BIO 106 - Animal Structure & Function: Chapters 34, 37, 40-42

Antihistamines What do they inhibit, the release of what?

*inhibit allergic reactions of inflammation*, redness, and itching caused by the release of histamine •Antihistamines •interfere with histamine's action and •*provide temporary relief* •Anaphylactic shock •is a dangerous allergic reaction, •may occur in people who are extremely sensitive to certain allergens, such as bee venom, penicillin, or allergens in peanuts or shellfish, and •can be treated with injections of epinephrine.

Hypersensitivities

•Allergies are hypersensitive (exaggerated) responses to otherwise harmless antigens in our surroundings. •Antigens that cause allergies are called allergens •Allergic reactions typically occur •very rapidly and •in response to tiny amounts of an allergen. •Allergic reactions can occur in many parts of the body, including •nasal passages, •bronchi, and •skin •The symptoms of an allergy result from a two-stage reaction. 1.The first stage, called sensitization, occurs when a person is first exposed to an allergen. 2.The second stage begins when the person is exposed to the same allergen later. •The allergen binds to mast cells. •Mast cells release histamine, causing irritation, itchy skin, and tears. Maladaptive immune responses toward harmless foreign substances or self antigens that occur after tissue sensitization are termed hypersensitivities. The types of hypersensitivities include immediate, delayed, and autoimmunity. A large proportion of the population is affected by one or more types of hypersensitivity. Allergies The immune reaction that results from immediate hypersensitivities in which an antibody-mediated immune response occurs within minutes of exposure to a harmless antigen is called an allergy. In the United States, 20 percent of the population exhibits symptoms of allergy or asthma, whereas 55 percent test positive against one or more allergens. Upon initial exposure to a potential allergen, an allergic individual synthesizes antibodies of the IgE class via the typical process of APCs presenting processed antigen to TH cells that stimulate B cells to produce IgE. This class of antibodies also mediates the immune response to parasitic worms. The constant domain of the IgE molecules interact with mast cells embedded in connective tissues. This process primes, or sensitizes, the tissue. Upon subsequent exposure to the same allergen, IgE molecules on mast cells bind the antigen via their variable domains and stimulate the mast cell to release the modified amino acids histamine and serotonin; these chemical mediators then recruit eosinophils which mediate allergic responses. Figure 42.26 shows an example of an allergic response to ragweed pollen. The effects of an allergic reaction range from mild symptoms like sneezing and itchy, watery eyes to more severe or even life-threatening reactions involving intensely itchy welts or hives, airway contraction with severe respiratory distress, and plummeting blood pressure. This extreme reaction is known as anaphylactic shock. If not treated with epinephrine to counter the blood pressure and breathing effects, this condition can be fatal. On first exposure to an allergen, an IgE antibody is synthesized by plasma cells in response to a harmless antigen. The IgE molecules bind to mast cells, and on *secondary exposure* = *2nd exposure* + *faster/stronger* than first + the *mast cells release histamines* and other modulators that *affect allergy symptoms* + *activates effector/memory* - Delayed hypersensitivity is a cell-mediated immune response that takes approximately one to two days after secondary exposure for a maximal reaction to be observed. This type of hypersensitivity involves the TH1 cytokine-mediated inflammatory response and may manifest as local tissue lesions or contact dermatitis (rash or skin irritation). Delayed hypersensitivity occurs in some individuals in response to contact with certain types of jewelry or cosmetics. Delayed hypersensitivity facilitates the immune response to poison ivy and is also the reason why the skin test for tuberculosis results in a small region of inflammation on individuals who were previously exposed to Mycobacterium tuberculosis. That is also why cortisone is used to treat such responses: it will inhibit cytokine production. Autoimmunity Autoimmunity is a type of hypersensitivity to self antigens that affects approximately five percent of the population. Most types of autoimmunity involve the humoral immune response. Antibodies that inappropriately mark self components as foreign are termed autoantibodies. In patients with the autoimmune disease myasthenia gravis, muscle cell receptors that induce contraction in response to acetylcholine are targeted by antibodies. The result is muscle weakness that may include marked difficultly with fine and/or gross motor functions. In systemic lupus erythematosus, a diffuse autoantibody response to the individual's own DNA and proteins results in various systemic diseases. As illustrated in Figure 42.27, systemic lupus erythematosus may affect the heart, joints, lungs, skin, kidneys, central nervous system, or other tissues, causing tissue damage via antibody binding, complement recruitment, lysis, and inflammation. Figure 42.27 Systemic lupus erythematosus is characterized by autoimmunity to the individual's own DNA and/or proteins, which leads to varied dysfunction of the organs. (credit: modification of work by Mikael Häggström) Autoimmunity can develop with time, and its causes may be rooted in molecular mimicry. Antibodies and TCRs may bind self antigens that are structurally similar to pathogen antigens, which the immune receptors first raised. As an example, infection with Streptococcus pyogenes (bacterium that causes strep throat) may generate antibodies or T cells that react with heart muscle, which has a similar structure to the surface of S. pyogenes. These antibodies can damage heart muscle with autoimmune attacks, leading to rheumatic fever. Insulin-dependent (Type 1) diabetes mellitus arises from a destructive inflammatory TH1 response against insulin-producing cells of the pancreas. Patients with this autoimmunity must be injected with insulin that originates from other sources. -*Inflammation* = *disinfect/clean injured tissue*, *limit spread of infection* to other organs -*Tissue damage triggers inflammatory response* a major component of our innate immunity •*Inflammation* may be *localized or widespread (systemic)* •Sometimes microorganisms get into the blood or release toxins that are carried throughout the body in the bloodstream. •Bacterial infections can bring about an overwhelming systemic inflammatory response leading to septic shock, characterized by very high fever and low blood pressure.

AIDS

•AIDS (acquired immunodeficiency syndrome), results from infection by HIV, the human immunodeficiency virus. •Since 1981, AIDS has killed nearly 30 million people, and more than 34 million people live today with HIV. •In 2010, •2.7 million people were newly infected with HIV, and •over 1.8 million died of AIDS. •Most HIV infections and AIDS deaths occur in nonindustrialized nations of southern Asia and sub-Saharan Africa. -The AIDS virus usually attacks helper T cells, impairing the cell-mediated immune response and humoral immune response, and opening the way for opportunistic infections -AIDS is currently incurable, although drugs can slow HIV reproduction and the progress of AIDS. •Drugs, vaccines, and education are areas of focus for prevention of HIV infection. -•HIV mutates at a very high rate during replication because reverse transcriptase does not have an editing function to correct mistakes as DNA polymerase does. •At one time, there was great hope that a "cocktail" of three anti-AIDS drugs could eliminate the virus in an infected person. •The continual use of anti-AIDS drugs has led to the spread of drug-resistant HIV strains.

Capiillaries Capillaries have ____ walls. Substances leave and enter through what fluid and by what process? Capillaries do ________ of nutrients and oxygen between blood and tissues under what pressure? There is an incr surface area bc more _________

•Capillaries have very *thin walls* •*Substances leave blood and enter interstitial fluid* by *diffusion*, •vesicles that *form by endocytosis* on one side of the cell and then *release their contents by exocytosis* on the other side, and •*pressure-driven flow through clefts* between epithelial cells. *EXCHANGE of nutrients + oxygen* between blood and tissues, *low pressure*, *epithelial*, *incr surface area* bc more exchange -has a *arterial high pressure end* and a *venous low pressure end* -*Lost fluid* is also *picked up by lymphatic system*, which includes a network of tiny vessels intermingled among the capillaries •Smooth muscles in arteriole walls can influence blood pressure by changing the resistance to blood flow out of the arteries and into arterioles. •*Blood flow* through capillaries is also *restricted by precapillary sphincters* •By opening and closing these precapillary sphincters, blood flow to particular regions can be increased or decreased. At any given time, only about 5-10% of your body's capillaries have blood flowing through them

Antigen-presenting Cells B white blood cells make what and T white blood cells help? There are 3 types of T cells: What are antigens? When an antigen is detected, what is increased? Not all antigens will provoke a ______________

-*Unlike NK cells of INNATE* immune system, *B cells* (B lymphocytes) = *white blood cell that make antibodies* whereas *T cells* (T lymphocytes) = *white blood cell* that help in *immune response* T cells are a key component in the cell-mediated response—the specific immune *response that utilizes T cells to neutralize cells that have been infected* -There are *3 types of T cells*: *cytotoxic, helper, suppressor* T cells -*Cytotoxic T cells destroy virus-infected cells* in the cell-mediated immune response, and *helper T cells activate antibody* + cell-mediated immune responses* -*Suppressor T cells* (opp of helper) *deactivate T cells/B cells* when needed, and thus *prevent immune response from becoming too intense* -An *antigen* = a *foreign or "non-self" macromolecule* that *reacts w/ cells of the immune system* -*Not all antigens provoke a response* - For instance, individuals produce *innumerable "self" antigens = constantly exposed to harmless foreign antigens* such as food proteins, pollen, or dust components. The suppression of immune responses to harmless macromolecules is *highly regulated and typically prevents damaging to the host* known as tolerance. -The *innate immune system contains cells that detect potentially harmful antigens*, and then *inform the adaptive* immune response about the presence of these antigens - An *antigen-presenting cell (APC)* is an immune cell that *detects, engulfs, informs the adaptive* immune response *about an infection* -When a pathogen is detected, these *APCs will phagocytose the pathogen and digest it to form many different fragments of the antigens* -Antigen fragments will then be transported to the surface of the APC, where they will serve as an *indicator to other immune cells* -*Dendritic cells* are immune cells that *process antigen material*; they are present in the skin (Langerhans cells) and the lining of the nose, lungs, stomach, and intestines. Sometimes a dendritic cell presents on the surface of other cells to induce an immune response, thus functioning as an antigen-presenting cell. Macrophages also function as APCs. Before activation and differentiation, B cells can also function as APCs. After phagocytosis by APCs, the phagocytic vesicle fuses with an intracellular lysosome forming phagolysosome. Within the phagolysosome, the components are broken down into fragments; the fragments are then loaded onto MHC class I or MHC class II molecules and are transported to the cell surface for antigen presentation -Note that T lymphocytes cannot properly respond to the antigen unless it is processed and embedded in an MHC II molecule. APCs express MHC on their surfaces, and when combined with a foreign antigen, these complexes signal a "non-self" invader -Once the fragment of antigen is embedded in the MHC II molecule, the immune cell can respond. Helper T- cells are one of the main lymphocytes that respond to antigen-presenting cells. Recall that all other nucleated cells of the body expressed MHC I molecules, which signal "healthy" or "normal." -*Antigens* are any *molecule that elicits adaptive immune response* or *nonself molecules* that *protrude from pathogens/viruses, bacteria, mold spores, pollen, house dust, transplanted organs* -When the immune system *detects an antigen*, it responds with an *incr in cells that attack/produce immune proteins* called *antibodies* + *found in plasma*

Negative and Positive Feedback

-Any *homeostatic process changes the direction of the stimulus is a negative feedback loop* -It *may either incr/decr the stimulus* but the *stimulus is not allowed to continue* as it did *before the receptor sensed it* -*If a level is too high*, the *body does something to bring it down*, and conversely, *if a level is too low*, the *body does something to make it go up -Hence the term *negative feedback* = An example is *animal maintenance of blood glucose levels* -When *an animal has eaten, blood glucose levels rise* -This is *sensed by the nervous system* *Specialized cells in the pancreas* sense this, and the *hormone insulin is released by the endocrine system* -*Insulin causes blood glucose levels to decr*, as would be expected in a *negative feedback system* -However, *if an animal has not eaten and blood glucose levels decr* this is sensed in another group of cells in the pancreas, and the *hormone glucagon is released causing glucose levels to incr* -This is still a *negative feedback loop, but not in the direction expected by the use of the term "negative."* Another example of an *increase as a result of the feedback loop is the control of blood calcium* If calcium levels decrease, specialized cells in the parathyroid gland sense this and release parathyroid hormone (PTH), causing an increased absorption of calcium through the intestines and kidneys and, possibly, the breakdown of bone in order to liberate calcium. The effects of PTH are to raise blood levels of the element. *Negative feedback loops are the predominant mechanism used in homeostasis* -A *positive feedback loop maintains the direction of the stimulus*, possibly *accelerating it*. Few examples of positive feedback loops *exist in animal bodies, but one is found in the cascade of chemical reactions* that result in *blood clotting, or coagulation* -As *one clotting factor is activated*, it *activates the next factor in sequence until a fibrin clot* is achieved. The *direction is maintained, not changed, so this is positive feedback* + another example of positive feedback is uterine contractions during childbirth -The hormone oxytocin, made by the endocrine system, stimulates the contraction of the uterus. This produces pain sensed by the nervous system. Instead of lowering the oxytocin and causing the pain to subside, more *oxytocin is produced until the contractions are powerful enough to produce childbirth* It is *possible to adjust a system's set point* + When this happens, the *feedback loop works to maintain the new setting* -An example of this is *blood pressure: over time*, the *normal or set point for blood pressure can incr as a result of continued incr in blood pressure* -The *body no longer recognizes the elevation* as *abnormal* and *no attempt is made to return to the lower set point* -The result is the maintenance of an *elevated blood pressure that can have harmful effects on the body* -Medication can *lower blood pressure and lower the set point* in the system to a more healthy level. This is called a *process of alteration of the set point in a feedback loop* -*Changes can be made in a group of body organ systems* in order to *maintain a set point* in another system. This is called *acclimatization*. This occurs, for instance, *when an animal migrates to a higher altitude than accustomed to*. -In order *to adjust to the lower oxygen levels at the new altitude*, the *body incr number of red blood cells* circulating in the blood to ensure *adequate oxygen delivery to the tissues*. Another example of *acclimatization is animals that have seasonal changes in their coats*: a heavier coat in the winter ensures adequate heat retention, and a light coat in summer assists in keeping body temperature from rising to harmful levels.

Antibodies of the Mucosal Immune System

Antibodies synthesized by the mucosal immune system include IgA and IgM. Activated B cells differentiate into mucosal plasma cells that synthesize and secrete dimeric IgA, and to a lesser extent, pentameric IgM. Secreted IgA is abundant in tears, saliva, breast milk, and in secretions of the gastrointestinal and respiratory tracts. Antibody secretion results in a local humoral response at epithelial surfaces and prevents infection of the mucosa by binding and neutralizing pathogens.

Immunological Memory What's a memory cell? What's an effector cell?

B lymphocytes are the cells of the immune system that make antibodies to invading pathogens like viruses. *They form memory cells that remember the same pathogen for faster antibody production in future infections.* In the immune system, *effector cells are the relatively short-lived activated cells that defend the body in an immune response.* Effector B cells are called plasma cells and secrete antibodies, and activated T cells include cytotoxic T cells and helper T cells, which carry out cell-mediated responses. The adaptive immune system possesses a memory component that allows for an efficient and dramatic response upon reinvasion of the same pathogen. Memory is handled by the adaptive immune system with little reliance on cues from the innate response. During the adaptive immune response to a pathogen that has not been encountered before, called a primary response, plasma cells secreting antibodies and differentiated T cells increase, then plateau over time -As B and T cells mature into effector cells, a *subset of the naïve populations differentiates* into B and T *memory cells* with the same antigen specificities, lie in *wait to help activate in 2nd exposure to the antigen* -A memory cell is an antigen-specific B or T lymphocyte that does *not differentiate into effector cells during primary immune response*, but that *can immediately become effector cells upon re-exposure* to the same pathogen -During the *primary immune response* = *1st exposure* + *much slower* than 2nd + *memory cells do not respond* to antigens and do not contribute to host defenses. As the infection is cleared and pathogenic stimuli subside, the effectors are no longer needed, and they undergo apoptosis. In contrast, the memory cells persist in the circulation. If the pathogen is never encountered again during the individual's lifetime, B and T memory cells will circulate for a few years or even several decades and will gradually die off, having never functioned as effector cells. However, if the host is re-exposed to the same pathogen type, circulating memory cells will immediately differentiate into plasma cells and CTLs without input from APCs or TH cells. One reason the adaptive immune response is delayed is because it takes time for naïve B and T cells with the appropriate antigen specificities to be identified and activated. Upon reinfection, this step is skipped, and the result is a more rapid production of immune defenses. Memory B cells that differentiate into plasma cells output tens to hundreds-fold greater antibody amounts than were secreted during the primary response, as the graph in Figure 42.17 illustrates. This rapid and dramatic antibody response may stop the infection before it can even become established, and the individual may not realize they had been exposed. Vaccination is based on the knowledge that exposure to noninfectious antigens, derived from known pathogens, generates a mild primary immune response. The immune response to vaccination may not be perceived by the host as illness but still confers immune memory. When exposed to the corresponding pathogen to which an individual was vaccinated, the reaction is similar to a secondary exposure. Because each reinfection generates more memory cells and increased resistance to the pathogen, and because some memory cells die, certain vaccine courses involve one or more booster vaccinations to mimic repeat exposures: for instance, tetanus boosters are necessary every ten years because the memory cells only live that long.

Oral Cavity: Trachea and Espohagus The oral cavity is the point of what in the digestive system? What enzyme is produced by salivary glands and what does it do? What pathways do the pharynx open up to? The trachea leads to what and the esophagus leads to what? What flap allows food to pass into esophagus not trachea? What process does food undergo as it travels down esophagus? Regulation of the passage of food from the stomach is accomplished by

Parts of the Digestive System: Oral Cavity, Esophagus, Stomach, Small Intestine, Large Intestine, Rectum & Anus, Accessory Organs -The *vertebrate digestive system* = *facilitates the transformation of food matter to nutrient components* that sustain organisms. Oral Cavity -The *oral cavity/mouth* is the *point of entry of food into the digestive system* -The *food is broken into smaller particles w/ mastication* (the chewing action of the teeth) -*All mammals have teeth* and *can chew* their food. -The extensive chemical process of *digestion begins in the mouth* -As *food is chewed* + *saliva* (by the *salivary glands- *glycoprotein moistening food*, *pH buffer*, *kill some bacteria*, *amylase*) *mixes w/ the food* -*Saliva* = *watery substance produced in the mouths* of many animals -*3 major glands that secrete saliva* = 1) the *parotid* 2) the *submandibular* 3) the *sublingual* -*Saliva contains mucus* that *moistens food/buffers the pH of the food* Saliva also contains immunoglobulins/lysozymes = *antibacterial action to reduce tooth decay by inhibiting growth of some bacteria* -*Saliva also contains an enzyme* called *salivary amylase* = *begins process of converting starches in the food into disaccharide-maltose* -Another enzyme called *lipase* = *produced by the cells in tongue* -*Lipases* are a class of *enzymes that break down triglycerides* -The *lingual lipase breaks down starches/fats in the food* -The *chewing/wetting action provided by teeth/saliva prepares food into a mass* = *bolus* (for swallowing) -The *tongue helps in swallowing*—*moving the bolus from the mouth to the pharynx* - The *pharynx opens to 2 passageways* = 1. *trachea* = leads *to the lungs* -The *trachea has an opening called the glottis*, which is *covered by a cartilaginous flap* = *epiglottis* -When *swallowing*, the *epiglottis closes the glottis* and *food passes into the esophagus NOT the trachea* -This arrangement *allows food to be kept out of the trachea* 2. *esophagus* = leads *to the stomach* -The esophagus is a *tubular organ connecting the mouth to the stomach* -The *(crop) chewed food passes through the esophagus after being swallowed* -The *smooth muscles* of the esophagus *undergo PERISTALSIS* = *a series of wave-like movements* that *push food toward the stomach* -The *peristalsis wave is unidirectional*—it *moves food from the mouth to the stomach*, and reverse movement is not possible. The *peristaltic movement of the esophagus is an involuntary reflex*; it takes place *in response to swallowing* -*SPHINCTER* = A *ring-like muscle forms valves in the digestive system* -The *gastro-esophageal sphincter is located at the STOMACH END of the esophagus* -*In response to swallowing/ pressure exerted by the bolus of food* = this *sphincter opens* + *bolus enters the stomach* -W/ *no swallowing action* = this *sphincter is shut/prevents contents of the stomach from traveling up the esophagus* -Many *animals have a true sphincter* -However, *in humans* = there is *no true sphincter*, but the *esophagus remains closed w/ no swallowing action* + *acid reflux/"heartburn"* occurs when the *acidic digestive juices escape into the esophagus*

A widely used weed killer demasculinizes male frogs

Scientists exposed developing male frogs to very low levels of atrazine for three years. An equal number of control and atrazine-exposed adult males of similar weights were placed into a pool with females. A mating contest was set up, in which control males and atrazine-exposed males competed for females. The scientists recorded each male frog's ability to successfully grasp a female with his front legs during a mating behavior called amplexus. Atrazine's demasculinizing effect on male frogs was demonstrated by reduced mating behaviors, testosterone deficiencies, and some sex reversals.

Arteries What is their function? What kind of blood? What is the main artery called and where does it take blood to? What are the 4 arteries? CBTI Major arteries are lined by ________ cells and contain what that allows them to stretch?

The *blood from the heart* is *carried* through the body *by complex network of blood vessels* -*ARTERIES* = take *OXYGENATED blood away from the heart* -The *main artery = aorta* that branches into major arteries that *take blood to diff limbs/organs* -These *major arteries include the CAROTID artery* = that takes *blood to the brain*, the *BRANCHIAL arteries* that take *blood to the arms*, and the *THORACIC artery* that takes *blood to the thorax* and then into the hepatic, renal, and gastric arteries for the liver, kidney, and stomach, respectively. The *ILIAC artery* takes *blood to the lower limbs* -The major arteries diverge into minor arteries, and then smaller vessels called arterioles, to reach more deeply into the muscles and organs of the body •are lined by a single layer of *epithelial cells* and •have *elastic fibers* in an outer *connective tissue* layer that allows these vessels to recoil after stretching. •Arteries contain a thick layer of *smooth muscle* in their walls that can constrict and reduce blood flow.

Hormonal Regulation of the Reproductive System What 2 hormones are released in posterior pituitary?

