bio test 2 34&36

Blood Vessel Function Anatomical Description arteriole

Arteries branch into smaller vessels called arterioles. Both arteries and arterioles are very flexible. They get bigger or smaller to help maintain your body's blood pressure.

In a circulatory system, exchange occurs in two general places. Blood goes to a respiratory surface (lungs, gills, skin) or to the organs and tissues of the body (systemic circulation). At which type of blood vessels does exchange actually occur?

Capillaries

. How do structure and function correlate in the capillaries?

Capillaries have thin walls to facilitate the exchange of substances between the blood in capillaries and the interstitial fluid.

What will stimulate its production?

EPO is produced by the kidney s if tissues do not receive enough O2

Why is a four-chambered heart a key adaptation required for endothermy?

Endotherms use about 10 times as much energy as equal-sized ectotherms. Their circulatory systems therefore need to deliver about 10 times as much fuel and O2 to their tissues (and remove 10 times as much CO2 and other wastes). This large traffic of substances is made possible by separate and independently powered systemic and pulmonary circuits and by large hearts that pump the necessary volume of blood.

Describe three ways in which the structure of an erythrocyte enhances its function, which is to transport oxygen.

Erythrocytes are small disks that are biconcave. This shape increases surface area, enhancing the rate of diffusion of O2 across their plasma membranes. Additionally, mammalian erythrocytes lack nuclei, leaving more space in these tiny cells for hemoglobin, the iron-containing protein that transports O2 . Erythrocytes also lack mitochondria and generate their ATP exclusively by anaerobic metabolism, making them more efficient.

What is erythropoietin (EPO)?

Erythropoietin is a hormone that stimulates erythrocyte production.

Contrast open circulatory systems with closed circulatory systems.

In an open circulatory system, the blood moves between vessels and open sinuses. In a closed circulatory system, the blood is always within vessels. In an open circulatory system, the circulatory fluid bathes the organs directly. Contraction of one or more hearts pumps the hemolymph through the circulatory vessels into interconnected sinuses, spaces surrounding the organs. In a closed circulatory system, blood is confined to vessels and is distinct from the interstitial fluid.

Why does the presence of blood proteins tend to pull fluid back into the capillaries?

Many blood proteins are too large to pass readily through the endothelium, and they remain in the capillaries. These dissolved proteins are responsible for much of the blood's osmotic pressure. The difference in osmotic pressure between blood and the interstitial fluid opposes fluid movement out of the capillaries.

Where are the two breathing control centers located in the brain?

Medulla oblongata and pons

Explain each of the following terms. cardiac output

amount of clood pumped out by ventricles in a given period of time, 2 factors are stroke volume and heart rate

Explain how a sphygmomanometer is used to measure blood pressure.

an inflatable cuff attached to a pressure gauge, measures blood pressure in an artery. The cuff is inflated until the pressure closes the artery, so that no blood flows past the cuff. When this occurs, the pressure exerted by the cuff exceeds the pressure in the artery. The cuff is allowed to deflate gradually. When the pressure exerted by the cuff falls just below that in the artery, blood pulses into the forearm, generating sounds that can be heard with the stethoscope. The pressure measured at this point is systolic pressure. The cuff is allowed to deflate further, just until the blood flows freely through the artery and the sounds below the cuff disappear. The pressure at this point is the diastolic pressure.

Blood Vessel Function Anatomical Description artery

are the blood vessels that deliver oxygen-rich blood from the heart to the tissues of the body. Each artery is a muscular tube lined by smooth tissue and has three layer

Blood Vessel Function Anatomical Description vein

blood vessel especially : any of the tubular branching vessels that carry blood from the capillaries toward the heart

Which type of system does each of the following organisms have? dog

circulatory system

Which type of system does each of the following organisms have? lobster

circulatory system

Which type of system does each of the following organisms have? squid

closed circulatory system

Which type of system does each of the following organisms have? earthworm

closed circulatory system.

