BIO 142: Blood vessels LOs

9a. Elastic arteries or conducting arteries

- closest to the heart (aorta, aortic branches, and pulmonary trunk). -Because of their proximity to the heart, these vessels are exposed to blood that is flowing through the lumen under high pressure. - It is for this reason that the tunica media consists of a larger proportion of elastic tissue relative to smooth muscle. -The extensive elastic tissue allows the vessel to stretch during ventricular contraction and recoil during ventricular relaxation. -The recoiling of elastic tissue propels blood through the circulation when the heart is not actively pumping blood. -The extensive circularly oriented fenestrated elastic sheets are interspersed with circularly oriented smooth muscle cells.

Adrenal medulla

- is innervated by preganglionic neurons of the sympathetic division of the ANS. -When the sympathetic nervous system is stimulated, chromaffin cells in the medulla are stimulated to release mainly epinephrine (a small amount of norepinephrine is also released) into the bloodstream. -Hormone release occurs quickly because the cells are innervated by neurons of the ANS. -Both hormones mimic the effects of the sympathetic nervous system and are therefore referred to as sympathetomimetic hormones.

12a. Describe the exchange that occurs at the level of capillaries.

-The exchange of nutri ents and wastes between the blood and the interstitial fluid occurs across the capillary wall by diffusion or transcytosis. Water is forced across the wall by filtration. -Capillaries form interweaving networks called capillary beds that increase the amount of surface area for exchange of substances between the blood and interstitial fluid.

23. Contrast the structure of a venule to a capillary

-Venules receive blood from capillary beds under low pressure, so their walls lack smooth muscle. - This lack of smooth muscle in the tunica media causes the wall to be thin and resemble capillary walls in histological section. -However, venules are much larger in size than capillaries with a lumenal diameter ranging from 15-20 microns, which is about 2-3 times the diameter of a RBC.

49. List and explain the mechanisms involved in intrinsic control of blood flow through a tissue's capillary bed.

1. Diffusion: substances such as O2, CO2, glucose, amino acids, and hormones are exchanged across the capillary wall down their concentration gradient. 2. Filtration: Water and small solute molecules are forced between endothelial cells or through pores (fenestrations) in the capillary endothelial cells. Large solute molecules and proteins cannot fit through the walls and remain in the blood. 3. Resorption: Half way through the capillary bed the hydrostatic pressure falls below the colloidal osmotic pressure. The colloidal osmotic pressure causes water and solutes that can fit through the capillary walls to flow back into the capillary. 85% of the filtered fluid is reabsorbed. 4. Fluid and solutes that are not reabsorbed are eventually returned to the cardiovascular system by the lymphatic system.

37. Explain the cardiac events and systemic arterial events associated with diastolic pressure.

1. During ventricular relaxation, the blood backflows against the aortic semilunar valve causing it to close. 2. The aorta recoils because of the large amount of elastic fibers in the wall, and this recoiling action continues to push blood through the circulatory system during ventricular diastole. 3. The pressure exerted by the blood after recoil has taken place is called the diastolic pressure.

4. List the components of the tunica media and explain the functional properties that each component imparts on blood vessel function.

1. It consists mostly of circularly arranged smooth muscle cells and fenestrated sheets of elastic tissue. 2. The outermost layer of elastic tissue in the media is called the external elastic lamina.

26. Contrast the pressure in the venous circulation to the pressure in the arterial circulation.

1. The pressure in the venous circulation is low compared to the arterial circulation, so the walls of veins can be thinner. 2. The low-pressure environment allows the possibility of blood to flow in a backward direction, which is compensated for by valves.

2. List and describe the three layers that compose the wall of an artery and vein.

1. The tunica intima is the innermost layer. 2. The tunica media is the middle layer of the blood vessel wall and varies greatly in vessels of different size and type. 3. The tunica adventitia or tunica externa is the outermost layer of the vessel wall.

