Chapter 20 Lecture 1224 HW

Fill in the blanks with the terms provided. Not all terms will be used.

Although net filtration occurs at the arterial end of a capillary and net reabsorption at its venous end, not all of the fluid is reabsorbed. The capillary typically reabsorbs only about 85% of the fluid that has passed into the interstitial fluid. The lymphatic system is responsible for picking up 15% of this excess fluid and returning it to the blood.

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In the simple pathway, one major artery delivers blood to the organ or body region and then branches into smaller and smaller arteries to become arterioles. Each arteriole feeds into a single capillary bed. A(n) venule drains blood from the capillaries and merges with other venules to form one major vein that drains blood from the organ or body region. Arteries that provide only one pathway through which blood can reach an organ are referred to as end arteries

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Relatively small amounts of blood are within the pulmonary circulation (about 18%) and the heart(about 12%). The largest percentage of blood is within the systemic circulation (about 70%), with the greatest amount (about 55%) within the body's systemic veins. The relatively large amount of blood within these vessels allows them to function as blood reservoirs. Blood may be shifted from these reservoirs in times of increased physical exertion with vasoconstriction. When less blood is needed at rest, it will be shifted back through by vasodilation

Fill in the blanks, then put the sentences into logical order to discuss the cardiovascular system.

The cardiovascular system is really two separate circuits of blood flow. The systemic circuit delivers blood to all the cells of the body. 1 The other circuit will involve the same structures you named but functions to deliver oxygen-poor and carbon dioxide-rich blood to the lungs and is the pulmonary circuit. 2 In these circuits, exchange takes place at the capillaries. These become larger vessels known as venules, which converge into even larger vessels known as veins before they return to the heart.

Place a single word into each sentence to make it correct, then arrange the sentences into a logical paragraph order.

Capillary beds have precapillary sphincters at the junction of capillaries and the met arteriole. Constriction of these sphincters reduces the blood flow through their respective capillaries. When this occurs, blood is diverted to tissue or organs elsewhere. When the sphincters are open, blood will fill the capillary bed.

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Blood flow is directly related to the pressure gradient. Thus, as the blood pressure gradient increases, total blood flow increases, and as the blood pressure gradient decreases, total blood flow lessens(assuming resistance remains the same). An increase in cardiac output will increase the pressure gradient, and a decrease in cardiac output will decrease the pressure gradient.

Which of the following would cause a temporary increase in arterial blood pressure? Check all that apply.

Increased blood volume Increased cardiac output Vasoconstriction

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The physical force exerted by a fluid on a structure is hydrostatic pressure. The main pressure is the blood hydrostatic pressure, which pushes materials out of the capillary. The other main force regulating filtration and reabsorption is osmotic pressure, which refers to the "pull" of water into an area by osmosis due to the higher relative concentration of solutes.

Select the correct word from the list to complete each sentence regarding the relationship between blood flow, vessel radius, and resistance.

The smaller the radius of a vessel, the greater the resistance. As the radius of a vessel increases, the resistance decreases. As the resistance decreases, the blood flow increases. The larger the radius of a vessel, the less the resistance. Blood flow to an organ will decrease with vasoconstriction. Blood flow to an organ will increase with vasodilation

Fill in the blanks, then put the sentences into logical order to discuss the cardiovascular system.

A major function of the cardiovascular system is to transport fluids. To fulfill this purpose, you have the following structures: The heart, provides pressure to pump the fluids into the large and elastic aorta, which will carry the blood to the body. The vessels leaving the heart will branch and become smaller in diameter, these are the arteries. The vessels will continue to branch and get smaller into arterioles. Eventually, they will become the capillaries, which are the sites of gas, nutrient, and waste exchange.

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A relatively small blood pressure gradient is generally insufficient to move blood through the veins under given conditions, thus venous return must be facilitated by valves within veins and two "pumps." The skeletal muscle pump assists the movement of blood primarily within the limbs. As skeletal muscles contract, veins are squeezed to help propel the blood toward the heart. The respiratory pump assists the movement of blood within the thoracic cavity. The diaphragm contracts and flattens as we inspire. Intra-abdominal pressure increases and places pressure on the vessels within the abdominal cavity. Concomitantly, thoracic cavity volume increases and intrathoracic pressure decreases. Blood is propelled from the abdominopelvic cavity into the thoracic cavity.