*STIMULATE TESTES/OVARIES TO PRODUCE REPRODUCTIVE HORMONES* -*Regulation of the reproductive system* is a process that *requires hormones from pituitary gland*,the *adrenal cortex*, the *gonads* -During *puberty in males/females*, the hypothalamus produces gonadotropin-releasing hormone (GnRH), which stimulates the production and *release of follicle-stimulating hormone (FSH)* and *luteinizing hormone (LH)* from the *anterior pituitary gland* -These *hormones regulate gonads* (*testes* in males and *ovaries* in females) and therefore are called *gonadotropins* -In both males and females, *FSH stimulates gamete prod* and *LH stimulates hormone prod by gonads* -An *incr in gonad hormone levels inhibits GnRH prod* through a *negative feedback loop* Steroid sex hormones affect growth, affect development, and regulate reproductive cycles and sexual behavior. The *synthesis of sex hormones* by the gonads is regulated by the *hypothalamus and pituitary* In males, FSH stimulates the maturation of sperm cells. FSH production is inhibited by the hormone inhibin, which is released by the testes. LH stimulates production of the sex hormones ( androgens) by the interstitial cells of the testes and therefore is also called interstitial cell-stimulating hormone. The most widely known androgen in males is testosterone. Testosterone promotes the production of sperm and masculine characteristics. The adrenal cortex also produces small amounts of testosterone precursor, although the role of this additional hormone production is not fully understood. In females, FSH stimulates development of egg cells, called ova, which develop in structures called follicles. Follicle cells produce the hormone inhibin, which inhibits FSH production. LH also plays a role in the development of ova, induction of ovulation, and stimulation of estradiol and progesterone production by the ovaries, as illustrated in Figure 37.9. Estradiol and progesterone are steroid hormones that prepare the body for pregnancy. Estradiol produces secondary sex characteristics in females, while both estradiol and progesterone regulate the menstrual cycle.

Red Blood Cells There are 5-6 mil red blood cells delivering what and removing what? They are stem cells from _______ _________ + when stem cells divide it equals = In what vertebrates do red blood cells have a nucleus? What is anemia? What is EPO and why do athletes inject this into themselves? Red blood cells have a small size but large ______ _______ What are red blood cells coated with?

- *5-6mil Red blood cells* = specialized cells that *circulate thru the body delivering O2* (binds 4 O) to cells + *from stem cells in the bone marrow* -*WHEN STEM CELLS DIVIDE*= *1 daughter* + *1 constant stem* -*In mammals* = *NO NUCLEUS* red blood cells -*In birds/non- avian reptiles* = *NUCLEUS* is still maintained in red blood cells -The *red* coloring of *blood* comes *from the iron-containing protein hemoglobin* = *carry O2 but remove CO2* -In mammals, the lack of organelles in erythrocytes leaves more room for the hemoglobin molecules, and the lack of mitochondria also prevents use of the oxygen for metabolic respiration -Only mammals have anucleated red blood cells + some mammals (camels, for instance) have nucleated red blood cells -*The advantage of nucleated red blood cells is that these cells can undergo mitosis* -*Anucleated red blood cells metabolize anaerobically* (without oxygen), to *produce ATP* + *incr efficiency of O2 transport* -Not all organisms use hemoglobin as the method of oxygen transport. Invertebrates that utilize hemolymph rather than blood use different pigments to bind to the oxygen. These pigments use copper or iron to the oxygen. Invertebrates have a variety of other respiratory pigments. -*Anemia* = can be caused by *abnormally low hemoglobin* or *low red blood cell count* •Anemia causes fatigue due to lack of oxygen in tissues. -*Adequate numbers of red blood cells* = *essential* for healthy body function. -After circulating for *3-4 months* = *red blood cells are broken down* and their molecules *recycled* -*Much iron removed from the hemoglobin* is *returned to the bone marrow*, where *new red blood cells are formed* at the amazing rate of 2 million per second -*Athlete's hormone erythropoietin (EPO)* = *stimulates* the bone marrow to produce *more red blood cells released from kidney* -More red blood cells can be deadly - heart failure, *strokes = lack of O2*, clotting -When someone has kidney problems = they are given erythopoietin -The *small size/large surface area* of red blood cells *diffuses O2 + CO2 across plasma membrane* -In the lungs, *CO2 is released* + *O2 is taken in by blood* In the tissues, oxygen is released from the blood and carbon dioxide is bound for transport back to the lungs. Studies have found that *hemoglobin also binds nitrous oxide (NO)* = a *vasodilator that relaxes blood vessels/capillaries* + may *help w/ gas exchange* -Nitroglycerin, a heart medication for angina and heart attacks, is converted to NO to help relax the blood vessels and increase oxygen flow through the body. -*Red blood cells* = *glycolipid + glycoprotein coating*; these are *lipids/proteins w/ carb molecules attached* -In humans, the surface glycoproteins and glycolipids on red blood cells vary between individuals, producing the different blood types, such as A, B, and O. Red blood cells have an average life span of 120 days, at which time they are broken down and recycled in the liver and spleen by phagocytic macrophages, a type of white blood cell.

Plasma and Serum The plasma has its own components which include (2)? What is serum? What protein is found in serum and is synthesized in the liver?

-*(55%) PLASMA* = *Solvent for* carrying other *substances* + the *liquid component of blood* + it's *separated by spinning/centrifuging blood at high rotations* -The blood cells and platelets are *separated by centrifugal forces to the bottom of a specimen tube* -The upper liquid layer, plasma, consists of 90% water + substances required for *maintaining ion concentration of interstitial fluid*, *maintaining pH*, *osmotic load*, and for *protecting the body* -The plasma also contains *coagulation factors + antibodies* -*SERUM* = the *plasma component* of blood *w/o coagulation factors* -Serum is *similar to interstitial fluid* where the *correct comp of key ions acting as electrolytes* is *essential* for normal functioning of muscles and nerves -Other components in the serum include *proteins assist w/ maintaining pH and osmotic balance* while *giving viscosity to the blood* -The serum also *contains antibodies, specialized proteins* that are important for *defense against viruses + bacteria* -*Lipids* (including cholesterol) are also *transported along w/ nutrients, hormones, metabolic waste, plus external substances, such as, drugs, viruses, and bacteria* -Human serum *albumin* is the most abundant protein *in human blood plasma* and is *synthesized in the liver* -Albumin, which *constitutes 1/2 of the blood serum protein*, *transports hormones* and *fatty acids*, *buffers pH*, *maintains osmotic pressures* -Immunoglobin is a protein antibody produced in the mucosal lining and plays an important role in antibody-mediated immunity.

Renal Tubule What do tubules do but which one does it most? What is the first part of the tubule called? What is the second part and what two limits? What is the third part that is usually connected to ______________?

The *renal tubule* = a *long + convoluted structure* that emerges *from the glomerulus* and can be *divided into 3 parts* based on function -The first part is called the *proximal convoluted tubule (PCT)* due to its proximity to the glomerulus; it *stays in the renal cortex* -The second part is called the *Loop of Henle*, or nephritic loop, because it forms a loop (with descending and ascending limbs) that *goes through the renal medulla* - The third part of the renal tubule is called the *distal convoluted tubule (DCT)* and this part is also *restricted to the renal cortex* -The DCT, which is the *last part of nephron connects/empties its contents into collecting ducts* that line the medullary pyramids -The *collecting ducts* amass contents *from nephrons + fuse as they enter the papillae of the renal medulla*

The Cardiac Cycle What is the main purpose of the heart? What is the cardiac cycle a coordination of? What is it called when the heart muscles contract (pump) and relax (fill)? What cells make up the cardiac muscle? What is the sinoatrial node and what is it also known as? What is the atrioventricular node? From the AV node, where do the electrical impulses enter? ________ fibers conduct the impulse from the fibers.

-*Main purpose of heart* = to *pump blood thru the body*; it does so in a *repeating sequence* = *CARDIAC CYCLE* -The cardiac cycle is the *coordination of filling/emptying the heart* of blood *by electrical signals that cause heart muscles to contract/relax* The human heart beats over 100,000 times per day -In each cardiac cycle, *the heart contracts (systole) pushing out blood* and pumping it through the body + blood flows from *atria* into *ventricles* this is followed by a *relaxation phase (diastole), where the heart fills* with blood where blood flows from *veins* to *heart chambers* -Closing of the atrioventricular valves produces a monosyllabic "lup" sound. Following a brief delay, the ventricles contract at the same time forcing blood through the semilunar valves into the aorta and the artery transporting blood to the lungs (via the pulmonary artery). Closing of the semilunar valves produces a monosyllabic "dup" sound -The *pumping the heart* = a *function of cardiac muscle cells*, or cardiomyocytes, that *make up the heart muscle* -Cardiomyocytes are *distinctive muscle cells that are striated like skeletal muscle* but *pump rhythmically/involuntarily like smooth muscle*; they are connected by intercalated disks exclusive to cardiac muscle. They are self-stimulated for a period of time and isolated cardiomyocytes will beat if given the correct balance of nutrients and electrolytes -The *autonomous beating of cardiac muscle cells* is *regulated by* = the heart's internal *PACEMAKER* that *uses electrical signals to time the beating of the heart* -The electrical signals and mechanical actions, are intimately intertwined -The internal pacemaker *starts at the SINOATRIAL (SA) node* which is located near the wall of the right atrium. *Electrical charges in atria* + *sets the two atria to contract in unison* -The *pulse reaches a second node* = *ATRIOVENTRICULAR (AV) node* between the right atrium and right ventricle where it *pauses for 0.1 second before spreading to the walls of the ventricles* + *triggers ventricular contractions* -From the AV node, the *electrical impulse enters the BUNDLE BRANCHES*, then to the left and right bundle branches extending through the interventricular septum -Finally, the *PURKINJE fibers conduct the impulse from the apex* of the heart up *the ventricular myocardium* and then the ventricles contract. This pause *allows the atria to empty completely* into the ventricles *before the ventricles pump out the blood* -The electrical impulses in the heart produce electrical currents that flow through the body and can be measured on the skin using electrodes. This information can be observed as an *ELECTROCARDIOGRAM(ECG)*—a *recording of the electrical impulses* of the *cardiac muscle* •*Cardiac output* = is the *volume of blood each ventricle pumps* per minute. •Heart rate is the number of heart beats per minute.

Mammalian Heart and Blood Vessels + Structure The heart is separated in _ chambers by the _______ bc left is oxygenated and right is deoxygenated The heart is a muscle that pumps blood in what 3 divisions of the circulatory system? Is the left side or right side of the heart bigger and why? Where is the heart located under_______ between the lungs? What is the base and what is the apex? What chambers receive blood and chambers pump blood? What valves are there and where are they?

-The heart is *separated in 4 chambers* by the *SEPTUM* bc left is oxygenated and right is deoxygenated -The *heart* is a complex *muscle that pumps blood in 3 divisions of the circulatory system*: the *coronary* (vessels that serve the heart), *pulmonary* (heart and lungs), and *systemic* (systems of the body) -*Coronary circulation* intrinsic to the heart *takes blood directly from the main artery (aorta)* coming from the heart. For pulmonary and systemic circulation, the heart has to pump blood to the lungs or the rest of the body, respectively. -In vertebrates, the lungs are relatively close to the heart in the thoracic cavity. The shorter distance to pump means that the muscle wall on the *right side of the heart is not as thick as the left side* which must have enough pressure to pump blood all the way to your big toe -The *heart muscle is ASYMMETRICAL* as a result of *the distance blood must travel in the pulmonary/systemic circuits* -Since the *right side of the heart sends blood to the pulmonary circuit* it is smaller than the left side which must send blood out to the whole body in the systemic circuit -In humans, *the heart is about the size of a clenched fist*; it is divided into *four chambers: two atria and two ventricles* -Heart located *under sternum*, between lungs + has *cardiac muscle tissue* *Base—wide, superior portion* of heart, large vessels attach here *Apex—tapered inferior* end, tilts to the left -The *atria are the chambers that receive blood* and the *ventricles are the chambers that pump blood* + the *right atrium receives deoxygenated blood from the superior vena cava* which drains blood from the jugular vein that *comes from the brain* and *from the arm veins*, as well as from the *inferior vena cava which drains blood from the veins that come from the lower organs* and the legs -In addition, the *right atrium receives blood from the coronary sinus* which drains *deoxygenated blood from the heart* itself -This *deoxygenated blood passes to right ventricle through the tricuspid valve* a flap of connective tissue that opens in only one direction to prevent the backflow of blood. The *valve separating the chambers on the left side* of the heart is biscuspid/*mitral valve* -*After it's filled* = the *right ventricle pumps blood through pulmonary arteries*, by-passing the semilunar valve (or pulmonic valve) *to the lungs for reoxygenation* -After blood passes through the pulmonary arteries, the right semilunar valves close preventing the blood from flowing backwards into the right ventricle -The *left atrium receives oxygen-rich blood from the lungs via pulmonary veins* + blood *passes through the mitral valve* (the atrioventricular valve on the left side of the heart) *to the left ventricle where the blood is pumped out through AORTA*, the *major artery taking oxygenated blood to the organs/muscles* of the body -Once blood is pumped out of the left ventricle and into the aorta, the aortic semilunar valve (or aortic valve) closes preventing blood from flowing backward into the left ventricle -*This pattern of pumping* is referred to as *double circulation* and is found *in all mammals*•blood is pumped a second time after it loses pressure in the lungs.

Hormonal Control of Osmoregulatory Functions Kidneys operate to maintain __________ balance + _________ ________ What are hormones? What is epinephrine and what condition is it released in? Every metabolic process is ____________ when this happens.

-While the *kidneys operate to maintain osmotic balance* + *blood pressure* in the body, they also *act in concert w/ hormones* -*Hormones* = *small molecules that act as messengers* within the body -Hormones are typically *secreted from 1 cell* + *travel in bloodstream to affect a target cell* in another portion of the body -*Diff regions of nephron* bear *specialized cells w/ receptors to respond to chemical messengers/hormones* Epinephrine and Norepinephrine Epinephrine and norepinephrine are released by the adrenal medulla and nervous system respectively. They are the flight/ fight hormones that are released when the body is under extreme stress. During stress, much of the body's energy is used to combat imminent danger. Kidney function is halted temporarily by epinephrine and norepinephrine. These hormones function by acting directly on the smooth muscles of blood vessels to constrict them. Once the afferent arterioles are constricted, blood flow into the nephrons stops. These hormones go one step further and trigger the renin-angiotensin- aldosterone system. Every metabolic process INCR Renin-Angiotensin-Aldosterone The renin-angiotensin-aldosterone system, illustrated in Figure 41.15 proceeds through several steps to produce angiotensin II, which acts to stabilize blood pressure and volume. Renin (secreted by a part of the juxtaglomerular complex) is produced by the granular cells of the afferent and efferent arterioles. Thus, the kidneys control blood pressure and volume directly. Renin acts on angiotensinogen, which is made in the liver and converts it to angiotensin I. Angiotensin converting enzyme (ACE) converts angiotensin I to angiotensin II. Angiotensin II raises blood pressure by constricting blood vessels. It also triggers the release of the mineralocorticoid aldosterone from the adrenal cortex, which in turn stimulates the renal tubules to reabsorb more sodium. Angiotensin II also triggers the release of anti-diuretic hormone (ADH) from the hypothalamus, leading to water retention in the kidneys. It acts directly on the nephrons and decreases glomerular filtration rate. Medically, blood pressure can be controlled by drugs that inhibit ACE (called ACE inhibitors). Mineralocorticoids Mineralocorticoids are hormones synthesized by the adrenal cortex that affect osmotic balance. Aldosterone is a mineralocorticoid that regulates sodium levels in the blood. Almost all of the sodium in the blood is reclaimed by the renal tubules under the influence of aldosterone. Because sodium is always reabsorbed by active transport and water follows sodium to maintain osmotic balance, aldosterone manages not only sodium levels but also the water levels in body fluids. In contrast, the aldosterone also stimulates potassium secretion concurrently with sodium reabsorption. In contrast, absence of aldosterone means that no sodium gets reabsorbed in the renal tubules and all of it gets excreted in the urine. In addition, the daily dietary potassium load is not secreted and the retention of K+ can cause a dangerous increase in plasma K+ concentration. Patients who have Addison's disease have a failing adrenal cortex and cannot produce aldosterone. They lose sodium in their urine constantly, and if the supply is not replenished, the consequences can be fatal. Antidiurectic Hormone As previously discussed, antidiuretic hormone or ADH (also called vasopressin), as the name suggests, helps the body conserve water when body fluid volume, especially that of blood, is low. It is formed by the hypothalamus and is stored and released from the posterior pituitary. It acts by inserting aquaporins in the collecting ducts and promotes reabsorption of water. ADH also acts as a vasoconstrictor and increases blood pressure during hemorrhaging. Atrial Natriuretic Peptide Hormone The atrial natriuretic peptide (ANP) lowers blood pressure by acting as a vasodilator. It is released by cells in the atrium of the heart in response to high blood pressure and in patients with sleep apnea. ANP affects salt release, and because water passively follows salt to maintain osmotic balance, it also has a diuretic effect. ANP also prevents sodium reabsorption by the renal tubules, decreasing water reabsorption (thus acting as a diuretic) and lowering blood pressure. Its actions suppress the actions of aldosterone, ADH, and renin.

Many of the protein hormones secreted from the anterior pituitary stimulate other endocrine glands to produce their hormones: What are the 6 hormones released from anterior pituitary? TAFLPG IS the anterior pituitary bigger and why?

1) thyroid-stimulating hormone (TSH), which regulates hormone production by the thyroid gland, 2) *Adrenocorticotropic hormone (ACTH)* from the *pituitary causes adrenal cortex* to *secrete STEROIDS corticosteroids* which include glucocorticoids, which function mainly in *mobilizing cellular fuel* thus *reinforcing effects of glucagon* and *mineralocorticoids* = *balance salt and water* Both help *maintain homeostasis* when the body experiences long-term stress. adrenocorticotropic hormone (ACTH), which stimulates the adrenal cortex, which in turn releases hormones that affect water balance and metabolism, 3) follicle-stimulating hormone (FSH) and luteinizing hormone (LH), which stimulate the testes and ovaries to produce reproductive hormones, 4) *Prolactin (PRL)* is *produced/secreted by anterior pituitary* under the direction of the hypothalamus and in humans, *stimulates mammary glands to grow* and *produce milk* during late pregnancy. *Suckling by a newborn* stimulates further *release of PRL* -PRL has many roles unrelated to childbirth, suggesting that PRL is an *ancient hormone diversified through evolution* In some nonhuman mammals, PRL *stimulates nest building* In *birds regulates fat metabolism* and reproduction. In *amphibians stimulates movement to water* In *fish that migrate* between salt and fresh water, PRL helps *regulate salt and water balance* in the gills and kidneys. 5) *growth hormone (GH)* = which *promo protein synthesis* and the use of *body fat for energy* metabolism. Anterior has more hormones than posterior.

Disruptions in the Immune System

A functioning immune system is essential for survival, but even the sophisticated cellular and molecular defenses of the mammalian immune response can be defeated by pathogens at virtually every step. In the competition between immune protection and pathogen evasion, pathogens have the advantage of more rapid evolution because of their shorter generation time and other characteristics. For instance, Streptococcus pneumoniae (bacterium that cause pneumonia and meningitis) surrounds itself with a capsule that inhibits phagocytes from engulfing it and displaying antigens to the adaptive immune system. Staphylococcus aureus (bacterium that can cause skin infections, abscesses, and meningitis) synthesizes a toxin called leukocidin that kills phagocytes after they engulf the bacterium. Other pathogens can also hinder the adaptive immune system. HIV infects TH cells via their CD4 surface molecules, gradually depleting the number of TH cells in the body; this inhibits the adaptive immune system's capacity to generate sufficient responses to infection or tumors. As a result, HIV-infected individuals often suffer from infections that would not cause illness in people with healthy immune systems but which can cause devastating illness to immune-compromised individuals. Maladaptive responses of immune cells and molecules themselves can also disrupt the proper functioning of the entire system, leading to host cell damage that could become fatal.

Mucosal Immune Memory

A subset of T and B cells of the mucosal immune system differentiates into memory cells just as in the systemic immune system. Upon reinvasion of the same pathogen type, a pronounced immune response occurs at the mucosal site where the original pathogen deposited, but a collective defense is also organized within interconnected or adjacent mucosal tissue. For instance, the immune memory of an infection in the oral cavity would also elicit a response in the pharynx if the oral cavity was exposed to the same pathogen.

Four feeders: Animals obtain and ingest their food in a variety of stages Food is processed in 4 stages 4 ways that food is processed? What are filter feeders? What are substrate feeders? What are fluid feeders? What are the bulk feeders?

Animals obtain and ingest their food in different ways. Filter feeders sift small organisms or food particles from water. Substrate feeders live in or on their food source and eat their way through it. Fluid feeders suck nutrient-rich fluids from a living host. Bulk feeders ingest large pieces of food. Food is processed in four stages. Ingestion is the act of eating. Digestion is the breaking down of food into molecules small enough for the body to absorb. Absorption is the take-up of the products of digestion, usually by the cells lining the digestive tract. Elimination is the removal of undigested materials from the digestive tract.

Primary Centers of the Immune System

Although the immune system is characterized by circulating cells throughout the body, the regulation, maturation, and intercommunication of immune factors occur at specific sites. The blood circulates immune cells, proteins, and other factors through the body. Approximately 0.1 percent of all cells in the blood are leukocytes, which encompass monocytes (the precursor of macrophages) and lymphocytes. The majority of cells in the blood are erythrocytes (red blood cells). Lymph is a watery fluid that bathes tissues and organs with protective white blood cells and does not contain erythrocytes. Cells of the immune system can travel between the distinct lymphatic and blood circulatory systems, which are separated by interstitial space, by a process called extravasation (passing through to surrounding tissue). The cells of the immune system originate from hematopoietic stem cells in the bone marrow. Cytokines stimulate these stem cells to differentiate into immune cells. B cell maturation occurs in the bone marrow, whereas naïve T cells transit from the bone marrow to the thymus for maturation. In the thymus, immature T cells that express TCRs complementary to self-antigens are destroyed. This process helps prevent autoimmune responses. On maturation, T and B lymphocytes circulate to various destinations. Lymph nodes scattered throughout the body, as illustrated in Figure 42.20, house large populations of T and B cells, dendritic cells, and macrophages. Lymph gathers antigens as it drains from tissues. These antigens then are filtered through lymph nodes before the lymph is returned to circulation. APCs in the lymph nodes capture and process antigens and inform nearby lymphocytes about potential pathogens. The spleen houses B and T cells, macrophages, dendritic cells, and NK cells. The spleen, shown in Figure 42.21, is the site where APCs that have trapped foreign particles in the blood can communicate with lymphocytes. Antibodies are synthesized and secreted by activated plasma cells in the spleen, and the spleen filters foreign substances and antibody-complexed pathogens from the blood. Functionally, the spleen is to the blood as lymph nodes are to the lymph.

