetic divisions. In general, the actions of the sympathetic and parasympathetic divisions oppose each other. They work antagonistically to accomplish the automatic, subconscious maintenance of homeostasis.

Some activated T cells become inactive memory cells, retaining receptors for the antigen that originally stimulated their production. If that antigen is presented to them again,

the memory cells are reactivated. Some form new helper T cells that multiply quickly to marshal an immune response. Others form a new army of cytotoxic T cells to attack and destroy. Like memory B cells, memory T cells are an important factor that distinguishes specific defenses from nonspecific defense mechanisms.

Most successful pathogens enter the body at places where we do not have skin. They enter through

the mucous membranes that line the digestive, urinary, respiratory, and reproductive tracts, where they can take advantage of moist surfaces in direct contact with living cells. They enter around the eyes or in the ears.

Axons of sensory neurons originate from a dendrite, whereas the axons of interneurons and motor neurons originate from

the point of union with the cell body, called the axon hillock (see Figure 11.2).

The respiratory system in humans and most animals has another function in addition to gas exchange, what's this function?

the production of sound (vocalization)

During exercise, the metabolic activity of the active skeletal muscles goes up dramatically. As a result,

the production of vasodilator waste products increases, and the local concentration of oxygen falls. Both of these contribute to dilation of the blood vessels. Consequently, blood flow through the active skeletal muscles increases.

The heart pumps blood through two circuits simultaneously;

the pulmonary circuit (lungs), where blood picks up oxygen and gets rid of CO2 the systemic circuit (the rest of the body) where oxygen is delivered and CO2 waste is produced

From a clinical standpoint, what does blood pressure gives valuable clues about?

the relative volume of blood in the vessels, the condition or stiffness of the arteries, and the overall efficiency of the cardiovascular system. Trends in blood pressure over time are a useful indicator of cardiovascular changes.

The lymphatic vessels merge to form larger and larger vessels, eventually creating two major lymphatic ducts:

the right lymphatic duct and the thoracic duct.

The PNS has two functional subdivisions:

the sensory division of the PNS carries information to the brain and spinal cord, and the motor division of the PNS carries information from the CNS to other parts of the body

What does the spleen cleanse and what does the lymph nodes cleanse?

the spleen cleanses the blood, and the lymph nodes cleanse lymph. Together, they keep the circulating body fluids relatively free of damaged cells and microorganisms.

What do tonsils protect?

the throat

A few bacteria are pathogens, however. What do pathogens rely on living human cells for?

their energy supply, and in the process, they damage or kill the human cells. They cause pneumonia, tonsillitis, tuberculosis, botulism, toxic shock syndrome, syphilis, Lyme disease, and many other diseases.

As we have seen, the lungs are air-filled structures consisting almost entirely of bronchioles, alveoli, and blood vessels. Lacking skeletal muscle, they cannot expand (increase in volume) or contract (decrease in volume) on their own. The lungs expand and contract only because

they are compliant (stretchable) and because they are surrounded by the pleural cavity, which is airtight and sealed. If the volume of the pleural cavity expands, the lungs will expand with it.

The specific defense mechanisms are also referred to as adaptive responses because

they change over time and adjust as immunologic memory develops.

If pathogens manage to breach our physical and chemical barriers and start to kill or damage cells, we have an invasion challenge of a different sort. Instead of passively waiting for pathogens to run into a physical or chemical barrier, the body must seek out the pathogens to get rid of them. It must also clean tissue infected with pathogens and heal injuries to tissue caused by pathogens. Our second line of defense includes a varied group of defense mechanisms that attack pathogens when they make it into our body. We refer to them as nonspecific because

they do not target specific infectious pathogens. Instead, they appear in response to all types of infectious pathogens without discriminating between them. These defenses are also known as the innate defenses because they are present at birth and always ready to operate without prior priming.

The larger arteries have a thick layer of muscle because

they must be able to withstand the high pressures generated by the heart.

Are viruses alive? Biologists are divided on the answer to this question. Most would say that viruses are not alive because they cannot reproduce on their own. Viruses have no observable activity associated with life when they are not in contact with another living cell. However, when they enter a living cell (host cell),

they take it over and use the cell's enzymes, amino acids, nucleotides, ATP, and ribosomes to make more viruses.

The lungs are organs consisting of supportive tissue enclosing the bronchi, bronchioles, blood vessels, and the areas where gas exchange occurs. They occupy most of the ____________ cavity. There are two lungs, one on the right side and one on the left, separated from each other by the __________ (Figure 10.7). The shape of the lungs follows the contours of the rib cage and the thoracic cavity. The base of each lung is broad and shaped to fit against the convex surface of the diaphragm. Each lung is enclosed in two layers of thin epithelial membranes called the ___________ ______________. One of these layers represents the outer lung surface and the other lines the thoracic cavity. The pleural membranes are separated by a small space, called the _______ cavity, that contains a very small amount of watery fluid. The fluid reduces friction between the pleural membranes as the lungs and chest wall move during breathing. Inflammation of the pleural membranes, a condition called pleurisy, can reduce the secretion of pleural fluid, increase friction, and cause pain during breathing. Pleurisy can be a symptom of pneumonia. (See section 10.6.) Lungs consist of several lobes, three in the right lung and two in the left. Each lobe contains a branching tree of bronchioles and blood vessels. The lobes can function fairly independently of each other, so it is possible to surgically remove a lobe or two without totally eliminating lung function.

thoracic, heart, pleural membranes, pleural

Each semilunar valve consists of how many flaps?

three pocketlike flaps

The thymus gland secretes two hormones that cause certain lymphocytes called T lymphocytes (T cells) to mature and takes an active role in specific immune defenses:

thymosin and thymopoietin

Where do T cells mature? thymus gland bone marrow spleen blood stream lymph nodes I DON'T KNOW YET

thymus gland T cells mature in the thymus. The easiest way to remember this is that T cells got their name since they mature in the thymus. T cells are a type of lymphocyte involved in adaptive immunity. Immature T cells from the bone marrow migrate to the thymus and mature. One critical role that occurs in the thymus is the elimination of any T cells that have the potential to attack "self." In other words, the thymus helps to minimize the potential for autoimmune disorders. Red bone marrow is the location of stem cells that give rise to all the formed elements of blood. Immature T cells are located in the bone marrow but then migrate to the thymus to become functional cells. The spleen stores mature T cells in the white pulp. Lymph nodes contain mature T cells. Lymph flowing through the lymph nodes can deliver antigens to the T cells and start an immune response. T cells mature in the thymus and then eventually end up in the blood, spleen, or lymph nodes where they remain inactive until they encounter an appropriate antigen.

The pericardium protects the heart and anchors it to surrounding structures. The pericardium also prevents the heart from overfilling with blood because although the heart is flexible, it is not very stretchable. Between the pericardium and the heart is a space called the

pericardial cavity

In its natural position within the chest cavity, the heart is closely surrounded by a tough fibrous sac called the

pericardium

The auditory tube connects the ____________ with the ____________. sinuses; middle ear nasal cavity; sinuses pharynx; inner ear pharynx; middle ear sinuses; inner ear I DON'T KNOW YET

pharynx; middle ear The auditory tube connects the middle ear with the pharynx. The auditorytube, which is also known as the auditory tube, functions to equalize pressure on each side of the eardrum. Sore throats can lead to otitis media, which is a middle ear infection, because bacteria can travel from the pharynx to the middle ear using the auditory tube. The pharynx and inner ear are not connected. The purpose of the auditory tube is to equalize pressure on either side of the eardrum. The inner ear does not make contact with the eardrum; hence the auditory tube wouldn't help to equalize pressure if it connected to the inner ear. The sinuses are hollow cavities found in certain bones of the skull. They do not connect to the eardrum; hence the auditory tube wouldn't serve a purpose connected in the sinuses.

The lymphatic system is somewhat similar to (and nearly parallel to) the venous system of blood vessels, except that the fluid of the lymphatic system (called lymph) does not contain

plasma proteins or RBCs

Some of the human microbiota are beneficial, while others can cause disease under certain circumstances. Beneficial bacteria help control

population levels of more harmful organisms by competing successfully against them for food, a process known as competitive exclusion. Beneficial bacteria may also make the body less vulnerable to pathogens. For example, Lactobacillus bacteria in the vagina metabolize the glycogen in vaginal secretions and lower vaginal pH to levels that many fungi and bacteria cannot tolerate.

➋ Repolarization:

potassium moves out of the axon After a short delay, the Na channels close automatically. But the reversal of the membrane polarity triggers the opening of K+ channels. This allows more K+ than usual to diffuse rapidly out of the cytoplasm of the axon into surrounding interstitial fluid. The loss of positive ions from the cell leads to repolarization, meaning that the interior of the axon becomes negative again.

Right where an arteriole joins a capillary is a band of smooth muscle called the

precapillary sphincter.

Notice that the main distinction between the spleen and lymph nodes is

which fluid they cleanse

Natural killer cells target

tumors and virus-infected cells

The process of activating the body's immune system in advance is called active immunization. This involves administering an antigen-containing preparation called a

vaccine

Which is not associated with the body trying to lower blood pressure (BP)? vasoconstrict arteries decreased cardiac output lower heart rate cardiovascular center of the brain is activated baroreceptors are activated I DON'T KNOW YET

vasoconstrict arteries Vasoconstriction is not used to lower blood pressure. Blood pressure is tightly regulated since high blood pressure can result in damage to organs, and low blood pressure can result in inadequate blood flow to tissues. Use the "finger" method to determine whether the arteries will vasoconstrict or dilate to lower blood pressure. Simply squeeze your fingers. Did the pressure go up or down? Obviously, it went up. If the pressure is too high, do we want it to go higher? No, hence, the body will not vasoconstrict to lower blood pressure. Make sure to remember that constriction means to tighten, just like the way some snakes constrict their prey. High blood pressure causes the blood vessels to stretch, which activates baroreceptors in the aorta and carotid arteries. The activated baroreceptors send signals to the medulla, which contains the cardiovascular center along with the vasomotor center that controls blood vessel diameter. The inhibitory portion of the cardiovascular center is activated, thereby lowering the heat rate. Less blood is sent to the body in a given period of time, thereby lowering blood pressure. The amount of blood sent out to the body in one minute is called cardiac output, and this is lowered when the heart rate is lowered.

Contraction of vascular smooth muscle is called

vasoconstriction

Relaxation of vascular smooth muscle is called

vasodilation

From the capillaries, blood flows back to the heart through venules (small veins) and

veins

As the fluid flows through a node, the macrophages destroy foreign cells in the process phagocytosis, and the lymphocytes activate other defense mechanisms. The cleansed lymph fluid flows out of the node and continues on its path to the

veins.

What are the two more muscular bottom chambers of the heart?

ventricles

The lowest pressure, diastolic pressure, occurs during

ventricular diastole when the ventricles relax.

The highest pressure of the cycle, systolic pressure, is the pressure reached during

ventricular systole when the ventricles contract to eject blood from the heart.

Which blood vessel(s) contains valves? arterioles and venules capillaries, venules, and arterioles venules and veins arterioles and arteries capillaries I DON'T KNOW YET

venules and veins Only venules and veins have valves. The reason for this anatomical distinction is that blood pressure is very low in these blood vessels. Venules and veins are at the end of the systemic circuit, and resistance has used up much of the energy that was used to keep the blood flowing. By the time blood is in venules or veins of the legs, gravity can overcome the flow and cause the blood to pool. To minimize this, valves are present to ensure one-way flow of blood. Faulty valves can cause blood to pool, and problems with spider veins and varicose veins can occur. Arteries and arterioles lack valves since blood pressure is high in these vessels so that there is no chance of backflow. Blood pressure is still high since these vessels come right after the heart and because resistance has not used up much energy. While capillary pressure is lower than arteries and arterioles, the pressure is still sufficient to ensure one-way flow of blood.

Interferons interfere with

viral reproduction

Antibody-mediated immunity works best against

viruses, bacteria, and foreign molecules that are suspended in blood and lymph.

crucial to an effective immune response—without them the immune response would be severely impaired or nonexistent. Helper T cells can be considered the "generals" that, when activated, hand out the "orders" (cytokines) to all of the other immune system cells, the "troops." The helper T cells coordinate and orchestrate the entire cell-mediated immune response and assist with the antibody-mediated response. The reason AIDS is so devastating is that HIV destroys helper T cells, and thus

weakens the body's ability to mount a cell-mediated immune response to a wide variety of other pathogens. When the "generals" are taken out, the "troops" fall into disarray, and chaos ensues. (See section 9.10, Immune Deficiency: The Special Case of AIDS.)

T cells develop from stem cells in bone marrow. They migrate to the thymus gland, where they become mature but remain inactive. During maturation, they also develop one of two sets of surface proteins, CD4 or CD8. These proteins determine

what type of T cell they will become.

Lymph is a milky body fluid. What does it contain?

white blood cells, proteins, fats, and the occasional bacterium and virus.

The third mechanism that assists blood flow involves pressure changes in the thoracic (chest) and abdominal cavities during breathing. When we inhale, abdominal pressure increases and squeezes abdominal veins. At the same time, pressure within the thoracic cavity decreases, dilating thoracic veins. The result is a push of blood from the abdomen into the chest and toward the heart. This effect is sometimes called the

"respiratory pump."

They open passively to permit blood to move toward the heart and then close whenever blood begins to flow backward. Together, skeletal muscles and valves form what is called the

"skeletal muscle pump" (refer to Figure 8.5).

There are hundreds of antibiotics in use today, and they work in several ways. In general, they take advantage of the following differences between bacteria and human cells:

(1) Bacteria have a cell wall; human cells do not. (2) Bacterial DNA is not safely enclosed in a nucleus; human DNA is. (3) Bacterial ribosomes are smaller than human ribosomes. (4) Bacterial rate of protein synthesis is very rapid as a bacterium grows and divides. Consider two examples of how antibiotics work: Penicillin blocks the synthesis of bacterial cell walls, a structure that is not a feature of our cells, and streptomycin inhibits bacterial protein synthesis by altering the shape of the bacterial ribosomes.

Fortunately, three mechanisms assist the veins in returning blood to the heart:

(1) contractions of skeletal muscles, (2) one-way valves inside the veins, and (3) movements associated with breathing.

Skin has four key attributes that make it such an effective barrier:

(1) its structure (2) the fact that it is constantly being replaced (3) its acidic pH (4) the production of an antibiotic by sweat glands.

Once air enters the ___________ , gas exchange and transport occur

alveoli

Some forms of immunotherapy make use of monoclonal antibodies as drugs to treat various diseases including cancer and rheumatoid arthritis. The names of pharmaceuticals that contain monoclonal antibodies end in

-mab.

Saliva functions

-moistening, lubricating -mechanical digestion -chemical digestion -dissolve food molecules -rinses microorganisms safely from the mouth into the stomach, where most of them are killed by stomach acid

How many chambers and valves does the heart have?

4 chambers and 4 valves

artery

A blood vessel that conducts blood away from the heart and toward the capillaries.

aneurysm

A ballooning or bulging of the wall of an artery caused by dilation or weakening of the wall.

Antigen

A substance or part of a substance (living or nonliving) that the immune system recognizes as foreign. It activates the immune system and reactions with immune cells or their products, such as antibodies.

Antibiotics

A substance that interferes with bacterial metabolism. Administered to cure bacterial diseases. (This is basically a chemotherapeutic agent that inhibits or kills bacteria)

Vein

A thin walled blood vessel that returns blood toward the heart from the venules.

Natural killer (NK) cells

A type of lymphocyte that can lyse and kill cancer cells and virus-infected body cells before the immune system is activated.

B cell (B lymphocyte)

A white blood cell that matures in bone marrow and gives rise to antibody-producing plasma cells.

summation

Accumulation of effects, especially those of muscular or neural activity.

Why does excess production of tears, perhaps due to strong emotions or irritating particles in your eyes, make your nose "runny."?

Air spaces called sinuses inside the skull are also lined with tissue that secretes mucus and helps trap foreign particles. The sinuses drain into the nasal cavity via small passageways. Two tear ducts, carrying fluid away from the eyes, drain into the nasal cavity as well.

Pandemic

An epidemic (outbreak of infectious disease) that has spread to multiple countries or continents, or even worldwide.

Axon

An extension of a neuron that carries nerve impulses away from the nerve cell body. The conducting portion of a nerve cell.

Immunosuppressive therapy can dramatically prolong the lives of transplant patients, but it brings risks. What are the risks? What's the key to a successful transplant?

An impaired immune system cannot protect the body as effectively against pathogens and abnormal cells, so patients who are taking immunosuppressive drugs are more vulnerable to infections and certain cancers. The key to a successful transplant is to suppress the immune system enough to prevent rejection while preserving as much immune function as possible. Antibiotics can help control infections as they arise.

Prion

An infectious misfolded protein that replicates by causing a normal protein in infected animal to misfold, producing another prion. Prions technically are not alive since they cannot reproduce on their own.

The CDC currently recommends that everyone between 13 and 64 be tested for HIV at least once as part of their routine health checkup. For those in a higher risk group (men having sex with men, sex workers, individuals who inject drugs), annual testing at a minimum and testing every 3-6 months is suggested. The most reliable tests require a blood sample, but there are some tests that can use an oral fluid or urine sample. There are three types of HIV testing available, and these vary in how quickly they can detect HIV infection after exposure:

Antibody tests detect the presence of antibodies against HIV. It may take 23 to 90 days for an antibody test to become positive. Antigen/antibody tests detect a protein antigen that is part of HIV (called p24) as well as antibodies produced against HIV. Generally, the antigen test will become positive even before the antibody tests, possibly as soon as 18 days after exposure. Nucleic acid tests (NATs) detect HIV RNA in the blood, but because of their expense, NATs are not generally used for routine screening. These are the most sensitive tests available and may become positive as soon as 10 days after exposure.

vaccine

Antigens prepared in such a way that when injected or taken orally they induce active immunity without causing disease.

Who's responsible for anti-mediated immunity? T cells or B cells?

B cells.