List the four major constituents of plasma. What are their functions? platelets

clots blood

Explain each of the following terms. cardiac cycle

complete contraction and relaxation of the heart

Explain each of the following terms systole

contraction of the chambers of the heart to drive blood into the aorta and pulmonary artery

How does blood pH change as CO2 increases?

decreases with the addition of CO2 more carbon acid

Blood Vessel Function Anatomical Description capillary

e very thin, approximately 5 micrometers in diameter, and are composed of only two layers of cells—an inner layer of endothelial cells and an outer layer of epithelial cells. They are so small that red blood cells need to flow through them single file. Oxygen and nutrients from the blood can move through the walls and get into organs and tissues..also take waste products away from your tissues

. What is myoglobin?

O2 storing protein, fround in muscle tissue, realeased after you injusre muscles.

Consider this question to see if you understand the advantage of a countercurrent exchange system. Without countercurrent exchange, what would be the maximum absorption percentage if O2 simply diffused from water to blood in the gills? (See Figure 34.18 in your text.)

Only 50% of the oxygen could be absorbed without countercurrent exchange because, at this point, the gas concentration would be at equilibrium, and there would be no further net diffusion of oxygen.

Name each type of cell in blood and give its function. Arteriole

Small vessel that leads from the larger arteries; when smooth muscle of wall contracts, blood pressure is affected Smaller in size than arterie; thick muscular wall

Gaining O2 and nutrients while shedding CO2 and other waste products occurs with every cell in the body. However, diffusion is rapid only over small distances. Describe the two general solutions to this problem.

The first solution is a body size and shape that keeps many or all cells in direct contact with the environment. Each cell can thus exchange materials directly with the surrounding medium. Second is a circulatory system that moves fluid between each cell's immediate surroundings and the tissues where exchange with the environment occurs.

The capillaries "leak" about 4 liters of fluid each day. How is this returned to the blood?

The lost fluid and proteins return to the blood via the lymphatic system, which includes a network of tiny vessels intermingled among capillaries of the cardiovascular system.

Blood clotting involves a pathway of several steps. It begins when platelets begin to form a plug in the blood vessel wall, and damaged platelets release a chemical that initiates a clotting cascade. Focus on what happens to the plasma proteins prothrombin and fibrinogen when this cascade begins. A. What is the name of the protein that actually forms a clot?

fibrin

A gas always diffuses from a region of __________ partial pressure to a region of __________ partial pressure.

higher, lower

What are three known predictors of cardiovascular disease?

hypertension, heart attack obesity stroke

As blood vessel diameter decreases, blood velocity will_______

increase

How does vasoconstriction affect blood pressure?

increases blood pressure

What is hemolymph?

is the circulatory fluid and interstitial fluid that bathes body cells in animals with an open circulatory system.

List the four major constituents of plasma.

red cells white blood cells platelets plasma

Because of the effect of subunit cooperativity, a slight drop in PO2 causes a(an) ____ _____ in the amount of O2 the blood unloads.

relatively large increase_

Blood clotting involves a pathway of several steps. It begins when platelets begin to form a plug in the blood vessel wall, and damaged platelets release a chemical that initiates a clotting cascade. Focus on what happens to the plasma proteins prothrombin and fibrinogen when this cascade begins. B. If a clot forms within a blood vessel and blocks the flow of blood, what is it called?

thrombus

Explain each of the following terms. diastole

widening of chambers of heart between 2 contractions when chambers fill with blood

What is the function of the ventricles?

________ are the chambers responsible for pumping blood out of the heart.

What is the function of the atria?

________ are the chambers that receive blood entering the heart

What is lymph? Is it more like blood or more like interstitial fluid?

________ is the fluid lost by the capillaries; its composition is about the same as that of interstitial fluid.

List the four major constituents of plasma. What are their functions? white blood cells

Gets rid of dead blood cells

Carbon dioxide is carried in the blood in three ways. Name each of them, and give the relative percentage of CO2 transported.

23%, when arterial blood flows through capillaries, CO2 diffuses from the tissues into the blood, 7% some CO2 is dissolved into the plasma, 70% some CO2 reacts with hemoglobin and other proteins to bicarbonate inos

If the blood pressure is reported as 110/80, what is the diastolic pressure?______

80

Larger animals must have a circulatory system to move fluid between cells and the outside environment. What are the three basic components of a circulatory system?