1. Beginning with the aorta and ending at the vena cavae, list the blood vessel types through which blood passes.

A. Aorta B. Arteries C. Arterioles D. Capillaries E. Venules F. Veins G. Vena cava

41. Define resistance and vascular resistance and state the major factor that plays a role in vascular resistance.

A. Resistance refers to any force that opposes movement (blood flow). B. Vascular resistance: The major determinant of peripheral resistance is the diameter of arterioles and is primarily due to friction between the blood and the blood vessel wall.

54. Predict the effects of inhibiting the vasomotor center in the medulla oblongata.

Decreased activity causes vasodilation

14b. Fenestrated capillaries

Fenestrated capillaries are found in the intestines and kidneys and contain numerous pores in the cell membrane that allow the rapid exchange of water and small molecules.

50. Explain the role of NO in vasodilation

Nitric oxide produced by endothelial cells is a strong vasodilator and plays a major role in causing vasodilation

48. Explain the importance of decreasing the velocity of flow at capillary beds.

The slow flow allows capillary exchange to occur.

24. Define vein.

Veins are the large vessels of the venous circulation.

62. Explain the role and physiology of the right atrium in regards to hormone production and regulation of blood pressure.

- ANP (atrial natriuretic peptide): a hormone produced by the atria in response to over-stretching (increased BP). a) ANP causes BP and blood volume to decline because it antagonizes aldosterone, which increases Na+ and water excretion. b) The resulting increase in urine output only lasts a short time.

22. Explain what is meant by the venous circulation being the major reservoir for blood in the circulatory system.

- During rest, approximately 60-70% of the blood volume of the body is contained within the venous circulation.

18. Explain the process by which large water soluble molecules are transported across a continuous capillary.

- Large water soluble molecules are transported by transcytosis, which is an active mechanism requiring energy.

9b. Muscular arteries or distributing arteries

-Are most of the named arteries in the body excluding the immediate branches of the aorta. -The tunica media of a muscular artery consists mostly of smooth muscle with some sheets of fenestrated elastic tissue between the muscular layers.

8. Define artery.

-Arteries are blood vessels that transport blood away from the heart. -The arterial circulation consists of vessels with thicker walls relative to a vein of the same size. -This difference in thickness is necessary because arteries receive blood under much higher pressure than veins due to their proximity to the heart.

10. Define arterioles, describe the structure of an arteriole, and explain their function.

-Arterioles are the smallest vessels of the arterial circulation. -They have the important roles of transporting and regulating blood into capillary beds. -The tunica media of arterioles can consist of 1-6 layers of smooth muscle, with the smallest arterioles only containing a single layer of smooth muscle cells.

47. Explain why the velocity of flow is decreased at capillary beds.

-Blood flows along the pressure gradient and reaches a capillary bed. -The flow of blood slows in the capillaries because of the total cross sectional area of all the capillaries in the body is greater than the total cross sectional area of arteries or veins.

34. List the mean arterial pressure gradients in the systemic arterial circulation systemic capillary circulation, and systemic venous circulation.

-Blood pressure: The force exerted on an arterial blood vessel wall by the blood contained in the arterial vessel, 100-35mm Hg. - Capillary hydrostatic pressure: the pressure exerted by the blood against the walls of the capillaries, 35-18mm Hg - Venous pressure: the force exerted by the blood against the walls of the venous vessels, 18-0 mm Hg -The decreasing pressure is the driving force that moves the blood through the circulatory system. Remember: Flow is from high pressure to low pressure.

11. Define capillary describe the structure of the capillary wall, and explain the function of capillaries.

-Capillaries are the smallest of the blood vessels and are the site of blood gas and nutrient exchange. -Capillaries consist of a simple squamous epithelium (endothelium) and underlying connective tissue. These two layers comprise the tunica intima. In some cases, one endothelial cell forms the entire circumference of the capillary. -Capillaries do not contain a tunica media or tunica adventitia.

20a. Define venous circulation

-Consists of large vessels called veins and smaller vessels called venules. -Typically, veins have thinner walls as compared to their accompanying arteries and the lumens of veins are larger and often collapsed.