Which type of cell is responsible for producing and releasing antibodies? macrophages B lymphocytes natural killer cells' mast cells T lymphocytes

B lymphocytes

Antibiotics can target bacteria for destruction while leaving human cells unaffected. All of the following are differences between human and bacterial cells that can account for this target specificity EXCEPT which one? Bacterial ribosomes are smaller than human ribosomes. Bacterial cells have weaker cell membranes than human cells. Bacteria have a much higher rate of cell division and protein synthesis than most human cells. Human DNA is in a nucleus; bacterial DNA is not. Bacterial cells have cell walls; human cells do not.

Bacterial cells have weaker cell membranes than human cells.

precapillary sphincter

Band of smooth muscle that controls blood flow into individual capillaries.

➌ Reestablishment of the resting potential

Because the K+ channels are slow to close, there is a brief overshoot of membrane voltage during which the interior of the axon is slightly hyperpolarized. Shortly after the K+ channels close, the resting potential is reestablished. At this point, the axon is prepared to receive another action potential. The entire sequence of three steps takes about three milliseconds. While an action potential is under way, an axon can't generate another action potential. This is because Na+ channels only remain open for a short period of time, and once they close, they cannot be opened again until the membrane potential returns to its resting potential. The period when another action potential cannot be generated is called the absolute refractory period. The presence of an absolute refractory period ensures that action potentials always travel in one direction only because an area of the axon that has just experienced an action potential cannot produce another one right away. The absolute refractory period is followed by a brief relative refractory period. During the relative refractory period, most of the K+ channels are still open and the membrane is slightly hyperpolarized, making it harder than usual to generate the next action potential. In practical terms, this means that by encroaching into the relative refractory period, very strong stimuli can generate more frequent action potentials than relatively weak stimuli can. The absolute and relative refractory periods are shown in Figure 11.6.

Surgical techniques for performing many organ transplants are really not that difficult. Historically, the major stumbling block to widespread transplantation of most organs has been the effectiveness of the immune system in rejecting foreign tissue. In the normal immune response, cytotoxic T cells swiftly attack and destroy any foreign cells. Before a transplant is even attempted, what must first be determined?

Before a transplant is even attempted, then, the donor's and recipient's ABO and other blood group antigens must first be determined. Next, donor and recipient tissues are tested to compare MHC antigens because cytotoxic T cells target foreign MHC proteins. The closer the relationship between donor and recipient, the better because their MHC antigens are likely to be similar. Although successful transplants can be done between unrelated people, at least a 75% match between MHC tissue types is essential. After surgery, the patient must take either immunosuppressive drugs such as corticosteroids that block the immune response to suppress inflammation or cytotoxic medications that kill rapidly dividing cells to block activated lymphocytes.

One-Way Valves Permit Only One-Way __________ _________

Blood flow

Immunoglobulin (Ig)

Blood plasma proteins (gamma globulins) that play a crucial role in immunity; there are 5 classes.

Read this

Blood pressure is recorded as mm Hg (millimeters of mercury, because early equipment used a glass column filled with mercury to measure the pressure). In young, healthy individuals, systolic pressures of less than 120 mm Hg and diastolic pressures of less than 80 mm Hg are considered desirable. With advancing age, there is a slight tendency for systolic blood pressure in particular to increase slightly, as a consequence of age-related stiffening of the arteries. Blood pressure is measured with a sphygmomanometer (sphygmo comes from the Greek word for "pulse"; a manometer is a device for measuring fluid pressures). An inflatable cuff is placed over the brachial artery in your upper arm and connected to the manometer, which is a gauge or digital screen that reports the pressure (Figure 8.16a). When the cuff is inflated to a pressure above systolic pressure, blood flow through the brachial artery stops because the high cuff pressure collapses the artery. The cuff is then deflated slowly while a health professional listens with a stethoscope for the sounds of blood flowing in your artery. As soon as pressure in the cuff falls below the peak of systolic pressure, some blood spurts briefly through the artery during the high point of the pressure pulse, making a characteristic light tapping sound that is audible through the stethoscope. The cuff pressure at which this happens is recorded as systolic pressure (Figure 8.16b). As the cuff continues to deflate, eventually blood flow through the artery becomes continuous and the tapping sound ceases. The point where the sound disappears is your diastolic pressure. This procedure yields two numbers, corresponding to your systolic and diastolic pressures. These represent the high and low points of blood pressure during the cardiac cycle.

How is HIV transmitted?

Bodily fluids -Blood -Semen -Vaginal fluid/secretions -Breast milk Most commonly, HIV is transmitted by sexual contact or contaminated hypodermic needles. In addition, infected mothers can pass it to their children during pregnancy, during labor and delivery, or when breast-feeding. A significant number of HIV infections resulted from blood transfusions until the mid-1980s, when it became routine to test blood for evidence of HIV infection. Because transmission of HIV generally requires direct contact with body fluids, HIV is considered relatively hard to transmit from person to person (at least when compared to such common diseases as the flu). However, unlike the flu, HIV is extremely virulent unless it is aggressively treated with an expensive regimen of drugs. In the absence of specific anti-HIV medications, an individual with HIV will survive about 10 years before succumbing to an AIDS-related illness.

Fever

Body temperature that has risen above the normal set point (in humans, approximately 37 C, 98.6 F) A fever often indicates illness.

What do B and T cells have in common?

Both B cells and T cells are activated by specific antigens, and both cell populations store information about their first exposure to a specific antigen in the form of memory cells. The presence of memory cells enables B cells and T cells to undergo clonal expansion (replication) more quickly the second and subsequent times they are exposed to the same antigen.

Dendrites

Branching neuron extension that serves as a receptive or input region. Dendrites conduct graded potentials toward the cell body.

The term respiration encompasses four processes:

Breathing (also called ventilation). The movement of air into and out of the lungs. External respiration. The exchange of gases between inhaled air and blood. Internal respiration. The exchange of gases between the blood and tissue fluids. Cellular respiration. The process of using oxygen to produce ATP within cells.

atrioventricular (AV) bundle

Bundle of specialized fibers that conduct impulses from the AV node to the right and left ventricles.

Larynx

Cartilaginous organ containing the vocal cords, located between the trachea and pharynx. The larynx is also called the voice box.

Neurons

Cell of the nervous system specialized to generate and transmit nerve impulses.

Neuroglial Cells

Cells that provide physical support and protection to neurons and help maintain healthy concentrations of important chemicals in the fluid surrounding them.

interferon

Chemical that is able to provide some protection against virus invasion of the body, Interferon inhibits viral reproduction.

When you inhale, air enters through your nose or your mouth (Figure 10.2). Your nose is to be appreciated, as it does more than serve as a passageway for respiration. The nose also

Contains receptors for the sense of smell Filters inhaled air and screens out some foreign particles Moistens and warms incoming air Provides a resonating chamber that helps give your voice its characteristic tone

There are many types of microbes that cause disease. Please look at the choices and pick the one that does not belong. Creutzfeldt-Jakob disease Warts Rabies Hepatitis Chicken pox I DON'T KNOW YET

Creutzfeldt-Jakob disease Creutzfeldt-Jakob disease (CJD) does not belong with the other choices. CJD is a very unique disease since it is caused by prions. Prions are non-living infectious agents that are made of protein. All other infectious agents contain some type of nucleic acid. CDJ is a misfolded protein that can cause normally folded proteins to misfold. These proteins are associated with neurons, and accumulation of these prions results in neurotoxicity and eventual death. The rest of the choices are caused by viruses. Viruses are much smaller than bacteria and don't have a cellular structure. They lack cytoplasm and a cell membrane. However, all viruses contain protein and nucleic acids. Hepatitis is caused by different viruses that infect the liver. A common symptom of hepatitis is jaundice, which is a yellowing of the skin and sclera of the eyes. Rabies is a rare disease for humans to contract. Luckily, there are vaccines for rabies and even passive immunity to treat someone who has been bitten by a rabid animal. Rabies attacks the CNS and causes a fatal encephalitis if left untreated. Warts are caused by a virus that causes a benign overgrowth of cells on the skin. Some warts can be associated with the genital region and can cause cervical cancer. Chicken pox is caused by a virus in the herpes family of viruses. There is no cure for this infection, and the body is not able to rid itself of the virus. The virus stays dormant in the dorsal root ganglion and can become active later in life. Reactivation leads to the condition known as shingles.

Which one of the following is correct regarding the structure of an antibody? Only the light chains of an antibody contain antigen-binding sites. Each chain of an antibody has both a constant region and a variable region. The constant regions of the antibody are the antigen-binding sites. Only the heavy chains of an antibody have both a constant region and a variable region. An antibody is made up of two polypeptide chains linked together.

Each chain of an antibody has both a constant region and a variable region.

Earwax functions

Earwax traps small particles and microorganisms.

Thymus gland

Endocrine gland that contributes to immune responsiveness. T cells mature in the thymus.

lysozyme

Enzyme in saliva and tears that kills certain kinds of bacteria.

Aneurysms develop quickly (True or false)

False. Aneurysms often take years to develop. During this time, many can be detected and repaired surgically. Some physicians recommend that anyone with a family history of aneurysm should be examined, even if there are no symptoms. Doctors can sometimes detect inward-bulging aneurysms with a stethoscope (an instrument for listening to sounds inside the body) because flowing blood produces characteristic sounds as it passes through a narrowed arterial lumen. A computerized tomography (CT) scan may also locate aneurysms before they rupture.

All immune deficiency diseases are inherited. (True or false)

False. Some immune deficiency diseases are inherited and others are acquired during one's lifetime.

myelin sheath

Fatty insulating sheath that surrounds the neuron axons of some types of neurons.

Of course, vaccines created from dead or weakened pathogens have their limitations. What are these limitations?

First, there are issues of safety, time, and expense. Living but weakened pathogens generally make better vaccines because they elicit a greater immune response. However, a vaccine that contains weakened pathogens has a slight potential to cause disease itself. This has happened, although rarely, with the oral polio vaccine (a live, weakened virus vaccine). Because of this risk, the oral polio vaccine (OPV) is no longer used in the United States and has been replaced with the inactivated polio vaccine. It takes a great deal of time, money, and research to verify the safety and effectiveness of a vaccine. Second, a vaccine confers immunity against only one pathogen, so a different vaccine is needed for every virus. This is why doctors may recommend getting a flu vaccine each time a new flu strain appears (nearly every year). Third, vaccines are not particularly effective after a pathogen has struck; that is, they do not cure an already existing disease.

epiglottis

Flaplike structure of elastic cartilage at the back of the throat that covers the opening of the larynx during swallowing.

Probiotics

Food or supplements that contain living microorganisms that are intentionally introduced into the body the restore the normal human microbiota or prevent growth of pathogens.

Prebiotics

Foods or nutrients that promote the growth and balance of beneficial bacteria in the body.

saltatory conduction

Form of rapid transmission of a nerve impulse along a myelinated fiber, in which the nerve impulse leaps from node to node.

There is not yet a cure for AIDS, but drug development continues to improve treatment options. In general, drugs for treating HIV work by interfering with HIV replication at one of the steps in the virus's life cycle:

Fusion inhibitors. These work by blocking the ability of the virus to lock onto receptors on the cell's surface, a necessary first step to entry. Reverse transcriptase inhibitors. These prevent the virus from taking over the cell's metabolic pathways that lead to replication of viral RNA after the virus has gained entry to the cell. Integrase inhibitors. These block the viral enzyme required to insert the newly made viral DNA into the host cell's DNA. Protease inhibitors. These drugs prevent the virus from being assembled within an infected cell, even though the virus may already have forced the cell to replicate its RNA and proteins. Obviously extra info: Because each class of drugs works by an entirely different mechanism, more effective treatment, referred to as antiretroviral therapy (ART), is achieved by taking several different drugs in combination. The earlier HIV infection is detected and ART is started, the better the outcome. Early treatment of HIV infection prevents the widespread destruction of the immune system that precedes the onset of AIDS symptoms. ART lowers the viral load (number of viruses in the blood) to nearly undetectable levels, reduces the incidence of HIV-related illnesses, and greatly lowers the risk of transmission. No combination of drugs has yet been found that completely cures an HIV infection. People who are HIV-positive must be prepared to take antiretroviral drugs throughout their lives. HIV infection no longer is viewed as a death sentence but instead can be viewed as a chronic disease that can be managed with antiretroviral medications that are taken consistently. With an ever-expanding arsenal of antiretroviral drugs at their disposal, doctors can now offer pre-exposure prophylaxis (PrEP) and post-exposure prophylaxis (PEP) to people at high risk for exposure or to individuals with a known exposure. PrEP is a drug combination available to individuals who are not infected with HIV but are at higher risk for infection (have a partner who is infected with HIV, have multiple partners, or who inject drugs). This drug combination (brand name Truvada) has been shown to reduce the risk of infection

pleural membranes

Membranes that line the thoracic cavity and cover the external surface of the lungs.

What is gas pressure caused by?

Gas pressure is caused by colliding molecules of gas.

To understand why air moves into and out of the lungs in a cyclic manner, we need to understand the following general principles of gas pressure and of how gases move:

Gas pressure is caused by colliding molecules of gas. When the volume of a closed space increases, the molecules of gas in that space are farther away from each other, and the pressure inside the space decreases. Conversely, when the volume in a closed space decreases, the gas pressure increases. Gases flow from areas of higher pressure to areas of lower pressure.

How does vomiting, urination and defecation keep pathogens out?

Generally speaking, the urinary system does not have a resident population of bacteria. Nevertheless, urine is usually slightly acidic, and the constant flushing action of urination tends to keep bacterial populations low. Urine pH can vary from fairly acidic to slightly basic, depending on diet. The movement of feces and the act of defecation also help remove microorganisms from the digestive tract. When we become ill, the muscles in the intestinal wall may start to contract more vigorously, and the intestine may secrete additional fluid into the feces. The result is diarrhea—increased fluidity, frequency, or volume of bowel movements. Unpleasant though diarrhea may be, mild cases serve a useful function by speeding the removal of pathogens.

The only sure way to eliminate the risk of contracting HIV/AIDS completely is to eliminate sexual contact altogether. Some people do choose abstinence for personal, practical, or professional reasons or at certain times in their lives. However, most persons do not remain abstinent throughout their lives. Given the risks of contracting HIV/AIDS, anyone who is sexually active should think seriously about how to make their sexual contacts as safe as possible. Below are several safer sex guidelines and some evidence for them. The suggestions do not guarantee complete safety, which is why they are called recommendations for "safer" rather than "safe" sex:

Get tested (and have your partner tested). There are three types of HIV diagnostic tests. (See the next section.) Your health care provider will determine which test is most appropriate for you. Avoid certain high-risk sexual practices. Any sexual behavior that increases the risk of direct blood contact, such as anal-genital sex, should be considered risky. Oral-genital sex is less risky but not risk-free. Use latex or polyurethane condoms or other barriers. Condoms are effective only if used consistently and correctly. Natural skin condoms are not as safe as latex condoms. The use of dental dams is recommended for oral-vaginal sex. Reduce the number of sexual partners. The more partners you have, the more likely you will have a partner with HIV. Fewer partners translates to lower risk. Choose a sexual partner with low-risk behavior. This is especially important. A partner who has a history of injecting drugs or a man who has sex with other men is a high-risk partner.

Electrocardiogram (ECG)

Graphic record of the electrical activity of the heart, using sensors (electrodes) attached to the skin of the chest, wrists, and ankles. The electrodes transmit the heart's electrical impulses, which are recorded as a continuous line on a screen or moving graph. (Go to figure 8.4 a)

Respiratory center

Groups of nerve cells in the medulla oblongata near the base of the brain that are responsible for the cyclic nature of respiration.

A child cannot produce enough surfactant. What is most likely going to happen? He or she is likely to develop cystic fibrosis. He or she will develop asthma later in life. He or she is likely to get the flu. Microbes will not be trapped in the nasal cavity. He or she will have infant respiratory distress syndrome. I DON'T KNOW YET

He or she will have infant respiratory distress syndrome. A child without surfactant will develop infant respiratory distress syndrome. Surfactant decreases the surface tension of water. Surface tension causes wet surfaces to cling together. Two pieces of paper won't stick together, but if they get wet, they will cling together. Surface tension is good in the pleural cavity to keep the lungs stuck to the walls and prevent them from collapsing. However, surface tension within the alveoli will cause them to collapse and prevent gas exchange. Surfactant is made by special cells associated with the alveoli. This compound decreases the surface tension and thereby prevents the alveoli from collapsing. Normally, plenty of surfactant is made. But enough may not be produced in cases of premature birth. These babies will have difficulty breathing and will suffer from a condition called infant respiratory distress syndrome. Surfactant is dripped down the lungs until the baby can produce his or her own surfactant. The flu is transmitted via respiratory aerosols or direct contact with an infected individual or by contacting virally contaminated material. Transmission of the virus to another individual typically results in infection. Presence or absence of surfactant does not influence transmission. Cystic fibrosis is due to a genetic defect that causes a thick sticky mucus to be produced. A lack of surfactant results in alveoli collapsing, not in the production of a sticky mucus. Asthma is due to histamine causing production of mucus and bronchoconstriction in the bronchioles. There appear to be various causes of asthma, including environmental and genetic factors. Mucus accounts for microbes being trapped in the nasal cavity. A lack of mucus, not surfactant, can cause microbes not to be trapped in the nasal cavity.

Pressures Associated with Breathing Push Blood Toward the

Heart

On their path back to the heart, veins pass between many skeletal muscles. As we move and these muscles contract and relax, they press against veins and collapse them, pushing blood toward the

Heart (Figure 8.5)

Semilunar valves

Heart valves located between the ventricles and the two major arteries of the body (pulmonary and aortic) that prevents blood from returning to the ventricles after contraction.

oxyhemoglobin

Hemoglobin combined with oxygen

What's the risk factors for hypertension?

Heredity: Family history of hypertension raises risk. Age: Blood pressure tends to rise throughout life. Race: African Americans have twice the incidence found in European Americans and Asian Americans. Sex: Males are more likely than females to develop hypertension. Obesity: The heart must pump harder to push blood through vessels. High salt intake: In some individuals (but not others), a high salt intake raises blood pressure slightly. Smoking: Smoking raises the blood concentration of epinephrine, a hormone that stimulates the heart. Sedentary lifestyle: Not well understood. May be due to higher blood lipids or weight gain. Persistent emotional stress: Emotional stress activates portions of the nervous system that elevate pressure. Diabetes mellitus: Diabetics have a higher incidence of hypertension, for reasons not yet known. Heavy alcohol consumption: Mechanisms unknown. Oral contraceptives and certain medications: Mechanisms vary by medication.