A circulatory system has three basic components: a circulatory fluid, a set of interconnecting vessels, and a muscular pump (the heart).

Explain the exchange of fluid at the two ends of a capillary. Include these terms in your discussion: interstitial fluid, osmotic pressure, and blood pressure.

Blood pressure tends to drive fluid out of the capillaries, and it is higher at the arterial end. The osmotic pressure exerted by blood proteins (not shown in this figure) tends to pull fluid back in. The interstitial fluid will also exert osmotic pressure. For example, if the osmotic pressure of the blood is low, more fluid will accumulate in the surrounding tissues, leading to edema. This diagram shows a hypothetical capillary in which blood pressure exceeds osmotic pressure throughout the entire length of the capillary. In other capillaries, blood pressure may be lower than osmotic pressure along all or part of the capillary.

Name each type of cell in blood and give its function. Artery

Carries blood away from the heart, Thick muscular wall

Name each type of cell in blood and give its function. Vein

Carries blood toward the heart Thin wall; valves inside veins maintain a unidirectional flow of blood

List the four major constituents of plasma. What are their functions? plasma

Carries red cells, white cells, and platelets and provides nutrients

What causes the development of a plaque in atherosclerosis?

Damage or infection can roughen the lining of the arteries and lead to inflammation. Leukocytes are attracted to the damaged lining and begin to take up lipids, including cholesterol. A fatty deposit, called a plaque, grows steadily, incorporating fibrous connective tissue and additional cholesterol. As the plaque grows, the walls of the artery become thick and stiff, and the obstruction of the artery increases.

Gills serve as the respiratory organ in many aquatic animals. Figure 34.18 in your text uses arrows to show the flow of water. The most significant part of this figure is the portion that shows the countercurrent flow of water and blood. Study carefully the paragraph that describes countercurrent exchange, and then explain how oxygen is taken up over the length of a capillary.

Fish gills use a design called 'countercurrent oxygen exchange' to maximize the amount of oxygen that their blood can pick up. They achieve this by maximizing the amount of time their blood is exposed to water that has a higher oxygen level, even as the blood takes on more oxygen. Countercurrent oxygen exchange (shown in the figure above) means the blood flows through the gills in the opposite direction as the water flowing over the gills. This flow pattern ensures that as the blood progresses through the gills and gains oxygen from the water, it encounters increasingly fresh water with a higher oxygen concentration that is able to continuously offload oxygen into the blood. The low-oxygen blood, which is just entering the gill, meets low-oxygen water. Since there is more oxygen in the water, the oxygen can flow from water to blood. Likewise, the high-oxygen blood, which has nearly passed the entire length of the gill, meets fresh, high-oxygen water, and oxygen continues to flow from water to blood.

Flatworms (phylum Platyhelminthes) such as planarians have a slightly different solution to this problem. What is it?

Flatworms' combination of a gastrovascular cavity and a flat body is well suited for exchange with the environment. A flat body optimizes diffusional exchange by increasing surface area and minimizing diffusion distances.

Explain why the four-chambered hearts of birds and mammals are considered an example of convergent evolution.

Four-chambered hearts arose independently in the distinct ancestors of mammals and birds and thus reflect convergent evolution. The selective pressure for increased efficiency in circulation in these endotherms drove the evolution of four chambers independently in these lineages; thus, the four chambered heart did not only arise in a single lineage that led to birds and mammals.

What is the role of hemoglobin?

Hemoglobin *transports oxygen*, within the red blood cells, from the lungs to the rest of the body.

Read carefully to answer this question: What has greater effect on the rate of respiration, low levels of O2 or high levels of CO2?

High levels of CO2 are detected by the breathing control centers in the medulla oblongata. Sensors in major blood vessels detect a decrease in blood pH, and the medulla receives the signals from these sensors. Signals from the medulla to the rib muscles and diaphragm increase the rate and depth of breathing. Because high levels of CO2 lower the pH, this has a greater effect on the rate of respiration.