46. Explain the role of elastic tissue in blood flow during cardiac diastole.

-During ventricular relaxation (diastole), the pressure in the ventricle decreases below the pressure in the aorta and blood backflows toward the ventricle causing the semilunar valve to close. -The elastic tissue in the walls of the aorta rebound, forcing blood into the arterial system from an area of high pressure to an area of low pressure.

19. Explain the function of fenestrated capillaries and give an example in the body where fenestrated capillaries are located.

-Fenestrated capillaries are found in the intestines and kidneys and contain numerous pores in the cell membrane that allow the rapid exchange of water and small molecules.

15. Describe the process of filtration and reabsorption across the wall of a continuous capillary.

-Fluid is then reabsorbed on the venous side of the capillary. -The water reabsorption is the result of capillary osmotic pressure due mostly to the presence of albumin, which is too large to be filtered. -More fluid enters the tissue spaces by filtration than what is returned to the bloodstream by reabsorption. -This excess fluid and any leaked proteins are transported by the lymphatic system back to the venous circulation.

58. Predict and explain the effect that low pH and low O2 has on cardiac output.

-Impulses are sent to the cardioacceleratory center from the chemoreceptors when O2 decreases or CO2 increases (low pH). -The result is stimulation of the sympathetic nervous system. a) CO is increased (SV and HR) b) Blood vessels constrict causing an increase in BP (This mechanism increases the return of blood to the heart and lungs) c) The respiratory center (inspiratory area) is also stimulated, which increases the rate and depth of respiration.

16. Explain the role of the lymphatic system in preventing edema.

-More fluid enters the tissue spaces by filtration than what is returned to the bloodstream by reabsorption. -This excess fluid and any leaked proteins are transported by the lymphatic system back to the venous circulation.

17. Describe the transport process by which blood gases are transported across a continuous capillary.

-O2, and CO2 diffuse across the endothelium by simple diffusion. -Large water soluble molecules are transported by transcytosis, which is an active mechanism requiring energy.

20. Explain the function of sinusoidal capillaries and give an example in the body where sinusoidal capillaries are located.

-Sinusoidal capillaries are found in the liver, bone marrow and some endocrine glands. - They are large irregular channels that slow the circulation of blood. -The endothelial cells are fenestrated and large gaps exist between the cells. -The basal lamina is also discontinuous in the region of the gaps. -Large molecules and proteins can pass through the gaps.

14c. Sinusoidal capillaries

-Sinusoidal capillaries are found in the liver, bone marrow and some endocrine glands. -They are large irregular channels that slow the circulation of blood. The endothelial cells are fenestrated and large gaps exist between the cells. -The basal lamina is also discontinuous in the region of the gaps. -Large molecules and proteins can pass through the gaps.

59. Explain the role of the adrenal medulla in regulation of blood pressure.

-The adrenal medulla is innervated by preganglionic neurons of the sympathetic division of the ANS. -When the sympathetic nervous system is stimulated, chromaffin cells in the medulla are stimulated to release mainly epinephrine (a small amount of norepinephrine is also released) into the bloodstream. - Hormone release occurs quickly because the cells are innervated by neurons of the ANS. Both hormones mimic the effects of the sympathetic nervous system and are therefore referred to as sympathetomimetic hormones. a) Increase HR b) Increase strength of contraction of heart muscle c) a & b above result in increased cardiac output and BP d) Blood flow to organs (1) Norepinephrine and epinephrine will cause vasoconstriction in blood vessels where the smooth muscle cells contain alpha-1 receptors (2) Epinephrine will causes vasodilation in blood vessels where the smooth muscle cells contain beta-2 receptors (heart and skeletal muscle).

12. Define microcirculation

-The flow of blood through a capillary bed.

5. Contrast the size of the tunica media in an artery to the tunica media of a vein that is of a comparable size

-The relative proportion of elastic tissue and smooth muscle in arteries varies depending upon the type of artery (elastic or muscular). -In a vein that is of comparable size to an artery, the vein has a considerably thinner tunica media.

7. Contrast the thickness of the tunica adventitia in an artery to the thickness of the adventitia in a vein of a comparable size.