Hypertension

High blood pressure. Clinically hypertension is defined as a systolic blood pressure of 140 mm Hg or higher or a diastolic blood pressure of 90 mm Hg or higher.

The human cardiovascular system is based on similar principles. Consider the following key points:

Homeostatic regulation of the cardiovascular system centers on maintaining a constant arterial blood pressure. A constant arterial blood pressure is achieved by regulating the cardiac output (the amount of blood the heart pumps into the aorta each minute), regulating the diameters of the arterioles (adjusting the overall resistance to flow through the blood vessels), and managing the blood volume. With arterial blood pressure held relatively constant, local blood flows are adjusted to meet local requirements.

How does hypertension affect the cardiovascular system, blood vessels, and the heart?

Hypertension is a significant risk factor for cardiovascular disease, because the greater the pressure, the greater the strain on the cardiovascular system. Blood vessels react to the pounding by becoming hardened and scarred, which makes them less able to stretch during systole. Hypertension also places a greater strain on the heart, because the work it must do is directly proportional to the arterial pressure against which it must pump.

Which of the following correctly describes the function of memory B-cells? They prevent viruses from entering the body a second time. If exposed to an antigen a second time, they quickly divide to become plasma cells. They remain in an active state, continuously producing antibodies. They produce antibodies and can become phagocytic. They prevent production of other proteins so that antibodies can be produced.

If exposed to an antigen a second time, they quickly divide to become plasma cells.

Which of the following antibodies would most likely be involved with the immune response against a microorganism entering the digestive or reproductive tract? IgA IgG IgD IgE IgM

IgA

IgA (15%):

IgA antibodies enter areas of the body covered by mucous membranes, such as the digestive, reproductive, and respiratory tracts. There they neutralize infectious pathogens. They are also present in a mother's milk and are transmitted to the infant during breast-feeding.

IgD (less than 1%):

IgD antibodies are in blood, lymph, and B cells. Their function is not clear, but they may play a role in activating B cells.

An antibody binds to mast cells. Which antibody is this? IgE IgA IgM IgG IgD I DON'T KNOW YET

IgE IgE is the antibody associated with allergic reactions. Allergens initially cause the production of plasma cells that secrete IgE, which bind to mast cells. This step is called sensitization. A second exposure to an allergen results in the allergen binding to the IgE on the mast cells, which triggers the immediate degranulation and release of large amounts of histamine into the blood steam. The histamine vasodilates blood vessels, dropping blood pressure. It increases capillary permeability resulting in edema. Histamine also bronchoconstricts the airways, making it extremely difficult to breathe. An epinephrine shot is administered, which will vasoconstrict and bronchodilate. IgA is made of two antibodies bonded at the tail. IgA is found in body secretions, such as tears and mucous membranes. It is considered the first line of adaptive defense. IgM is composed of five bonded antibodies. It is known as a pentamer since it is composed of 5 antibody subunits. IgM is the main antibody in the primary response. IgD and IgG are all single antibodies; however, they differ in their functions. IgD is the receptor found on the surface of B cells that binds to a complementary antigen. Upon binding, the B cell is activated and changes into plasma cells and memory cells. IgG is the main antibody associated with the secondary immune response.

The immune response has three important characteristics:

It can distinguish self (the body's own cells and proteins) from non-self (pathogens and foreign substances) and recognizes and targets specific pathogens or foreign substances for destruction or removal. It exhibits tremendous diversity in its ability to recognize a multitude (estimated to be in the millions) of different pathogens and foreign substances. It has a "memory," the capability to store information from past exposures to a pathogen so that it can respond more quickly to later invasions by the same pathogen

Most veins contain valves consisting of small folds of the inner layer that protrude into the The structure of these valves allows blood to flow in one direction only: toward the _______

Lumen Heart

T cells (T lymphocytes)

Lymphocytes responsible for cell-mediated immunity, which depends on the actions of several types of T cells.

What is not true about anaphylactic shock? IgE is the antibody responsible for this immune overresponse. It occurs within minutes of exposure to the allergen. It causes extreme vasoconstriction of blood vessels. It is due to the release of histamine. Mast cells and basophils are involved.

It causes extreme vasoconstriction of blood vessels. Anaphylactic shock does not cause extreme vasoconstriction. Anaphylactic shock is a life-threatening condition due to systemic histamine release. An allergen, such as the poison in a bee sting, an antibiotic, or even a peanut, can cause a massive release of histamine. Recall that histamine is an inflammatory chemical that starts inflammation. Histamine is a potent vasodilator, not constrictor. The vasodilation results in a large drop in blood pressure due to loss of peripheral resistance. Physiological shock means a large drop in blood pressure. Anaphylactic shock is a drop in blood pressure in response to an encounter with an allergen. Allergens initially cause the production of plasma cells that secrete IgE, which bind to mast cells. This step is called sensitization. A second exposure to allergen results in the allergen binding to the IgE on the mast cells, which triggers the immediate degranulation and release of large amounts of histamine into the bloodsteam. The histamine vasodilates blood vessels, dropping blood pressure. It increases capillary permeability resulting in edema. Histamine also bronchoconstricts the airways, making it extremely difficult to breathe. An epinephrine shot is administered, which will vasoconstrict and bronchodilate.

The spleen has two main functions:

It controls the quality of circulating red blood cells, and it helps fight infection.

The lymphatic system performs three important functions:

It helps maintain the volume of blood in the cardiovascular system. It transports fats and fat-soluble vitamins absorbed from the digestive system to the cardiovascular system. It defends the body against infection.

carbon monoxide (CO)

It is a colorless, odorless, highly poisonous gas produced by burning carbon-containing substances such as coal, natural gas, gasoline, wood, and oil

What is unique about the great saphenous vein? It is the shortest vein in the body. It is the only oxygenated vein in the body. It is the longest vein in the body. There aren't pairs of them; there is just a single one of them. It is the only deoxygenated vein in the body. I DON'T KNOW YET

It is the longest vein in the body. The great saphenous vein is unique since it is the longest vein in the body. While this may seem like trivia, there is great medical importance with this vein since surgeons will use it during bypass surgery. If coronary circulation is blocked, then one possible solution is to graft portions of the vein to bypass the blocked regions. Removing the vein is not detrimental since other veins can take over the job of the missing vein. The great saphenous vein is the longest, not the shortest, vein in the body. Look at a figure of blood vessels of the body and note how they run the length of the leg without branching. While the femoral vein looks long, it does branch around the knee. All veins of systemic circulation are deoxygenated. Only pulmonary veins are oxygenated since they are returning oxygenated blood to the heart from the lungs. The great saphenous veins do indeed come in pairs; there is one per leg. There are single veins in the body, with most of them associated in the abdominal cavity.

What is true about the secondary immune response? It provides immunity for a short period of time. It occurs the first time an antigen is encountered. It produces a high antibody concentration. It produces cytotoxic T cells against a variety of antigens. It produces antibodies against a variety of antigens. I DON'T KNOW YET

It produces a high antibody concentration. The secondary response produces a high concentration of antibodies. Adaptive responses differ from innate responses in that adaptive responses have memory. A more potent response occurs the second time the antigen is encountered. The first time an antigen is encountered, a primary response occurs that produces some effector cells and some memory cells. If these memory cells encounter the same antigen, then they divide to produce many more memory cells and many more effector cells. In this case, the effector cells are plasma cells, and by having many plasma cells, a very high concentration of antibodies is produced. By virtue of its name, the secondary response happens the second time an antigen is encountered. The primary response starts when an antigen is encountered for the first time by a B cell. The B cell is activated and forms memory cells and plasma cells. The secondary response starts when the memory cell encounters the same antigen and divides to produce many memory cells and plasma cells. Plasma cells are genetically capable of producing just one type of antibody. Each antibody can only bind to only one antigen, just like the way one key works on only one type of lock. Cytotoxic T cells are also produced in a similar manner as plasma cells. Each cytotoxic T cells has the capability to attack only one type of antigen because it has specific receptors that bind to a particular antigen. The secondary response can last for long periods of time since many antibodies and memory cells were produced that will produce more memory cells and plasma cells if the antigen is encountered again.

The myelin sheath around the axon serves three important functions:

It saves the neuron energy. The insulating layer of myelin prevents some of the slow inward leak of sodium and outward leak of potassium that would otherwise occur. These leaks normally have to be replaced by active transport processes requiring energy (see section 11.3). It speeds up the transmission of impulses. The myelin sheath causes action potentials to jump from node to node at a very fast rate. This "leaping" pattern of conduction along myelinated neurons is called saltatory conduction (from saltare, Latin for "dance") (Figure 11.7c). Continuously propagated action potentials in unmyelinated neurons travel at a speed of only about 5 mph (2.3 meters per second). In contrast, saltatory conduction in myelinated neurons can reach speeds of up to 250 mph (about 110 meters per second). It helps damaged or severed axons of the peripheral nervous system regenerate. If a neuron axon is severed, the portion of the axon distal to the cell body may degenerate. However, the cut end of the axon still attached to the cell body can regrow through the channel formed by the sheath, eventually reconnecting with the cell that it serves. Depending on the length of the axon, the regeneration process can take anywhere from a few weeks to more than a year.

In addition to these major risks, at least three other factors are associated with cardiovascular disease, although the precise link has not yet been determined. This is why doctors recommend the following:

Maintain a healthy weight. It's not clear how obesity contributes to cardiovascular problems, but overweight people have a higher rate of heart disease and stroke even if they do not have other risk factors. One hypothesis is that increased weight strains the heart. Increased weight also has adverse effects on other risk factors such as blood cholesterol and hypertension. Keep diabetes under control. Diabetes mellitus is a disorder of blood sugar levels. Untreated diabetes damages blood vessels, but effective treatments reduce cardiovascular damage significantly. (Diabetes will be described in more detail when we discuss the endocrine system.) Avoid chronic stress. Again, the mechanism is unclear, but there is an association between a person's perceived stress and behavior patterns and the development of cardiovascular disease. Stress may also affect other risk factors, for example, how much a smoker smokes or whether a person starts smoking.

The larynx serves to

Maintain an open airway. Route food and air into the appropriate channels. Assist in the production of sound.

What is the purpose of the major histocompatibility complex (MHC)? It slows down viral infections. It is a set of proteins that promotes phagocytosis and inflammation. It is released by bacteria and results in a fever. It causes the formation of holes in pathogens. It tags cells in order for the immune system to recognize them as "self." I DON'T KNOW YET

It tags cells in order for the immune system to recognize them as "self." MHC are proteins that body cells contain to enable the immune system to recognize them as "self." MHC is another key mechanism that prevents the immune system from attacking "self." MHC binds small portions of proteins from the cell and presents them to T cells. The T cells will recognize the cells as "self" and not attack them. However, if a bacteria invaded the host cell, then bacterial proteins will be associated with the MHC and the T cell will not recognize the bacterial proteins. Lack of recognition will cause the T cell to attack and kill the cell with the bacterial infection. Complement is a set of proteins that functions to promote phagocytosis and inflammation. Bacteria release pyrogens that result in a fever. Complement and perforin from natural killer cells form holes in pathogens. Interferon slows down viral infections by causing uninfected cells to become resistant to future viral invasion. Note that complement, pyrogens, and perforin are all a part of innate or nonspecific defense, while MHC directly interacts with T cells; thus it is a part of controlling specific or adaptive defense.

Spleen

Largest lymphoid organ. The spleen removes old and damaged red blood cells and helps fight infections.

What do veins and lymphatic vessels have in common?

Like veins, lymphatic vessels have walls consisting of three thin layers, and they contain one-way valves to prevent backflow of lymph. Also, like veins, flow in lymphatic vessels is aided by skeletal muscle contractions and pressure changes in the chest during respiration.

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Look at the overall process and you can see how together these control mechanisms deliver blood efficiently to all tissues. First, a negative feedback control loop works to maintain a relatively constant arterial blood pressure. Second, with pressure held constant, cells and tissues can get exactly the amount of blood they need by adjusting the vascular resistance of the small vessels supplying them. Some tissues and organs need a more consistent blood supply than others. This is taken into account by our control systems. Consider what would happen if you lost a substantial volume of blood due to injury, producing a precipitous fall in blood pressure. The negative feedback control of arterial blood pressure would stimulate your heart and constrict your arterioles, reducing flow to most organs in an effort to raise blood pressure. However, organs whose survival depends critically on a constant blood supply (your brain and heart, for example) can override the generalized vasoconstriction with their local control mechanisms. Blood vessels in organs whose metabolic activities are not required for their immediate survival (such as your kidneys and digestive tract) just remain vasoconstricted for a while. In effect, the limited available blood supply is shunted to essential organs. You may wonder why, if these homeostatic controls are working properly, people ever develop hypertension. Every time blood pressure went up a little, wouldn't feedback mechanisms bring it back to normal?

Diastolic pressure

Lowest point of arterial blood pressure during a cardiac cycle. Diastolic pressure is the second of two numbers recorded by the health care provider, the first being systolic pressure.

Tears functions

Lubricate & prevent drying, Flush debris, Contain Lysozome & Antibodies to prevent infection, Provide nutrients & O2 to cornea

Mucus is a thick, gel-like material secreted by cells at various surfaces of the body, including the lining of the digestive tract and the branching airways of the respiratory system. What's it's function?

Microorganisms get stuck in the mucus and cannot gain access to the cells beneath. In addition, the cells of the airways have tiny hairlike projections called cilia that beat constantly in a wavelike motion to sweep mucus upward into the throat. There we get rid of the mucus by coughing or swallowing it. Sometimes, we remove mucus and microorganisms by sneezing, which is also one of the primary ways we pass microorganisms to other people.

Myocardium

Middle and largest layer of the heart wall, composed of cardiac muscle

Purkinje fibers

Modified cardiac muscle fibers that are part of the electrical conduction system of the heart. smaller fibers that carry the impulse to all cells in the myocardium of the ventricles.

Viruses have several ways of gaining entry into living cells. What are they?

Most viruses that infect human cells are taken into the cell cytoplasm by endocytosis. Once inside the cell, the capsids are dismantled and the viral genetic material is released for incorporation into the cell's genetic material. Other viruses merge their envelope with the cell membrane of the host cell and release their capsid and its genetic contents into the cell's cytoplasm.

Tobacco smoke contains chemicals and particles that irritate the respiratory tract. What happens to mucus production and cilia?

Mucus production increases in response, but the smoke impairs the activity of the cilia (Figure 10.6). Continued smoking destroys the cilia, allowing mucus and debris from the smoke to accumulate in the airway. "Smoker's cough" refers to the violent coughing necessary to dislodge the mucus from the airway. Mucus pooling leads to frequent infections because pathogens and irritants remain in the respiratory tract. It also increases the risk of bronchitis, emphysema, and lung cancer. (See section 10.6, Disorders of the Respiratory System.)

Is the inside of a neuron positively or negatively charged compared to the outside?

Negatively

myelinated neurons

Neurons in which the axon is wrapped in a myelin sheath.

What is the purpose of antibody-mediated immune responses? Destroy cancer cells. Destroy cells associated with transplants Neutralize bacterial toxins. Destroy cells infected with viruses. Destroy cells infected with viruses, cancer cells, and cells associated with transplants. I DON'T KNOW YET

Neutralize bacterial toxins. One of the functions of antibodies is to neutralize bacterial toxins. Antibodies bind to things that are relatively "tiny." They bind to red blood cells, viruses that are outside of their host cells, bacteria, and proteins. Some bacterial toxins can be proteins, and antibodies can "neutralize" the toxins. A toxin harms a host cell only if the toxin makes contact with the host cell. Antibodies can cover the toxin and prevent it from physically making contact with the host cell, thereby rendering the toxin harmless or neutralized. Cytotoxic T cells will release perforin and kill the cancer cell, the foreign organ cell, and the cell with viruses within them. Antibodies do not kill. They merely tag and promote phagocytosis, activation of complement, precipitate the antigens, or neutralize the antigens. But cancer cells and virally infected cells are too big to engulf. Hence, the solution is to kill them by putting holes in their cell membranes.

Phagocytes

Neutrophils and macrophages engulf and digest foreign cells; eosinophils bombard large parasites with digestive enzymes and phagocytize foreign proteins.

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Neutrophils are the body's "first responders," the first white blood cells that arrive to fight an infection. They engulf, digest, and destroy (phagocytize) bacteria and some fungi in the blood and tissue fluids. Other white blood cells, known as monocytes, leave the vascular system, enter the tissue fluids, and develop into macrophages that can phagocytize large numbers of foreign invaders. Technically, macrophages are not white blood cells because when they develop from monocytes they are no longer in the blood. Macrophages serve a cleanup function by scavenging old blood cells, dead tissue fragments, and cellular debris, and they release chemicals that stimulate the production of white blood cells. When invaders are too big to be engulfed and digested by phagocytosis, other white blood cells called eosinophils take action. Although they are capable of phagocytosis, the primary action of eosinophils is to attack pathogens such as fungi, protozoa, and parasitic worms that are too large to be phagocytized. Eosinophils cluster around large parasites such as flukes and pinworms and bombard them with digestive enzymes.

Is blood stored in the white pulp?

No blood is stored in the white pulp.

Do antibiotics work on viral infections?

No. Several antiviral drugs have been developed that either prevent certain viruses from entering living cells or stop an infected host cell from producing more viruses. However, to date, there has been more success preventing viral infections with vaccines (see section 9.7) than there has been in developing antiviral medications.

Do lungs have skeletal muscle tissue?

No. The lungs expand passively because the surrounding bones and muscles expand the size of the chest cavity.

List, in order, all of the anatomical structures that a molecule of oxygen passes through as it moves from the nose to a pulmonary capillary. Where does diffusional gas exchange occur?

Nose, nasal cavity, pharynx, glottis, larynx, trachea, bronchus, bronchiole, alveolus, and finally across the layers of cells that compose the alveolus and the capillary. Diffusional gas exchange occurs only across the cell layers of the alveolus and capillary.

alveoli

One of the microscopic air sacs of the lungs.