Select all the hormones that affect blood pressure.

Angiotensin II Aldosterone Antidiuretic hormone (ADH) Atrial natriuretic peptide (ANP)

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Angiotensin II and ADH (in high doses) increase peripheral resistance and blood pressure; and angiotensin II, aldosterone, and ADH decrease urine output to help maintain blood volume and blood pressure. ANP stimulates vasodilation, which decreases peripheral resistance and increases urine output, which decreases blood volume. The net effect is a decrease in blood pressure.

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Blood delivered to the capillaries of a specific tissue is local blood flow and is measured in millilitersper minute. The specific amount of blood entering capillaries per unit time per gram of tissue is called perfusion. The ultimate goal of the cardiovascular system is adequate perfusion of all tissues. The amount of blood transported throughout the entire vasculature in a given period of time is total blood flow and is usually expressed in liters per minute. This type of blood flow equals cardiac output. If this increases, the amount of blood available to body tissues increases.

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Resistance also influences total blood flow. Resistance is defined as the amount of friction the blood experiences as it travels through the blood vessels. Blood flow is always opposed by resistance. Friction is due to the contact between blood and the blood vessel wall. The term peripheral resistance is typically used when discussing the resistance of blood in the blood vessels (as opposed to the resistance of blood in the heart). Several factors affect this friction, including blood viscosity, blood vessel length, and the size of the lumen of blood vessels (as indicated by vessel radius).

Complete each sentence by dragging the proper label into the appropriate position.

The aorta is the first vessel blood enters upon exiting the heart. The large (elastic) arteries expand and recoil with every heartbeat due to a histologically dominant network of elastic tissue in the tunica media. Just prior to entering capillary beds, arterioles have become extremely thin and present only a few layers of smooth muscle. The site of gaseous exchange, or capillaries, are characterized by extremely thin walls with only endothelium and basal lamina, which better suits diffusional requirements. After exiting the capillary, venules contain no muscle and are the first vessel that blood enters on its way back to the heart. The medium veins contain abundant but irregularly spaced smooth muscle with frequent valves present in the tunica interna. The superior vena cava is an example of a large vein that includes smooth muscle circularly and longitudinally arranged in the tunica media and externa respectively.

Complete each sentence by dragging the proper label into the appropriate position.

The highest pressure exerted on the arterial walls during the heart cycle is referred to as systolic blood pressure . When one-third of pulse pressure is added to the diastolic pressure, a good estimate of mean arterial pressure is obtained. The diastolic blood pressure is measured when the heart is relaxing and represents the lowest pressure exerted in the walls of the arteries during the heart cycle. Subtracting the SBP from the DBP results in pulse pressure which is directly proportional to the overall strength of one's pulse.

Place a single word into each sentence to make it correct.

Typically fluid filters out the arterial end of a capillary. Fluid will then osmotically reenter at the venous end. This fluid delivers materials to the cells and removes its waste. This shift in fluid balance at the arterial end is referred to as hydrostaticpressure. This is the physical force exerted by a liquid against a surface like a capillary wall.

Check all that could potentially result in an increase in arterial blood pressure.

Vasoconstriction of arterioles Increase in cardiac rate Increase in stroke volume

How do veins return blood to the heart? Check all that are correct.

Veins have one-way valves that prevent backflow in the limbs. The contraction of skeletal muscles helps push the veins back toward the heart.

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Within systemic capillaries, substances such as oxygen, hormones, and nutrients move by diffusionfrom their relatively high concentration in the blood into the interstitial fluid and then into the tissue cells, where the concentration of these materials is low. Very small solutes and fluids may pass via the ____________ , while larger solutes, must pass through the fenestrations in capillaries or gaps in sinusoids. Endothelial cells may use pinocytosis to fuse fluid-filled vesicles with the plasma membrane. This type of vesicular transport can move contents either from the blood to the interstitial fluid or from the interstitial fluid into the blood. Solutes such as certain hormones and fatty acids are transported across the endothelial cells by this method.