-The thickness of the adventitia ranges from a relatively thin layer in most arteries to a thick layer in venules and veins where it is the thickest of the three tunics.

21. Explain the function of valves in the venous and lymphatic circulation.

-They prevent the backflow of blood.

9. Contrast the structure and function of elastic arteries to muscular arteries and give an example of each.

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32. Explain why blood flow must be adjusted to maintain tissue perfusion.

1. Active tissues require more blood flow than inactive tissues. 2. Positional changes of the body require the cardiovascular system to make changes in peripheral resistance to maintain proper tissue perfusion.

9c. Due to the presence of both elastic tissue and smooth muscle, arteries exhibit two functional properties.

1. Elasticity refers to the ability of the vessel wall to expand under pressure and then recoil as the hydrostatic pressure declines. 2. Contractility refers to the ability of the vessel to contract the smooth muscle in the wall to reduce the diameter of the lumen.

6. Describe the structure and components of the tunica adventitia.

1. It consists of longitudinally arranged collagen and a few elastic fibers that gradually merge with loose connective tissue surrounding the vessel.

45. Predict the effect that altered blood vessel length has on blood flow.

1. Resistance increases when the total length of the blood vessels increases. 2. FYI: an estimated 200 miles of additional blood vessels for every extra pound of fat

13. Describe the structure and function of precapillary sphincters.

1. Smooth muscle surrounding the area where capillaries branch from arterioles. Their function is to regulate the flow of blood through a capillary bed. 2. They help to maintain arterial pressure and regulate flow to selective vascular beds.

39. Define and calculate mean arterial pressure.

1. The average pressure within an artery over a complete cycle of one heartbeat. 2. MABP = diastolic pressure + systolic BP - diastolic BP)

38. Define and calculate pulse pressure. Explain why pulse pressure increases in arteriosclerosis.

1. The difference between systolic and diastolic pressure 2. A large pulse pressure can result from the inability of the walls of the vessels to expand causing an increase in systolic pressure. A condition that would result in a large pulse pressure is arteriosclerosis.

3. List the three layers that compose the tunica intima and describe the structural components that compose each layer.

1. The endothelium is a simple squamous epithelium that lines the lumen of the blood vessel. 2. The subendothelial layer is a layer of loose connective tissue that supports the endothelium and can contain a few scattered smooth muscle cells. 3. The internal elastic lamina (IEL) is the innermost layer of fenestrated elastic tissue. The IEL is prominent in muscular arteries and large arterioles, but absent in small arterioles. In veins the IEL is thin, and in venules it is usually absent.

36. Explain the cardiac events and systemic arterial events associated with the systolic pressure.

1. The left ventricle contracts forcing blood into the aorta causing it to stretch. This stretch is the result of pressure exerted by the blood. 2. The peak pressure is the systolic pressure. 3. The pressure in the aorta is greater than the pressure in the distal vessels, so blood flows into the distal vessels.

40. Explain the mechanics and physiology of taking a brachial artery blood pressure measurement.

1. The tools needed to record a blood pressure are a a sphygmomanometer and a stethoscope. However, a systolic pressure can be obtained by only using a sphygmomanometer. 2. The cuff is placed over the brachial artery. 3. The cuff is inflated with enough air pressure to completely occlude the brachial artery and stop blood flow (the correct amount of air pressure is known by first determining the palpatory systolic BP) 4. The stethoscope is placed in the antecubital fossa. 5. No sound should be heard at this time. 6. Air is released from the cuff; the first Korotkoff sound is the systolic pressure. 7. Air is continually released from the cuff until no sound is heard and that is the diastolic pressure.

29a. describe blood flow

1. The volume of blood that flows through a vessel or group of vessels per unit of time (ml/min) 2. Blood flow is dependent upon pressure gradients and resistance.

25. List 5 differences between a medium sized vein and a medium sized muscular artery.

1. Their walls are thinner relative to an artery of the same size. 2. Their lumens are larger relative to an artery of the same size. 3. The tunica media contains a small amount of smooth muscle and elastin relative to an artery of the same size. 4. The tunica adventitia is usually the thickest of the 3 layers. 5. They contain valves to prevent backflow of blood.