Bacteria

One of the three domains of life. Bacteria are prokaryotic (single-celled organisms that do not have a nucleus or membrane-bound organelles) microorganisms responsible for many human diseases.

Coronary artery

One of the two arteries of the heart leading to capillaries that supply blood to cardiac muscle. The coronary arteries branch from the aorta just above the aortic semilunar valve and encircle the heart's surface. (The word coronary comes from the Latin corona, meaning, "encircling like a crown.") From the surface, they send branches inward to supply the myocardium. Cardiac veins collect the blood from the capillaries in the heart muscle and channel it back to the right atrium.

Atria

One of the two chambers of the heart that receive blood from veins and deliver it to the ventricles.

Memory cells are long-lived, and many retain their ability to generate a secondary immune response over a lifetime. The secondary immune response is often so effective that you don't even realize you've been exposed to the pathogen a second time. At worst, you may experience only a fleeting sensation of feeling unwell. Some memory cells, such as the ones for the bacterial toxin that causes tetanus, need to be reactivated (exposed to the antigen again to undergo clonal expansion) every 10 years or so. Given this immunity, though, why is it possible to get a cold or the flu over and over, sometimes several times a year?

One reason is that there are more than 100 different viruses that can cause colds. Even if your latest respiratory ailment feels like the previous one, it may actually be due to an entirely different pathogen. Furthermore, the viruses that cause flu evolve so rapidly that they are essentially different each year. Their antigens change enough that each one requires a different antibody, and each exposure triggers a primary response. Rapid evolution is their survival mechanism. Our survival mechanism is a healthy immune system.

glottis

Opening between the vocal cords in the larynx.

Respiratory system

Organ system responsible for gas exchange.

Allergy

Overzealous immune response to an otherwise harmless substance.

A healthy heart produces a characteristic pattern of voltage changes. A typical ECG tracks these changes as a series of three formations:

P wave, QRS complex, and T wave (Figure 8.14b).

Monoclonal antibodies

Pure preparations of identical antibodies produced in the laboratory by a colony of genetically identical cells.

Advantages and disadvantages of passive immunization

Passive immunization has the advantage of being somewhat effective against an existing infection. It can be administered to prevent illness in someone who has been unexpectedly exposed to a pathogen, and it confers immediate, though short-term, immunity. Protection is not as long lasting as active immunization following vaccine administration because the administered antibodies disappear from the circulation quickly. Passive immunization also can't confer long-term immunity against a second exposure because the person's own B cells aren't activated, so memory cells for the pathogen do not develop.

Diastole

Period of the cardiac cycle when a heart chamber is relaxed.

Systole

Period when either the ventricles or the atria of the heart are contracting.

Peripheral Nervous System (PNS)

Portion of the nervous system that lies outside the brain and spinal cord.

A child receives the MMR vaccine. What is not true about the vaccination? Plasma cells will be formed. Vaccines produce a long-term immunity. A series of booster shots is likely required. Memory cells will be formed. Pre-made antibodies were injected. I DON'T KNOW YET

Pre-made antibodies were injected. Pre-made antibodies are not injected during a vaccination. Vaccinations contain antigens that stimulate the primary response and promote the formation of antibodies. The antibodies produced will circulate in the bloodstream and will be available to neutralize any viruses that enter the bloodstream. Vaccinations are typically given in a series of shots over time. The first shot stimulates the primary response. The other shots, which are called booster shots, stimulate the formation of long-lasting secondary response. The antigens in the vaccine bind to B cells causing them to divide and produce plasma cells and memory cells. The plasma cells will secrete antibodies. The memory cells last for a long time, which accounts for long-term immunity. Upon exposure to the same antigen found in the vaccine, the memory cells will divide to produce many more memory cells and plasma cells that will secrete lots of antibodies against the antigens found in the vaccine.

Phagocytosis

Process by which phagocytes surround, engulf and destroy foreign cells.

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Pulmonary Capillaries Bring Blood and Air into Close Contact. The right ventricle of the heart pumps deoxygenated blood into the pulmonary trunk, which splits into the left and right pulmonary arteries. The pulmonary arteries divide into smaller and smaller arteries and arterioles, eventually terminating in a capillary bed called the pulmonary capillaries. In the pulmonary capillaries, blood comes into very close proximity to the air in the alveoli. Only two living cells (the squamous epithelial cell of the alveolus and the cell of the capillary wall) separate blood from air at this point. A series of venules and veins collects the oxygenated blood from the pulmonary capillaries and returns the blood to the left side of the heart, from whence it is transported to all parts of the body.

As each surge of blood enters the arteries during systole, the artery walls are stretched to accommodate the extra volume, and arterial pressure rises. Arteries recoil passively during diastole as blood continues to flow out of them through the capillaries. You can feel this cycle of rapid expansion and recoil in the wall of an artery if it's located near the skin's surface. This is called a

Pulse

Pulmonary circuit

That part of the vascular system that takes deoxygenated blood to the lungs and returns oxygenated blood to the heart

Several different artificial hearts are currently under development, but only one is currently approved by the FDA. What's it called?

The SynCardia heart (Figure 8.23) is approved only for temporary use, that is, until a suitable donor can be found. So far, over 1800 patients have received the SynCardia heart. About 80% of them survived until they received a human heart transplant.

Immune response

The activities of the immune system

Cardiac output

The amount of blood the heart pumps into the aorta each minute.

In taking a blood pressure, what happens during diastole? The arteries are complete closed, and there are no sounds. The arteries are completely opened, and there are no sounds. The arteries are opening and closing, and there are no sounds. The arteries are completely opened, and there are sounds. The arteries are opening and closing, and there are sounds. I DON'T KNOW YET

The arteries are completely opened, and there are no sounds. During diastole, the arteries are completely opened and there are no sounds. To answer this, you need to understand how taking a blood pressure works. An instrument called a sphygmomanometer is used to take a blood pressure. The cuff is wrapped around the arm and inflated until no blood is flowing through the brachial artery. Pressure is slowly deflated until the cuff pressure is now less than the cuff pressure. This allows blood to flow through, and sounds are produced. The cuff pressure is still greater than the diastolic pressure; hence the blood vessel closes due to the cuff pressure during ventricular diastole. The pressure in the cuff keeps dropping until it is less than diastole. At that point, the blood vessel remains opened, and there are no more sounds. The arteries are completed closed once the cuff is fully inflated. The pressure of the cuff collapses the brachial artery and prevents blood from flowing. There are no sounds when the blood vessel remains closed. The arteries start to open and close once the cuff pressure goes below systolic pressure. Blood flows through the arteries when they open, and this causes a sound to be produced. The moment when blood flows through the arteries and sounds are produced is the systolic pressure. Diastolic pressure occurs when the brachial artery remains opened, and sounds are no longer produced.

What happens during ventricular systole? The ventricles are filling with blood. The atrioventricular valves are closed. A P-wave is occurring on the EKG, the ventricles are filling with blood, and the semilunar valves are closed. A P-wave is occurring on the EKG. The semilunar valves are closed. I DON'T KNOW YET

The atrioventricular valves are closed. The atrioventricular valves (AV) are closed during ventricular systole. The cardiac cycle is a set of events that describes blood flow, pressure changes, and EKG events during one beat of the heart. As you learn this material, always ask yourself, "Does this make sense?" The first thing to understand is that during ventricular systole, the ventricles are contracting. If they are contracting, where are they sending blood? They are sending blood through the semilunar valves to enter either the pulmonary trunk or the aorta. Recall that the chordae tendinae pull the AV valves closed so blood does not reenter the atria. The pulmonary and aortic semilunar valves are opened during ventricle systole. As the ventricles contract, they push open the semilunar valves so blood can leave the ventricles and either either the pulmonary trunk or the aorta. Systole means contraction; thus the AV valves are closed during this time period. AV valves are in between the atria and ventricles and blood cannot enter the venticles if the AV valves are closed. A P-wave represents atrial depolarization. Muscles contract during depolarization, and if the atria are contracting, then they are sending blood to the ventricle and the AV valves must be opened. But the question stated ventricular systole. Even if an answer sounds good, such as stating a P-wave is occurring, the ventricles are filling with blood, and the semilunar valves are closed, always make sure the question is being answered. The answer sounds good, but it is describing ventricular diastole, which is ventricular relaxation.

Once a macrophage engulfs a bacterium, what happens to the foreign cell? It is released into the lymph system for removal from the body. Antibodies penetrate the macrophage to lyse the bacterial cell. The macrophage is attacked by antibodies, killing the cell and bacterium. It is released into the digestive tract for removal from the body. The bacterium is killed by digestive enzymes released from lysosomes.

The bacterium is killed by digestive enzymes released from lysosomes.

The HIV virus attacks and destroys T helper cells. What happens as a consequence? The body loses its antibody-mediated and cell-mediated responses. The body only loses its cell-mediated response. The body only loses its antibody-mediated response. The body loses its abilty to activate macrophages. The body loses its ablity to form white blood cells. I DON'T KNOW YET

The body loses its antibody-mediated and cell-mediated responses. The death of T helper cells results in the loss of antibody-mediated and cell-mediated responses. Helper T cells are required to help activate B cells and naïve T cells. B cells turn into plasma cells when activated, and the plasma cells secrete antibodies. Activated naïve T cells turn into cytotoxic T cells. Without the helper T cells, antibodies and cytotoxic T cells cannot be formed and both sides of specific defense are lost, leaving the body susceptible to infectious agents and cancer. Innate defense is not powerful enough to protect the body. It takes all three lines of defense to keep the body healthy. Helper T cells function to help form plasma cells and cytotoxic T cells. The loss of helper T cells is devasting since this leads to a lack of cell-mediated (use of cytotoxic T cells) and antibody-mediated immunity. Macrophages are part of innate defense and are always active. They do not need to first encounter an antigen to become functional. White blood cells are formed in the red bone marrow. Anything that attacks the red bone marrow, such as leukemia or aplastic anemia, can result in an inability to form white blood cells.

Central Nervous System (CNS)

The brain and spinal cord It receives, processes, stores, and transfers information.

Where in a neuron would the nucleus, mitochondria and other cell organelles be located?

The cell body.

Chronic HIV Infection (Phase II)

The chronic HIV infection phase, also referred to as clinical latency, is marked by the continuous decline of the number of helper T cells. Some people will experience opportunistic infections, infections that take advantage of the weakened immune system to establish themselves in the body. Yeast infections, diarrhea, and shingles are opportunistic infections. Otherwise, there are no specific symptoms during this phase. If an HIV infected person is unaware of the infection, phase II would not cause them to suspect it. During Phases I and II, many people pass the virus on to others without realizing it. Those they infect may transmit the virus to still others. Phase II can progress to Phase III in as little as 6 months, but on average it takes about 10 years to progress to Phase III. Left untreated, 95% of people in Phase II progress to Phase III.

Ventricular Systole

The contraction that began in the atria spreads to the ventricles, and both ventricles contract simultaneously. The rapidly rising ventricular pressure produced by contraction of the ventricles causes the two AV valves to close, preventing blood from flowing backward into the atria and veins. At this time, the atria relax and begin filling again. The pressure within the ventricles continues to rise until it is greater than the pressure in the arteries, at which point, the pulmonary and aortic semilunar valves open and blood is ejected into the pulmonary trunk and the aorta. With each ventricular systole, about 60% of the blood in each ventricle is forcibly ejected.

Like the walls of arteries, the walls of veins consist of three layers of tissue. However, the outer two layers of the walls of veins are much thinner than those of arteries. Veins also have a larger diameter lumen than arteries. The anatomical differences between arteries and veins reflect their functional differences. As blood moves through the cardiovascular system, blood pressure becomes lower and lower. The pressure in veins is only a small fraction of that in arteries, so veins do not need nearly as much wall strength as arteries. The larger diameter and high distensibility of veins allow them to stretch like tubular balloons to accommodate large volumes of blood at low pressures.n addition to their transport function, then, veins serve as a blood volume reservoir for the entire cardiovascular system. Nearly two-thirds of all the blood in your body is in your veins. Thanks to their blood reservoir function, even if you become dehydrated or lose a little blood, your heart will still be able to pump enough blood to keep your blood pressure fairly constant. The distensibility of veins, however, can lead to problems, why?

The distensibility of veins, however, can lead to problems in returning blood to the heart against the force of gravity. When you stand upright, blood tends to collect in the veins of your legs and feet. People who spend a lot of time on their feet may develop varicose veins, permanently swollen veins that look twisted and bumpy from pooled blood. Varicose veins can appear anywhere, but they are most common in the legs and feet. In severe cases, the skin surrounding veins becomes dry and hard because the tissues are not receiving enough blood. Often, varicose veins are treated by injecting an irritating solution that shrivels the vessels and makes them less visible. This should not affect blood flow because surrounding undamaged veins take over and return blood to the heart.

Why is it impossible to talk when you are swallowing?

The epiglottis is a flexible flap of cartilage located at the opening to the larynx. When air is flowing into the larynx, the epiglottis remains open, but when we swallow food or liquids, the epiglottis tips to block the opening into the trachea temporarily. This "switching mechanism" routes food and beverages into the esophagus and digestive system rather than into the trachea.

Blood pressure

The force exerted by blood against blood vessel walls, generated by the pumping action of the heart.

Systolic pressure

The highest pressure reached in the arterial blood vessels during the cardiac cycle, and the first of two blood pressure numbers recorded by the health care provider. Systolic pressure is achieved during ventricular systole.

IgE (approximately 0.1%)

The least abundant of the immunoglobulins, IgE antibodies are in B cells, mast cells, and basophils. They activate the inflammatory response by triggering the release of histamine. They are also the troublemakers behind allergic responses (covered in section 9.9).

vital capacity

The maximum volume of air that can be expelled from the lung by forcible expiration after the deepest inspiration.

human microbiota

The microorganisms (Bacteria, fungi, protozoa) that live in and on the human body.

Why do noses vary in shape and size?

The nose varies in size and shape from person to person, primarily as a result of individual differences in the cartilage tissue.

What is likely to happen if a person has an inflamed epiglottis? Mucus will accumulate in the lungs. The person will not be able to breathe. Pressure in the middle ear can develop. Liquids ingested could possibly end up in the nasal cavity Food can enter the lower respiratory system. I DON'T KNOW YET

The person will not be able to breathe. A person with an inflamed epiglottis will not be able to breathe. The epiglottis is a flaplike structure made of elastic cartilage that covers the glottis of the larynx. The glottis is an opening that air goes through to travel from the pharnxy to the trachea. Inflammation results in swelling. Swelling of the epiglottis will cause it to get bigger and block the glottis, preventing ventilation. This can occur with an allergic reaction and will be life threatening. The epiglottis is found by the larynx, which is just above the trachea. It is not near the nasal cavity. The soft palate, which is in the back of the mouth, raises up to prevent food and drink from reaching the nasal cavity during swallowing. Talking while swallowing can result in liquids going through the nose due to the soft palate not doing its job. Pressure in the middle ear develops when air pressure can't equalize between the middle ear and the outer ear. The auditory tube functions to do this. When pressure doesn't equalize, people sometimes hold their nose and try to breath through it. This causes the tube to open and equalize pressure. Mucus can accumulate in the lungs if excess mucus is produced or if the cilia lining the airways are damaged from smoking. Food can enter the respiratory system if a person is talking and swallowing. This can cause the epiglottis to raise up and food can enter it. The question asks about an inflamed epiglottis. Always review terms if you are not familiar with them. Inflammation results in swelling, and a swollen epiglottis can block the movement of air.

Acute Infection (Phase I)

The phase of acute infection begins 2-4 weeks after initial exposure to the virus and lasts anywhere from a few weeks to a few years. There is a brief spike in HIV in the blood, and some people experience mild flulike symptoms, including swollen lymph nodes, fever, fatigue, and body aches. The virus multiplies rapidly and attacks the helper T cells, causing T cell numbers to decline briefly then rebound as the body continues to produce more cells and begins to produce antibodies against the virus. However, the antibodies do not destroy the virus entirely because many of the virus particles remain inside cells, where antibodies and immune cells cannot reach them. The presence of antibodies against the virus is the basis for a diagnosis of HIV infection, and a person having these antibodies is said to be HIV-positive. However, they will not yet have the disease syndrome called AIDS. It is important to recognize that the level of HIV in the blood is very high during Phase I, which means the risk of HIV transmission is also very high before an individual would know they are infected. Unless a person suspects that he or she has been exposed to HIV, the idea of being tested does not tend to come to mind.

Partial Pressure

The pressure exerted by one particular gas in a mixture of gases.

active immunization

The process of activation of the immune system in advance of the presence of a disease. Generally, active immunization is accomplished by administration of a vaccine.

ventilation

The process of breathing, moving air into and out of the lungs.

passive immunization

The process of fighting an existing or anticipated infection by the administration of specific antibodies against the infective agent. The antibodies usually are isolated from a human or animal with immunity to the infective agent.

pharynx

The region of the digestive and respiratory system that extends from behind the nasal cavities to the esophagus, also called the throat. Both air and food pass through the pharynx.

What is more muscular, the right ventricle or the right atrium? Why?

The right ventricle is more muscular than the right atrium because it pumps blood at considerable pressure through a second valve and into the artery leading to the lungs.

resting potential

The slight difference in voltage (electrical potential) between the inside and outside of a cell.

Arteriole

The smallest of the arterial blood vessels. Arterioles supply the capillaries, where nutrient and gas exchange takes place.

Capillary

The smallest type of blood vessel. Capillaries are the site of exchange between blood and tissue cells. (Check figure 8.3a)

The motor division of the peripheral nervous system is further subdivided along functional lines. Explain this.

The somatic division of the PNS controls skeletal muscles, and the autonomic division of the PNS controls smooth muscles, cardiac muscles, and glands.

Systemic circuit

The system of blood vessels that transport blood to all cells of the body except those served by the pulmonary circuit.