Antibody Structure Antibodies do not kill ______________ An antibody has 2 related function in what type of immune response? What is their structure made up of and what does it look like?

An antibody, also known as an immunoglobulin (Ig), is a protein that is produced by plasma cells after stimulation by an antigen. Antibodies are the functional basis of humoral immunity. Antibodies occur in the blood, in gastric and mucus secretions, and in breast milk. Antibodies in these bodily fluids can bind pathogens and mark them for destruction by phagocytes before they can infect cells. An antibody molecule is comprised of four polypeptides: two identical heavy chains (large peptide units) that are partially bound to each other in a "Y" formation, which are flanked by two identical light chains (small peptide units) - *Antibodies do not kill pathogens* •An antibody has two related *functions in the humoral immune response*: 1.to *recognize and bind to a certain antigen* and 2.to *assist in eliminating that antigen* •The structure of an antibody allows it to perform both of these functions. •A *computer-generated rendering of an antibody* molecule illustrates the *Y shape of antibodies* •Each antibody molecule consists of *four polypeptide chains bonded together to form a Y shape* •The tip of each arm of the Y forms an antigen-binding site, a region of the molecule responsible for the antibody's recognition-and-binding function. •A huge variety in the three-dimensional shapes of the binding sites of different antibodies •accounts for the diversity of lymphocytes and •gives the humoral immune response the ability to react to virtually any kind of antigen. Bonds between the cysteine amino acids in the antibody molecule attach the polypeptides to each other. The areas where the antigen is recognized on the antibody are variable domains and the antibody base is composed of constant domains. In germ-line B cells, the variable region of the light chain gene has 40 variable (V) and five joining (J) segments. An enzyme called DNA recombinase randomly excises most of these segments out of the gene, and splices one V segment to one J segment. During RNA processing, all but one V and J segment are spliced out. Recombination and splicing may result in over 106 possible VJ combinations. As a result, each differentiated B cell in the human body typically has a unique variable chain. The constant domain, which does not bind antibody, is the same for all antibodies. Similar to TCRs and BCRs, antibody diversity is produced by the mutation and recombination of approximately 300 different gene segments encoding the light and heavy chain variable domains in precursor cells that are destined to become B cells. The variable domains from the heavy and light chains interact to form the binding site through which an antibody can bind a specific epitope on an antigen. The numbers of repeated constant domains in Ig classes are the same for all antibodies corresponding to a specific class. Antibodies are structurally similar to the extracellular component of the BCRs, and B cell maturation to plasma cells can be visualized in simple terms as the cell acquires the ability to secrete the extracellular portion of its BCR in large quantities.

Flame Cells of Planaria and Nephridia of Worms

As multi-cellular systems evolved to have organ systems that divided the metabolic needs of the body, individual organs evolved to perform the excretory function. Planaria are flatworms that live in fresh water. Their excretory system consists of two tubules connected to a highly branched duct system. The cells in the tubules are called flame cells (or protonephridia) because they have a cluster of cilia that looks like a flickering flame when viewed under the microscope, as illustrated in Figure 41.10a. The cilia propel waste matter down the tubules and out of the body through excretory pores that open on the body surface; cilia also draw water from the interstitial fluid, allowing for filtration. Any valuable metabolites are recovered by reabsorption. Flame cells are found in flatworms, including parasitic tapeworms and free-living planaria. They also maintain the organism's osmotic balance. Earthworms (annelids) have slightly more evolved excretory structures called nephridia, illustrated in Figure 41.10b. A pair of nephridia is present on each segment of the earthworm. They are similar to flame cells in that they have a tubule with cilia. Excretion occurs through a pore called the nephridiopore. They are more evolved than the flame cells in that they have a system for tubular reabsorption by a capillary network before excretion.

Antibody Functions What are the 4 functions of antibodies? What is active immunity? What is passive immunity?

Differentiated plasma cells are crucial players in the humoral response, and the antibodies they secrete are particularly significant against extracellular pathogens and toxins. Antibodies circulate freely and act independently of plasma cells. Antibodies can be transferred from one individual to another to temporarily protect against infectious disease. For instance, a person who has recently produced a successful immune response against a particular disease agent can donate blood to a nonimmune recipient and confer temporary immunity through antibodies in the donor's blood serum. This phenomenon is called passive immunity; it also occurs naturally during breastfeeding, which makes breastfed infants highly resistant to infections during the first few months of life. Antibodies coat extracellular pathogens and neutralize them, as illustrated in Figure 42.24, by blocking key sites on the pathogen that enhance their infectivity (such as receptors that "dock" pathogens on host cells). Antibody neutralization can prevent pathogens from entering and infecting host cells, as opposed to the CTL-mediated approach of killing cells that are already infected to prevent progression of an established infection. The neutralized antibody-coated pathogens can then be filtered by the spleen and eliminated in urine or feces. Antibodies also mark pathogens for destruction by phagocytic cells, such as macrophages or neutrophils, because phagocytic cells are highly attracted to macromolecules complexed with antibodies. Phagocytic enhancement by antibodies is called opsonization. In a process called complement fixation, IgM and IgG in serum bind to antigens and provide docking sites onto which sequential complement proteins can bind. The combination of antibodies and complement enhances opsonization even further and promotes rapid clearing of pathogens. Affinity, Avidity, and Cross Reactivity Not all antibodies bind with the same strength, specificity, and stability. In fact, antibodies exhibit different affinities (attraction) depending on the molecular complementarity between antigen and antibody molecules. An antibody with a higher affinity for a particular antigen would bind more strongly and stably, and thus would be expected to present a more challenging defense against the pathogen corresponding to the specific antigen. The term avidity describes binding by antibody classes that are secreted as joined, multivalent structures (such as IgM and IgA). Although avidity measures the strength of binding, just as affinity does, the avidity is not simply the sum of the affinities of the antibodies in a multimeric structure. The avidity depends on the number of identical binding sites on the antigen being detected, as well as other physical and chemical factors. Typically, multimeric antibodies, such as pentameric IgM, are classified as having lower affinity than monomeric antibodies, but high avidity. Essentially, the fact that multimeric antibodies can bind many antigens simultaneously balances their slightly lower binding strength for each antibody/antigen interaction. Antibodies secreted after binding to one epitope on an antigen may exhibit cross reactivity for the same or similar epitopes on different antigens. Because an epitope corresponds to such a small region (the surface area of about four to six amino acids), it is possible for different macromolecules to exhibit the same molecular identities and orientations over short regions. Cross reactivity describes when an antibody binds not to the antigen that elicited its synthesis and secretion, but to a different antigen. Cross reactivity can be beneficial if an individual develops immunity to several related pathogens despite having only been exposed to or vaccinated against one of them. For instance, antibody cross reactivity may occur against the similar surface structures of various Gram-negative bacteria. Conversely, antibodies raised against pathogenic molecular components that resemble self molecules may incorrectly mark host cells for destruction and cause autoimmune damage. Patients who develop systemic lupus erythematosus (SLE) commonly exhibit antibodies that react with their own DNA. These antibodies may have been initially raised against the nucleic acid of microorganisms but later cross-reacted with self-antigens. This phenomenon is also called molecular mimicry •The antigen-antibody complex boosts the function of phagocytic cells of innate immunity in three ways: 1.*neutralization*, *binding to surface proteins on virus* or bacterium and *blocking ability to infect* a host, 2. *agglutination*, using *both binding sites of an antibody to join invading cells together into a clump*, and 3.*precipitation*, similar to agglutination, except that the *antibody molecules link dissolved antigen molecules* together. 4.*Activation of complement* = the *proteins attach to a foreign cell* •Antibodies are widely used in •laboratory research and •the treatment of disease. •Toxin-linked antibodies carry out a precise search-and-destroy mission, selectively attaching to and killing tumor cells *Active Immunity* - *antibodies developed in a person's own immune system* after the body is *exposed to an antigen through a disease/vaccine* *Passive Immunity* - *antibodies given to a person to prevent disease* or to treat disease after the body is exposed to an antigen

Veins What are capillary beds? Veins bring _______ blood to the heart except the pulmonary vein. Veins have valves- what are the 4 valves?

Large Arteries to Arterioles diverge into capillary beds. *Capillary beds* = contain a *large number (10 to 100) of capillaries that branch among cells/tissues* of the body + *infiltrate every organ/tissue* in the body -*Capillaries* = *narrow-diameter tubes* that can *fit red blood cells thru* in single file and are the *sites for exchange of nutrients, waste, oxygen w/ tissues at the cellular level* -Fluid also *crosses into the interstitial space from capillaries* -The *capillaries converge into venules* that connect to minor veins that finally connect to major veins that *take blood high in CO2 back to the heart* -Veins are blood vessels that bring blood back to the heart. The major veins drain blood from the same organs and limbs that the major arteries supply. Fluid is also brought back to the heart via the lymphatic system. -Arteries are just thicker veins w/o valves -*Veins* BRING *pulmonary vein DEOXYGENATED BLOOD BACK TO HEART*, *low pressure*, *valves* that prevent backflow have *one-way valves* that restrict backward flow of blood *except pulmonary vein* •Veins are squeezed by pressure from muscle contractions between two muscles or muscles and bone or skin. •One-way valves limit blood flow to one direction, toward the heart.

Two main types of cholesterol occur in the blood What are the 2 types? When does low density lipoprotein occur? When does high density lipoprotein occur?

Low-density lipoproteins (LDLs) generally correlate with a tendency to develop blocked blood vessels, high blood pressure, and consequent heart attacks. High-density lipoproteins (HDLs) may decrease the risk of vessel blockage, perhaps because HDLs convey excess cholesterol to the liver, where it is broken down. You can decrease your levels of "bad" cholesterol by avoiding a diet high in saturated fats and hydrogenated oils. You can increase your levels of "good" cholesterol by eating mainly unsaturated fats and avoiding hydrogenated oils.

MHC

Major Histocompatability complex, a set of proteins found on the plasma membranes of cells that help display antigen to T cells. MHC I is found on all cells and displays bits of proteins from within the cell; this allows T cells to monitor cell contents and if abnormal peptides are displayed on the surface, the cell is destroyed by killer T cells. MHC II is found only on macrophages and B cells. This class of MHC allows these cells (known as antigen presenting cells) to display bitts of "eaten" (phagocytosed or internalized) proteins on their surface, allowing the activation of helper Ts --> thus further activating immune response. •Genes at multiple chromosomal loci code for major histocompatibility complex (MHC) molecules, the main self proteins. •When a person receives an organ transplant or tissue graft, the person's T cells recognize the MHC markers on the donor's cells as foreign. •Donors are used that most closely match the patient's tissues. •Transplants between identical twins do not typically have this problem.

Gout

Mammals use uric acid crystals as an antioxidant in their cells. However, too much uric acid tends to form kidney stones and may also cause a painful condition called gout, where uric acid crystals accumulate in the joints, as illustrated in Figure 41.14. Food choices that reduce the amount of nitrogenous bases in the diet help reduce the risk of gout. For example, tea, coffee, and chocolate have purine-like compounds, called xanthines, and should be avoided by people with gout and kidney stones.

Hormone signaling involves three stages:

Reception of the signal occurs when a hormone  binds to a specific receptor protein on or in the  target cell. Signal transduction converts the signal from one  form to another. Response is a change in the cell's behavior.

Rectum and Anus + Accessory Organs What is the rectum and anus? What is voluntary and involuntary: spinchter? What do accessory organs mean and what are the 4? What does each do?

Rectum and Anus -The *rectum* = the *terminal end of large intestine* -The *primary role of the rectum* = to *store the feces until defecation* -Feces are propelled using peristaltic movements during elimination -The *anus* = an opening at the far-end of digestive tract* + the *exit point for waste* material -*Two sphincters btwn rectum + anus control elimination*: the *inner sphincter = involuntary* and the *outer sphincter = voluntary* Accessory Organs -*Accessory organs* are *organs that add secretions (enzymes) that catabolize food into nutrients* -*Accessory organs* = *salivary glands, liver, pancreas, gallbladder* are regulated *by hormones in response to the food consumed* -The *liver* = the *largest internal organ in humans* + *digests fats* + *detoxify blood* + *converts glucose to glycogen* -The *liver produces bile*, a digestive juice that is required for the *breakdown of fatty components* of the food in the duodenum The liver also *processes the vitamins/fats* + *synthesizes plasma proteins* -The *pancreas* =important *gland that secretes digestive juices* + *chyme produced from the stomach is HIGHLY ACIDIC* -The *pancreatic juices contain high levels of bicarbonate* = an *alkali that neutralizes acidic chyme* + contain a *large variety of enzymes for the digestion of protein/carbohydrates* -The *gallbladder* = a small *organ aids liver w/ storing bile/concentrating bile salts* When *chyme containing fatty acids enters the duodenum*, the *bile is secreted from the gallbladder into the duodenum*

Layers of the Heart Name the heart layers outside to in PEME. What do the capillaries do? What is ATHEROCLEROSIS?

The *heart* = *composed of 3 layers*; the *epicardium*, the *myocardium*, the *endocardium* -The *innermost wall of the heart* = *ENDOCARDIUM* - The *MYOCARDIUM* = consists of the *heart muscle cells in middle layer* and *bulk of the heart wall* -The *outer layer of cells* is = *EPICARDIUM* of which the *outermost/second layer* is a membranous layered structure = *PERICARDIUM* that *surrounds/protects the heart*; it allows enough room for vigorous pumping but also keeps the heart in place to reduce friction between the heart and other structures. -The heart has its own blood vessels that supply the heart muscle with blood. *The coronary arteries* branch from the aorta and *surround the outer surface of the heart* + *bring blood flow to the heart* like a crown -They *diverge into capillaries* where the heart muscle is *supplied w/ O2* before converging again into the coronary veins to take the deoxygenated blood back to the right atrium where the blood will be re-oxygenated through the pulmonary circuit -The heart muscle will die without a steady supply of blood. *ATHEROCLEROSIS* = the *blockage of artery* bc the *buildup of fatty plaques* Because of the size (narrow) of the coronary arteries and their function in serving the heart itself, atherosclerosis can be deadly in these arteries -The *slowdown of blood flow* and subsequent oxygen deprivation that results from *atherosclerosis causes severe pain*, known as angina, and complete *blockage of the arteries* will cause *myocardial infarction*: the *dead cardiac muscle tissue* + from a *blocked coronary artery* = commonly known as a heart attack.

Capillary Network within the Nephron

The capillary network that originates from the renal arteries supplies the nephron with blood that needs to be filtered. The branch that enters the glomerulus is called the afferent arteriole. The branch that exits the glomerulus is called the efferent arteriole. Within the glomerulus, the network of capillaries is called the glomerular capillary bed. Once the efferent arteriole exits the glomerulus, it forms the peritubular capillary network, which surrounds and interacts with parts of the renal tubule. In cortical nephrons, the peritubular capillary network surrounds the PCT and DCT. In juxtamedullary nephrons, the peritubular capillary network forms a network around the loop of Henle and is called the vasa recta.

Nervous vs. Endocrine What does the nervous system use, is it slow or fast, it specific or general, where is it secreted? What does the endocrine system use, is it slow or fast, is it specific or general, where is it secreted? What do both systems want to maintain?

The nervous system reacts in split second, whereas the hormones secreted by the endocrine glands work more slowly in initiating a response -The *nervous system* also communicates, regulates, and *uses electrical signals* via *nerve cells called neurons* and they're *faster* bc target cells Comparing the endocrine and nervous systems: The *nervous system reacts faster* The responses of the *endocrine system creates hormones that control body functions* but *last longer* and *more generalized bc released in BLOOD*

Renal corpuscle

The renal corpuscle, *located in the renal cortex* is made up of a *network of capillaries* = known as the *glomerulus* and the *capsule = cup-shaped chamber* that surrounds it, called the *Glomerular/ Bowman's capsule* -filters blood plasma

Mucosal Surfaces and Immune Tolerance

The innate and adaptive immune responses discussed thus far comprise the systemic immune system (affecting the whole body), which is distinct from the mucosal immune system. Mucosal immunity is formed by mucosa-associated lymphoid tissue, which functions independently of the systemic immune system, and which has its own innate and adaptive components. Mucosa-associated lymphoid tissue (MALT), illustrated in Figure 42.15, is a collection of lymphatic tissue that combines with epithelial tissue lining the mucosa throughout the body. This tissue functions as the immune barrier and response in areas of the body with direct contact to the external environment. The systemic and mucosal immune systems use many of the same cell types. Foreign particles that make their way to MALT are taken up by absorptive epithelial cells called M cells and delivered to APCs located directly below the mucosal tissue. M cells function in the transport described, and are located in the Peyer's patch, a lymphoid nodule. APCs of the mucosal immune system are primarily dendritic cells, with B cells and macrophages having minor roles. Processed antigens displayed on APCs are detected by T cells in the MALT and at various mucosal induction sites, such as the tonsils, adenoids, appendix, or the mesenteric lymph nodes of the intestine. Activated T cells then migrate through the lymphatic system and into the circulatory system to mucosal sites of infection. MALT is a crucial component of a functional immune system because mucosal surfaces, such as the nasal passages, are the first tissues onto which inhaled or ingested pathogens are deposited. The mucosal tissue includes the mouth, pharynx, and esophagus, and the gastrointestinal, respiratory, and urogenital tracts. The immune system has to be regulated to prevent wasteful, unnecessary responses to harmless substances, and more importantly so that it does not attack "self." The acquired ability to prevent an unnecessary or harmful immune response to a detected foreign substance known not to cause disease is described as immune tolerance. Immune tolerance is crucial for maintaining mucosal homeostasis given the tremendous number of foreign substances (such as food proteins) that APCs of the oral cavity, pharynx, and gastrointestinal mucosa encounter. Immune tolerance is brought about by specialized APCs in the liver, lymph nodes, small intestine, and lung that present harmless antigens to an exceptionally diverse population of regulatory T (Treg) cells, specialized lymphocytes that suppress local inflammation and inhibit the secretion of stimulatory immune factors. The combined result of Treg cells is to prevent immunologic activation and inflammation in undesired tissue compartments and to allow the immune system to focus on pathogens instead. In addition to promoting immune tolerance of harmless antigens, other subsets of Treg cells are involved in the prevention of the autoimmune response = *occur when immune system turns against own molecules*, which is an inappropriate immune response to host cells or self-antigens. Another Treg class suppresses immune responses to harmful pathogens after the infection has cleared to minimize host cell damage induced by inflammation and cell lysis.

Cytotoxic T lymphocytes The destruction/deactivation of _____________ Produces what kind of adaptive response Battles pathogens in ___________

direct destruction of antigen carrying cells •The *cell-mediated immune response* •is *produced by cytotoxic T cells* and •*battles pathogens* that have *already in body cells* •Cytotoxic T cells are the only T cells that kill infected cells. Once activated, •clonal selection ensues, and •effector cytotoxic T cells identify infected cells through a self-nonself complex. •An infected cell has foreign antigens, molecules belonging to the viruses or bacteria infecting it, attached to self proteins on its surface. •The self-nonself complex on an infected body cell is like a red flag to cytotoxic T cells that have matching receptors. 1.A cytotoxic T cell binds to the infected cell, which activates the T cell, to synthesize several toxic proteins, including one called perforin. 2.Perforin is discharged from the cytotoxic T cell and attaches to the infected cell's plasma membrane, making holes in it. T cell enzymes then enter the infected cell and promote its death by a process called apoptosis. 3.The infected cell is destroyed, and the cytotoxic T cell may move on to destroy other cells infected with the same pathogen. CTLs, a subclass of T cells, function to clear infections directly. The cell-mediated part of the adaptive immune system consists of CTLs that attack and destroy infected cells. CTLs are particularly important in protecting against viral infections; this is because viruses replicate within cells where they are shielded from extracellular contact with circulating antibodies. When APCs phagocytize pathogens and present MHC I-embedded antigens to naïve CD8+ T cells that express complementary TCRs, the CD8+ T cells become activated to proliferate according to clonal selection. These resulting CTLs then identify non-APCs displaying the same MHC I-embedded antigens (for example, viral proteins)—for example, the CTLs identify infected host cells. Intracellularly, infected cells typically die after the infecting pathogen replicates to a sufficient concentration and lyses the cell, as many viruses do. CTLs attempt to identify and destroy infected cells before the pathogen can replicate and escape, thereby halting the progression of intracellular infections. CTLs also support NK lymphocytes to destroy early cancers. Cytokines secreted by the TH1 response that stimulates macrophages also stimulate CTLs and enhance their ability to identify and destroy infected cells and tumors. CTLs sense MHC I-embedded antigens by directly interacting with infected cells via their TCRs. Binding of TCRs with antigens activates CTLs to release perforin and granzyme, degradative enzymes that will induce apoptosis of the infected cell. Recall that this is a similar destruction mechanism to that used by NK cells. In this process, the CTL does not become infected and is not harmed by the secretion of perforin and granzymes. In fact, the functions of NK cells and CTLs are complementary and maximize the removal of infected cells, as illustrated in Figure 42.14. If the NK cell cannot identify the "missing self" pattern of down-regulated MHC I molecules, then the CTL can identify it by the complex of MHC I with foreign antigens, which signals "altered self." Similarly, if the CTL cannot detect antigen-embedded MHC I because the receptors are depleted from the cell surface, NK cells will destroy the cell instead. CTLs also emit cytokines, such as interferons, that alter surface protein expression in other infected cells, such that the infected cells can be easily identified and destroyed. Moreover, these interferons can also prevent virally infected cells from releasing virus particles. -Plasma cells and CTLs are collectively called effector cells: they *represent differentiated versions of their naïve counterparts* + *act immediately to combat infection* and they are involved in bringing about the immune defense of killing pathogens and infected host cells.