44. Predict the effect that altered viscosity has on blood flow.

1. Viscosity is the resistance to flow caused by interactions of molecules and suspended materials in a liquid. 2. The viscosity of a fluid is defined relative to the viscosity of water, which is 1.0 3. The greater the viscosity of blood the higher the resistance. a) An increase in the number of formed elements can result in an increase in viscosity (ex: polycythemia). b) A reduction in the plasma relative to the formed elements can result in an increase in viscosity (ex: dehydration).

69. Define aneurysm.

A balloon-like out pocketing of an artery wall that places the artery at risk for rupture.

28. Contrast an arterial anastomosis and venous anastomosis, and arteriovenous anastomosis and explain the function of each.

A. Arterial anastamoses: 1. Two arteries that join to feed the same capillary bed 2. Assures that the capillary bed circulation will continue if one of the vessels is damaged or blocked B. Venous anastomosis: -interconnections of veins that allow for alternative passageways of blood if an occlusion occurs C. Arteriovenous anastomosis: -connections between arterioles and venules that bypass the capillary bed. -Arteriovenous anastomoses are important in the skin to regulate the amount of heat loss from the body.

67. Explain the physiological effects relating to blood flow that occur during exercise.

A. O2 consumption increases and the skeletal muscles respond by releasing vasodilators that result in more blood flow and more O2 to be delivered to the skeletal muscles. B. Venous return to the heart is increased because of increased activity of the skeletal muscle pump and the respiratory pump. C. CO is increased because of the increased venous return (Frank-Starling principle). D. With increasing levels of activity, the sympathetic nervous system is stimulated causing and increase in CO and vasoconstriction. Vasoconstriction occurs in vessels that supply non-essential organs (digestive organs), which in turn causes more blood to flow between the heart and skeletal muscles.

68. Define chronic hypertension explain the effects that hypertension has on the cardiovascular system, and differentiate between essential hypertension and secondary hypertension.

A. Primary or essential hypertension: no known cause and is responsible for 90% of the cases. B. Secondary hypertension: the cause of hypertension is known. C. Prolonged hypertension is the major cause of heart failure, vascular disease, renal failure, and stroke. D. Hypertension is defined as a systemic pressure of 140/90 mm Hg or higher. E. Hypertension is usually asymptomatic for the first 10-20 years and for this reason is considered a "silent killer." F. The heart is forced to pump blood against a greater resistance and as a result, the myocardium enlarges. G. When the heart is strained beyond its capacity to respond the muscle weakens. H. The blood vessels also develop small tears in the endothelium making them more susceptible to atherosclerosis. I. Eventually blood flow to the tissues becomes inadequate and vascular complications appear in the vessels in the brain, heart, kidneys, and retinas.

31. Predict the effect that cardiac output has on blood flow.

A. Under normal conditions, blood flow is equivalent to cardiac output. B. When CO increases, so does the blood flow through capillaries. C. When CO decreases, so does the blood flow through capillaries. D. The pumping action of the heart generates CO, and therefore blood flow.

70. Define varicose veins and explain the reason their development.

A. Veins that are tortuous and dilated as a result of incompetent valves. B. Heredity and factors that hinder venous return such as prolonged standing, obesity, and pregnancy contribute to the onset of varicose veins.

23a. explain the function of venules

A. Venules are small vessels of the venous circulation that transport blood from capillaries to larger veins. B. Vessels that drain blood from capillaries into veins C. Several capillaries join to form venules.

65. Predict the effect that elevated ANP ADH (vasopressin), and aldosterone (hyperaldosteronism) have on blood pressure.

ADH: - causes the body to conserve water by acting on tubule cells in the kidneys and as a result the blood volume is increased, which increases BP. -ADH also causes vasoconstriction ANP: - causes BP and blood volume to decline because it antagonizes aldosterone, which increases Na+ and water excretion. -The resulting increase in urine output only lasts a short time. Aldosterone: - a hormone that causes the renal tubules to increase Na+ reabsorption, which results in conservation of water in the blood. Increaing BP and BV.