The structure of arteries is ideally suited to their functions. The vessel wall is a sandwich of three distinct layers surrounding the lumen, or hollow interior of the vessel:

The thin inner layer: a layer of flattened, squamous epithelial cells. It is a continuation of the lining of the heart. The flattened cells fit closely together, creating a slick surface that keeps friction to a minimum and promotes smooth blood flow. Just outside the endothelium: a layer composed primarily of smooth muscle with interwoven elastic connective tissue. In most arteries this is the thickest of the three layers. Steady partial contraction of the smooth muscle of large and medium-sized arteries stiffens the arteries and helps them resist the high pressures within, but it does not constrict them enough to alter blood flow. The elastic tissue makes large and medium-sized arteries slightly distensible so they can stretch passively to accommodate the blood that enters with each heartbeat. The outermost layer of large and medium-sized arteries: Consists of a tough supportive layer of connective tissue, primarily collagen. This sturdy casing anchors vessels to surrounding tissues and helps protect them from injury.

What happens during the QRS portion of an EKG? The ventricles no longer receive electrical activity and relax. The ventricles relax. The ventricles contract. The semilunar valves close. It signals the end of the electrical activity in the ventricles. I DON'T KNOW YET

The ventricles contract. The ventricles contract during the QRS portion of an EKG. An EKG shows the electrical changes that occur in different portions of the heart. There are three main waves associated with an EKG. The P wave represents atrial depolarization in which the atria contract; the QRS wave represents ventricular depolarization in which the ventricles contract. The last wave is the T wave in which the ventricles repolarize and relax. There is a pattern here. Note that depolarization precedes muscular contraction and repolarization precedes muscular relaxation. Ventricles relax during the T wave, which represents ventricular repolarization. The question is asking about the QRS wave; thus the ventricles depolarize and contract. Ventricular contraction results in blood leaving the ventricles through the semilunar valves; hence the valves are opened, not closed.

What's the structure of HIV

The virus consists of nothing more than 2 copies of single-stranded RNA and enzymes, packaged in a protein capsid and a phospholipid envelope studded with glycoprotein (part sugar, part protein) spikes. It has no nucleus and no organelles.

Epidemic

The widespread occurrence of an infectious disease in a particular community, population, or region.

The B and T cell's names are based on where they mature. Where do they mature?

Their names are based on where they mature: B cells mature in bone marrow; T cells in the thymus gland.

The lymphatic system begins as a network of small, blind-ended lymphatic capillaries in the vicinity of the cells and blood capillaries. Lymph capillaries have wide spaces between overlapping cells. What does their structure allow them to do?

Their structure allows them to take up substances (including bacteria) that are too large to enter a blood capillary.

Epinephrine (adrenaline) and norepinephrine are two hormones secreted by the adrenal medulla (part of the adrenal glands which are located on top of the kidneys) in response to nerve stimulation from the brain. What do these hormones do?

These hormones increase the heart rate and the force of contraction (resulting in an increased in blood pressure) and can constrict or dilate blood vessels in many organs, controlling blood flow to those organs.

The bronchi and bronchioles have several other functions in addition to air transport. What are these functions?

They also clean the air, warm it to body temperature, and saturate it with water vapor before it reaches the delicate gas-exchange surfaces of the lungs. The air is warmed and humidified by contact with the moist surfaces of the cells lining the bronchi and bronchioles.

How do arterioles help regulate the amount of blood that flows to each capillary?

They do this by contracting or relaxing the smooth muscle layer, altering the diameter of the arteriole lumen.

By the time blood flows through the arterioles, blood pressure has fallen considerably. Consequently, arterioles can be simpler in structure. Generally, they lack the outermost layer of connective tissue, and their smooth muscle layer is not as thick. In addition to blood transport and storage, arterioles have a third function not shared by the larger arteries:

They help regulate the amount of blood that flows to each capillary.

You may have noticed that you tire more easily when you stand still than when you walk around. Why?

This is because walking improves the return of blood to your heart and prevents fluid accumulation in your legs. It also increases blood flow and the supply of energy to your leg muscles.

IgG (75% of immunoglobulins):

This is the most abundant class. Found in blood, lymph, intestines, and tissue fluid, the long-lived IgG antibodies activate the complement system and neutralize many toxins. They are the only antibodies that cross the placenta during pregnancy and pass on the mother's acquired immunities to the fetus.

Cell-mediated immunity

Those components of the body's adaptive defenses that are dependent on the activation and action of T lymphocytes (T cells) and the cells they recruit.

antibody-mediated immunity

Those components of the body's adaptive defenses that result in activation of B lymphocytes (B cells) and the production of antibodies, proteins that bind to and neutralize specific antigens.

Pericardium

Tough fibrous sac that encloses and protects the heart and prevents it from overfilling.

immunotherapy

Treatments that promote the general responsiveness of the immune system so that it can fight cancer more effectively.

Do gases have mass? How are gases attracted to the earth?

Yes. By gravity

The spleen is covered with

a dense capsule of connective tissue interspersed with smooth muscle cells.

Large and medium-sized arteries are like thick garden hoses, stiff yet somewhat elastic (distensible). Arteries stretch a little in response to high pressure but are strong enough to withstand high pressures year after year. The ability to stretch under pressure is important because

a function of arteries is to store the blood that is pumped into them with each beat of the heart and then provide it to the capillaries (at high pressure) even between heartbeats. The elastic recoil of arteries is the force that maintains the blood pressure between beats. Think of the arteries as analogous to a city's water system of branching iron or steel pipes that provide nearly constant water pressure to nearly every building in the vicinity.

A syndrome is a medical term for

a group of symptoms that occur together

Sweat glands produce and secrete dermicidin, a natural antimicrobial peptide. Dermicidin is effective against

a range of harmful bacteria as well as some fungi.

Bacterial ribosomes are smaller than ours and float freely in the cytoplasm. The outer surface of bacteria is covered by

a rigid cell wall that gives bacteria their distinctive shapes, including cocci (spheres), bacilli (rods), and spirals (Figure 9.1).

As air continues down the respiratory tract through the glottis, it enters the trachea, the windpipe that extends from the larynx to the left and right bronchi. The trachea consists of

a series of C-shaped, incomplete rings of cartilage held together by connective tissue and muscle. As shown in Figure 10.5a, each cartilage ring extends only three-quarters of the circumference of the trachea. The rings of cartilage keep the trachea open at all times, but because they are not complete circles of cartilage, they permit the trachea to change diameter slightly when we cough or breathe heavily. Like the nasal cavity, the trachea is lined with cilia-covered epithelial tissue that secretes mucus. The mucus traps foreign particles, and the cilia move them upward, away from the lungs.

Sometimes heart failure is so complete that it becomes necessary to replace the heart entirely. For most patients, the only option is a heart transplant, using a heart from a human cadaver. Heart transplants are expensive (over $1.4 million), but the chances of success are fairly good; currently, the average length of survival after a heart transplant is about 15 years. The main problem is

a shortage of healthy hearts from recently deceased human donors. More than 25% of all patients on heart transplant lists die before they get a suitable heart.

If something goes wrong with the cardiac conduction system or if the heart muscle becomes damaged, what happens to the electrical impulses and contractions?

abnormal heart electrical impulses and contractions may occur.

Tissue fluid, dead phagocytes and microorganisms, and cellular debris accumulate at the infection site, producing a characteristic discharge called pus. If pus becomes trapped and cannot drain, the body may wall it off with connective tissue. The result is an

abscess. Common places for abscesses to form include the breast (mastitis), the gums (dental abscesses), and more rarely the liver or brain. Many abscesses subside after being drained, whereas others require antibiotic drugs or surgical removal.

Severe combined immunodeficiency disease (SCID) is an example of an inherited immune deficiency. For the rare person who inherits SCID, even a minor infection can become life threatening. People with SCID have too few functional lymphocytes to defend the body against infections. The most common and best-known severe immune deficiency condition is

acquired immune deficiency syndrome (AIDS)

Graded potentials can initiate an

action potential

Neurons are cells specialized for communication. They generate and conduct electrical impulses, also called _____________ ____________, from one part of the body to another.

action potentials

The process of activating the body's immune system in advance is called

active immunization

The size and activity level of the thymus gland vary with

age.

Gas Exchange Occurs in

alveoli

Humans have learned to harness bacteria to produce commercial products, including

antibiotic drugs, hormones, vaccines, and foods including yogurt, sauerkraut, and soy sauce.

An antibody's structure enables it to bind to a specific

antigen

Cytotoxic T cells specifically seek and destroy self cells that are infected with a virus or bacteria as well as self cells that have become cancerous (tumor cells). They can also recognize and destroy foreign cells that might be present in transplanted tissue or a transplanted organ. These abnormal self cells or cells in the transplant are the

antigen presenting cells

Inactive T cells cannot recognize and attack whole foreign cells. Before T cells can begin to do their jobs, they need to have the foreign cell's antigens presented to them in a way that they can recognize. Certain macrophages and activated B cells—called _____________-__________________ _________ (__ ____ ____) —fulfill this role (Figure 9.12).

antigen-presenting cells (APCs)

What does the immune system target?

antigens

What's the largest artery in the body?

aorta

An abnormality of the rhythm or rate of the heartbeat is called an

arrhythmia.

Baroreceptors monitor and maintain

arterial blood pressure

As blood leaves the heart, it is pumped into large, muscular, thick-walled _____________.

arteries

From the aorta, blood travels through the

arteries and arterioles to the systemic capillaries, venules, and veins and then back to the right atrium again.

We classify the body's blood vessels into three major types:

arteries, capillaries, and veins

The myocardium is the layer that contracts every time the heart beats. The structure of cardiac muscle cells allows electrical signals to flow directly from cell to cell. An electrical signal in one cardiac muscle cell can spread to adjacent cells, enabling large numbers of cells to contract as a coordinated unit. Every time the myocardium contracts, it squeezes the chambers inside the heart, pushing blood outward into the

arteries.

When a human heart is not available soon enough or the patient is not eligible for one, the only short-term solution may be an Another option being explored is a

artificial heart. xenotransplant (an organ from another species), most likely from pigs or baboons.

What are the two chambers of the heart at the top?

atria

First is the small P wave, representing the electrical impulse traveling across the

atria (see Figure 8.13), causing atrial systole.

From the AV node, the electrical signal sweeps to a group of conducting fibers in the septum between the two ventricles called the _______________. These fibers branch and extend into __________.

atrioventricular (AV) bundle, Purkinje fibers

The electrical impulse traveling across the atria eventually reaches another mass of muscle cells called the

atrioventricular (AV) node

On rare occasions, the immune system's remarkable ability to distinguish self from nonself fails. When that happens, the immune system may produce antibodies and cytotoxic T cells that target its own cells. Conditions in which this happens are called __________ disorders

autoimmune Approximately 23.5 million adults in North America, two-thirds of them women, have some type of autoimmune disorder. We don't yet know all the details of how these diseases arise. In some cases, certain antigens simply are never exposed to the immune system as it undergoes fetal development. These antigens were never programmed into the system as self, so when tissue damage exposes them, the mature immune system responds as if they are foreign. In other cases, antibodies produced against a foreign antigen may cross-react with the person's own tissues. At the moment, there are no cures for autoimmune disorders. Treatments include therapies that depress the body's defense mechanisms and relieve the symptoms. Autoimmune conditions include a wide range of diseases, including multiple sclerosis, a progressive disorder of the central nervous system (see Chapter 11), and Type 1 diabetes mellitus, which targets cells in the pancreas (see Chapter 13). Next, we will look at two other autoimmune disorders: systemic lupus erythematosus and rheumatoid arthritis.

At its other end, the axon branches into slender extensions called

axon terminals. Each axon terminal ends in a small, rounded tip called an axon bulb.

The cilia beat in a coordinated motion, creating a gentle current that moves the particle-loaded mucus toward the back of the nasal cavity and pharynx. There, we cough it out, or swallow it to be digested by powerful digestive acids in the stomach. Ordinarily, we are unaware of our nasal cilia. However, exposure to cold temperatures can _____ ______ their activity, allowing mucus to pool in the nasal cavity and drip from the nostrils. This is why your nose "runs" in cold weather. a. speed up b. slow down

b. slow down

Pathogens include

bacteria, viruses, fungi, a few protozoa, and prions. Larger parasites, including various worms, can also be pathogens, although they are relatively rare in industrialized countries.

Why is the left ventricle the most muscular of the heart's four chambers?

because it must do more work than any other chamber. The left ventricle must generate pressures higher than aortic blood pressure in order to pump blood into the aorta. (We'll see how high aortic pressure is in a minute.) The right ventricle has a thinner wall and does less work because the blood pressure in the arteries leading to the lungs is only about one-sixth that of the aorta.

Regardless of the virus's method of entry, the presence of the viral genetic material causes the cell to

begin producing thousands of copies of the virus instead of carrying out its own metabolic activities Extra info: Sometimes the newly formed viruses are released by a type of budding from the cell membrane while the cell is still alive. In other cases, the cell becomes so packed with viruses that it dies and bursts, releasing a huge number of viruses all at once.

The excess plasma fluid is absorbed by

blind-ended capillaries that join together into a collection system of larger vessels, collectively called the lymphatic system.

The spleen cleanses

blood

Thin-walled veins store

blood and return it to the heart.

In addition to absorbing excess interstitial fluid, the capillaries of the lymphatic system also pick up substances in the interstitial fluid that are too large to diffuse into the The lymphatic system transports the lymph back to

blood capillaries, such as lipid droplets absorbed during digestion and invading microorganisms. veins near the heart, where the lymph rejoins the venous blood.

Arterioles and precapillary sphincters regulate

blood flow

The precapillary sphincters serve as gates that control ___________ ____into individual capillaries.

blood flow

Thick-walled arteries transport

blood to body tissues under high pressure.

The innermost layer of the heart, the endocardium, is a thin endothelial layer resting on a layer of connective tissue. The endocardium is continuous with the endothelium that lines the

blood vessels.

The lymphatic system helps maintain ___________ ________

blood volume

Asthma is a problem with the ____________. trachea bronchi bronchioles larynx alveoli I DON'T KNOW YET

bronchioles Asthma is a problem with the bronchioles of the lower respiratory system. During an asthma attack, inflammatory chemicals, such as histamine, are released, resulting in excess mucus production and bronchoconstriction of these tiny airways. The bronchioles, unlike the bronchi, lack cartilage for structure support. The bronchioles are mainly tubes of smooth muscle that can prevent the flow of air if they are full of mucus and constrict. The trachea has a fairly large opening as compared to the bronchioles. More importantly, the trachea is reinforced with cartilage, so it will not constrict. The larynx also doesn't constrict since it is made of cartilage. The problem is that inflammation of the epiglottis can result in problems with ventilation. Asthma is a problem that involves just the bronchioles. The alveoli do not contain any smooth muscle; thus they are not affected by histamine. However, pneumonia can cause the alveoli to fill up with fluid, and this can prevent gas exchange. The bronchi can become inflamed and cause bronchitis. Excess mucus can result in coughing and difficulty in breathing. However, bronchoconstriction does not occur with the bronchi since they are reinforced with cartilage, unlike the bronchioles that lack cartilage.

Arterioles connect to the smallest blood vessels, called

capillaries

The characteristic lub-DUB sounds that a doctor listens for using a stethoscope is due to ____________. closing of the semilunar valves followed by closing of the atrioventricular valves closing of the atrioventricular valves followed by closing of the semilunar valves opening of the atrioventricular valves followed by opening of the semilunar valves opening of the semilunar valves followed by closing of the semilunar valves opening of the semilunar valves followed by opening of the atrioventricular valves I DON'T KNOW YET

closing of the atrioventricular valves followed by closing of the semilunar valves The characteristic lub-Dub heart sounds is due to closing of the atrioventricular (AV) valves followed by closing of the semilunar (SL) valves. Understanding what causes the sounds makes it easier than just memorizing the answer. There are two aspects to this question that need to be considered. The order of events in terms of which valve is first and understanding whether the opening or closing results in a sound. Let's consider the opening or closing aspect first and use a door to understand the process. Assume there is a well-oiled door and you open and then close it. Which one makes a sound? Closing the door since the door likely will hit the frame. The same is true for the valves. They produce a sound when the flaps of the valves come together and close. Thus, which valve closes first? The answer is based on the cardiac cycle. Recall that the ventricles contract after filling up with blood, and as they contract, the AV valves close producing the lub sound. However, the SL valves open due to the force of blood during ventricular ejection. Once the ventricles have contracted, there is no more blood to keep th SL valves open, and they then close producing the DUB sound. While opening of the AV valves and opening of the SL valves are in the correct order, note that sounds are only produced during closure of the valves, not when they open. Take your hands and clap. Sounds are produced when they come hit each other, not when they separate. The next answer is partially correct since it does indicate closing of the valves; however, the order is wrong. The AV valves close before the SL valves close. Again, sounds are produced during closure of the valves, not opening of them. Medically speaking, doctors are interested in these sounds to see if they sound correct or not. Valves that don't close completely produce a sound called a murmur. Incompletely closed valves result in backflow of the blood.

What are the three main shapes of bacteria?

coccus (spheres) , bacillus (rods) , spirilla (spirals)

Hemoglobin can transport and molecules simultaneously because the two gases attach to different sites on the hemoglobin molecule:

combines with heme (the iron-containing part of hemoglobin) and with globin (the protein part of hemoglobin).

Systemic lupus erythematosus (or SLE) is an autoimmune disorder in which the immune system attacks the body's ______ ________.

connective tissue Individuals with SLE develop several different autoantibodies, including one directed against their cell nuclei, referred to as antinuclear antibody (ANA). This is a serious disease that affects numerous tissues and organs including the heart, blood vessels, lungs, kidneys, joints, and brain. SLE often starts as a red skin rash on the face or head. Other symptoms include fever, fatigue, joint pain, and weight loss. Spreading inflammation can lead to osteoarthritis (see Chapter 5), pericarditis (see Chapter 8), or pleurisy (inflammation of the lining of the lungs). Inflammation of the kidneys is one of the more common and serious complications and the leading cause of death among people with SLE. Lupus affects nine times as many women as men. Typically, it occurs during childbearing age and is more common in certain ethnic groups such as African Americans, West Indians, and Chinese. Medications can reduce the inflammation and alleviate the symptoms.

There are hundreds of lymph nodes, clustered in the areas of the digestive tract, neck, armpits, and groin (Figure 9.4). They vary in diameter from about 1 millimeter to 2.5 centimeters. Each node is enclosed in a dense capsule of

connective tissue pierced by lymphatic vessels. Inside each node are connective tissue and two types of white blood cells, macrophages and lymphocytes, which identify microorganisms and remove them.