B Lymphocytes

form in the bone marrow and release antibodies that fight bacterial infections When stimulated by the TH2 pathway, naïve B cells differentiate into antibody-secreting plasma cells. A plasma cell is an immune cell that secrets antibodies; these cells arise from B cells that were stimulated by antigens. Similar to T cells, naïve B cells initially are coated in thousands of B cell receptors (BCRs), which are membrane-bound forms of Ig (immunoglobulin, or an antibody). The B cell receptor has two heavy chains and two light chains connected by disulfide linkages. Each chain has a constant and a variable region; the latter is involved in antigen binding. Two other membrane proteins, Ig alpha and Ig beta, are involved in signaling. The receptors of any particular B cell, as shown in Figure 42.13 are all the same, but the hundreds of millions of different B cells in an individual have distinct recognition domains that contribute to extensive diversity in the types of molecular structures to which they can bind. In this state, B cells function as APCs. They bind and engulf foreign antigens via their BCRs and then display processed antigens in the context of MHC II molecules to TH2 cells. When a TH2 cell detects that a B cell is bound to a relevant antigen, it secretes specific cytokines that induce the B cell to proliferate rapidly, which makes thousands of identical (clonal) copies of it, and then it synthesizes and secretes antibodies with the same antigen recognition pattern as the BCRs. The activation of B cells corresponding to one specific BCR variant and the dramatic proliferation of that variant is known as clonal selection. This phenomenon drastically, but briefly, changes the proportions of BCR variants expressed by the immune system, and shifts the balance toward BCRs specific to the infecting pathogen. T and B cells differ in one fundamental way: whereas T cells bind antigens that have been digested and embedded in MHC molecules by APCs, B cells function as APCs that bind intact antigens that have not been processed. Although T and B cells both react with molecules that are termed "antigens," these lymphocytes actually respond to very different types of molecules. B cells must be able to bind intact antigens because they secrete antibodies that must recognize the pathogen directly, rather than digested remnants of the pathogen. Bacterial carbohydrate and lipid molecules can activate B cells independently from the T cells.

Lymphatic System How do you define this system? What other system is this system closely associated with? What 2 immunities are involved? What are lymphatic vessels, bodes, lymph? What are the 2 main functions of the system?

the network of vessels through which lymph drains from the tissues into the blood. •The lymphatic system (closely associated w/ circulatory system) •is *involved in innate/adaptive immunity* and •consists of a branching network of •*lymphatic vessels (Bone marrow, spleen)*, •*lymph nodes (lymphocytes and macrophages)*, and •*lymph*, which is similar to the interstitial fluid that surrounds body cells but contains less oxygen and fewer nutrients •*Lymphatic vessels* = •*collect fluid from tissues* and •*returned as lymph to the blood* •The lymphatic system thus has two main functions: 1. to *return tissue fluid back to the circulatory system* (NODES FILTER INFECTIOUS AGENTS BACK) and (*LYMPH organs collect microbes* and the *lymph nodes bring them to macrophages* who *recognize antigens* to *bring to lymphocytes* to *mount an adaptive response*) 2. to *fight infection* -*T lymphocytes mature* in *bone marrow* - cells -*B lymphocytes mature* in *thymus* - blood -These *lymphocytes differentiate by synthesizing copies of a specific protein: antigen receptors* , capable of *binding 1 specific type of antigen* then they do *clonal selection*, which are then incorporated into the plasma membrane. -Lymphocytes can't live in lymph nodes w/o property of recognition -B and T cells recognize specific antigens by receptors in maturation = CANT FUNCTION W/O THIS STEP •B cells bind antigens directly. •T cells require an additional step for recognition.

White Blood Cells White blood cells are primarily involved with? Some leukocytes become _____________ that stay at the same site or gather at infection sites What are B cells and T cells and what types of responses do they create? Monocytes and neutrophils are called _______________ What types of white blood cells are there NBELM? What is leukemia?

-*5K-10K White blood cells* (leukocytes) make up approx *1% by volume of cells in blood* = function *inside/outside circulatory system* and fight infections -The role of *white blood cells is very diff than red blood cells* = they are *primarily involved in immune response to target bacteria, viruses, foreign organisms* -White blood cells are *formed continually*; some only *live for hours/days/years* -*They have nuclei* but not hemoglobin -The *diff types* of white blood cells are *identified by microscopic appearance after histologic staining* -*Granulocytes* = contain *granules in cytoplasm*; the *agranulocytes don't* -*Some leukocytes* become *macrophages* that either *stay at same site* or *move thru blood stream* and *gather at infection* + *attract to foreign particles and damaged cells* -Lymphocytes include B cells, T cells, and natural killer cells -*B cells* destroy *bacteria* and *inactivate toxins* and *produce antibodies* -*T cells* attack *viruses, fungi, transplanted cells, cancer cells* •*Monocytes and neutrophils* are white blood cells called *phagocytes, which engulf and digest bacteria/dead cells* -*Types*: -*Neutrophils* = digest bacteria -*Basophils* = fight infection + allergic response bc of histamine -*Eosinophils* = allergies - pollen, animals -*Lymphocytes* (from lymphoids): B and T cells + antibodies -*Monocytes*: eat dead bacteria + phagocytic cell -Ex: HIV poses significant management challenges is bc the virus directly targets T cells entry via a receptor. Once inside the cell, HIV then multiplies using the T cell's own genetic machinery. After the HIV virus replicates, it is transmitted directly from the infected T cell to macrophages. The presence of HIV can remain unrecognized for an extensive period of time before full disease symptoms develop. •*Leukemia* •is *cancer of white blood cells* (leukocytes), •results in extra leukocytes that do not function properly, and •is usually fatal unless treated. •Leukemia may be treated by •radiation, •chemotherapy, or •the replacement of cancerous bone marrow with healthy bone marrow.

Essential Nutrients What 3 things must animals obtain? How do you define essential nutrients? What are coenzymes and how are they also essential nutrients? What are cofactors and how are they also essential nutrients that help in structure and regulation? What are the 4 classes of essential nutrients?

-*ANIMALS MUST OBTAIN*= *1. organic building blocks for macromolecules* *2. chem energy* to *power cellular work* *3. essential nutrients* to *maintain health* *While the animal body can synthesize many of the molecules required for function from the organic precursors*, there are *some nutrients that need to be consumed from food* -These *nutrients are termed essential nutrients*, meaning *they must be eaten* body cannot produce them. -*The omega-3 alpha-linolenic acid* and the *omega-6 linoleic acid* = *essential fatty acids* needed *to make some membrane phospholipids* -*Vitamins* are *another class of essential organic molecules* that are *required in small quantities for enzymes to function* and, for this reason, are considered to be *COENZYMES* -Absence or low levels of vitamins can have a dramatic effect on health -*Fat-soluble/water-soluble vitamins* must be *obtained from food* -*Minerals = inorganic essential nutrients* that *must be obtained from food* -*Among their many functions* = *minerals help in structure + regulation* = *co-factors* -Certain *amino acids must be from food* + *cannot be synthesized by body* -These amino acids are the "essential" amino acids. *The human body can synthesize only 11/20 required amino acids*; the rest must be *obtained from food* -*4 classes* = 1. *Essential fatty acids*, such as linoleic acid, are •used to make phospholipids of cell membranes and •found in seeds, grains, and vegetables. 2. *Essential amino acids* are •used to make proteins and •found in meats, eggs, milk, and cheese. 3. *Essential vitamins and minerals* are •required in *minute amounts* + absolutely *essential to good health* 4. *Vitamins are organic nutrients* that may be *water-soluble* (vitamins B and C) or *fat-soluble* (vitamins A, D, E, K)

Introduction of Digestive Systems All living organisms need what to survive? How do plants obtain molecules for cellular function, with what process? What biological molecules are needed for animal function? What must animals convert to maintain cellular functions? What is the challenge in human nutrition?

-*All living organisms need nutrients to survive* -While *plants obtain molecules for cellular function thru* = *PHOTOSYNTHESIS*, *most animals obtain their nutrients by consumption of organisms* -At the cellular level, the *biological molecules* necessary for *animal function* = are *amino acids, lipid molecules, nucleotides, and simple sugars* -However, the *food consumed* consists of *protein, fat, complex carbohydrates* -*Animals must convert macromolecules into simple molecules* required for *maintaining cellular functions = new molecules, cells, tissues* -The *conversion of food consumed to nutrients* required is a *multi-step process involving digestion + absorption* IN *SMALL INTESTINE* -*During digestion, food particles are broken down to smaller components*, and later, they are *absorbed* by the body -One of the *challenges in human nutrition* = is maintaining a *balancing food intake, storage, energy expenditure* -*Imbalances* can have *serious health consequences* -For example, eating too much food while *not expending much energy leads to obesity* -*Over 1/3rd American adults* = are *obese* -The *obesity epidemic*, combined with increasingly *sedentary jobs* and *inactive* lifestyles, has contributed to *higher incidences of heart disease*, *diabetes*, *cancer*, and other weight-related health problems -More than 300,000 deaths per year in the United States are attributed to weight-related issues -*Animals obtain their nutrition from the consumption of other organisms* -*Depending on their diet* = *animals can be classified as plant eaters (herbivores), meat eaters (carnivores)* and *those that eat both plants and animals (omnivores)* -The *nutrients and macromolecules present in food* are *not immediately accessible to the cells* -There are a *number of processes that modify food* within the animal body in order to *make the nutrients and organic molecules accessible for cellular function* -As *animals evolved in complexity of form and function* their *digestive systems have evolved to accommodate various dietary needs*

Plasma Membrane Hormone Receptors What are the 3 steps but what is different about the 1st step?

-*Amino acid derived hormones/polypeptide hormones* are *NOT LIPID-DERIVED (lipid-soluble)* and therefore *cannot diffuse* through the plasma membrane of cells -*Lipid insoluble hormones bind to receptors* on the outer surface of the plasma membrane, via plasma membrane hormone receptors -*Unlike steroid hormones*, *lipid insoluble hormones do not affect target cell* because they *cannot enter* the cell and act directly on DNA -*Binding* of these hormones to a cell surface receptor results in *activation of signaling pathway* which triggers intracellular activity and *carries out specific effects associated w/ hormone* -In this way, nothing passes through the cell membrane; the hormone that binds at the surface remains at the surface of the cell while the intracellular product remains inside the cell. The hormone that initiates the signaling pathway is called a first messenger, which activates a second messenger in the cytoplasm.

Blood Flow and Blood Pressure Regulation What is blood pressure and what side of the heart is it taken on behalf of?

-*Blood pressure (BP)* = the *pressure exerted by blood* on the walls of a blood vessel that *helps to push blood* thru the body. **Blood pressure is taken on behalf of left side of the heart + dependent on cardiac output + ability to stretch/resistance -*Systolic blood pressure* measures the *amount of pressure blood exerts on vessels* while the heart is beating -The *optimal systolic blood pressure is 120 mmHg* -*Diastolic blood pressure* measures the *pressure in the vessels btwn heartbeats* -The *optimal diastolic blood pressure is 80 mmHg* -Many factors can affect blood pressure, such as *hormones, stress, exercise, eating, sitting, standing* Blood flow through the body is regulated by the size of blood vessels, by the action of smooth muscle, by one-way valves, and by the fluid pressure of the blood itself -The *pressure of blood flow in the body is produced by hydrostatic pressure of the fluid* (blood) against the walls of the blood vessels -*Fluid will move from HIGH to LOW hydrostatic pressures* -In the *arteries, the hydrostatic pressure near the heart is very high* and blood flows to the arterioles where the rate of flow is slowed by the narrow openings of the arterioles -During *systole, new blood is entering arteries*, the *artery walls stretch to accommodate the incr of pressure of the extra blood*; during diastole, the walls return to normal because of their elastic properties. The blood pressure of the systole phase and the diastole phase, gives the two pressure readings for blood pressure. For example, 120/80 indicates a reading of 120 mm Hg during the systole and 80 mm Hg during diastole. Throughout the cardiac cycle, the blood continues to empty into the arterioles at a relatively even rate. This *resistance to blood flow is called peripheral resistance* •A typical blood pressure for a healthy young adult is about 120/70. •*Blood pressure* is commonly measured using a *sphygmomanometer* •*Hypertension* (high blood pressure) is a serious *cardiovascular prob in which blood pressure is at/above 140 systolic* and/or *90 diastolic* -*Hypertension* causes •the *heart to work harder, weakening the heart over time* •*incr plaque* formation from tiny ruptures •*incr risk of blood clot* formation •Hypertension can contribute to •heart attacks, •strokes, and/or •kidney failure.

Homeostasis

-*Animal organs and organ systems constantly adjust to internal and external changes*= *HOMEOSTASIS* ("steady state") -*These changes might be in the level of glucose or calcium in blood* or in external temperatures -*Homeostasis* means to maintain *dynamic equilibrium in the body*. It is *dynamic because it is constantly adjusting to the changes that the body's systems encounter*. It is equilibrium because *body functions are kept within specific ranges*. Even an animal that is apparently *inactive is maintaining this homeostatic equilibrium* -The *goal of homeostasis is the maintenance of equilibrium* around a point or value called a set point. While *there are normal fluctuations from the set point*, the body's systems will usually attempt to go back to this point. -*A change in the internal or external environment* = *stimulus and is detected by a receptor*; the response of the system is to *adjust the deviation parameter* toward the set point. For instance, *if the body becomes too warm, adjustments are made to cool the animal*. If the blood's glucose rises after a meal, adjustments are made to lower the blood glucose level by getting the nutrient into tissues that need it or to store it for later use. -*When a change occurs in an animal's environment*, an *adjustment* must be made. The *receptor senses the change in the environment, then sends a signal to the control center* (in most cases, the brain) which in turn generates a *response signaled to an effector* -The *effector is a muscle* (that contracts or relaxes) or a *gland that secretes*. Homeostasis is maintained by *negative feedback loops* + *Positive feedback loops actually push the organism further out of homeostasis* but may be necessary for life to occur. Homeostasis is *controlled by the nervous and endocrine system of mammals*

Endotherms and Ectotherms What is an endotherm? What is an ectotherm? What 4 mechanisms could heat be exchanged through?

-*Animals can be divided into 2 groups*: some *maintain a constant body temp in the face of differing environmental temps*, while others have a *body temp that is the same as their environment* and thus varies with the environment. -*Animals that do not control their body temperature* = *ectotherms* -This group has been called *cold-blooded*, but the term may not apply to an animal in the desert with a very warm body temperature -In contrast to ectotherms, which *rely on external temperatures to set their body temperatures*, *poikilotherms are animals with constantly varying internal temps* -An animal that *maintains a constant body temperature in the face of environmental changes* = *homeotherm* -*Endotherms are animals that rely on internal sources for body temp* but which can *exhibit extremes in temp* These animals are able to maintain a level of *activity at cooler temperature, which an ectotherm cannot due to differing enzyme levels of activity* -*Heat can be exchanged between an animal and its environment* through four mechanisms: *radiation, evaporation, convection, and conduction* -*Radiation is the emission of electromagnetic "heat" waves* Heat comes from the sun in this manner and radiates from dry skin the same way. *Heat can be removed with liquid from a surface during evaporation* This occurs when a mammal sweats. *Convection currents of air remove heat from the surface of dry skin as the air passes over it* Heat will be conducted from one surface to another during direct contact with the surfaces, such as an animal resting on a warm rock

Endotherms and Ectotherms

-*Animals can be divided into 2 groups*: some *maintain a constant body temp in the face of differing environmental temps*, while others have a *body temp that is the same as their environment* and thus varies with the environment. -*Animals that don't control their body temperature* + *gains energy from outside sources* = *ectotherms* -This group has been called *cold-blooded*, but the term may not apply to an animal in the desert with a very warm body temperature -In contrast to *ECTOTHERMS* = which *rely on external temperatures to set their body temperatures*, *poikilotherms are animals with constantly varying internal temps* -An animal that *maintains a constant body temperature in the face of environmental changes* = *homeotherm* -*Endotherms are animals that rely on internal sources for body temp* but which can *exhibit extremes in temp* These animals are able to maintain a level of *activity at cooler temperature, which an ectotherm cannot due to differing enzyme levels of activity* -*Heat can be exchanged between an animal and its environment* through four mechanisms: *radiation, evaporation, convection, and conduction* -*Radiation is the emission of electromagnetic "heat" waves* Heat comes from the sun in this manner and radiates from dry skin the same way. *Heat can be removed with liquid from a surface during evaporation* This occurs when a mammal sweats. *Convection currents of air remove heat from the surface of dry skin as the air passes over it* Heat will be conducted from one surface to another during direct contact with the surfaces, such as an animal resting on a warm rock

Heat Conservation and Dissipation

-*Animals conserve/dissipate heat* in a variety of ways -In certain climates, *endothermic animals have some form of insulation*, such as *fur, fat, feathers* -*Animals with thick fur or feathers create an insulating layer of air btwn their skin and internal organs* -Polar bears and seals live and swim in a subfreezing environment and yet maintain a constant, warm, body temperature -The arctic fox, for example, uses its fluffy tail as extra insulation when it curls up to sleep in cold weather -*Mammals have a residual effect from shivering and incr muscle activity: arrector pili muscles cause "goose bumps,"* causing small hairs to stand up when the individual is cold; this has the *intended effect of incr body temp* -*Mammals use layers of fat to achieve the same end* + *Loss of body fat will compromise this ability* to conserve heat. -*Endotherms use their circulatory systems to help maintain body temp* -*Vasodilation brings more blood and heat to the body surface**, facilitating *radiation and evaporative heat loss*, which *helps to cool the body* -*Vasoconstriction reduces blood flow in peripheral blood vessels*, forcing *blood toward the core and the vital organs found there*, and *conserving heat* -*Some animals* have adaptions to their circulatory system that *enable them to transfer heat from arteries to veins*, *warming blood returning to the heart* -This is called a *countercurrent heat exchange*; it *prevents the cold venous blood from cooling the heart and other internal organs* -This adaption *can be shut down in some animals to prevent overheating the internal organs* -The countercurrent adaption is *found in many animals, including dolphins, sharks, bony fish, bees, and hummingbirds* -In contrast, *similar adaptations can help cool endotherms when needed*, such as dolphin flukes and elephant ears. -*Some ectothermic animals use changes in their behavior to help regulate body temp* -For example, a desert ectothermic animal may simply seek cooler areas during the hottest part of the day in the desert to keep from getting too warm -The *same animals may climb onto rocks to capture heat during a cold desert night* Some animals seek water to aid evaporation in cooling them, as seen with reptiles. Other ectotherms use group activity such as the activity of bees to warm a hive to survive winter. -*Many animals, especially mammals, use metabolic waste heat as a heat source* -When *muscles are contracted, most of the energy from the ATP used in muscle actions is wasted energy* that translates into heat -*Severe cold elicits a shivering reflex that generates heat* for the body. Many *species also have a type of adipose tissue* called *brown fat* that *specializes in generating heat*

The Role of Blood in the Body How does blood help maintain homeostasis (3)? How does blood play a protective role in preventing blood loss?

-*Blood* = *important for regulation of body's systems + homeostasis*. Blood helps *maintain homeostasis by stabilizing pH, temp, osmotic pressure + eliminating excess heat* -Blood supports growth by *distributing nutrients, hormones, removing waste* -Blood plays a protective role by *transporting clotting factors/platelets to prevent blood loss* and transporting the disease-fighting agents or white blood cells to sites of infection

Invertebrate Digestive System Animals have diff types of ______________ systems to aid in digestion of diff foods they consume Simplest example is the gastrovascular cavity which is? Ingested material does what? Cells in the cavity secrete what that help break down food? What is the alimentary canal? Once the food is ingested, through what does it pass through and where is it stored?

-*Animals have evolved diff types of digestive systems* to *aid in the digestion of the diff foods they consume* -The *simplest example is that of a gastrovascular cavity* and is *found in organisms w/ only 1 opening for digestion* -Platyhelminthes (flatworms), Ctenophora (comb jellies), and Cnidaria (coral, jelly fish, and sea anemones) use this type of digestion -*Gastrovascular cavities* = are typically a *blind tube/cavity w/ only 1 opening, the "mouth"*, which *also serves as an "anus"* -*Ingested material enters the mouth and passes through a hollow, tubular cavity* -*Cells in cavity secrete digestive enzymes* that *break down the food* -The *food particles are engulfed by cells lining the gastrovascular cavity* -Undigested come back up out of mouth -*The alimentary canal* = *more advanced system*: it consists of *1 tube w/ a mouth at one end and an anus at the other* + *specialized regions w/ 1-way flow of food* -Earthworms are an example of an animal with an alimentary canal. Once the *food is ingested thru the mouth + passes thru the esophagus* + *stored in an organ called the crop* then it passes into the gizzard where it is *churned and digested* From the gizzard, the food passes through the intestine, the nutrients are absorbed, and the *waste is eliminated as feces, called castings, through the anus*

Food Energy and ATP Animals need food to obtain ___________ and maintain _____________ What is homeostasis? The primary source of energy for animals is ________ and __________ is the body's fuel The digestable carbs are then converted to _________ with what catabolic or anabolic reaction? When does ATP release energy and convert to ADP + phosphate group? What happens when there is an excess amount of ATP available? When blood sugar drops, what does the liver release from glycogen?