66. Predict the effect that decreased ANP ADH (vasopressin), and aldosterone (hypoaldosteronism) have on blood pressure.

ADH: -A decrease in ADH would decrease BV, by allowing more water to be taking out of the blood, also decrease vasoconstriction. ANP: -A decrease in ANP would allow for reabsorption of water in the blood and would allow for an increase of BV. Aldosteron: -A decrease would allow water absorption in the kidneys and urinary system, and decrease BP and BV.

71. Define circulatory shock hypovolemic (hemorrhagic) shock, and vascular shock and explain the physiological response to shock.

Circulatory Shock: A. A condition in which blood vessels are inadequately filled and blood can't circulate properly. If the condition persists, cells may die as a result of a decreased blood flow. B. Hypovolemic shock: shock that is the result of a large-scale loss of fluid. 1. A thready pulse results as the heart rate increases to compensate for a drop in blood pressure. 2. Fluid replacement must occur quickly. Vascular shock: 1. Blood volume is normal and constant but blood pressure drops as a result of severe vasodilation. 2. Occurs when there is a failure of autonomic nervous system control: a) anaphylactic shock: severe vasodilation as a result of a massive release of histamine b) septicemia: severe systemic bacterial infection that results in vasodilation

56. Predict and explain the effect that decreasing the stretch of baroreceptors has on cardiac output.

Decreased stretch causes fewer impulses to be transmitted to the vasomotor center.

53. Predict the effects of stimulating the vasomotor center in the medulla oblongata.

Increased activity causes vasoconstriction

55. Predict and explain the effect that increasing the stretch of baroreceptors has on cardiac output.

Increased stretch, which corresponds to an increase in BP, causes a rapid series of impulses to be sent to the vasomotor center of the medulla oblongata via sensory neurons.

57. Predict into which organs blood flow will be increased and decreased during a "fight or flight" sympathetic response and explain the physiology of each response.

Sympathetic stimulation of smooth muscle in the tunica media results in strong vasoconstriction of blood vessels that supply the following regions (alpha-1 receptors). (1) Abdominal viscera (2) Salivary glands (3) Mucous membranes (4) Kidneys (5) Skin

43. List 3 substances produced by the body that induce vasoconstriction and 3 factors/substances that induce vasodilation.

Vasoconstriction: -Endothelin; biochemical -Epinephrine, ADH, and angiostensin; hormones. Vasodilation: -Nitric oxide; biochemical. -histamine, prostaglandins; biochemicals. -Lack of sympathetic nervous system stimulation to the smooth muscle in the tunica media results in vasodilation/relaxation.

29b. Describe velocity of flow

Velocity of flow refers to how quickly the fluid is passing through a vessel, which is independent of the total amount of fluid that is moving (mm/min). 1. The velocity of blood flow is inversely proportional to the cross sectional area of blood vessels. 2. Velocity of blood flow is the greatest in large vessels and theslowest in the capillaries.

30a. Hydrostatic pressure

a pressure exerted by a liquid against the wall of its contained

42b. Describe vasodilation

a) A large lumen offers less resistance to blood flow and therefore blood pressure is less than the pressure in a vessel with a smaller lumen. b) The blood in the center of a vessel with a large lumen does not come in contact with the wall, so it does not encounter resistance from friction. c) The lack of sympathetic nervous system stimulation to the smooth muscle in the tunica media results in relaxation (vasodilation). d) Nitric oxide produced by endothelial cells is a strong vasodilator and plays a major role in causing vasodilation e) Inflammatory biochemicals (histamine and prostaglandins) that are released in response to tissue damage, infection, and allergic reaction cause vasodilation. f) Many pharmacological agents induce vasodilation and are used to decrease blood pressure.