The human heart is a muscular, cone-shaped organ slightly larger than your fist (Figure 8.6). It consists mostly of a special type of muscle called cardiac muscle. Unlike skeletal muscle, which attaches to bone and requires nerve signals for contraction, cardiac muscle

contracts spontaneously and is not connected to bone. The heart contracts in a cyclic, coordinated, squeezing motion that propels blood through the blood vessels.

As you might expect of such a hardworking muscle, the heart requires a great deal of oxygen and nutrients to fuel its own operations. The myocardium is too thick to be served by diffusion of oxygen and nutrients from the blood passing through. Thus, the heart has its own set of blood vessels called the _________ ____________ that supply the heart muscle (Figure 8.10).

coronary arteries

Which is not associated with the first and second lines of defense? cytotoxic T cell complement eosinophils macrophages natural killer cells I DON'T KNOW YET

cytotoxic T cell Cytotoxic T cells are not associated with the first and second lines of defense. Defense against infectious agents is categorized into three groups. The first and second lines of defense deal with innate defense, what you are born with. The third line or adaptive defense is produced when needed against specific pathogens. Cytotoxic T cells are part of adaptive defense. They are only produced when the immune system responds to cancer cells, cells infected with viruses, or transplanted materials from another individual. Natural killer cells are part of the second line of defense, which is based on having cells or biochemicals always present and ready to attack and destroy an infectious agent. Natural killer cells behave essentially like cytotoxic T cells but mount a faster attack since they are always present and ready to attack an infectious agent. Complement is a set of proteins that binds to pathogens and causes at least two things to happen to them. First, it tags the cells so neutrophils and macrophages will be more likely phagocytize them. Second, it forms pores in the cell membrane that results in leakage of cytoplasm and pathogen death. The presence of complement also causes inflammation. Macrophages are part of the second line of defense since they are always present and are ready to phagocytize foreign invaders. Eosinophils destroy parasitic worms by releasing chemicals that digest them. The worms are too big for the cells to engulf. While all three lines of defense are protective, the first two are always present, while cytotoxic T cells only form after the body is exposed to the foreign invaders.

A person has had a heart transplant. What is most likely going to cause organ rejection? antibodies suppressor T cells cytotoxic T cells helper T cells macrophages I DON'T KNOW YET

cytotoxic T cells Cytoxic T cells are most likely to cause organ rejection. The cytotoxic T cells seach the major histocompatibility complex (MHC) on cells to determine if the cell is from self or not. The MHC on a transplanted organ will signal it is foreign, and then cytotoxic T cells will attack the organ and destroy it. Antibodies bind to bacteria, viruses, and proteins. They do not mount an effective response to large cellular objects. Cytotoxic T cells are capable of attacking cellular targets and destroying them. Macrophages are involved with nonspecific defense. They engulf cells that are smaller than them. They wouldn't be able to attack tissues or cells due to size contraints. Suppressor T cells do not attack cells or bind to antigens. These cells release biochemicals that influence the activity of cytotoxic T cells. Helper T cells do not attack cells or bind to antigens. They activate naïve B and T cells to start antibody-mediated and cell-mediated immunity.

CD4 T cells will become helper and memory cells, and CD8 T cells will become

cytotoxic T cells and regulatory T cells.

On average, only about 350 ml of each normal breath actually reach the alveoli and become involved in gas exchange. The other 150 ml remain in the airways, and because that amount does not participate in gas exchange, the air is referred to as ________________ ______________ ___________.

dead space volume Dead space volume is not measured by a spirometer.

The cleansed blood is then stored in the red pulp. Your body can call on this reserve of blood when you lose blood, when you experience a fall in blood pressure, or whenever your cells need

extra oxygen-carrying capacity.

function of respiratory system

facilitate the diffusion of gases (O2) and (CO2) between the atmosphere and blood.

Which of the following is a branch of the common iliac artery? femoral artery inferior vena cava femoral vein renal artery aorta I DON'T KNOW YET

femoral artery The femoral artery is a branch of the common iliac artery. Blood vessels and nerves are typically named after bones. A knowledge of the skeletal system will prove beneficial in learning the main blood vessels of the body. Recall that the pelvis is made from three fused bones, one being the ilium. The iliac artery is in that general vicinity. The femoral artery runs alongside the femur. Hence, the iliac artery branches, giving rise to the femoral artery. The aorta branches and gives rise to the left and right iliac arteries. The right atrium receives blood from the inferior vena cava (IVC). The IVC receives blood from the common iliac vein. The aorta receives blood from the left ventricle. The renal artery receives blood from the aorta. Make sure to get the direction of blood flow correct. The question asked, "Where does blood go after the iliac arteries?" not where the blood was before. Then consider whether arteries or veins are involved in the flow described. The flow involved arteries; hence any answer with a vein was automatically wrong.

Which of the following is not a cardinal sign of inflammation? pain swelling redness localized warmth fever I DON'T KNOW YET

fever Fever is not a cardinal sign of inflammation. Pyrogens from bacteria or from the body induce the formation of fever, which does not typically kill microbes but slows down their growth. Fever also makes a person less active, so they can rest and put their energies into fighting the infection. Note that inflammation typically results from tissue damage, but a fever can result from biochemicals secreted by microbes. Inflammation is a result of tissue injury causing the release of inflammatory mediators, including histamine. Histamine has many effects, including increasing capillary permeability. The capillaries are normally impermeable to proteins, but histamine changes that, and proteins leak out. Proteins are a solute and water follows the solute to the interstitial space. This extra fluid in the interstitial space results in swelling or edema. The purpose of this is to get antibodies and nutrients to the damage area to fight potential infectious agents and promote healing. Histamine also causes vasodilation, which increases blood flow to the damaged area. The increased blood flow brings nutrients and antibodies to the area, but it is the increased capillary permeability that gets the antibodies out of the circulatory system. Vasodilation results in the characteristic redness and warmth experienced during an inflammatory response. Other mediators of inflammation include prostaglandins, which stimulate free nerve endings, creating pain.

Like the branches of a tree, the two bronchi divide into a network of smaller and smaller bronchi. The bronchi walls contain

fibrous connective tissue and smooth muscle reinforced with cartilage. As the airways branch, the amount of cartilage declines. By definition, the smaller airways that lack cartilage are called bronchioles.

Early symptoms of CO poisoning include

flushed skin (especially the lips), dizziness, headache, nausea, and feeling faint. Continued exposure leads to unconsciousness, brain damage, and death.

One might ask how any beneficial bacteria ever get to the small and large intestine if they have to pass through the stomach first. The answer is that

following a meal the stomach contents are not so acidic because food both dilutes and buffers the stomach acid, so some bacteria pass through the stomach with the food we eat.

Immune deficiency is a general term

for an immune system that is not functioning properly.

How do natural killer cells kill pathogens? form holes in the pathogen promote fever activate complement phagocytosis release histamine I DON'T KNOW YET

form holes in the pathogen Natural killer (NK) cells form holes in the pathogen, causing the cytoplasm to leak out. NK cells target other cells for destruction, such as cancer cells and cells infected with viruses. Those cells are too large to destroy by phagocytosis; hence another method is needed to kill them. NK cells get next to the cell and release a protein called perforin (as in perforate and form a hole) that places holes in the cell membrane and causes leakage of the cytoplasm. Complement functions essentially the same way when they attack cells. Macrophages and neutrophils perform phagocytosis, typically of bacteria and antibody-antigen complexes. Basophil and mast cells release histamine during inflammation. Pyrogens from bacteria or from the body induce the formation of fever, which does not typically kill microbes but slows down their growth. Complement is activated when the proteins directly bind to bacteria.

An antigen provides all the information the immune system needs to know about a foreign substance. Essentially, antigens are the locks on an enemy's doors. The immune system can identify the lock, produce the antibody key, and then send in immune system cells to open the door and neutralize the invader. How does this happen? All antibodies share the same basic structure, represented by an IgG antibody (Figure 9.11). Each IgG antibody (or surface receptor, if it is attached to a B cell) consists of

four linked polypeptide chains arranged in a Y shape. The two larger chains are called "heavy" chains, and the two smaller ones are called "light" chains. Each of the four chains has a constant region that forms the trunk and two branches and a variable region that represents the antigen-binding site. Because it has a unique amino acid sequence, each variable region has a unique shape that fits only one specific antigen.

Antibodies belong to the group of blood plasma proteins called

gamma globulins

Typically, an interneuron or motor neuron receives incoming information from other neurons at its dendrites or cell body. If the incoming information is of the right kind and is strong enough, the neuron responds by

generating an electrical impulse of its own at its axon hillock. In contrast, in a sensory neuron the impulse is initiated where the dendrite joins the axon, and the impulse is then transmitted from one end of the axon to the other, bypassing the cell body entirely.

Veins return blood to the

heart

Hypertension is called "the silent killer" because usually it has no symptoms or warning signs. The American Heart Association estimates that approximately 100 million Americans have hypertension and many don't even realize it. If left untreated, hypertension increases the risk of serious health problems such as

heart attack, heart failure, stroke, kidney damage, and even damage to the tissues inside the eyes.

When a T cell with CD4 receptors encounters an APC displaying an antigen and MHC (Figure 9.13), ➊ it is activated to become a

helper T cell

Which of the following is not a cell associated with nonspecific defense? macrophage neutrophil helper T cell natural killer cell eosinophil I DON'T KNOW YET

helper T cell Helper T cells are not a part of nonspecific defense. Helper T cells are part of adaptive or specific defense. Helper T cells function to activate cytotoxic T cells and to help form antibodies. Helper T cells only get activated once they encounter an antigen. Neutrophils and macrophages function to attack bacteria. They do not need to have already encountered the bacteria; they are "primed" to attack any bacteria they encounter. Both perform phagocytosis on bacteria they encounter. Eosinophils attack parasitic worms, such as round worms and tape worms. They release digestive enzymes to destroy the worm since the worm is too large to engulf. Natural killer cells attack cancer cells and cells infected with viruses. Helper T cells are part of adaptive immunity and must encounter the antigen before they become active. All of the other choices are active to start with and will immediately attack any foreign invaders they encounter.

Their small size means that bacteria have a ______ surface-to-volume ratio, a decided advantage when it comes to diffusion, the means by which they obtain raw materials and get rid of wastes. a. high b. low c. moderate

high

Which best describes a sinus? unction in mucus production contain olfactory receptors and function in mucus production provide a connection between the nasal cavity and the middle ear hollow cavities associated with certain bones of the skull hollow spaces associated with the alveoli I DON'T KNOW YET

hollow cavities associated with certain bones of the skull A sinus can best be described as hollow cavities associated with certain bones of the skull. The frontal, maxillary, ethmoid, and sphenoid bones contain hollow areas called sinuses. The sinuses serve many functions, including mucus production, warming and humidifying an area, and helping to add "resonance" to the voice. Sinuses can become infected and result in sinusitis, which feels as a pressure in the front of the head or around the nose. Congestion is also typically found with sinusitis. The alveoli are in the lungs, while the sinuses are hollow areas within certain bones associated with the skull. Alveoli form grapelike clusters. Air is within the hollow portion of the alveoli, and oxygen will diffuse from within the alveoli to the blood, while carbon dioxide will diffuse from the blood to the hollow portion of the alveoli. The nasal cavity has olfactory receptors that function as odor detectors. Cells there also form mucus to help trap microbes. Even though the nasal cavity is a hollow space, it is found outside of bones, while the sinuses are found within the bone itself. The auditory tube connects the middle ear to the throat, not to the nasal cavity. The function of the tube is to equalize pressure on either side of the eardrum.

Some viruses have a phospholipid bilayer, known as the envelope, covering the capsid. Viruses have no cytoplasm, ribosomes, or organelles of their own, so they can't grow and reproduce without access to a living cell, which is referred to as a

host cell. (check out figure 9.2)

Certain strains of beneficial bacteria normally live in the mucous membranes lining the vagina, the digestive tract, and the nose and throat. These are members of the _________ ______________ , the total of all microorganisms that live in and on our body.

human microbiota

Prions are resistant to cooking, freezing, and even drying. There is no known cure for prion infection. Because infection occurs when

humans (or cattle) eat prion-infected cattle tissues

However, as you have learned, B and T cells create a population of memory cells. The presence of these memory cells is the basis for __________ from disease.

immunity

Where does internal respiration and cellular respiration take place?

in the tissues throughout the body

Many murmurs result from

incomplete closing of the heart valves due to unusually shaped valve flaps or stiffening of the flap tissue. If a valve does not close completely, some blood is forced through it during the cardiac cycle, creating a swishing noise that can be detected through a stethoscope. Murmurs are not necessarily a sign of disease, but physicians can diagnose a variety of heart conditions, including leaking or partially blocked valves, from their sound and timing. If the defect is serious enough, an artificial valve may be used to replace the defective valve (Figure 8.12).

What causes swelling during an inflammatory response? increased capillary permeability increased blood flow to a body area vasodilation the release of prostaglandins vasoconstriction I DON'T KNOW YET

increased capillary permeability Swelling is due to increased capillary permeability. Inflammation is a result of tissue injury causing the release of inflammatory mediators, including histamine. Histamine has many effects, including increasing capillary permeability. The capillaries are normally impermeable to proteins, but histamine changes that, and proteins leak out. Proteins are a solute, and water follows the solute to the interstitial space. This extra fluid in the interstitial space results in swelling or edema. The purpose of this is to get antibodies and nutrients to the damage area to fight potential infectious agents and promote healing. Histamine cause vasodilation, which increases blood flow to the damaged area. The increased blood flow brings nutrients and antibodies to the area, but it is the increased capillary permeability that gets the antibodies out of the circulatory system. Vasodilation results in the characteristic redness and warmth experienced during an inflammatory response. Histamine promotes vasodilation, not vasoconstriction. The sympathetic nervous system and epinephrine promote vasoconstriction. Prostaglandins are chemicals that activate free nerve endings resulting in the pain that is typical of an inflammatory reaction.

What is the main stimulus for activating central chemoreceptors? increased oxygen concentrations increased hydrogen ion concentrations decreased oxygen concentrations decreased carbon dioxide concentrations increased carbon dioxide concentrations I DON'T KNOW YET

increased hydrogen ion concentrations Increased hydrogen ion concentration is the main stimulus for activating central chemoreceptors. The central chemoreceptors are located in the medulla. These chemoreceptors are sensitive to the pH of the cerebrospinal fluid that surrounds the medulla. A low pH, which is due to an increased hydrogen ion concentration, stimulates the chemoreceptors to fire. This activates the breathing centers and increases ventilation to flush out carbon dioxide. High levels of carbon dioxide result in a high level of hydrogen ions. The central chemoreceptors are mainly sensitive to hydrogen ions, though low levels of oxygen may stimulate them too. The carotid and aortic bodies are peripheral chemoreceptors, and they are sensitive to very low levels of oxygen, which cause them to send neural impulses to the breathing centers to increase ventilation. High levels of oxygen do not appear to influence the breathing rate. Decreased carbon dioxide levels will cause less carbonic acid to form, thereby producing fewer hydrogen ions. This will cause less stimulation of the central chemoreceptors, and the breathing rate will decrease. This is a negative feedback loop. High levels of carbon dioxide cause increased breathing to flush out the carbon dioxide; when the levels go too low, breathing slows down to allow carbon dioxide levels to increase again.

Vasodilation of arterioles and precapillary sphincters ________ their diameter and thus _________ blood flow to the capillaries.

increases, increases

Rheumatoid arthritis is a type of arthritis involving

inflammation of the synovial membrane that lines certain joints In rheumatoid arthritis, complexes of antibodies (IgG, IgM) are deposited in the joints and complement is activated, leading to chronic inflammation that causes further tissue damage. At first, fingers, wrists, toes, or other joints become painful and stiff. Over time, the inflammation destroys joint cartilage and the neighboring bone. Eventually, bony tissue begins to break down and fuse, resulting in deformities and reduced range of motion. The disease is intermittent, but with each recurrence the damage is progressively worse. Pain-relieving medications can help many people with rheumatoid arthritis, as can regular mild exercise and physical therapy to improve range of motion. Powerful drugs that neutralize chemicals in the inflammatory response can prevent joints from becoming deformed. Surgery to replace damaged joints with artificial joints can restore the ability to move and prevent painful disabilities.

The coordinated sequence of the cardiac cycle is due to the cardiac conduction system, a group of specialized cardiac muscle cells that

initiate and distribute electrical impulses throughout the heart. These impulses stimulate the heart muscle to contract in an orderly sequence that spreads from atria to ventricles.

The amount of additional air that can be inhaled beyond the tidal volume (about 3100 ml) is called the

inspiratory reserve volume

One of the most interesting defense mechanisms is an early warning system between virus-infected and still-healthy cells. As mentioned earlier, viruses cannot reproduce on their own. Instead, they invade body cells and use the cells' machinery to make more viruses. Cells that become infected by viruses secrete a group of proteins called

interferons

Although the imbalance between the amount of plasma fluid filtered by the capillaries and the amount reabsorbed is not large, over the course of a day it would amount to about 2 or 3 liters. This excess plasma fluid must be returned to the cardiovascular system somehow, or all the plasma would end up in the

interstitial fluid.

In fact, capillaries are the only blood vessels that can exchange materials with the

interstitial fluid. (Go to figure 8.4)

Some aneurysms cause the smooth muscle and endothelial layers to bulge __________ as they develop, narrowing the lumen enough to reduce blood flow to an organ or region of the body. Others force the outer connective tissue layer to bulge ________. Sometimes aneurysms cause severe chest pain, but in other cases they are completely symptomless until they rupture or "blow out," causing massive internal bleeding and often death. If you've ever seen a water line burst, you know how quickly it can be devastating. Aneurysms of the aorta (the body's largest artery) kill more than 10,000 Americans every year. (inward, outward) (inward, outward)

inward, outward

Generally, if systolic pressure is high, diastolic pressure will be, too. However, sometimes systolic pressure can register at above-normal levels while diastolic pressure remains normal, a condition called __________ ________________ hypertension. Most common in older adults, it is diagnosed as a systolic pressure of 130 mm Hg or higher with a diastolic reading of less than 80 mm Hg. Like the more common form of hypertension, isolated systolic hypertension is associated with increased health problems.

isolated systolic

The complement system, or complement, comprises at least 30 plasma proteins that circulate in the blood and complement, or assist, other defense mechanisms. Normally, these plasma proteins circulate in an inactive state. When activated by the presence of an infection, however, they become a potent defense force. Once one of these plasma proteins is activated,

it activates another, leading to a cascade of reactions. Each protein in the complement system can activate many others, creating a powerful "domino effect."