-*Animals need food to obtain energy* + *maintain homeostasis* -*Homeostasis* = the *ability of a system to maintain a stable internal environment* in the face of external changes to the environment. Ex: the *norm body temp of humans is 37°C (98.6°F)* -*Humans maintain this temp even when external temp is hot/cold* -It *takes energy to maintain this body temp* + *animals obtain this energy from food* -The *primary source of energy for animals is carbs* (mainly glucose) -*Glucose* (body's fuel) -The *digestible carbohydrates in an animal's diet* = *converted to glucose molecules thru catabolic chem reactions* -*Adenosine triphosphate/ATP* = the *primary energy currency in cells*; *ATP stores energy in phosphodiester bonds* -*ATP releases energy when phosphodiester bonds* = *broken + ATP is converted to ADP* + *phosphate group* -*ATP is produced by the oxidative reactions in the cytoplasm* and mitochondrion of the cell, where carbohydrates, proteins, and fats undergo a series of metabolic reactions collectively called cellular respiration. For example, *glycolysis is a series of reactions in which glucose is converted to pyruvic acid* and some of its *chemical potential energy is transferred to NADH and ATP* -*ATP* = *required for all cellular functions* -It is *used to build the organic molecules required for cells/tissues* + it provides *energy for muscle contraction* + *transmission of electrical signals in nervous system* -When the *amount of ATP is available in excess of the body's requirements*, the *liver uses excess ATP* and *excess glucose to produce molecules* = *glycogen* -*Glycogen is a polymeric form of glucose* and is *stored in the liver/skeletal muscle cells* -*When blood sugar drops*, the *liver releases glucose from stores of glycogen* -*Skeletal muscle converts glycogen to glucose* during intense exercise -The process of *converting glucose/excess ATP to glycogen* and the storage of excess energy is an evolutionarily *important step in helping animals deal with mobility, food shortages, and famine*

Need for Osmoregulation

-*Biological systems* constantly *interact/exchange water + nutrients* with the environment by *consumption of food/water* + through *excretion in sweat, urine, feces* -*W/o a mechanism to regulate osmotic pressure*, or when a disease damages this mechanism, there is a *tendency to accumulate toxic waste/water* which can have dire consequences. -*Mammalian systems* have *evolved to regulate osmotic pressure across membranes* but also specific *concentrations of electrolytes in blood plasma, extracellular fluid, intracellular fluid* -Since *osmotic pressure* = *regulated by movement of water across membranes*, the *volume of fluid compartments can change temporarily* -Because *blood plasma = fluid component*, *osmotic pressures* have a *direct bearing on blood pressure*

Nitrogenous Waste in Birds and Reptiles: Uric Acid 37

-*Birds, reptiles, terrestrial arthropods* = *convert toxic ammonia* to *uric acid or guanine (guano) instead of urea* -*Mammals* also *form some uric acid* during *breakdown of nucleic acids* -*Uric acid* is a *compound similar to purines in nucleic acids* -It is *water insoluble* and tends to *form a white paste or powder* it is *excreted by birds, insects, reptiles* -Conversion of *ammonia to uric acid* requires *more energy* and is much *more complex than* conversion of *ammonia to urea* -*Uric acid* is *excreted by land animals* (insects, land snails, and many reptiles), *relatively nontoxic*, *water-insoluble*, excreted as a *semisolid paste*, *conserving water*, but *more energy-expensive* to produce.

Platelets and Coagulation Factors Blood must do what to heal wounds and prevent blood loss? 250-400k cell fragments in plasma called what? What do they convert (protein) to cause the clot? What vitamin is required to clot? What do you call a bunch of platelets sticking the wound? What are megakaryocytes? What white blood cell is a lymphoid and which are myeolids?

-*Blood must clot* to *heal wounds* and *prevent blood loss* -250-400K Small *cell fragments suspended in plasma = PLATELETS* (thrombocytes) are *attracted to wound* site where they adhere by extending many projections and releasing their contents -These contents *activate other platelets* and also interact with other coagulation factors, which *convert fibrinogen- water-soluble protein into fibrin* (a non-water-soluble protein), causing the blood to clot -*Many clotting factors require vitamin K* to work, and vitamin K deficiency can lead to problems with blood clotting. -*PLATELET PLUG* = *many platelets stick together at the wound* -The plug or clot lasts for a number of days and stops the loss of blood -*MEGAKARYOCYTES* = how *platelets are formed* from *disintegration of larger cells* •When a *blood vessel is damaged* = •*platelets adhere to the connective tissue* and release chemicals that make nearby platelets sticky, •a cluster of *=*sticky platelets form plug*, and •*clotting factors set off a chain of reactions* that culminate in the formation of a *reinforced patch* = *SCAB* -In this complex process, an *activated enzyme converts fibrinogen to threadlike protein fibrin* Threads of fibrin reinforce the plug, forming a fibrin clot. Lymphoids = lymphocytes Myeolid = every other white blood cell (erythrocytes, platelets, monocytes, neutrophils, eosinophils, basophils)

Transport of Electrolytes across Cell Membranes

-*Electrolytes* (sodium chloride) *ionize in water* meaning that *they dissociate into their component ions* -In water, *sodium chloride (NaCl), dissociates into sodium ion (Na+) + chloride ion (Cl-)* -The most important ions, whose *concentrations regulated in body fluids* are the *cations sodium (Na+), potassium (K+), calcium(Ca+2), magnesium (Mg+2)* and the *anions chloride (Cl-), carbonate (CO3-2), bicarbonate (HCO3-), phosphate(PO3-)* -*Electrolytes* = *lost from body during urination* and *perspiration* -For this reason, athletes are encouraged to replace electrolytes and fluids during periods of increased activity and perspiration. -*Osmotic pressure* = influenced by the *concentration of solutes in a solution* is *directly proportional to the solute atoms/molecules* and *not on size of solute molecules* -Because *electrolytes dissociate into component ions* + they, in essence, *add more solute to the solution* and have a *greater effect on osmotic pressure than compounds that DON'T dissociate in water* (glucose) -*Water* = can *pass membranes via passive diffusion* -If *electrolyte ions could passively diffuse across membranes* = *impossible to maintain specific concentrations* of ions in each fluid compartment therefore they *require special mechanisms to cross the semi-permeable membranes* in the body. This movement *can be accomplished by facilitated diffusion* and *active transport* -*Facilitated diffusion* = requires *protein-based channels for moving solute* -*Active transport* requires *energy in ATP* conversion, *carrier proteins*, or *pumps to move ions against the concentration gradient*

Basic circulatory systems of some vertebrates: fish, amphibians, reptiles, and mammals Which vertebrate has the simplest circulatory system with only single circulation and ___ chambers? The fish does not have enough pressure to move through the? What 2 vertebrates both have double circulation and 3 chambers? What is pulmonary and systemic circulation? What is the most efficient circulatory system and why?

-*FISH* = have the *simplest circulatory systems* of the vertebrates: *blood flows unidirectionally from 2-chambered heart thru gills to body* = *SINGLE CIRCULATION* -*not enough pressure to move blood thru capillaries* of the lungs and *then to the body capillaries of terrestrial vertebrate* -*LAND VERTEBRATES* Amphibians = *2 circulatory routes*: 2 aria mixes w/ ventricles + *blood is pumped after losing lung pressure* - oxygenation of the blood through the lungs and skin (PULMOCUTANEOUS) = *PULMONARY*= *right side* of the heart, *deoxygenated* blood, *goes to lungs* via pulmonary, *low pressure* - oxygen to the rest of the body = *SYSTEMIC* = *left side*, *oxygenated* blood, supplies blood to *all parts of the body* via *aorta*, *high pressure* The blood is pumped from a three-chambered heart with two atria and a single ventricle -*REPTILES* = *2 circulatory routes* + blood is only oxygenated through the lungs. The heart = *3-chambered* but the *ventricles are partially separated* so some mixing of oxygenated and deoxygenated blood occurs •Because *gas exchange* in the *lungs/skin* = *PULMOCUTANEOUS circuit* -*MAMMALS/BIRDS* = *most efficient heart w/ 4 chambers* that *completely separate oxygenated/deoxygenated blood* it pumps only oxygenated blood through the body and deoxygenated blood to the lungs -*2 atria + 2 ventricles* (right = oxygen poor) (left = oxygen rich)

Glomerular Filtration What process is used to filter out?

-*Glomerular filtration* = *filters out* in *RENAL CORTEX* most of the solutes *due to high blood pressure* and specialized membranes in the afferent arteriole -*The blood pressure in the glomerulus* is maintained *independent of systemic blood pressure* -The *"leaky" connections btwn endothelial cells* of the glomerular capillary network *allow solutes to pass through easily* -*All solutes* in the *glomerular capillaries*, *except macromolecules* like proteins, *pass through by passive diffusion* -There is *no energy requirement for filtration process* -Glomerular filtration rate (GFR) is the volume of glomerular filtrate formed per minute by the kidneys. GFR is regulated by multiple mechanisms and is an important indicator of kidney function.

Components of the Blood What red protein is found in blood and what is it responsible for? What 3 things make up blood? What are the percentages of plasma and blood in cellular components? What is found in plasma (5)?

-*Hemoglobin* = responsible for *distributing O2 +CO2* throughout the circulatory systems of humans, vertebrates, invertebrates -The *blood is more than proteins* though. Blood is actually a term used to describe the *liquid that moves through the vessels* = *PLASMA* (*water, proteins, salts, lipids, glucose*) + the *CELLS* (*red/white cells*) + cell fragments called *PLATELETS* -Blood plasma = *water, proteins, electrolytes (balance osmorality), lipids, glucose* -The cells are responsible for carrying the gases (red cells) and immune the response (white) -The platelets are responsible for blood clotting -*Interstitial fluid* = *surrounds cells* is separate from the blood, but in *hemolymph = they are combined* -*In humans* = *cellular components make up 45% of blood + 55% plasma* -Blood is 20 percent of a person's extracellular fluid and eight percent of weight

Herbivores, Omnivores, and Carnivores What types of foods do each eat? How can herbivores be further classified (4)? How can carnivores be further classified and which one is basically an omnivore (2)?

-*Herbivores* are animals whose primary food source = *PLANT-BASED* -Ex: "deer, koalas, bird species* as well as *Invertebrates such as crickets and caterpillars* -These *animals have evolved digestive systems capable of handling large amounts of plant material* -*Herbivores can be further classified into: *frugivores (fruit-eaters)* *granivores (seed eaters)* *nectivores (nectar feeders)* *folivores (leaf eaters)* -*Carnivores* are *animals that eat other animals* = *"meat eater"* -Ex: *Wild cats* = lions, tigers* of vertebrate carnivores, snakes, sharks, while *invertebrate carnivores include sea stars, spiders, ladybugs* -*Obligate carnivores* = those that *rely ONLY on animal flesh to obtain their nutrients* -Ex: obligate carnivores are *members of the cat family* = lions and cheetahs -*Facultative carnivores* = those that also *eat non-animal food in addition to animal food* -*Facultative carnivores = Omnivores*; *dogs would be considered facultative carnivores* -*Omnivores are animals that eat both plant- and animal*-derived food. In Latin, omnivore means to eat everything -Ex: *Humans, bears, chickens = vertebrate* omnivores *cockroaches, crayfish = invertebrate* omnivores

How Hormones Work Hormones bring changes in target cells by binding to specific hormone __________ Receptors are ______________ for hormones What is up regulaltion and down regulation?

-*Hormones mediate changes in target cells* by *binding to specific hormone receptors* In this way, even though hormones circulate throughout the body and come into contact with many different cell types, they *only affect cells that possess necessary receptors* -*Receptors for a specific hormone* may be *found on many/few cells* or may be limited to a small number of specialized cells -For ex: *thyroid hormones act on diff tissue types* *stimulating metabolic activity* throughout the body -*Cells* = *receptors for same hormone* but often also *possess receptors for diff hormones* -The *number of receptors that respond to a hormone* determines the *cell's sensitivity to that hormone*, and the resulting cellular response -Additionally, the number of receptors that respond to a hormone can change over time, resulting in *increased or decreased cell sensitivity* -In *up-regulation* = the *number of receptors incr to rising hormone levels* making the *cell more sensitive to hormone* + *allowing more cellular activity* -When the *number of receptors decr* in response to rising hormone levels, called *down-regulation* cellular activity is reduced. -*Receptor binding* alters cellular activity and results in an *incr/decr in normal body processes* -Depending on the location of the protein receptor on the target cell and the chemical structure of the hormone, hormones can mediate changes directly by binding to intracellular hormone receptors and modulating gene transcription, or indirectly by binding to cell surface receptors and stimulating signaling pathways.

Immunodeficiency The immune response is ____________ The immune system may also be suppressed by __________________, ________________, ______________ The lymphatic system is a network of _______________ + ________________ that rid the body of waste

-*Immunodeficiency* diseases are *underreactions of the immune system*, in which an *immune response = defective or absent* •The immune system may also be suppressed by •*cancer of the lymphatic system* •*radiation* and •*physical/emotional stress* -The *lymphatic system* = a *network of tissues + organs* that help *rid the body of toxins, waste, unwanted materials* -The primary function of the lymphatic system is to *transport lymph = a fluid containing infection-fighting white blood cells*, throughout the body -Failures, insufficiencies, or delays at any level of the immune response can allow pathogens or tumor cells to gain a foothold and replicate or proliferate to high enough levels that the immune system becomes overwhelmed. Immunodeficiency is the failure, insufficiency, or delay in the response of the immune system, which may be acquired or inherited. Immunodeficiency can be acquired as a result of infection with certain pathogens (such as HIV), chemical exposure (including certain medical treatments), malnutrition, or possibly by extreme stress. For instance, radiation exposure can destroy populations of lymphocytes and elevate an individual's susceptibility to infections and cancer. Dozens of genetic disorders result in immunodeficiencies, including Severe Combined Immunodeficiency (SCID), Bare lymphocyte syndrome, and MHC II deficiencies. Rarely, primary immunodeficiencies that are present from birth may occur. Neutropenia is one form in which the immune system produces a below-average number of neutrophils, the body's most abundant phagocytes. As a result, bacterial infections may go unrestricted in the blood, causing serious complications.

Kidney Function and Physiology How does glomerular filtration occur? How does reabsorption occur? How does tubular secretion?

-*Kidneys filter blood in a 3-step process* -First, the *nephrons filter blood through the capillary network in the glomerulus* -*Almost all solutes*, except for red blood cells/proteins, are *filtered out into the glomerulus* by a process called = GLOMERULAR FILTRATION* -Second, the *filtrate is collected in renal tubules* -Most of the *solutes get reabsorbed in PCT* by a process called = *TUBULAR RESPIRATION* -In the *loop of Henle* = the *filtrate exchanges solutes/water w/ the renal medulla* and the *peritubular capillary network* -*Water is also reabsorbed* during this step -Then, additional *solutes/wastes secreted into kidney tubules* = during *TUBULAR SECRETION*, which is, in essence, the opposite process to tubular reabsorption -The *collecting ducts collect filtrate from nephrons* + and *fuse in the medullary papilla* - From here, the papillae deliver the filtrate, now called urine, into the minor calyces that eventually connect to the ureters through the renal pelvis 1) The glomerulus forces small solutes out of the blood by pressure. (2) The proximal convoluted tubule reabsorbs ions, water, and nutrients from the filtrate into the interstitial fluid, and actively transports toxins and drugs from the interstitial fluid into the filtrate. The proximal convoluted tubule also adjusts blood pH by selectively secreting ammonia (NH3) into the filtrate, where it reacts with H+ to form NH4+. The more acidic the filtrate, the more ammonia is secreted. (3) The descending loop of Henle is lined with cells containing aquaporins that allow water to pass from the filtrate into the interstitial fluid. (4) In the thin part of the ascending loop of Henle, Na+ and Cl- ions diffuse into the interstitial fluid. In the thick part, these same ions are actively transported into the interstitial fluid. Because salt but not water is lost, the filtrate becomes more dilute as it travels up the limb. (5) In the distal convoluted tubule, K+ and H+ ions are selectively secreted into the filtrate, while Na+, Cl-, and HCO3- ions are reabsorbed to maintain pH and electrolyte balance in the blood. (6) The collecting duct reabsorbs solutes and water from the filtrate, forming dilute urine.

Intracellular Hormone Receptors What 3 steps are taken to mount a hormonal response? Which hormones need a receptor to bind to, to enter the membrane? Which ones can diffuse but then bind to a transport protein inside?

-*Lipid-derived (soluble) hormones* such as *steroid hormones diffuse across the membranes* of the endocrine cell -Once *outside* the cell, they *bind to transport proteins that keep them soluble in bloodstream* -At the *target cell* = the *hormones are released from carrier protein* and *diffuse across the lipid bilayer* of the plasma membrane of cells -The *steroid hormones pass* through the plasma membrane of a target cell and *adhere to intracellular receptors in the cytoplasm* or in the nucleus -The *cell signaling pathways by the steroid hormones* *regulate specific genes* on the cell's DNA. The hormones and receptor complex act as *transcription regulators by incr/decr the synthesis of mRNA* molecules of specific genes. This, in turn, determines the amount of *corresponding protein that is synthesized by altering gene expression in the hormone receptor complex* -This protein can be used either to *change the structure of the cell*, *activate gene*, or to *produce enzymes* that catalyze chemical reactions. In this way, the steroid hormone regulates specific cell processes -Other lipid-soluble hormones that are not steroid hormones, such as *vitamin D and thyroxine, have receptors in nucleus* -The hormones diffuse across both the plasma membrane and the nuclear envelope, then *bind to receptors in the nucleus* -The *hormone-receptor complex stimulates transcription of specific genes* Water-soluble hormones need a receptor to bind to enter, receptor proteins on target cell = signal transduction pathway

Natural Killer Cells T cells and B cells are of the adaptive immunity bc of ? Infected cells are identified/destroyed by? MHC allows large proteins to identify_________ proteins

-*Lymphocytes are leukocytes* that are histologically *identifiable by their large, darkly staining nuclei*; they are small cells with very little cytoplasm -*Infected cells* are identified/*destroyed by natural killer (NK) cells*, lymphocytes that can *kill cells infected w/ viruses/cancer/tumor cells* (abnormal cells that uncontrollably divide and invade other tissue) -*T cells + B cells* of the *adaptive* immune system also are classified as *lymphocytes* -*T cells are lymphocytes* that *mature in thymus gland*, and *B cells are lymphocytes* that *mature in bone marrow* -NK cells *identify intracellular infections from viruses by* the altered expression of *major histocompatibility class (MHC) I molecules* -MHC I molecules are *proteins on surfaces of all nucleated/infected cells* thus they are *scarce red blood cells/platelets* = *non-nucleated* -The function of *MHC I molecules* is to *display fragments of proteins from infectious agents in the cell to T-cells*, healthy cells will be ignored, while *"non-self" or foreign proteins will be attacked* by the immune system -MHC II molecules are found mainly on cells containing antigens ("non-self proteins") and on lymphocytes. MHC II molecules *interact w/ helper T-cells to trigger immune response*, which may include the inflammatory response. -An *infected cell* (or a tumor cell) is usually *incapable of synthesizing and displaying MHC I molecules* appropriately. The metabolic resources of cells infected by some viruses produce proteins that interfere with MHC I processing and/ or trafficking to the cell surface -The *reduced MHC I on host cells varies from virus to virus* and *results from active inhibitors* being produced by the viruses. This process can *deplete host MHC I molecules on the cell surface*, which *NK cells detect as "unhealthy" or "abnormal"* while searching for cellular MHC I molecules. Similarly, the dramatically altered gene expression of tumor cells leads to expression of extremely deformed or absent MHC I molecules that also signal "unhealthy" or "abnormal." -*NK cells are always active*; an interaction with normal, intact *MHC I molecules on a healthy cell disables the killing sequence*, and the NK cell moves on. After the NK cell detects an infected or tumor cell, its cytoplasm secretes granules comprised of perforin, a destructive protein that creates a pore in the target cell. Granzymes are released along with the perforin in the immunological synapse. A granzyme is a protease that digests cellular proteins and induces the target cell to undergo programmed cell death, or apoptosis. Phagocytic cells then digest the cell debris left behind. NK cells are constantly patrolling the body and are an effective mechanism for controlling potential infections and preventing cancer progression.

T and B Lymphocytes

-*Lymphocytes in human circulating blood* are approximately *80-90% T cells*, and *10-20% B cells* •spend most of their time in the blood and the tissues and organs of the lymphatic system, -Recall that the *T cells are involved in the cell-mediated immune response* whereas *B cells are part of the humoral immune response* -*T cells encompass a heterogeneous population of cells* with extremely diverse functions. Some *T cells respond to APCs of the innate immune system*, and indirectly induce immune responses by *releasing cytokines* -Other *T cells stimulate B cells to prepare their own response* -Another population of *T cells detects APC signals and directly kills the infected cells* -Other *T cells are involved in suppressing inappropriate immune reactions to harmless or "self" antigens* -T and B cells exhibit a *common theme of recognition/binding of specific antigens via a complementary receptor*, followed by *activation/self-amplification/maturation* to specifically *bind to the particular antigen of the infecting pathogen* -*T and B lymphocytes* are also *only expresses 1 type of antigen receptor* -Any individual may possess a *population of T and B cells* that together express a *near limitless variety of antigen receptors recognizing any infecting pathogen* -T and B cells are *activated when they recognize* small *components of antigens* = *epitopes* presented by APCs -Note that recognition occurs at a specific epitope rather than on the entire antigen; for this reason, epitopes are known as "antigenic determinants." In the *absence of information from APCs*, *T and B cells* remain *inactive, or naïve* and are unable to prepare an immune response -*Naïve T cells* can express one of two different molecules, These molecules are important because they *regulate how a T cell will interact with and respond to an APC* -*Naïve CD4+* cells *bind APCs via antigen-embedded MHC II molecules* and *are stimulated to become helper T (TH) lymphocytes* cells that go on to stimulate B cells (or cytotoxic T cells) directly or secrete cytokines to inform more and various target cells about the pathogenic threat -In contrast, *CD8+ cells engage antigen-embedded MHC I molecules on APCs* and are stimulated to *become cytotoxic T lymphocytes (CTLs)* which direct = *kill infected cells by apoptosis* and *emit cytokines to amplify the immune response* •Whether antigens enter the body naturally (if you catch the flu) or artificially (if you get a flu vaccine), the resulting immunity is called *active immunity*, because the person's own immune system actively produces antibodies. •It is also possible to acquire *passive immunity* by receiving premade antibodies for *fetus for 6 months, TEMP*ORARY bc *recipient immune system is not activated by antigens*, last for weeks to months, *once the immune system is developed = PASSIVE IS GONE*

Contractile Vacuoles in Microorganisms

-*Microorganisms/invertebrate animals* use *more primitive/simple mechanisms to rid metabolic wastes than the mammalian system of kidney + urinary function* -Three *excretory systems* evolved in organisms before complex kidneys: *vacuoles, flame cells, Malpighian tubules* -The most fundamental feature of life is the presence of a cell -In other words, a cell is the simplest functional unit of life -*Bacteria are unicellular, prokaryotic organisms* that have some of the *least complex life* processes in place; however, prokaryotes such as bacteria *do not contain membrane-bound vacuoles* -The *cells of microorganisms* like bacteria, protozoa, and fungi are *bound by cell membranes* and use them to *interact w/ the environment* -Some cells, including some *leucocytes in humans*, are able to *engulf food by endocytosis*—the *forming vesicles by involution of the cell membrane* within the cells -The *same vesicles* are able to *interact/exchange metabolites w/ intracellular environment* -In some *unicellular eukaryotic organisms* such as the *amoeba*, *cellular wastes + excess water excreted by exocytosis*, when the contractile vacuoles merge with the cell membrane and expel wastes into the environment -*Contractile vacuoles (CV)* should *not be confused w/ vacuoles* which *store food or water* Some unicellular organisms, such as the amoeba, ingest food by endocytosis. The food vesicle fuses with a lysosome, which digests the food. Waste is excreted by exocytosis.