Remember from Chapter 33 that you should look at how various animal groups solve the same problem. Cnidarians, which include the hydras and jellyfish, do not have a distinct circulatory system. How have they solved the problem of exchange?

In hydras, jellyfish, and other cnidarians, a central gastrovascular cavity functions in the distribution of substances throughout the body and in digestion. An opening at one end connects the cavity to the surrounding water.

What is the role of iron in hemoglobin?

Iron is responsible for the production of hemoglobin, a protein that allows red blood cells (image at R red blood cell) to carry oxygen to every part of your body.

Name three places you have lymph nodes. What are two functions of these nodes?

Lymph nodes can be found in your neck, armpit, and groin. Lymph nodes filter the lymph and contain white blood cells that attack viruses and bacteria and are therefore important in the body's defense

Heartbeat rhythm is maintained by electric impulses that are generated from modified cells found in the wall of the right atrium, called the sinoatrial (SA) node. What is the common name for the SA node?

Pacemaker

What is meant by the partial pressure of a gas?

Partial pressure is the pressure exerted by a gas in a mixture of gases.

We don't have a second heart to pump lymph. What keeps it moving along?

Rhythmic contractions of the vessel walls draw fluid into the small lymphatic vessels. In addition, skeletal muscle contractions play a role in moving lymph.

Where are blood stem cells found?

Stem cells are located in the red marrow of bones, particularly in the ribs, vertebrae, sternum, and pelvis

Why does blood slow as it moves from arteries to arterioles to capillaries? Why is this important?

The reason is that the number of capillaries is enormous. Each artery conveys blood to so many capillaries that the total cross-sectional area is much greater in capillary beds than in the arteries or any other part of the circulatory system. The result is a dramatic decrease in velocity from the arteries to the capillaries.

There are several requirements for a respiratory surface. The first is that it must be moist. The second is that it must have a large surface area and be thin. What four different organs satisfy these requirements?

The skin of some animals, such as earthworms; gills; tracheae; and lungs

What is the most common respiratory structure among terrestrial animals? What group has this system?

The tracheal system is the most common; it can be found in insects.

List the four major constituents of plasma. What are their functions? red cells

Transport oxygen from lungs to all living tissues of the body and carry away carbon dioxide

What anatomical feature of the veins maintains a unidirectional flow of blood back toward the heart?

Valves inside the veins maintain unidirectional flow of blood despite the low blood pressure

Electrical impulses from the SA node cause the atria to contract and are conducted to a relay station, the atrioventricular (AV) node. When an impulse is generated by the AV node, what contracts

Ventricles

Gas exchange with water as the respiratory medium is much more demanding than exchange with the air. What are three reasons for this?

Water is a much more demanding medium for exchange with the air because of its lower O2 content, greater density, and greater viscosity.

Blood Vessel Function Anatomical Description venule

much thinner, less muscular walls than arteries and arterioles, largely because the pressure in veins and venules is much lower. Veins may dilate to accommodate increased blood volume.

Which type of system does each of the following organisms have? clam

open circulatory system

What is countercurrent exchange?

opposite flow of adjacent fluids with maximum transfer rates

. Blood separates into two components, a liquid matrix called ______ and the cellular elements.

plasma

What are two mechanisms that regulate blood flow in capillaries?

precapillary sphincters and arterioles controlled by smooth muscle and hormones

Changes in blood pressure as the heart contracts and relaxes can be felt, such as a gentle throb at the wrist or neck. What is this called?_______

pulse

Name each type of cell in blood and give its function. Venule

smalls vessel that flows into larger veins Thin wall small diameter

Explain how the sympathetic and parasympathetic nerves affect the pacemaker.

sympathetic nerves increase heart rate by causing pacemaker cells to generate action potentials more frequently. parasympathetic nerves to the opposite

Why is it important that the arteries are so much thicker than the veins?

the blood in arteries needs to be under greater pressure to keep flowing in the right direction and move faster, preventing oxygen loss