42a. Describe vasoconstriction

a) A smaller lumen increases the resistance to blood flow and therefore increases blood pressure. b) In a vessel with a narrow lumen, blood flow is reduced by friction that occurs between the blood and the vessel wall. c) Sympathetic nervous system stimulation to the smooth muscle of the tunica media causes it to contract. d) A biochemical endothelin, which is produced by endothelial cells is a strong vasoconstrictor e) Hormones such as epinephrine, antidiuretic hormone (ADH), and angiotensin also stimulate the smooth muscle in the tunica media to contract.

63. Explain the role and physiology of the renin-antiogensin aldosterone system in the regulation of blood pressure.

a) Cells in the kidney sense a decrease in BP and secrete an enzyme renin into the blood. b) Renin acts on a blood protein angiotensinogen to produce angiotensin I. Angiotensin I is converted to the active form, Angiotensin II, by angiotensin converting enzyme (ACE). ACE is produced mainly by endothelial cells in the lung (pulmonary capillaries) c) Angiotensin II causes vasoconstriction of blood vessels and stimulates the adrenal cortex to release aldosterone, which results in water conservation by the kidney. d) Vasoconstriction by blood vessels and an increased blood volume causes BP to increase.

Effects of adrenal medulla on the heart

a) Increase HR b) Increase strength of contraction of heart muscle c) a & b above result in increased cardiac output and BP d) Blood flow to organs: (1) Norepinephrine and epinephrine will cause vasoconstriction in blood vessels where the smooth muscle cells contain alpha-1 receptors (2) Epinephrine will causes vasodilation in blood vessels where the smooth muscle cells contain beta-2 receptors (heart and skeletal muscle).

60. Explain the role of the hypothalamus and posterior pituitary in regulation of blood pressure.

a) Neuron cell bodies located in nuclei of the hypothalamus project axons into the posterior pituitary where they terminate near capillary beds. This bundle of axons forms the hypothlamohypophyseal tract. b) Antidiuretic hormone (ADH or vasopressin) is produced in the cell body and transported to the axonal terminals by fast axonal transport for storage. When nerve impulses reach the axonal terminals, the terminals exocytose ADH, which then diffuses into the bloodstream and is transported in the blood to target organs c) ADH causes the body to conserve water by acting on tubule cells in the kidneys and as a result the blood volume is increased, which increases BP. ADH also causes vasoconstriction.

61. Explain the role of the adrenal cortex in the regulation of blood pressure.

a) One of the hormones produced by the cells of the adrenal cortex is aldosterone (a mineralcorticoid). b) Aldosterone is a hormone that causes the renal tubules to increase Na+ reabsorption, which results in conservation of water.

33. Correlate location relative to the heart and pressures in the cardiovascular system.

a) The closer the fluid is to the pump, the greater the pressure the fluid is under. b) The pressure exerted on a fluid decreases the farther the fluid is away from the pump.

14a. Continuous capillaries

a) They are found in muscle, brain, and connective tissue and are characterized as a continuous sheet of endothelial cells that lack pores or fenestrations and are joined by tight junctions. The tight junctions are usually incomplete leaving gaps between endothelial cells called intercellular clefts. A continuous basal lamina surrounds the endothelial layer. b) Water and small hydrophilic molecules (amino acids and sugars) are forced through the spaces between cells (intercellular clefts) by hydrostatic pressure (filtration) on the arterial side of a capillary bed.

52. Predict and explain the effects of stimulating the cardioinhibitory center of the medulla oblongata.

decreases CO by action of the parasympathetic nervous system

51. Predict and explain the effects of stimulating the cardioacceleratory center of the medulla oblongata.

increases CO by the action of the sympathetic nervous system

30d. Vascular resistance

resistance that is due to friction between the blood and the blood vessel wall

30b. Blood pressure

the hydrostatic pressure in the arterial system that is the driving force that pushes blood through the capillary beds

30c. Venous pressure

the hydrostatic pressure in the venous system

27. Define anastomosis.

the junction point between two different vessels

30e. Peripheral resistance

the resistance of the arterial system which is affected by vascular resistance and viscosity

30f. Total peripheral resistance

the resistance of the total cardiovascular system