Obesity Directly linked with what disease(s) Animals tend to seek what type of rich food for higher energy content? Fatty acids and glycerol are absorbed by what cells?

-*Obesity* = major *health concern in US* + there is a *growing focus on reducing obesity* and the *diseases it may lead to = diabetes, cancers of the colon/breast, *cardiovascular disease* = *Heart/blood vessel disorder* -How does the food consumed contribute to obesity? -*Fatty foods = calorie-dense*, they have *more calories per unit mass than carbs/proteins* -*1g carbohydrates* = *4 calories* + *1g of protein* = *4 calories* + *1g of fat* = *9 calories* -*Animals* tend to *seek lipid-rich food for higher energy content* -The *signals of hunger* ("time to eat") + *satiety* ("time to stop eating") = *controlled in the hypothalamus region* of the brain. Foods that are rich in *fatty acids tend to promote satiety* more *than foods rich only in carbohydrates* -Fatty acids and glycerol are absorbed by intestinal cells, recombined into fats, coated with proteins, and transported into lymph vessels. -*Excess carbohydrate/ATP* = *used by liver to synthesize glycogen* -The pyruvate produced during glycolysis is used to synthesize fatty acids. When there is more glucose in the body than required, the resulting excess pyruvate is converted into molecules that eventually result in the synthesis of fatty acids within the body. These fatty acids are stored in adipose cells—the fat cells in the mammalian body whose primary role is to store fat for later use. It is important to note that some animals benefit from obesity. Polar bears and seals need body fat for insulation and to keep them from losing body heat during Arctic winters. When food is scarce, stored body fat provides energy for maintaining homeostasis. Fats prevent famine in mammals, allowing them to access energy when food is not available on a daily basis; fats are stored when a large kill is made or lots of food is available

Osmoregulation and Osmotic Balance What is osmosis? What is osmoregulation? What is an electrolyte? The body's fluids include the _________ and the __________ within cells The body's membranes are = What is hypotonic, hypertonic, isotonic?

-*Osmosis* = the *diffusion of water across a membrane* in response to *osmotic pressure* caused by an *imbalance of molecules* on either side of the membrane -*Osmoregulation* = the process of *maintenance of salt/water balance* (osmotic balance) across membranes within the body's fluids, which are composed of water, plus *electrolytes and non-electrolytes* -An *electrolyte* = a *solute that dissociates into ions when dissolved in water* -A *non-electrolyte* = *DOESN'T dissociate into ions during water dissolution* -Both *electrolytes and non-electrolytes contribute to the osmotic balance* -The body's fluids include *blood plasma*, the *cytosol* within cells, and *interstitial fluid*, the *fluid btwn cells/tissues* of the body -The *membranes of the body* = (such as the pleural, serous, and cell membranes) *semi-permeable membranes* -*Semi-permeable membranes* = *permeable* (or permissive) to *certain types of solutes/water* -*Solutions* on *2 sides of semi-permeable membrane* tend to *equalize in solute concentration by movement of solutes/water* across the membrane -A *cell placed in water* tends to *swell due to gain of water* from the *HYPOTONIC* or "low salt" environment. -A *cell placed in solution w/ higher salt concentration* tends to make the *membrane shrivel up* due to *loss of water* into the *HYPERTONIC* or "high salt" environment -*ISOTONIC* cells have an *equal concentration of solutes inside/outside the cell*; this *equalizes the osmotic pressure* on either side of the cell membrane which is a semi-permeable membrane. The blood maintains an isotonic environment so that cells neither shrink nor swell. -The *body does not exist in isolation* so there is a *constant input of water and electrolytes* into the system. -While *osmoregulation is achieved* across membranes within the body, *excess electrolytes and wastes are transported to the kidneys and excreted*, helping to maintain osmotic balance.

Blood Types Related to Proteins on the Surface of the Red Blood Cells Red blood cells are coated in antigens made of? People w/ blood type A have antigen A People w/ blood type B have antigen _ What is the Rh blood group?

-*Red blood cells* are *coated in antigens* made *of glycolipids and glycoproteins* -The *composition of these molecules* is *determined by genetics* which have evolved over time -In humans, the *diff surface antigens are grouped into 24 blood groups* with more than 100 different antigens on each red blood cell -The two *most well known blood groups* are the *ABO and Rh* systems -*GLYCOLIPIDS* = The *surface antigens in the ABO* blood group called *antigen A*and *antigen B* -People with blood type A have antigen A, those with blood type B have antigen B, those with blood type AB have both antigens, and *people w/ blood type O have neither antigen* -*Antibodies called agglutinougens* are found *in the blood plasma* and *react w/ A or B antigens* if the 2 are mixed -When *type A and B blood are combined* = *agglutination (clumping) of blood occurs bc of antibodies in the plasma* that bind with the opposing antigen; this causes clots that coagulate in the kidney causing kidney failure. Type O blood has neither A or B antigens, and therefore, type O blood can be given to all blood types -*Type O* negative blood is the *universal donor* + *Type AB* positive blood is the *universal acceptor* because it has both A and B antigen. The ABO blood groups were discovered in 1900 and 1901 by Karl Landsteiner at the University of Vienna. -The *Rh blood group* was first discovered in *Rhesus monkeys* -Most people *have the Rh antigen (Rh+)* and *do not have anti-Rh antibodies* in their blood -The *few people w/o the Rh antigen* and are *Rh- can develop anti-Rh antibodies if exposed to Rh+ blood* -This can happen after a blood transfusion or after an Rh- woman has an Rh+ baby. The first exposure does not usually cause a reaction; however, at the second exposure, enough antibodies have built up in the blood to produce a reaction that causes agglutination and breakdown of red blood cells. An injection can prevent this reaction.

Tubular Reabsorption and Secretion

-*Tubular reabsorption occurs in the PCT part of the renal tubule* Almost all nutrients are reabsorbed, and this occurs either *by passive or active transport* -*Reabsorption of water* and *some key electrolytes* are *regulated/influenced by hormones* -Sodium (Na+) is the most abundant ion and most of it is reabsorbed by active transport and then transported to peritubular capillaries. Because *Na+ is actively transported out of the tubule*, water follows it to *even out the osmotic pressure* -*Water is independently reabsorbed into the peritubular capillarie*s due to the presence of *aquaporins/water channels* in the PCT -This occurs due to the *low blood pressure + high osmotic pressure in the peritubular capillaries* -However, *every solute has a transport maximum* and the excess is not reabsorbed. -In the *loop of Henle* = the *permeability of membrane changes* The descending limb is permeable to water, not solutes; the opposite is true for the ascending limb. Additionally, the loop of Henle invades the renal medulla, which is naturally high in salt concentration and tends to absorb water from the renal tubule and concentrate the filtrate. The osmotic gradient increases as it moves deeper into the medulla. Because two sides of the loop of Henle perform opposing functions, it acts as a countercurrent multiplier. The vasa recta around it act as the countercurrent exchanger -By the time the filtrate reaches the DCT, most of the urine and solutes have been reabsorbed. If the body requires additional water, all of it can be reabsorbed at this point. Further reabsorption is controlled by hormones, which will be discussed in a later section. Excretion of wastes occurs due to lack of reabsorption combined with tubular secretion. Undesirable products like metabolic wastes, urea, uric acid, and certain drugs, are excreted by tubular secretion. Most of the tubular secretion happens in the DCT, but some occurs in the early part of the collecting duct. Kidneys also maintain an acid-base balance by secreting excess H+ ions -Although parts of the renal tubules are named proximal and distal, in a cross-section of the kidney, the tubules are placed close together and in contact with each other and the glomerulus. This allows for exchange of chemical messengers between the different cell types. For example, the DCT ascending limb of the loop of Henle has masses of cells called macula densa, which are in contact with cells of the afferent arterioles called juxtaglomerular cells. Together, the macula densa and juxtaglomerular cells form the juxtaglomerular complex (JGC). The JGC is an endocrine structure that secretes the enzyme renin and the hormone erythropoietin. When hormones trigger the macula densa cells in the DCT due to variations in blood volume, blood pressure, or electrolyte balance, these cells can immediately communicate the problem to the capillaries in the afferent and efferent arterioles, which can constrict or relax to change the glomerular filtration rate of the kidneys.

Vertebrate Digestive Systems Which vertebrates have a single-chambered stomach and which have 2, 3, 4? What does the monogastric digestive system start with? 4 playing factors human (monogastric) digestion? What are the effects (3)? What challenge do birds face when obtaining nutrition from food? What about ruminants and pseudo ruminants? What are the 2 stomachs of the bird? What are the 4 stomachs of ruminants and what's the pseudo-ruminant's? What do birds and ruminants not have? What do they have since they need to fly around? What are 2 parts of the bird's stomach? Most chemical digestion/absorption happens where? What are ruminants and what do they eat? What can they not eat? What are pseudo ruminants and what do they eat a lot of?

-*Vertebrates evolved more complex digestive systems* to *adapt to their dietary needs* -Some animals have a *single stomach + some have multi-chambered stomachs* -*Birds have developed a digestive system* adapted to *eating unmasticated food* -*Monogastric: Single-chambered Stomach* + *humans and many animals have a monogastric digestive system*. The process of *digestion begins w/ the mouth*(intake of food) -The *teeth* play an important role in *masticating (chewing)* or physically *breaking down food* into smaller particles -The *enzymes* present *in saliva chemically break down food* -The *esophagus* is a *long tube connecting mouth to stomach* -Using *peristalsis/wave-like smooth muscle contractions* = the *muscles of esophagus push food to stomach* -In order to *speed up enzymes in the stomach* the stomach is an *extremely acidic environment* w/ a *pH of 2* - *H. pylori doesn't die* -The *gastric juices* include *enzymes in the stomach*, act on the *food particles + continue digestion* + *mucus* -Further *breakdown of food takes place in the small intestine* where *enzymes produced by the liver, small intestine*, *pancreas continue the process of digestion* -The *nutrients are absorbed into bloodstream via epithelial cells* lining the walls of the small intestines by *DIFFUSION* + *Against con. gradient* The *waste material travels to the large intestine* where *water is absorbed* and the *drier waste material is feces*; it is stored until it is excreted through the rectum. Avian -*Birds have special challenges when obtaining nutrition from food* -They *DON'T have teeth* and so their *digestive system must be able to process un-masticated food* -Birds have *evolved a variety of beak types* that reflect the *vast variety in their diet* ranging *from seeds, insects, fruits, nuts* -Bc most birds fly, they *have HIGH metabolic rates to efficiently process food + keep body weight low* -The *stomach of birds has 2 chambers*: the *proventriculus = gastric juices are produced to digest food before entering stomach* + *gizzard = where the food is stored, soaked, mechanically ground*' -The *undigested material forms food pellets* = *regurgitated* -Most of the *chemical DIGESTION/ABSORPTION happens in the intestine *and the *waste is excreted through the cloaca* + needed bc because animals cannot directly use the proteins, carbohydrates, fats, and nucleic acids in food. -*Mechanical digestion and chemical digestion* begin in the *mouth* Ruminants -*Ruminants are HERBIVORES* (cows, sheep, goats) whose *entire diet consists of eating roughage/fiber* -They have *evolved digestive systems* that help them *digest vast amounts of cellulose* -Ruminants' mouth is that they *don't have upper incisor teeth* + instead *use their lower teeth, tongue, lips to chew* their food -From the mouth, the food travels to the esophagus and on to the stomach. To help digest lots of plant material, the *stomach of the ruminants is a MULTI-CHAMBERED ORGAN* w/ 4 compartments of the stomach = the *rumen, reticulum, omasum, abomasum* -These *chambers contain many microbes that break down cellulose + ferment ingested food* -The *abomasum* = *"true" stomach* and is the *equivalent of the monogastric stomach chamber* where *gastric juices are secreted* -The *4-compartment gastric chamber* DOESN'T HAVE ENZYMES TO DIGEST CELLULOSE but has *larger space* + *bacteria/protists to help digest* -The *fermentation process produces large amounts of gas* in the stomach chamber, which must be eliminated. As in other animals, the *small intestine does nutrient absorption* + *large intestine helps rid waste* Pseudo-ruminants -Some *animals* (camels, alpacas) *are pseudo-ruminants* -They *eat a lot of plant material/roughage* -*Digesting plant material* is *not easy bc plant cell walls have cellulose* + the digestive enzymes of these animals cannot break down cellulose, but *microorganisms present in the digestive system can* -Therefore, the *digestive system must be able to handle roughage + break down the cellulose* -*Pseudo-ruminants* have a *3- chamber stomach in the digestive system* However, their *cecum—a pouched organ at the beginning of the large intestine* containing many microorganisms that are necessary for the digestion of plant materials—is large and is *the site where the roughage is fermented/digested* -These animals *DON'T have a rumen but have an omasum, abomasum, reticulum*

Stomach: Small and Large Intestine What kind of environment is needed for the stomach and what is released? It stops if too much is released = __________________ feedback Protein is mediated by enzyme _______ ad its inactive form ___________ It activates more inactive form to make more enzymes = _________________ feedback What do parietal cells do, what is secreted? Microvilli allow for what in the __________ intestine. Increases __ 3 parts of stomach? What is bile? What does the large intestine do? 3 parts of large intestine?

-A *large part of digestion* occurs *in STOMACH* -The *stomach* = a *saclike organ* sometimes *secreting gastric digestive juices* w/ *pH of 1.5-2.5* but don't digest the stomach wall -*Acidic environment is required for breakdown of food* + *extraction of nutrients* + *inhibits gastrin release* when stomach is too acidic- *neg feedback* -When *empty* = the *stomach becomes a small organ* but *expands to 20x the resting size when filled w/ food* -Useful for animals that need to eat when food is available. The *stomach* = the *major site for protein digestion in animals besides ruminants* -*Protein digestion* is *mediated by an enzyme* = *PEPSIN* (stomach chamber) that's *secreted by chief cells in stomach* in an *inactive form* = *PEPSINOGEN* -*Pepsin breaks peptide bonds* + *cleaves proteins to smaller polypeptides*; it also helps *activate more pepsinogen that generates more pepsin* = *POSITIVE FEEDBACK* -*Parietal cells* = *secrete H+* (hydrogen) and *Cl-*(chloride) ions *into lumen to form hydrochloric acid*(primary acidic component of the stomach juices) -*HCl (Hydrochloric acid) helps to convert the inactive pepsinogen to pepsin* -*Pepsinogen, H+, and Cl-* are *secreted into lumen of stomach* -*Pepsin* helps *activates more pepsinogen*, starting a chain reaction. -Pepsin *begins chemical digestion of proteins* -The highly *acidic environment kills many microorganisms in food w/ action of enzyme pepsin*, results in the *hydrolysis of protein* in the food -Chemical digestion is facilitated by the churning action of the stomach -*Contraction/relaxation of smooth muscles* = *mixes the stomach contents to form CHYME* every 20 secs -passes *from the stomach to small intestine* -*Acid reflux of chyme* from the stomach back *into the esophagus* causes the feeling of *heartburn* + gastroesophogeal reflux *GERD harms lining* -Further protein digestion takes place in the small intestine. *Gastric emptying occurs within 2-6 hours after a meal* Only a small amount of chyme is released into the small intestine at a time -The *movement of chyme from the stomach to small intestine is regulated by the pyloric sphincter* -When *digesting protein/some fats* = the *stomach lining must be protected from digestion by pepsin* -*Enzyme pepsin synthesized in the inactive form protects chief cells bc pepsinogen doesn't have the same enzyme functionality of pepsin* -*Stomach has a thick mucus lining protecting the underlying tissue* from the digestive juices -*When mucus lining is ruptured* = *ulcers can form in the stomach* (open wounds in/on an organ by bacteria) -*Chyme moves from stomach to small intestine* = *organ for digestion of protein, fats, carbs* -The *small intestine* = 6m, site of chemical digestion/absorption, *long tube-like organ w/ highly folded surface containing finger-like projections = VILLI* -*Microvilli line epithelial cells on the luminal side and allow nutrient absorption* + *absorbed into blood stream* on the other side -The *villi/microvilli w/ their many folds incr surface area of the intestine* + *absorption efficiency* of the nutrients carried into the hepatic portal vein to the liver which regulates the distribution of nutrients to the rest of the body and removes toxic substances -*3 parts*: 1. *duodenum* = *"C-shaped," fixed part* of the small intestine + *separated from stomach by the pyloric sphincter which allows chyme to mix w/ pancreatic juices* + acts as a *buffer* 2. *jejunum* = *hydrolysis of nutrients + carbohydrates/amino acids digestion and absorption via intestinal lining* 3. *ileum* = *last part of small intestine where salts/vitamins are absorbed* into blood + *ileum ends/large intestine begins at ileocecal valve* -*BILE* = *produced in the liver and stored and concentrated in the gallbladder* -Bile contains bile salts which emulsify lipids while the pancreas produces enzymes that catabolize starches, disaccharides, proteins, and fats. These digestive juices break down the food particles in the chyme into glucose, triglycerides, and amino acids in the duodenum too. -The *large intestine* = *reabsorbs water from the undigested food material* + *processes waste material* -The *human large intestine is MUCH SMALLER* in length *compared to small intestine* but *LARGER in diameter* -3 parts: 1) the *cecum* = joins the ileum to the colon and is the *receiving pouch for the waste matter*+ *bears the appendix* 2) the *colon*= *home to many bacteria/"intestinal flora"* that *aid in the digestion* + can be *divided into 4 regions* = the *ascending colon, transverse colon, descending colon, sigmoid colon* -*extracts the water/mineral salts from undigested food* + *stores waste material* Carnivorous mammals have a shorter large intestine compared to herbivorous mammals due to their diet. 3) the *rectum* = helps form *firm feces stored until elimination*

The Main Osmoregulatory Organ What is the major osmoregulatory organ? The adrenal glands on top of each kidney = Three functions of kidney? What are nephrons? Where are kidneys located? The ureters transport urine to ________ which passes it through the _________ Kidneys regulate (3) How does your kidney or liver fail?

-Although the *kidneys* = are the *major osmoregulatory organ* + the *skin/lungs play a role* in the process -*Water/electrolytes* are *lost in sweat glands* in the skin, which helps *moisturize/cool the skin* surface, while the *lungs expel water* in the form of *mucous secretions + via evaporation* of water vapor. The *kidneys* = a pair of *bean-shaped structures located below/posterior to liver in peritoneal cavity* - The *adrenal glands on top of each kidney* = *suprarenal glands* -Kidneys *filter blood* and *purify it* -All the *blood* in the human body is *filtered 180L a day* by the kidneys but we only *pee 3-4L* these organs use up almost 25 percent of the oxygen absorbed through the lungs to perform this function -*O2 allows kidney cells to efficiently manufacture chemical energy* in the form of *ATP thru aerobic respiration* -The *filtrate out of kidneys* = *URINE* *Nephrons* = functional *unit of kidneys*, contains *blood vessels and tubes* **Kidneys* = *2* kidneys located in *lumbar region* -*Ureters transport urine* to *bladder* and *urethra passes urine* - *Kidneys* = regulate *blood pressure*, controls *pH*, controls *electrolyte concentration* when getting rid of waste *Secretes AMMONIA (NH3)*, converted into *urea in liver and excreted by kidneys w/ uric acid* (to maintain acid, maintains pressure) in urethra, *liver failure* = *ammonia incr.* Kidneys excrete waste w/ metabolism UREA, URIC ACID, CREATINE, DRUGS = test to check kidney levels Reabsorption -The *urinary system* = *forms/excretes urine* and *regulates amount of water/solutes in body fluids* In humans, the *kidneys* = the *main processing centers* of the *urinary system*

Introduction to the Endocrine System How does the endocrine system control body processes ( 3)? What does it serve to maintain? What are common endocrine system diseases? What 3 factors are needed to maintain homeostasis? Hormones are released into where and to target what, what does that target have? What do the adrenal glands produce? What about the thyroid gland? What 2 types of hormones are there? Which one can pass through the membranes?