The right AV valve is called the tricuspid valve because

it has three flexible flaps.

Lupus erythematosus is an autoimmune disorder in which the body attacks

its own connective tissue.

All the DNA in most bacteria is contained in

just one chromosome, which usually forms a continuous loop.

Where are the breathing centers located? medulla oblongata intercostal muscles diaphragm cerebral cortex lungs I DON'T KNOW YET

medulla oblongata The breathing centers are located in the medulla oblongata. The breathing centers are regions in the brain that control the process of ventilation. The medulla is part of the brainstem and controls many important functions, including heartrate, blood vessel diameter, and breathing. The breathing centers contain pacemaker cells that set the breathing rate. The cerebral cortex is able to change the breathing rate, but it is the medulla that controls the automatic rate of breathing. What is unique about breathing is that voluntary muscles are controlled in an automatic manner, essentially meaning that breathing is not normally under conscious control. It becomes part of conscious control when the cerebral cortex changes the breathing rate. The diaphragm and intercostal muscles are involved with ventilation. Neural impulses from the breathing centers in the medulla travel to the diaphragm and intercostal muscles, causing them to contract. Contraction of those muscles results in inspiration. Expiration occurs when the neurons in the breathing centers turn off. Impulses are no longer sent to the diaphragm and intercostal muscles, and they relax, resulting in expiration. The lungs expand during inspiration and then deflate during expiration due to elastic recoil.

What do lymph nodes remove?

microorganisms, cellular debris, and abnormal cells from the lymph before returning it to the cardiovascular system.

Incoming air enters the pharynx (throat), which connects the mouth and nasal cavity to the larynx (voice box). The nasopharynx (upper pharynx) extends from the nasal cavity to the roof of the mouth. Into it open the two auditory tubes (eustachian tubes) that drain the

middle ear cavities and equalize air pressure between the middle ear and outside air. The oropharynx (lower pharynx) is a common passageway for food and air. Food passes through on its way to the esophagus, and air flows through to the lower respiratory tract.

The nose is divided into chambers by the nasal septum. Air enters the nostrils, the two openings at the base of the external nose, where the air is partially filtered by nose hairs before it flows into the nasal cavity. This cavity is lined with

moist epithelial tissue that is supplied with blood vessels. The blood vessels warm incoming air, and the epithelial tissue secretes mucus, which humidifies the air. The epithelium is covered with hairlike projections called cilia.

The adenoids often enlarge during early childhood, but in most people, they usually shrink after age 5 and disappear by puberty. In some cases, they continue to enlarge and obstruct airflow from nose to throat. This can cause

mouth breathing, a nasal voice, and snoring. Like the tonsils, the adenoids can be surgically removed if they grow large enough to cause problems.

The internal portion of the nose is called the

nasal cavity

Lymphatic tissue called the adenoids lies at the back of the

nasal passages.

Under normal circumstances, the heart's rate of pumping is controlled by

nerve signals originating in the brain. But unlike skeletal muscle, the heart can beat on its own without any nerve signals at all.

A wide variety of external and internal factors can produce vasodilation or vasoconstriction, including

nerves, hormones, and conditions in the local environment of the arterioles and precapillary sphincters. If you go outside on a cold day, you may notice that your fingers start to look pale. This is because vasoconstriction produced by nerves is narrowing your vessels to reduce heat loss from your body. On the other hand, hot weather will make your skin appear flushed as vasodilation occurs to speed up heat loss and cool you off. Emotions can also have an impact: Vasodilation is partly responsible for the surge in blood flow that causes the penis or clitoris to become erect when we are sexually aroused. (Check figure 8.2)

What is the function of chordae tendinae? function in the internal conduction system of the heart provide strong muscular contractions to pump blood prevent the atrioventricular (AV) valves from going into the atria provide a smooth surface for blood to flow over prevent the semilunar valves from going into the aorta or pulmonary artery I DON'T KNOW YET

prevent the atrioventricular (AV) valves from going into the atria Chordae tendinae prevent the atrioventricular (AV) valves from going into the atria. The chordae tendinae (essentially tendon chords) are string-like structures that connect AV valves to nipple-like muscular structures called papillary muscles. During ventricular contraction, the blood needs to leave the ventricles and travel either to the pulmonary or systemic circuits. What stops the blood from pushing its way back through the AV valves and back into the atria? The chordae tendinae prevents this from happening. As the ventricles contract, the papillary muscles also contract, thereby pulling down on the chordae tendinae and in turn the AV valves are prevented from opening up into the atria. Imagine an umbrella turning inside out when it is windy. This is what would happen if there were no chordae tendinae; the AV valves would enter the atria. The SA node, AV node, AV bundle, bundle branches, and Purkinje fibers are all part of the internal conduction system of the heart and function to produce and propagate action potentials. Chordea tendinae only connect to AV valves, not to semilunar valves. This is one of the key ways to quickly distinguish an AV valve from a semilunar valve. The heart is lined with endothelium, just like blood vessels, and this serves to provide a smooth surface for blood to flow over. The myocardium is made up of cardiac fibers and provides strong muscular contractions of the heart. The chordae tendinae are neither nervous nor muscular tissues. They are just connective tissues that ensure one-way flow of blood by working with the AV valves and preventing them from entering the atria.

Your first exposure to a particular antigen generates a

primary immune response. As we have seen, this involves recognition of the antigen and production and proliferation of B and T cells. Typically, the primary immune response has a lag time of three to six days after the antigen first appears. During this period, B cells specific to that antigen multiply and develop into plasma cells. Antibody concentrations rise, typically reaching their peak close to two weeks after first exposure. Then they start to level off or fall (Figure 9.16).

Generally, antigens are large protein or polysaccharide molecules. In much the same way that a key fits a lock, each antigen has a unique shape, and every bacterial species and type of virus has antigens of different shapes. The immune system responds to each uniquely shaped antigen by

producing specific antibodies or specialized T-cells to attack and inactivate the antigen (and the bacterium, virus, or cancer cell displaying it).

Vasodilation brings more blood into the injured area, making it red and warm. The rising temperature increases phagocyte activity. The increased leakiness of capillary walls allows more fluid and phagocytes to enter tissue spaces, causing swelling. The extra fluid dilutes pathogens and toxins and brings in clotting proteins that form a fibrin mesh to wall off the damaged area from healthy tissue. As a bonus, the fluid carries in extra oxygen and nutrients to

promote tissue healing while the phagocytes remove dead cells, microorganisms, and other debris.

In adults, B cells mature in the bone marrow. As they mature, they develop unique surface receptors (with the same structure as an antibody) that allow them to

recognize specific antigens (Figure 9.9). Then they travel in the bloodstream to the lymph nodes, spleen, and tonsils, where they remain inactive until they encounter that particular antigen.

Which of the following is not found in lymph? fat white blood cells red blood cells solutes fluid from capillaries I DON'T KNOW YET

red blood cells Red blood cells (RBCs) are not found in lymph. Lymph is a liquid found in lymph vessels. To appreciate why RBCs are not found in lymph, you need to understand how lymph is formed. Blood pressure forces liquid and dissolved solutes out of the capillaries. RBCs are too big to be pushed out of the capillary; hence they stay within the capillary. The liquid is called interstitial fluid once it exits the capillary. The excess interstitial fluid enters lymph capillaries. It is called lymph once it enters the lymph capillaries. White blood cells are capable of leaving blood vessels and are found in lymphatics where they function to provide protection against infectious agents. Fluids from capillaries form interstitial fluid, and the excess interstitial fluid enters lymph capillaries forming lymph. Solutes, such as sugars and ions, are tiny enough to leave the capillary as water is forced out of it by blood pressure.

Inflammation has four outward signs:

redness warmth swelling pain

The pericardial cavity contains a film of lubricating fluid that

reduces friction and allows the heart and the pericardium to glide smoothly against each other when the heart contracts.

When macrophages detect and attack bacteria, viruses, or other foreign substances, they release certain chemicals into the bloodstream. These chemicals, called pyrogens, cause the brain to

reset your body's "thermostat" to a higher temperature.

No matter how forcefully you exhale, some air always remains in your lungs. This is your _____________ ___________, approximately 1200 ml.

residual volume

In a neuron capable of producing an electrical impulse but not generating one at the moment, the membrane potential at rest, called its ______________, is the same as the membrane potential in all cells.

resting potential

HIV belongs to a particular class of viruses, called

retroviruses, that have a unique way of replicating (Figure 9.20)

The trachea branches into two airways called the

right and left bronchi

Blood returning to the heart from the body's tissues enters the heart at the __________.

right atrium.

Which blood vessel takes blood from the heart muscle and returns blood back to the heart? right cardiac vein left coronary artery superior vena cava left pulmonary veins left pulmonary arteries I DON'T KNOW YET

right cardiac vein The right coronary vein takes blood from the heart and returns it back to the heart. The blood in the ventricles and atria do not supply nutrients to the myocardium nor get rid of wastes from the myocardium. The heart has its own blood supply to supply the myocardium with nutrients and get rid of metabolic wastes. Coronary veins are so named because they are part of the coronary or heart circulation. If blood is entering a structure, then blood must exit. Veins, by definition are structures that send blood to the heart. Coronary veins receive blood from the myocardium and send it a larger vein called the coronary sinus that directly dumps the blood into the right atrium. The left coronary artery is also part of the coronary blood supply. Being an artery, it sends blood to the myocardium; it doesn't receive blood from the myocardium. The left pulmonary vein sends blood to the left atrium; however, it receives blood from the lungs, not from the heart. Note the blood vessel is pulmonary. Structures associated with lungs typically have the name "pulmonary" associated with them. Left pulmonary arteries send blood from the right ventricle to the lungs. The head, neck, and arms drain blood into the superior vena cava, which sends blood to the right atrium.

. From the right atrium, the blood passes through a valve into the ______________.

right ventricle.

When the body is actively fighting an infection, the mortality rate of white blood cells ________ dramatically. a. lowers b. rises

rises

The most important barrier against entry of any pathogen into our bodies is the

skin

What is the function of interferon? functions in adaptive immunity promotes phagocytosis promotes inflammation slows the spread of viruses forms holes in pathogens I DON'T KNOW YET

slows the spread of viruses Interferon slows the spread of viruses. It is a chemical involved with innate or nonspecific defense. Infection by any virus, hence nonspecific, causes hosts cells to produce and secrete interferon. This biochemical acts as a hormone because it targets nearby cells and causes them to go on a "heightened alert" and changes occur that protect the uninfected cells from future viral invasion. Complement is a set of proteins that bind to pathogens and causes at least two things to happen to them. First, it tags the cells so neutrophils and macrophages will more likely phagocytize them. Second, it forms pores in the cell membrane that results in leakage of cytoplasm and pathogen death. The presence of complement also causes inflammation. Antibodies and T cells function in adaptive immunity. While interferon and complement both function in innate defense, interferon is specialized for protecting the body against viruses, while complement can bind to bacteria and other pathogens.

A patient arrives at the doctor fatigued and with an inability to exhale completely. What is a likely cause of these problems? smoking viral infection fungal infection bacterial infection genetic disorder I DON'T KNOW YET

smoking Smoking causes emphysema, which results in fatigue and an inability to completely exhale. Emphysema is almost always due to smoking, although it can also be caused by a genetic mutuation. Emphysema is characterized by a loss of elasticity of the lungs and destruction of the alveolar walls. Loss of elasticity results in loss of elastic recoil, which causes the use of accessory muscles to exhale. The inability to completely exhale results in a barrel chest, which is seen in advanced stages of emphysema. The inability to exhale causes carbon dioxide levels to increase and oxygen levels to decrease. The lack of oxygen and use of accessory muscles to exhale results in extreme fatigue. Bacterial infection can account for tuberculosis, strep throat, or pneumonia. Tuberculosis (TB) is a bacterial disease of the lungs. It causes a chronic inflammation and destruction of lung tissue. The body typically is able to "wall" off the infection, but given time and lack of treatment, the bacteria typically spread to bones, the brain, and other organs of the body. Signs and symptoms include weakness, weight loss, and coughing up a bloody sputum. Strep throat is a bacterial infection of the pharynx characterized by fever and inflamed tonsils. Antibiotics can cure it. Pneumonia is an infection of the lungs. Viruses, fungi, and bacteria can all cause pneumonia. The infection leads to inflammation, and the edema associated with inflammation causes problems with gas exchange. Pneumonia can be very mild, as in the cases of walking pneumonia, or deadly, depending on the infectious agent and the health of the individual. Genetic disorders associated with the lungs can be emphysema or cystic fibrosis. Cystic fibrosis is characterized by a thick and sticky mucus. Cystic fibrosis is a genetic disease that causes an overproduction of mucus in the respiratory and digestive tracts. Emphysema is almost always due to smoking, although it can also be caused by a genetic mutation. Emphysema is characterized by a loss of elasticity of the lungs and destruction of the alveolar walls. previous

➊ Depolarization

sodium moves into the axon When threshold is exceeded, voltage-sensitive Na channels in the axon's membrane open briefly and Na+ from interstitial fluid diffuse rapidly into the cytoplasm of the axon. This influx of positive ions causes depolarization, meaning that the membrane potential shifts from negative to positive (about ).

Microscopic capillaries exchange

solutes and water with the cells of the body

In many countries, vaccines are too costly and difficult to administer: Generally, they must be injected by a health care worker with some basic level of training. To get around this problem, what are some researchers doing? Who is developing and distributing COVID-19 vaccines?

some researchers are developing potatoes or bananas that are genetically modified to produce vaccines against diseases such as hepatitis B, measles, and the diarrhea-causing Norwalk virus. These "edible vaccines" are still in the research and development phase. Development and distribution of COVID-19 vaccines—immense responsibilities—fall to scientists at universities, government agencies, and private pharmaceutical companies. (For more information on vaccines, refer to the Chapter 20 Health and Wellness.)

e activities of the immune system are collectively called the immune response. Because the immune system targets specific enemies, we refer to these operations as

specific defense mechanisms.

Lung volumes and vital capacity are measured with a device called a How are these measurements made?

spirometer The measurements are made by having a person breathe normally into the device and then take a maximum breath and exhale it forcibly and as completely as possible.

What's the largest lymphatic organ?

spleen

Which of the following has red pulp and white pulp? spleen thymus gland lymph nodes tonsils Peyer's patches I DON'T KNOW YET

spleen The spleen has red and white pulp. The spleen is a lymphatic organ found in the abdominal cavity. Histological examination reveals two distinct regions of tissue. The red pulp has macrophages that help recycle red blood cells. White pulp has B cells and T cells, which are lymphocytes that function in your immune system. Lymph nodes are tiny, bean-shaped lymphatic organs found throughout the body, although some areas have clusters of them. Typically, when a doctor is feeling your neck for swollen "glands," she is really feeling for swollen lymph nodes, which can be a sign of an infection. The thymus gland is a lymphatic organ found between the heart and neck. It functions in developing T cells, which get the name "T" cells because they mature in the thymus. Peyer's patches are lymphatic tissue found in the small intestines and functions to start an immune response if an infection occurs there. Tonsils are like Peyer's patches, except found in the mouth and throat region. While all these structures are associated with the lymphatic system, only the spleen has two distinct areas of red pulp and white pulp. All lymphatics function one way or the other with the immune system, but the spleen has the additional capability of being able to recycle red blood cells.

The lower respiratory tract

starts with the larynx and includes the trachea, the two bronchi that branch from the trachea, and the lungs.

A test was done, and an embolism was found in a carotid artery. What most likely will occur with this patient? heart failure angina stroke shortness of breath heart attack I DON'T KNOW YET

stroke A person with an embolism in the carotid arteries is at risk for a stroke or cerebrovascular accident. The trick with this question is to have an understanding where blood vessels lead to. An embolism is a blood clot or some other foreign material traveling with the blood. In this case, the embolism is traveling toward the brain since the carotid artery leads to the brain. An embolism will eventually get stuck in a blood vessel, and this will impede blood flow to a region of the brain, resulting in a stroke. A heart attack can occur if an embolism is within a coronary artery and gets stuck within the coronary circulation. A heart attack results in permanent tissue death of cells of the mycocardium. Heart failure is due to a weakened heart, which can result from a heart attack or from high blood pressure. An embolism doesn't directly cause heart failure. Angina results from poor blood flow to the heart, as can occur with narrowed coronary arteries. Angina causes chest pain but does not result in death of cardiac tissues. Shortness of breath can be due to a pulmonary embolism in which an embolism enters pulmonary circulation. While an embolism is due to a floating mass in the blood, the symptoms vary depending on where an embolism eventually lodges. An embolism that enters the brain will impede blood flow to the brain and produce a stroke.

Interferons diffuse to nearby healthy cells, bind to their cell membranes, and stimulate the healthy cells to produce proteins that interfere with the

synthesis of viral proteins, making it harder for the viruses to infect the protected cells.

The pumping action of the heart is pulsatile rather than continuous, meaning that it delivers blood in separate and distinct pulses. A complete cardiac cycle involves contraction of the two atria, which forces blood into the ventricles, followed by contraction of the two ventricles, which pumps blood into the pulmonary artery and the aorta, followed by relaxation of the entire heart. The term _________ refers to the period of contraction, and _______________ refers to the period of relaxation. The entire sequence of contraction and relaxation is called the ___________ ______________.

systole, diastole, cardiac cycle

The left AV valve has two flaps, so it is referred to as

the bicuspid, or mitral, valve

Although a moderate fever tends to be beneficial, a high fever can be dangerous. Because

the chemical bonds that give a protein its shape are relatively weak, they may be broken by high temperatures. If that happens, the shape of the protein will change and the protein may not function normally.