-An *animal's endocrine system* = controls body processes through the *production, secretion, hormone regulation*, which serve as *chemical "messengers" functioning in cellular/organ activity*, *maintaining homeostasis* -The *endocrine system* plays a role in *growth, metabolism, sexual development* -In *humans* = *common endocrine system diseases* include *thyroid disease* + *diabetes mellitus* -In *organisms under metamorphosis* = the process is *controlled by endocrine system* -The transformation from *tadpole to frog*, for example, is *complex and nuanced to adapt to specific environments and ecological circumstances* -*Maintaining homeostasis* within the body requires the *coordination of systems/organs*, *communication of cells* and between cells and tissues in distant parts of the body, occurs through the *release of chemicals called hormones* -*Hormones* = are *released into body fluids* (usually blood) that *carry these chemicals to target cells* -*At target cells* = which are *cells w/ a receptor for a signal/ligand from a signal cell*, the *hormones create a response* -The *cells, tissues, organs secrete hormones* = make up the *endocrine system* -Examples of glands of the endocrine system include the *adrenal glands* = produce *hormones such as epinephrine (adrenaline) and norepinephrine (not)* that *regulate responses to stress*, and the *thyroid gland* = which *produces thyroid hormones* that *regulate metabolic rates* -Although there are many *diff hormones* in the human body, they can be divided into three classes based on their chemical structure: *lipid-derived, amino acid-derived, peptide (peptide and proteins) hormones* -One of the key distinguishing features of *lipid-derived hormones* is that they *can diffuse across plasma membranes* whereas the *amino acid- derived and peptide hormones cannot* -*Toxic chemicals interfere w/ the endocrine system* are aptly named *ENDOCRINE DISRUPTORS* Endocrine disruptors include *atrazine (weed killers*/farm water runoff that makes its way to ground and surface reservoirs) and *bisphenol A (BPA) (plastics that line bottles, canned goods)* -*Organ systems must communicate* with one another to maintain *homeostasis* and to carry out other coordinated functions. -*Organ systems* use *chem/electrical signals* that *travel thru body* by 2 major organ systems: the *endocrine* system and *nervous* system -The *endocrine system* = a group of *interacting glands and tissues* throughout the animal body that *produce and secrete chemicals to initiate* and *maintain body functions* and activities **LIPID SOLUBLE HORMONES (sex hormones and steroids) CAN PASS THROUGH MEMBRANES Water-soluble: HYDROPHILIC, receptor protein is outside Steroids/lipid soluble: HYDROPHOBC, receptor protein is inside -In the endocrine system, *chemical signals* called *hormones* = are *made/secreted by organs called endocrine glands*, *released into blood*stream by endocrine cells, are *carried to all over body*, and *affect target cells w/ receptors* for that specific hormone

Pathogen Recognition An infection could be _____________ or ______________ depending on the pathogen. What is a macrophage? What is a monocyte?

-An *infection may be INTRACELLULAR/EXTRACELLULAR* depending *on the pathogen* -All *viruses infect/replicate cells* (only *intra*cellularly), whereas *bacteria/parasites may replicate intracellularly or extracellularly*, depending on the species -The *innate immune system* must respond accordingly: by *identifying the extracellular pathogen* and/ or by *identifying infected host cells* -When a *pathogen enters the body* = *cells in the blood + lymph detect* the specific pathogen-associated molecular patterns (PAMPs) on the pathogen's surface -*PAMPs* are *carbohydrate, polypeptide, nucleic acid "signatures"* that are *expressed by viruses, bacteria, parasites* but which *differ from molecules on host cells* -The *immune system* has *specific cells*, with *receptors that recognize these PAMPs* -A *macrophage* is a *large phagocytic cell that engulfs foreign particles/pathogens* -Macrophages *recognize PAMPs via complementary pattern recognition receptors (PRRs)*. PRRs are molecules on macrophages and dendritic cells which are in contact with the external environment -A *monocyte* is a type of *white blood cell that circulates in the blood and lymph* and *differentiates into macrophages* after it moves into infected tissue -*Dendritic cells* = *bind molecular pathogens* and *promote pathogen engulfment/destruction* -*Toll-like receptors (TLRs)* are a type of PRR that *recognizes molecules shared by pathogens* but distinguishable from host molecules). TLRs are present in *invertebrates + vertebrates* and appear to be one of the most ancient components of the immune system. TLRs have also been identified in the mammalian nervous system.

Complement What is a complement system? Liver/Macrophages synthesize what continuously? They are particularly attracted to pathogens that are?

-An array of *approx 30 types of soluble proteins* = *COMPLEMENT system* functions to *destroy extracellular pathogens* + act w/ other *defenses* -*Cells of liver/macrophages synthesize complement proteins continuously*; these proteins are *abundant in the blood serum* and are capable of *responding immediately to infecting microorganisms* -The complement system is so named because it is *complementary to antibody response of ADAPTATIVE immune system* -Complement proteins *bind to the surfaces of microorganisms* and are particularly *attracted to pathogens already bound by antibodies* -*Binding complement proteins* occurs in a *specific and highly regulated* sequence, with each successive protein being activated by cleavage and/or structural changes induced upon binding of the preceding protein(s). After the first few complement proteins bind, a cascade of sequential binding events follows in which the *pathogen rapidly becomes coated in complement proteins* -*Complement proteins* perform several functions. The proteins serve as a *marker to indicate presence of a pathogen* to phagocytic cells, such as macrophages and B cells, and enhance engulfment; this process is called *opsonization* Certain complement proteins can combine to form attack complexes that open pores in microbial cell membranes. These structures destroy pathogens by causing their contents to leak

Physical and Chemical Barriers What are invertebrates innate immunities (4)? What are the human innate immunities (10)? What do natural killer cells release chemicals to kill What do interferons limit the spread of? What are macrophages and neurophils?

-Before any immune factors are triggered, the *skin functions* as a *continuous, impassable barrier to potentially infectious pathogens* -*Pathogens* are *killed/inactivated on skin by desiccation (drying out)* + by the *skin's acidity* -In addition, *beneficial microorganisms coexist on skin compete w/ invading pathogens*, preventing infection -Regions of the body that are not protected by skin (such as the *eyes and mucus* membranes) have *alternative defenses*, such as tears and mucus secretions that *trap + rinse away pathogens*, and *cilia in the nasal passages/respiratory tract* that *push mucus w/ the pathogens out* of the body -Throughout the body are other defenses, such as the *low pH of the stomach* (which inhibits the growth of pathogens), *blood proteins that bind/disrupt bacterial cell membranes*, and the *process of urination* (which flushes pathogens from the urinary tract) -Despite these barriers, *pathogens* may *enter body w/ skin abrasions/punctures* or by collecting on mucosal surfaces in large numbers that overcome the mucus or cilia. Some pathogens have evolved specific mechanisms that allow them to overcome physical and chemical barriers. When pathogens do enter the body, the innate immune system responds with inflammation, pathogen engulfment, and secretion of immune factors and proteins. -*Human's INNATE IMMUNITY*: born with/built in *mucous membranes* lining organs, *stomach acid*, *cilia*, *hairs*, digestive *enzymes*, *phagocytic cells (neutrophils/macrophages)*, *proteins* (interferons), *natural killer cells*, inflammation - protection/awareness to illness -good bacteria protecting bad bacteria from coming in **NO LYMPHOCYTES THEY HAVE MACROPHAGES/NEUTROPHILS *Invertebrates' INNATE IMMUNITY*: *exoskeleton*, *low pH*, *enzymes (lysozome)*, *(immune cells) phagocytosis* -Babies have a weak immune system bc its undeveloped but as we grow, it grows too -*If INNATE doesn't work we have ADAPTIVE* -If there is a *cut in the skin* = *microbes can enter* and *phagocytic cells/white blood cells* can fight -*Natural killer cells release chemicals* to *killer cancer cells/viruses* -*Interferons*: *limit* the *spread of viruses* -*Macrophages and Neutrophils*: *phagocytes* or white blood cells that eat bacteria by *recognizing the antigen receptors*

Kidney Structure What are the 3 layers?

-Externally, the *kidneys are surrounded* by *3 layers* -The *3rd/innermost layer* = the *RENAL capsule* -Internally, the *kidney has 3 regions* = an *outer CORETX*, a *MEDULLA in middle*, and *RENAL PELVIS in hilum* of the kidney -The hilum is the *concave part of the bean-shape* where blood *vessels/nerves enter + exit the kidney* it is also the point of exit for the ureters -The *renal cortex is granular* due to the presence of *nephrons*—the functional unit of the kidney + *glomerulus capillary receives blood* and *does filtration* -The *medulla* consists of multiple *pyramidal tissue masses*, called the *renal pyramids*. In between the pyramids are spaces called renal columns through which the blood vessels pass. The *tips of the pyramids* = called *RENAL PAPILLAE* point toward the renal pelvis. There are, on average, 8 renal pyramids in each kidney -The *renal PYRAMIDS* along with the adjoining cortical region are called the *lobes of the kidney* - The *renal pelvis* leads to the *ureter* on the outside of the kidney. On the inside of the kidney, the *renal pelvis branches* out into two or three extensions = *MAJOR CALYX*, which further *branch into MINOR CALYX* -The *ureters are urine-bearing tubes* that *exit kidney* and *empty into the urinary bladder* -Because the *kidney filters blood*, its *network of blood vessels* is an important component of its structure and function -The *arteries, veins, nerves* that *supply the kidney enter/exit* at the *RENAL HILIUM* -Renal blood supply starts with the *branching the aorta into renal arteries* (named based on the region of the kidney they pass through) and *ends w/ exiting of the renal veins* to *join the inferior vena cava* -The renal arteries split into several segmental arteries upon entering the kidneys. Each segmental *artery splits into interlobar arteries* and * enter the renal columns* which supply the renal lobes -The *interlobar arteries split at junction of the renal cortex/medulla* to form the arcuate arteries -The arcuate "bow shaped" arteries form arcs along the base of the medullary pyramids. Cortical radiate arteries, as the name suggests, radiate out from the arcuate arteries. The cortical radiate arteries branch into numerous afferent arterioles, and then enter the capillaries supplying the nephrons. Veins trace the path of the arteries and have similar names, except there are no segmental veins. -As mentioned previously, the functional unit of the kidney is the nephron -*Each kidney* = made up of *over 1 mil nephrons around renal cortex* giving it a *granular* appearance when sectioned sagittally -There are two types of nephrons— *cortical nephrons (85%)*, which are deep in the *renal cortex*, and *juxtamedullary nephrons (15%)*, which lie in the renal cortex close to the renal medulla. A nephron consists of three parts—a *renal corpuscle, renal tubule, capillary network*, which originates from the cortical radiate arteries Nephrons = functional unit of kidneys, blood vessels and tubes **Kidneys = 2 kidneys located in lumbar region -*Ureters transport urine to bladder and urethra passes urine* - Kidneys regulate blood pressure, controls pH, controls electrolyte concentration when getting rid of waste -*Renal cortex* = *outer, nephrons, glomerulus capillary receives blood and does filtration* -*Renal medulla = inner, nephrons*

Introduction of the Circulatory System What does the circulatory system transport (3)? What process did the circulatory system evolve from for cells only a few layers thick? The network supplies ________, __________, _________ w/ O2 and removes ___ What organ drives the circulation of blood? Heart contractions are driven by what impulses? What is bulk flow?

-Just as highway systems transport people and goods through a complex network, *the circulatory system transports nutrients, gases, wastes throughout the animal body* -Most *animals* = complex *multicellular organisms* that require a *mechanism for transporting nutrients throughout their bodies/removing waste prods* -The *circulatory system* has *evolved from simple diffusion thru cells in early evolution of animals* to a *complex network of blood vessels that reach all of the human body* -This extensive network *supplies cells, tissues, organs w/ O2 + nutrients*, and *removes CO2 + waste* which are byproducts of respiration -At the *core of circulatory system* = *heart* = muscular pump that *drives the circulation of blood* -The *human heart is protected beneath rib cage* -Made of *specialized/unique cardiac muscle* it pumps blood throughout the body and to the heart itself -*Heart contractions* are *driven by intrinsic electrical impulses* that the *brain/endocrine hormones help to regulate*. Understanding the heart's basic anatomy and function is important to understanding the body's circulatory and respiratory systems -*Gas exchange* = *essential* to the *circulatory system* -A *circulatory system* is *not needed in organisms w/o specialized respiratory organs* bc *O2 + CO2 diffuse btwn body tissues + external environment* but *for lungs/gills, O2 must transport to organs* to the body tissues via a circulatory system. Therefore, circulatory systems have had to evolve to accommodate the great diversity of body sizes and body types present among animals -In *all animals* = *circulatory system is used to transport nutrients and gases* through the body. Simple *diffusion* allows some water, nutrient, waste, and gas exchange into primitive animals that are *only a few cell layers thick*; however, *bulk flow* = only method by which the entire body of *larger more complex organisms is accessed* •The blood *flows through closed circuit of vessels to every tissue in the body* delivering oxygen from the lungs and nutrients from the digestive tract and picking up wastes for disposal. •Most animals have a circulatory system that connects organs involved in gas exchange, digestion, and waste processing.

Nitrogenous Wastes 32-34 Of the 4 major macromolecules, which 2 contain nitrogen? Nitrogenous wastes form what toxin that raises pH of body fluids? How do animals detoxify ammonia? By turning it into what (2)? Why can't it be stored in the body?

-Of the *4 major macromolecules* in biological systems, both *proteins/nucleic acids contain nitrogen* -During the *catabolism/breakdown of nitrogen-containing macromolecules* = *carbon, hydrogen, oxygen* = *extracted* and *stored in carbs/fats* -*Excess nitrogen* is *excreted* from the body -*Nitrogenous wastes* tend to *form toxic ammonia (NH3)* which *raises pH of body fluids* -The formation of *ammonia* itself *requires ATP* + large quantities of *water to dilute* it out of a biological system -*Animals* that live *in aquatic environments* tend to *release ammonia* into the water -*Animals excrete ammonia* are said to be = *AMMONOTELIC* -*Terrestrial organisms* have *evolved* other mechanisms to *excrete nitrogenous wastes* -The *animals must detoxify ammonia* by *converting it to a nontoxic form* such as *urea/uric acid* -*Mammals*, including humans, *produce urea*, whereas *reptiles/invertebrates produce uric acid* -*Animals* that *secrete urea* as the *primary nitrogenous waste* material are called *UREOTELIC* -*Waste disposal* = crucial part of *osmoregulation bc metabolic wastes must be dissolved* in water *to be removed* from the body -*Metabolism .produces* a number of *toxic by-products*, such as the *nitrogenous wastes* that result *from breakdown of proteins/nucleic acids* -An *animal disposes metabolic wastes* by *converting them to chemicals* that can be *excreted* through an opening in the body. -The type of *waste product* produced and *how the animal disposes* of it depends on *adaptations + habitat* -*Ammonia (NH3)* is too *toxic to be stored* in the body, *highly soluble* in water, and easily *disposed W/ aquatic animals*

Osmoregulators and Osmoconformers

-Persons lost at sea without any fresh water to drink are at risk of severe dehydration because the *human body cannot adapt to drinking seawater* = *hypertonic* in comparison to body fluids -Organisms such as goldfish that can tolerate only a relatively narrow range of salinity are referred to as stenohaline. About *90% of all bony fish are restricted to either freshwater/seawater* -They are *incapable of osmotic regulation* in the opposite environment -It is possible, however, for a few fishes like salmon to spend part of their life in fresh water and part in sea water -*Organisms (salmon and molly)* that can *tolerate a relatively wide range of salinit* are referred to as *euryhaline organisms* -This is possible because some *fish have evolved osmoregulatory mechanisms to survive* in all kinds of *aquatic environments* -When they live *in freshwater* = their *bodies take up water bc the environment is relatively HYPOTONIC* -In such hypotonic environments, these fish do not drink much water. Instead, they pass a lot of very dilute urine, and they achieve *electrolyte balance by active transport of salts through the gills* -When they move to a hypertonic marine environment, these fish start drinking sea water; they excrete the excess salts through their gills and their urine -Most *marine invertebrates*, on the other hand, *may be isotonic with seawater (osmoconformers)* -Their *body fluid concentrations conform to changes in seawater concentration* -Cartilaginous fishes' salt composition of the blood is similar to bony fishes; however, the blood of sharks contains the organic compounds urea and trimethylamine oxide (TMAO). This does not mean that their electrolyte composition is similar to that of sea water. They *achieve isotonicity w/ sea by storing large concentrations of urea* -These animals that *secrete urea* = *UREOTOLIC* animals. TMAO stabilizes proteins in the presence of high urea levels, preventing the disruption of peptide bonds that would occur in other animals exposed to similar levels of urea. Sharks are cartilaginous fish with a rectal gland to secrete salt and assist in osmoregulation.

Oxytocin What 2 responses does oxytocin play a part in? (WOMEN) What gland releases this hormone?

-Recently, *scientists studied whether it's a hormone that induces the human-dog relationship* -The *hormone oxytocin plays a part in uterine contractions*, *mammary milk ejection*, and *promotes mating* and *maternal bonds* -Levels of the *hormone rise when human mothers gaze into babies' eyes* or when dog owners received long gazes from their dogs -The *posterior pituitary releases* the hormone oxytocin, which *stimulates uterine contractions during childbirth* -The *uterine smooth muscles* are *not very sensitive to oxytocin until late* in pregnancy when the number of oxytocin receptors in the uterus peaks -*Stretching of tissues in uterus/cervix* stimulates *oxytocin release* during childbirth -*Contractions incr* in intensity as *blood levels of oxytocin rise* via a *positive feedback* mechanism until the birth is complete -Oxytocin also stimulates the contraction of myoepithelial cells around the milk-producing mammary glands. As these cells contract, milk is forced from the secretory alveoli into milk ducts and is ejected from the breasts in milk ejection ("let-down") reflex. Oxytocin release is stimulated by the suckling of an infant, which triggers the synthesis of oxytocin in the hypothalamus and its release into circulation at the posterior pituitary.

The vertebrate endocrine system consists of more than a dozen major glands Hormones are controlled through what kind of feedback?

-Some *endocrine glands (such as the thyroid*) primarily secrete *hormones into the blood* -Other glands (such as the *pancreas) have endocrine and nonendocrine functions* -Other organs (such as the *stomach and heart) are primarily nonendocrine* but have some *cells that secrete hormones* What stimulates an *endocrine gland to produce a hormone* = *STIMULI*? We can categorize *stimuli* into three major types. 1) For some endocrine glands, a *change in levels of certain ions/nutrients* is the stimulus. 2) Other endocrine glands, such as the *adrenal glands*, are stimulated directly *by the nervous system* 3) *Hormones* can also stimulate endocrine glands. The *hormones* produced by endocrine glands have a *wide range of effects*, including *regulating ion/nutrient levels*, *water balance*, and *metabolism*, *controlling reproduction*, *growth*, and *development*, and initiating responses to stress and the environment. For a particular example of hormonal effects, let's take a brief look at the pineal gland.

Adaptive Immune Response MAJORLY INVOLVES WHAT? This immunity activates when? What are the 2 types of adaptive responses by B and T cells? What are differences between innate and adaptive (4)?

-The *ADAPTIVE/acquired immune response* = *INVOLVES LYMPHOCYTES* takes *days/weeks to establish* (slower than innate) however, adaptive immunity is *more specific to pathogens via memory* differs from individual to individual depending on prev exposed pathogens *found in vertebrates* -Adaptive immunity is an *immunity that activates after exposure to antigen* from pathogen/vaccination -This part of the immune system is *activated when innate immune response is insufficient to control an infection* -In fact, *without info from innate immune system, the adaptive response could not work* but still *stronger than innate* bc MEMORY, activated when sees an antigen (house dust, pollen) -There are *2 types of adaptive responses*: the *cell- mediated immune response by T cells*, and the *humoral immune response by activated B cells* and *antibodies* Adaptive Responses (lymphocytes- white blood cells) -*Defense against pathogens in body fluids* = *humoral response B lymphocytes* and antibodies -*Defense against pathogens inside cells* + *promo antibodies in blood* = *cell-mediated response T lymphocytes* -*Adaptive immunity* = also *involves a memory to provide the host w/ long-term protection* from reinfection with the same type of pathogen; on re-exposure, this memory will facilitate an efficient and quick response.

Cytokine Release Affect

-The *binding of PRRs w/ PAMPs triggers release of cytokines* = which *signal that a pathogen is present* and needs to be *destroyed w/ any infected cells* -A *cytokine* = a *chemical messenger regulating cell differentiation* (form and function), *proliferation (production)*, *gene expression* to affect immune responses. At least 40 types of cytokines exist in humans that differ in terms of the cell type that produces them, the cell type that responds to them, and the changes they produce -One subclass of cytokines is the interleukin (IL), so named because they mediate interactions between leukocytes (white blood cells). *Interleukins are involved in bridging the innate and adaptive immune responses*. *Cytokines are released by PAMP/infected cells* = which *bind to nearby uninfected cells* and induce those cells to release cytokines, which results in a = *CYTOKINE BURST* -*Another class of cytokines*: *INTERFERON* = *proteins produced by virus-infected cells* that *help limit the cell-to-cell spread of viruses* as a warning to nearby uninfected cells -One of the functions of interferon is to *inhibit viral replication* + *tumor surveillance* -Interferons work by *signaling neighboring uninfected cells to destroy RNA* and *reduce protein synthesis*, *signaling neighboring infected cells to undergo apoptosis* (programmed cell death), and *activating immune cells* -In response to interferons, uninfected cells alter their gene expression, which increases the cells' resistance to infection. One effect of interferon-induced gene expression is a sharply reduced cellular protein synthesis. Virally infected cells produce more viruses by synthesizing large quantities of viral proteins. Thus, *by reducing protein synthesis, a cell becomes resistant to viral infection*

Circulatory System Architecture The circulatory system is a network of ______,_______,_______ What is a closed system? What organisms use this? What is an opened system? What organisms use this?

-The *circulatory system* = effectively a network of *cylindrical vessels: arteries, veins, capillaries* that emanate from a pump, the heart -In *all VERTEBRATE organisms* = this is a *CLOSED-LOOP system* in which *blood is not free in a cavity. In a closed circulatory system, *blood is contained inside blood vessels* and *circulates unidirectionally from the heart around systemic circulatory route* then returns to the heart again -As opposed to a *closed system* = *ARTHROPODS* (insects, crustaceans, mollusks) have an *OPEN circulatory system* -In an *OPEN circulatory system* = the *blood's not enclosed in blood vessels but pumped into a cavity called HEMOCOEL* and is called *hemolymph bc the blood mixes w/ interstitial fluid*. As the heartbeats and the animal moves, the hemolymph circulates around the organs within the body cavity and then reenters the hearts through openings called OSTIA. This movement allows for gas and nutrient exchange. An open circulatory system does not use as much energy as a closed system to operate or to maintain; however, there is a trade-off with the amount of blood that can be moved to metabolically active organs and tissues that require high levels of oxygen. In fact, one reason that insects with wing spans of up to two feet wide (70 cm) are not around today is probably because they were outcompeted by the arrival of birds 150 million years ago. Birds, having a closed circulatory system, are thought to have moved more agilely, allowing them to get food faster and possibly to prey on the insects. -In (a) *CLOSED* circulatory systems, the *heart pumps blood thru vessels separate from the interstitial fluid of the body*. Most vertebrates and some invertebrates, like this annelid earthworm, have a closed circulatory system -In Arthropods like this bee and most mollusks have open circulatory systems •To sustain life, an *animal must* •*acquire nutrients*, •*exchange gases*, and •*dispose of waste* products. •In most animals, circulatory systems facilitate these exchanges. •An internal transport system must bring resources close enough to cells for diffusion to be effective.

Introduction of the Innate Immune Response The environment has numerous pathogens that do what in hosts? What is a host and what are they invaded by? What are 5 features of the immune system? What is the innate immune response? The adaptive? What do viruses cause? What did HPV cause?

-The *environment* = consists of numerous *pathogens (microorganisms)* that cause *diseases in hosts* -A *HOST is the organism* = is *invaded* and often harmed *by a pathogen* -*PATHOGENS* include *bacteria, protists, fungi, infectious organisms*.We are constantly exposed to pathogens in food and water, on surfaces, and in the air -*Mammalian immune systems evolved* for *protection* from such pathogens; they are composed of an extremely diverse array of specialized *cells/soluble molecules that coordinate flexible defense system* capable of providing protection from a majority of these disease agents -Components of the immune system constantly search the body for signs of pathogens. *When pathogens are found* = *immune factors are mobilized* to the site of an infection -The immune factors *identify pathogen's nature*, *strengthen corresponding cells/molecules to combat it* efficiently, *halt immune response after the infection is cleared* to avoid unnecessary host cell damage -The *immune system can REMEMBER prev pathogens* to which it has been exposed to create a more efficient response upon re-exposure. This memory *can last several decades* -*Features of the immune system* = *pathogen identification*, specific *response (innate/active)*, *amplification*, *retreat*, *remembrance* are essential for survival against pathogens -The *INNATE immune response* = what we are born with - always present and *attempts to defend against pathogens rather than focusing on specific ones* -Conversely, the *ADAPTIVE immune response* = *stores info* about *past infections* and mounts pathogen-specific defenses -*Viruses* can *cause cancers* -In the 1980s, scientists discovered that the sexually transmitted *human papillomavirus (HPV) caused all cervical cancers* and most cases of anal cancers -In the last several years two *HPV vaccines* have been developed: *Gardasil in 2006* and *Cervarix in 2009* -Experts believe that for an *HPV vaccine to reduce the incidence of cancer* = it must provide *long-term immunity (protection)* ideally for *3-4 decades* Without long-term protection, it might simply postpone susceptibility to the infection. How long does immunity from HPV last with Gardasil and Cervarix vaccination? The short answer is we do not know yet. The decades worth of data on the long-term effects of the vaccines are not available.

Phagocytosis and Inflammation The first cytokines that are produced encourage what response including redness? This moves what towards infection? Neutrophils and eoisinophils engulf _____________ What is a mast cell and what does it produce? What leaves the capillaries?

-The *first cytokines* to be produced are *pro-inflammatory*;encourage inflammation, the localized *redness, swelling, heat, pain that result from the movement of leukocytes* and fluid through increasingly permeable capillaries *to a site of infection* -The *population of leukocytes* that *arrives at an infection site* depends *on nature of infecting pathogen* -Both *macrophages/dendritic cells* = *engulf pathogens and cellular debris* through phagocytosis -A *neutrophil* = a *phagocytic leukocyte that engulfs and digests pathogens* + *most abundant* leukocytes of the immune system Neutrophils have a *nucleus w/ 2-5 lobes + contain organelles, called lysosomes that digest engulfed pathogens* -An *eosinophil is a leukocyte w/ other eosinophils to surround a parasite*; it is involved in the *allergic response/protection* against helminthes (parasitic worms). Neutrophils and eosinophils are particularly important leukocytes that engulf large pathogens, such as bacteria and fungi -A *mast cell* = is a *leukocyte producing inflammatory molecules*, such as histamine, in response to large pathogens -A *basophil* = is a *leukocyte releases chemicals to stimulate inflammatory response*. Basophils are also involved in *allergy and hypersensitivity responses* and induce specific types of inflammatory responses -Eosinophils and basophils produce additional inflammatory mediators to recruit more leukocytes. A hypersensitive immune response to harmless antigens, such as in pollen, often involves the release of histamine by basophils and mast cells. -In response to a cut, mast cells secrete histamines that cause nearby capillaries to dilate. *Neutrophils and monocytes leave the capillaries* -*Monocytes* mature *into macrophages* - *Neutrophils* dendritic cells and macrophages release chemicals to stimulate the inflammatory response. Neutrophils and macrophages also *consume invading bacteria by phagocytosis* Cytokines also send feedback to cells of the nervous system to bring about the overall symptoms of feeling sick, which include lethargy, muscle pain, and nausea. These effects may have evolved because the symptoms encourage the individual to rest and prevent them from spreading the infection to others. Cytokines also increase the core body temperature, causing a fever, which causes the liver to withhold iron from the blood. Without iron, certain pathogens, such as some bacteria, are unable to replicate; this is called *nutritional immunity*

Lipid-Derived Hormones (or Lipid-soluble Hormones) What hormones do they include and from what molecule are they made from? Can they pass through the billayer and they bind to what in cells? What are 5 examples (3 are sex)?

-The *lipid-soluble hormones* include the *steroid hormones*, *small molecules* made *from cholesterol* -*Lipid-soluble hormones* = such as steroid hormones, *pass thru phospholipid bilayer* and *bind to receptors in the cell* -*Most lipid hormones* are *derived from cholesterol* and thus are structurally similar to it -The primary class of *lipid hormones in humans* is the *steroid hormones* -Chemically, these *hormones are usually ketones or alcohols*; their chemical names will end in "-ol" for alcohols or "-one" for ketones -Examples of *steroid hormones* = include *estradiol, which is an estrogen*/female sex hormone, and *testosterone, which is an androgen*, or male sex hormone. These two hormones are *released by reproductive organs*, respectively. -Other steroid hormones include *aldosterone and cortisol*, which are *released by the adrenal glands* along with some other types of androgens. -*Steroid hormones* are *insoluble in water*, and they are transported *move by transport proteins in blood* -As a result, they remain in circulation longer than peptide hormones. For example, cortisol has a half-life of 60 to 90 minutes, while epinephrine, an amino acid derived-hormone, has a half-life of approximately one minute.

Organic Precursors Organic molecules are required for what and where do they come from? Humans don't produce what enzyme? What does glycogen provide and what is excess glycogen converted to? What source does protein catabolism provide (also building blocks for nucleotides) and what is excess excreted as?

-The *organic molecules required for building cellular material/tissues must come from food* = *Carbohydrates or sugars* are the primary sources in the animal body -During *digestion* = *digestible carbs are ultimately broken down into glucose* + *used to provide energy thru metabolic pathways* = *complex carbs including polysaccharides* can be *broken down into glucose thru biochem modification* -*Humans DON'T prod the enzyme cellulase* + *lack the ability to derive glucose from the polysaccharide cellulose* -In humans, *these molecules provide the fiber required for moving waste thru large intestine* + *healthy colon* -The *intestinal flora* in the *human gut* are able to *extract some nutrition* from these *plant fibers* -The *excess sugars are converted into glycogen* and *stored in the liver/muscles for later* -*Glycogen stores fuel prolonged exertions*, (long-distance running) and to *provide energy during food shortage* -*Excess glycogen can be converted to fats*, which are *stored in lower layer of skin* of mammals *for insulation + energy storage* -*Excess digestible carbs* are *stored by mammals* to *survive famine/aid in mobility* -Another important requirement is that of nitrogen. *Protein catabolism provides a source of organic nitrogen*. Amino acids are the building blocks of proteins and *protein breakdown provides amino acids that are used for cellular function* -The *carbon + nitrogen from these become the building block for nucleotides, nucleic acids, proteins, cells, tissues* -*Excess nitrogen* must be *excreted as it is toxic* -*Fats* add flavor to food and *promote satiety* -*Fatty foods* = *significant sources of energy* bc *1g of fat contains 9 calories* *Fats are required* in the diet *to aid absorption of fat-soluble vitamins* and the *production of fat-soluble hormones*

Nitrogenous Waste in Terrestrial Animals: The Urea Cycle 36 What is the urea cycle? Where is urea made and in what is it excreted?

-The *urea cycle* = the *primary mechanism where mammals convert ammonia to urea* -*Urea* is *made in liver* and *excreted in urine* -*Urea* is *produced in vertebrate liver* by *combining ammonia and carbon dioxide*, *less toxic*, and a *soluble nitrogenous waste* -The overall chemical reaction by which ammonia is converted to urea is 2 NH3 (ammonia) + CO2 + 3 ATP + H2O → H2N-CO-NH2 (urea) + 2 ADP + 4 Pi + AMP. -The *urea cycle* utilizes *5 steps* catalyzed by *5 diff enzymes*, to *convert ammonia to urea* -The *amino acid L-ornithine* gets *converted into diff intermediates* before being *regenerated at end of the urea cycle* -Hence, the *urea cycle = ornithine cycle* -The enzyme ornithine transcarbamylase catalyzes a key step in the urea cycle and its deficiency can lead to accumulation of toxic levels of ammonia in the body. The *first 2 reactions in the mitochondria* and *last 3 reactions in cytosol* -*Urea concentration* in the blood, called *blood urea nitrogen* or BUN, is used as an *indicator of kidney function* The theory of evolution proposes that life started in an aquatic environment. It is not surprising to see that biochemical pathways like the urea cycle evolved to adapt to a changing environment when terrestrial life forms evolved. Arid conditions probably led to the evolution of the uric acid pathway as a means of conserving water.

Amino Acid-Derived Hormones + Peptide Hormones What do these hormones include? Can they pass through the bilayer?

-The *water-soluble hormones* include *proteins, short polypeptides*, and some *modified versions of single amino acids* -*Most hormones by endocrine glands* = are *water-soluble* -*Water-soluble hormones cannot pass* through the phospholipid bilayer of the plasma membrane, but they *can bring cellular changes* without entering their target cells. The amino acid-derived hormones are relatively small molecules that are derived from the amino acids tyrosine and tryptophan, shown in Figure 37.3. If a hormone is amino acid-derived, its chemical name will end in "-ine". Examples of amino acid-derived hormones include epinephrine and norepinephrine, which are synthesized in the medulla of the adrenal glands, and thyroxine, which is produced by the thyroid gland. The pineal gland in the brain makes and secretes melatonin which regulates sleep cycles. The structure of peptide hormones is that of a polypeptide chain (chain of amino acids). The peptide hormones include molecules that are short polypeptide chains, such as antidiuretic hormone and oxytocin produced in the brain and released into the blood in the posterior pituitary gland. This class also includes small proteins, like growth hormones produced by the pituitary, and large glycoproteins such as follicle-stimulating hormone produced by the pituitary. Figure 37.4 illustrates these peptide hormones. Secreted peptides like insulin are stored within vesicles in the cells that synthesize them. They are then released in response to stimuli such as high blood glucose levels in the case of insulin. Amino acid-derived and polypeptide hormones are water- soluble and insoluble in lipids. These hormones cannot pass through plasma membranes of cells; therefore, their receptors are found on the surface of the target cells.

Circulatory System Variation in Animals

-The circulatory system *varies from simple systems in invertebrates to more complex systems in vertebrates* -The simplest animals, such as the *sponges (Porifera) and rotifers (Rotifera) DON'T need a circulatory system* because *diffusion allows adequate exchange of water* nutrients, and waste, as well as dissolved gases -Organisms that are *more complex but still only have 2 layers of cells* in their body plan, such as *jellies (Cnidaria) and comb jellies (Ctenophora)* also use *diffusion thru their epidermis* and internally through the gastrovascular compartment -Both their internal and external tissues are bathed in an aqueous environment and exchange fluids by diffusion on both sides -Exchange of fluids is assisted by the pulsing of the jellyfish body. -Simple animals consisting of a single cell layer such as the (a) sponge or only a few cell layers such as the (b) jellyfish do not have a circulatory system -*Instead, gases, nutrients, wastes are exchanged via diffusion* -For more *complex organisms* = *diffusion is not efficient for cycling gases, nutrients, waste* effectively through the body; therefore, more complex circulatory systems evolved -*Most arthropods/mollusks* have an *OPEN system* = an *elongated beating heart pushes the hemolymph in the body + muscle contractions help move fluids* -The *larger more complex crustaceans* including lobsters, have developed *arterial-like vessels to push blood thru their bodies* and the most active mollusks, such as squids, have evolved a closed circulatory system and are able to move rapidly to catch prey -*CLOSED circulatory systems are a characteristic of vertebrates* however, there are *significant differences in heart + blood circulation* between the different vertebrate groups due to adaptation during evolution and associated differences in anatomy consist of a circulatory fluid, *blood is confined to vessels* keeping blood distinct from the interstitial fluid.

Innate Immune Response It is not induced by infection/vaccination but works to ______ the workload for adaptive immune response. What 3 things do both the innate and adaptive levels involve?

-The immune system comprises *both INNATE and ADAPTIVE immune responses* -*Innate immunity* occurs naturally bc of *genetic factors* or *physiology*; it is *not induced by infection/vaccination* but works to *reduces workload for adaptive* immune response -*BOTH* the innate and adaptive levels of the immune response *involve secreted proteins*, *receptor-mediated signaling*, *intricate cell-to-cell com* -The *INNATE* immune system *developed early in animal evolution*, roughly 1bil years ago, as an *essential response to infection* -*Innate immunity* has a *limited number of specific targets*: any pathogenic threat triggers a consistent sequence of events that can *identify the pathogen type* + either *clear the infection/mobilize adaptive* immune response. For example, tears and mucus secretions contain microbicidal factors -Nearly everything in the environment teems with pathogens, agents that cause disease. -The *immune system* = the *body's system of defenses* against agents that *cause disease* -*Innate immunity* is a *series of defenses that act immediately upon infection* and are the same whether or not the pathogen has been encountered before

Concept of Osmolality and Milliequivalent

-To calculate osmotic pressure = it is necessary to understand how solute concentrations are measured -The unit for measuring solutes is the mole. One mole is defined as the gram molecular weight of the solute. For example, the molecular weight of sodium chloride is 58.44. Thus, one mole of sodium chloride weighs 58.44 grams. The molarity of a solution is the number of moles of solute per liter of solution. The molality of a solution is the number of moles of solute per kilogram of solvent. If the solvent is water, one kilogram of water is equal to one liter of water. While molarity and molality are used to express the concentration of solutions, electrolyte concentrations are usually expressed in terms of milliequivalents per liter (mEq/L): the mEq/L is equal to the ion concentration (in millimoles) multiplied by the number of electrical charges on the ion. The unit of milliequivalent takes into consideration the ions present in the solution (since electrolytes form ions in aqueous solutions) and the charge on the ions. Thus, for ions that have a charge of one, one milliequivalent is equal to one millimole. For ions that have a charge of two (like calcium), one milliequivalent is equal to 0.5 millimoles. Another unit for the expression of electrolyte concentration is the milliosmole (mOsm), which is the number of milliequivalents of solute per kilogram of solvent. Body fluids are usually maintained within the range of 280 to 300 mOsm.

Antibody Classes

Antibodies can be divided into five classes—IgM, IgG, IgA, IgD, IgE—based on their physiochemical, structural, and immunological properties. IgGs, which make up about 80 percent of all antibodies, have heavy chains that consist of one variable domain and three identical constant domains. IgA and IgD also have three constant domains per heavy chain, whereas IgM and IgE each have four constant domains per heavy chain. The variable domain determines binding specificity and the constant domain of the heavy chain determines the immunological mechanism of action of the corresponding antibody class. It is possible for two antibodies to have the same binding specificities but be in different classes and, therefore, to be involved in different functions. After an adaptive defense is produced against a pathogen, typically plasma cells first secrete IgM into the blood. BCRs on naïve B cells are of the IgM class and occasionally IgD class. IgM molecules make up approximately ten percent of all antibodies. Prior to antibody secretion, plasma cells assemble IgM molecules into pentamers (five individual antibodies) linked by a joining (J) chain, as shown in Figure 42.23. The pentamer arrangement means that these macromolecules can bind ten identical antigens. However, IgM molecules released early in the adaptive immune response do not bind to antigens as stably as IgGs, which are one of the possible types of antibodies secreted in large quantities upon re-exposure to the same pathogen. Figure 42.23 summarizes the properties of immunoglobulins and illustrates their basic structures. IgAs populate the saliva, tears, breast milk, and mucus secretions of the gastrointestinal, respiratory, and genitourinary tracts. Collectively, these bodily fluids coat and protect the extensive mucosa (4000 square feet in humans). The total number of IgA molecules in these bodily secretions is greater than the number of IgG molecules in the blood serum. A small amount of IgA is also secreted into the serum in monomeric form. Conversely, some IgM is secreted into bodily fluids of the mucosa. Similar to IgM, IgA molecules are secreted as polymeric structures linked with a J chain. However, IgAs are secreted mostly as dimeric molecules, not pentamers. IgE is present in the serum in small quantities and is best characterized in its role as an allergy mediator. IgD is also present in small quantities. Similar to IgM, BCRs of the IgD class are found on the surface of naïve B cells. This class supports antigen recognition and maturation of B cells to plasma cells.

Homeostasis: Thermoregulation

Been able to maintain equilibrium between inter-dependent elements. Allows organisms to keep its body temperature and it's normal temperature Homeostasis: We *respond to any change to create a balance through a mechanism called THERMOREGULATION* -*Body temp affects body activities* Generally, *as body temperature rises, enzyme activity rises as well* -For *every 10 degree centigrade rise in temp*, *enzyme activity doubles*, up to a point. *Body proteins, including enzymes, begin to denature and lose their function* with high heat (around 50oC for mammals) -*Enzyme activity will decr by 1/2 for every 10 degree centigrade drop* in temperature, to the point of freezing, with a few exceptions. *Some fish can withstand freezing solid and return to normal with thawing*

Malpighian Tubules of Insects

Malpighian tubules are found lining the gut of some species of arthropods, such as the bee. They are usually found in pairs and the number of tubules varies with the species of insect. Malpighian tubules are convoluted, which increases their surface area, and they are lined with microvilli for reabsorption and maintenance of osmotic balance. Malpighian tubules work cooperatively with specialized glands in the wall of the rectum. Body fluids are not filtered as in the case of nephridia; urine is produced by tubular secretion mechanisms by the cells lining the Malpighian tubules that are bathed in hemolymph (a mixture of blood and interstitial fluid that is found in insects and other arthropods as well as most mollusks). Metabolic wastes like uric acid freely diffuse into the tubules. There are exchange pumps lining the tubules, which actively transport H+ ions into the cell and K+ or Na+ ions out; water passively follows to form urine. The secretion of ions alters the osmotic pressure which draws water, electrolytes, and nitrogenous waste (uric acid) into the tubules. Water and electrolytes are reabsorbed when these organisms are faced with low-water environments, and uric acid is excreted as a thick paste or powder. Not dissolving wastes in water helps these organisms to conserve water; this is especially important for life in dry environments.

Helper T Lymphocytes Triggers what 2 adaptive responses when an antigen is detected? Initiates production of what and neutralizes what?

•A type of T cell called a *helper T cell triggers* both the *humoral and cell-mediated* immune responses. •Signals from helper T cells •*initiate prod of antibodies* that *neutralize pathogens* and •*activate cytotoxic T cells* that *kill infected cells* •Two requirements must be met for a helper T cell to activate adaptive immune responses. 1.A foreign molecule must be present that can bind specifically to the antigen receptor. 2.This antigen must be displayed on the surface of an antigen-presenting cell. (Macrophages and B cells are two types of antigen-presenting cells.) •Consider a typical antigen-presenting cell, a macrophage 1.The macrophage ingests a microbe or other foreign particle and breaks it into fragments—foreign antigens. 2.Then molecules of a special protein belonging to the macrophage, a self protein, bind the foreign antigens—nonself molecules. 3.They then display them on the cell's surface. 4.Helper T cells recognize and bind to the combination of a self protein and a foreign antigen, called a self-nonself complex. •Activated helper T cells promote the immune response, with a major mechanism being the secretion of additional stimulating proteins. These signaling molecules have three major effects. 1.They stimulate clonal selection of the helper T cell, producing memory cells and more effector helper T cells. 2.They help activate B cells, thus stimulating the humoral immune response. They stimulate the activity of cytotoxic T cells of the cell-mediated immune response, -The TH lymphocytes function indirectly to identify potential pathogens for other cells of the immune system. These cells are important for extracellular infections, such as those caused by certain bacteria, helminths, and protozoa. TH lymphocytes recognize specific antigens displayed in the MHC II complexes of APCs. There are two major populations of TH cells: TH1 and TH2. TH1 cells secrete cytokines to enhance the activities of macrophages and other T cells. TH1 cells activate the action of cyotoxic T cells, as well as macrophages. TH2 cells stimulate naïve B cells to destroy foreign invaders via antibody secretion. Whether a TH1 or a TH2 immune response develops depends on the specific types of cytokines secreted by cells of the innate immune system, which in turn depends on the nature of the invading pathogen. The TH1-mediated response involves macrophages and is associated with inflammation. Recall the frontline defenses of macrophages involved in the innate immune response. Some intracellular bacteria, such as Mycobacterium tuberculosis, have evolved to multiply in macrophages after they have been engulfed. These pathogens evade attempts by macrophages to destroy and digest the pathogen. When M. tuberculosis infection occurs, macrophages can stimulate naïve T cells to become TH1 cells. These stimulated T cells secrete specific cytokines that send feedback to the macrophage to stimulate its digestive capabilities and allow it to destroy the colonizing M. tuberculosis. In the same manner, TH1-activated macrophages also become better suited to ingest and kill tumor cells. In summary; TH1 responses are directed toward intracellular invaders while TH2 responses are aimed at those that are extracellular.