In cross section, we see that the walls of the heart consist of three layers

the epicardium, myocardium, and endocardium

External respiration

the exchange of gases between air and blood

Blood pressure deals with ____________. the velocity of blood in a given blood vessel the volume of blood in the circulatory system a single number obtained using a sphygmomanometer the force of blood against the walls of the blood vessel numbers that do not change during the course of a day, unless there is a pathology I DON'T KNOW YET

the force of blood against the walls of the blood vessel Blood pressure deals with the force of blood against the walls of the blood vessel. This is an important physiological aspect that is monitored when you go to the doctor. A blood pressure that is too high creates too much force and can damage capillary beds, but a pressure that is too low can result in poor blood flow. The force is created when the ventricles pump. Pressure is also created when blood vessels contrict. Take your finger, and squeeze it. You can feel the "pressure" or force that is applied to your finger. The velocity of blood is the speed of blood traving through a given region of the circulatory system. The velocity is the quickest in the aorta and vena cava and slowest in the capillaries. The volume of blood is the amount of blood in the circulatory system, which is about 4-5 liters in a female and 5-6 liters in a male. The volume does impact the blood pressure. Low volume, due to lack of water intake or blood loss, will result in a low blood pressure. Think about a tire. Too much air results in the tire pressure being too high. Blood pressure changes as body activities change. For example, exercise will increase blood pressure. Blood pressure is represented by two numbers. A normal blood pressure is 120/80. The upper number represents systolic pressure while the lower pressure represents diastolic pressure. Recall that systolic pressure is created by the ventricles contracting, while diastolic pressure is the pressure in the arteries during ventricular relaxation.

Within each alveolus, certain epithelial cells secrete a lipoprotein called surfactant that coats the interior of the alveoli and reduces surface tension. Surface tension is due to the attraction of water molecules toward each other. Without surfactant, what happens?

the force of surface tension could collapse the alveoli. This can occur in infants who are born prematurely because the surfactant-secreting cells in their lungs are underdeveloped. Called infant respiratory distress syndrome, the condition is treated with surfactant replacement therapy.

Which of these is the lowest volume? residual volume expiratory reserve volume inspiratory reserve volume tidal volume vital capacity I DON'T KNOW YET

tidal volume Tidal volume is the lowest volume. The tidal volume is the amount of air breathed in and out during normal passive breathing. The volume is 0.5 l. It is called tidal due to the resemblance of water moving in and out of a beach. The residual volume is a bit more than a liter. This is the volume that remains in the lung no matter how hard one exhales. The residual volume keeps the lungs inflated and prevents them from collapsing. The inspiratory reserve volume is how much can be breathed in after taking a normal breath. This volume is between 1.9 and 3.3 l. The expiratory reserve volume is about a liter and is the volume that is blown out after a normal breath. The maximal amount of air that can be inhaled or exhaled in a single breath is known as the vital capacity (VC). Without memorizing the numbers, one can test each volume by seeing the relative amount of air that is moved with each one.

Xenotransplants are less ideal because

tissue incompatibility can lead to transplant rejection by the immune system and also because these species do not live as long as humans, raising the question of whether the hearts would last long enough. If these issues could be resolved, xenotransplants could save thousands of lives each year.

Because the goal of the immune system is to protect the body from invasion by non-self cells, it is not surprising that the immune system attacks non-self human tissues with vigor. This phenomenon is called

tissue rejection.

The familiar tonsils at the back of the throat are the largest and most often infected. When they become infected, the resulting inflammation is called

tonsillitis If the infection becomes recurrent, the tissues can be surgically removed.

The ________ are lymphatic tissues that protect the throat. uvulas salivary glands vocal cords tonsils

tonsils

A very common type of tissue rejection occurs with blood transfusion, when a donor's blood is rejected by the recipient patient. It's called a __________ _________, and it can be fatal.

transfusion reaction

Some pathogens are clearly a greater threat to human health than others. Factors that determine the danger of a particular pathogen include

transmissibility (how easily it is transferred from one person to another) mode of transmission (the method of transfer) virulence (how severe the resulting disease is).

Blood pressure varies from minute to minute even in healthy individuals. Simply getting up in the morning raises it, as do exercise, emotions, smoking cigarettes, eating, drinking, and many other factors. Even having your blood pressure measured can make you nervous enough for your blood pressure to rise—a situation that health professionals call "___________ __________ hypertension." This is why physicians generally have you sit quietly while measuring your blood pressure.

white coat

Interneurons

within the CNS transmit impulses between components of the CNS. Interneurons receive input from sensory neurons, integrate this information, and influence the functioning of other neurons.

Where does external respiration take place?

within the lungs

Other hormones, including antidiuretic hormone (ADH) secreted by the pituitary gland and aldosterone (secreted by the adrenal cortex), the renin-angiotensin system (involving the kidneys, lungs, and liver), as well as atrial natriuretic hormone (ANH) secreted by atria of the heart influence blood pressure by

working with the kidneys to manage blood volume.

Phagocytosis process

➊ A phagocyte first captures a bacterium with its cytoplasmic extensions. ➋ Then it draws the bacterium in, eventually engulfing it (endocytosis) and ➌ enclosing it in a membrane-bound vesicle. ➍ Inside the cell, the vesicle containing the bacterium fuses with lysosomes, and ➎ the powerful enzymes in the lysosomes digest the bacterial components. Once digestion is complete, ➏ the phagocyte jettisons the bacterial wastes by exocytosis. (Figure 9.7).

Figure 9.6 shows how some activated complement proteins attack and destroy bacteria. What are the steps of how some activated complement proteins attack and destroy bacteria?

➊ Activated complement proteins link together, forming protein complexes that create large holes through the bacterial cell wall. ➋ Water and salts leak into the bacterium through the holes. ➌ Eventually, the bacterium swells and bursts, in a process called lysis.

The baroreceptors regulate arterial blood pressure in the following manner:

➊ An increase in blood pressure stretches the baroreceptors passively, just as it stretches all blood vessels. ➋ Sensory neurons in the baroreceptors fire at an increased rate when the baroreceptors are stretched. ➌ These neuron signals travel to a region of the brain called the cardiovascular center. The cardiovascular center correctly interprets increased sensory neuron activity coming from the baroreceptors as an arterial pressure that is too high. ➍ It responds by changing its normal rate of nerve stimulation—the firing of motor neurons from the brain to the heart and blood vessels decreases. ➎ The effect on the heart is to lower heart rate and the force of contraction, thereby lowering cardiac output. ➏ The effect on blood vessels is to reduce vascular resistance, leading to increased blood flow through the blood vessels. Together, decreases in both cardiac output and vascular resistance lower blood pressure back toward normal. Exactly the opposite sequence of events occurs when arterial pressure falls below normal. When pressure falls and the arteries are stretched less than normal, the baroreceptors send fewer sensory neuron signals to the brain. The brain correctly interprets this as a fall in pressure and sends signals to the heart and blood vessels that increase cardiac output and vascular resistance, raising arterial blood pressure again.

How an allergic reaction develops:

➊ At some point, exposure to an allergen triggers a primary immune response referred to here as a sensitizing exposure, causing B cells to produce specific IgE antibodies. ➋ The IgE antibodies bind to mast cells (found primarily in connective tissue) and to circulating basophils. These cells are then said to be sensitized. ➌ When the same allergen enters the body the next time—a subsequent exposure—it binds to the IgE antibodies on mast cells and basophils, causing them to release histamine. ➍ The result is an allergic reaction, a typical inflammatory response that includes warmth, redness, swelling, and pain in the area of contact with the allergen. Histamine also increases secretion of mucus in the region. Every time the body is exposed to this allergen, the body reacts as if it has an injury or infection, even though it doesn't. Some allergens affect only the areas exposed. Other allergens, including food allergens and bee sting venom, are absorbed or injected into the bloodstream. Absorbed or injected substances are carried quickly to mast cells throughout the body, including connective tissue in the respiratory, digestive, and circulatory systems. Such allergens often elicit a systemic response, meaning they affect several organ systems. Systemic responses include constriction of smooth muscle in the lungs and digestive system and dilation of blood vessels. Symptoms of a severe systemic allergic reaction can include difficulty breathing (caused by constricted airways), severe stomach cramps (muscle contractions), swelling throughout the body (increased capillary permeability), and circulatory collapse with a life-threatening fall in blood pressure (dilated arterioles). This is known as anaphylactic shock. Anyone who appears to be suffering from anaphylactic shock should receive immediate medical attention because the reaction can be fatal. The symptoms often begin suddenly, and doctors advise people with a history of strong allergic reactions to carry an emergency kit with them at all times. The kit contains a self-injectable hypodermic syringe of epinephrine, a hormone that dilates the airway and constricts peripheral blood vessels, preventing shock. Most allergies, however, are more annoying than dangerous. Antihistamines—drugs that block the effects of histamine—are often effective treatments fo

Every cardiac cycle consists of three steps, as shown in Figure 8.11, starting with the heart as it first begins to contract:

➊ Atrial Systole ➋ Ventricular Systole ➌ Diastole

The pattern of blood flow within the cardiovascular system is shown in Figure 8.8. Let's follow the flow of blood through the system, starting with the return of blood to the heart from the systemic circuit.

➊ Deoxygenated venous blood returns to the heart and ➋ enters the right atrium. ➌ From there it passes through the right atrioventricular valve into the right ventricle. The right ventricle pumps blood through the pulmonary semilunar valve into ➍ the pulmonary trunk (the main pulmonary artery) leading to the lungs. ➎ The pulmonary trunk divides into the right and left pulmonary arteries, which supply the right and left lungs, respectively. ➏ Blood entering the lungs passes through the pulmonary capillaries. This is where gas exchange occurs; blood gives up and receives a fresh supply of from the air we inhale. ➐ The freshly oxygenated blood flows into the pulmonary veins leading back to the heart. On returning to the heart after its trip through the lungs, ➑ the now-oxygenated blood flows into the left atrium and then ➒ passes through the left atrioventricular valve to enter the left ventricle. ➓ The left ventricle pumps the blood into the aorta. ⓫ Some of the blood travels up the main arteries to the head and upper body, and the rest passes down the aorta to the torso and lower limbs. ⓬ Upon arrival at the capillaries in the systemic circuit, blood delivers to the tissues and picks up waste . Then it returns to the venous system, eventually making its way back to the great veins that enter the heart.

How a macrophage acts as an antigen-presenting cell (APC):

➊ First, an APC encloses and then engulfs a foreign cell or pathogen in a vesicle and ➋ partially digests it. ➌ Then the vesicle fuses with another vesicle containing MHC molecules, ➍ forming antigen-MHC complexes. ➎ Finally, the vesicle migrates to the surface of the cell and fuses with the cell membrane, displaying the antigen-MHCs on the cell's surface. In essence, the cell "presents" the antigen for T cells to recognize, along with its own cell-surface self marker.

How HIV replicates:

➊ HIV first attaches to the CD4 receptor of a helper T cell. The attachment fuses the retrovirus's envelope with the cell's membrane, ➋ releasing the viral RNA and enzymes into the cell. ➌ Under the influence of the viral enzymes and using the viral RNA as a template (a pattern), the host cell is forced to make double-stranded "viral" DNA. This process of synthesizing double-stranded DNA using an RNA template in retrovirus replication is called reverse transcription because the genetic flow of information is opposite that in normal transcription. Reverse transcription is catalyzed by an enzyme unique to retroviruses called reverse transcriptase. ➍ The newly transcribed double-stranded DNA fragment containing the retrovirus' genetic information is then inserted into the cell's DNA. The cell, not recognizing the DNA as foreign, ➎ uses it to produce more viral RNA and proteins, which are then assembled into thousands of new viruses within the cell. ➏ New viruses are released from the infected helper T cell by a budding process. The sheer magnitude of viral replication saps the T cell's energy, shortening its lifespan. The new viruses move on to infect, other helper T cells.

The inflammatory response (Figure 9.8)

➊ Histamine, which promotes vasodilation of small blood vessels, and other chemicals are released by damaged cells and mast cells. White blood cells called basophils also release histamine. ➋ Chemicals released by the tissue damage also activate complement proteins, which diffuse out of the leaky capillaries and begin destroying bacteria. Recall that most white blood cells (phagocytes) are too large to cross capillary walls. ➌ As histamine dilates blood vessels, however, the endothelial cells in vessel walls pull slightly apart, and the vessels become more permeable. This allows additional phagocytes to squeeze through capillary walls into the interstitial fluid. There they attack foreign organisms and damaged cells. After destroying pathogens, some phagocytes travel to the lymphatic system, where their presence activates lymphocytes to initiate specific defense mechanisms

Inspiration (inhalation) pulls air into the respiratory system as lung volume expands, and expiration (exhalation) pushes air out as lung volume declines again. Let's look at a cycle of inspiration and expiration, starting from the relaxed state at the end of an expiration (Figure 10.9):

➊ Relaxed state. At rest, both the diaphragm and the intercostal muscles are relaxed. The relaxed diaphragm appears dome shaped. ➋ Inspiration. As inspiration begins, the diaphragm contracts, flattening it and pulling its center downward. At the same time, the intercostal muscles contract, pulling the ribs upward and outward. These two actions of skeletal muscle increase the volume of and lower the pressure within the pleural cavity. Because the lungs are elastic and the pressure around them has just fallen relative to the atmosphere, they expand with the pleural cavity. Expansion of the lungs reduces air pressure within the lungs relative to the atmosphere, allowing air to rush in. ➌ Expiration. Eventually, the muscle contractions end. As the muscles relax the diaphragm returns to its domed shape, the ribs move downward and inward, and the pleural cavity becomes smaller. The rest of the process reverses as well. The lungs become smaller, so pressure within the lungs rises relative to the atmosphere and air flows out.

How antibodies inactivate pathogens:

➊ Some antibodies cause a pathogen's cells to agglutinate (clump together), preventing them from entering human cells and causing disease. Agglutination also reduces the number of phagocytic events necessary to dispose of the microbes. ➋ Some antibodies need only bind to their antigen, creating an antigen-antibody complex, to mark the antigen (and the bacterial cell that carries it) for destruction by phagocytes. ➌ Some antigen-antibody complexes activate complement proteins that enhance inflammation and ultimately lyse the bacterial cell. ➍ Sometimes antibodies bind to an invading bacteria, a virus, or a toxin molecule and prevent it from attaching to a host cell, effectively neutralizing the threat.

How monoclonal antibodies are produced

➊ Typically, after a mouse has been immunized with a specific antigen to stimulate B cell production, ➋ B cells are removed from the mouse's spleen. ➌ The B cells are fused with myeloma (cancer) cells to create hybridoma (hybrid cancer) cells that have desirable traits of both parent cells: They each produce a specific antibody, and they proliferate with cancer-like rapidity. As these hybridoma cells grow in culture, ➍ those that produce the desired antibody are separated out and ➎ cloned, ➏ producing millions of copies. ➐ The antibodies the hybridoma cells produce are harvested and processed to create preparations of pure monoclonal antibodies.

The production of antibodies by B cells:

➊ When a B cell with just the right surface receptor encounters the appropriate antigen, its surface receptors bind to the antigen. ➋ This activates the B cell to grow and then multiply rapidly, producing more B cells exactly like the original and bearing the same surface receptors. The resulting identical cells, all descended from the same cell, are called clones and this process is referred to as clonal expansion. Some of these descendants differentiate into specialized antibody-producing cells called plasma cells and others form memory cells. In some cases, ➌ a B cell may require assistance from activated helper T cells to initiate clonal expansion. The help comes in the form of stimulatory chemicals (cytokines) secreted by the helper T cells. ➍ The plasma cells begin to secrete their antibodies into the lymph fluid and ultimately into the blood plasma. A typical plasma cell can make antibody molecules at a staggering rate—about 2,000 molecules per second. A plasma cell maintains this frantic pace for a few days and then dies, but its antibodies continue to circulate in blood and lymph. ➎ Memory cells are long-lived cells that remain inactive until an antigen in the body encountered in the past reappears in the body. Memory cells store information about encountered pathogens, which means, if there is a second exposure to a pathogen, the immune response is "known" and therefore occurs faster than with the first encounter. With the second exposure and every subsequent exposure, memory cells quickly divide forming plasma cells that start to secrete antibodies. Memory cells are the basis for long-term immunity.

Cell-mediated immunity in action:

➊ When a cytotoxic T cell locates and binds to a target cell (this might be a tumor cell or a cell infected with a virus or intracellular bacteria), secretory vesicles migrate to the cell surface and fuse with it, ➋ releasing a protein called perforin into the space between the two cells. The perforin molecules assemble themselves into a pore in the target cell, allowing water and salts to enter. That alone should eventually kill the cell in much the same way that activated complement protein does (review Figure 9.8). ➌ But to ensure the target cell dies, the cytotoxic T cell also releases granzyme, a toxic enzyme that is small enough to pass through the pore. The cytotoxic T cell then detaches from the target cell and goes off in search of other prey.

The resting potential of a neuron undergoes a slight change when an impulse arrives from another neuron (Figure 11.4). Depending on the type of signal and its strength, the change might be to

➊ depolarize the membrane (move the voltage closer to zero) or ➋ hyperpolarize it (make it even more negative). These transient local changes in resting potential are called graded potentials because they can vary in size. A key feature of graded potentials is that they can add up in space and time, ➌ meaning that many incoming signals from other neurons produce a bigger change in membrane potential than does one impulse alone. This is known as summation. ➍ If the sum of all graded potentials is sufficiently strong to reach a certain triggering membrane voltage called the threshold, an action potential results. ➎ An action potential is a sudden, temporary reversal of the voltage difference across the cell membrane. Once an action potential is initiated, it sweeps rapidly down the axon at a constant amplitude and rate of speed until it reaches the axon terminals.

The activation and clonal expansion of helper T cells:

➊ it is activated to become a helper T cell. ➋ The new helper T cell undergoes clonal expansion, quickly producing a clone of identical helper T cells. Because all the cells in the clone carry the same receptors, they all recognize the same antigen. ➌ Most of the cells in the helper T cell clone begin secreting a class of signaling molecules called cytokines. ➍ Cytokines are proteins that stimulate other immune cells such as phagocytes, NK cells, and T cells with CD8 receptors. They also attract other types of white blood cells to the area, enhancing nonspecific defenses and activate B cells, creating an important link between antibody-mediated and cell-mediated immunity. ➎ A few cloned helper cells become memory T cells. Like memory B cells, memory T cells become inactive, to be reactivated upon future encounters with the antigen.