Chapter 19

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1

1. what are the three major types of blood vessels?
1. what are the smallest branches of arteries?
3. what are venules?

1. arteries, veins, capillaries
2. arterioles
3. smalles veins

2

1. in which direction do arteries carry blood? veins?
2. Name the three tunics of the walls of blood vessels.
3. endothelium is found in which tunic? what kind of epithelium is this endothelium?

1. away from the heart; to the heart
2. tunica intima, media, externa
3. tunica intima; simple squamous

3

1. how is the tunica media arranged? how is the activity of smooth muscle regulated?
2. why are the activities of the tunica media important?

1. in circularly arranged smooth muscle cells, sheets of elastin. regulated by the vasomotor nerve fibers of the autonomic nervous system and chemicals.
2. critical in regulating circulatory dynamics because small changes in vessel diameter greatly influence blood flow and BP

4

1. which tunic is the bulkiest layer, which bear the chief responsibility for maintaining BP and continuous blood circulation?

2. which tunic is largely composed of loosely woven collagen fibers that protect and reinforce the vessel, and anchor it to surrounding structures?

3. what is a lumen?

1. Media
2. externa
3. a central blood containing space surrounded by tunics

5

CHECK YOUR UNDERSTANDING
1. which branch of the ANS innervates blood vessels? which layer of the blood vessel wall do these nerves innervate? what are the effectors (cells that carry out the response)?

2. when the vascular smooth muscle contracts, what happens to the diameter of the blood vessel? what is this called?

1. the sns innervates blood vessels. sympathetic nerves innervate the tunica media. the effector cells in tunica media are smooth muscle cells.

2. when vascular smooth muscle contracts, the diameter of the blood vessel becomes smaller, this is called vasoconstriction.

6

1. thick walled arteries near the heart. these arteries area largest in diameter, ranging from 2.5 CM and 1 cm, and the most elastic.
2. why are elastic arteries sometimes called conducting arteries?

1. elastic arteries
2. because their large lumens make them low resistance pathways that conduct blood from heart to medium sized arteries.

7

1. in elastic arteries, they contain more elastin than any other artery, and it is present in all three tunics. which tunic contains the most elastin in elastic arteries?

2. these types of arteries deliver blood to specific body organs and are about .3 mm to 1 cm wide. they have the thickest tunica media of all vessels, and contain more smooth muscle and less elastic tissue than elastic arteries.

1. tunica media
1. muscular (distributing) arteries

8

1. would muscular arteries be better at vasoconstriction or vasodilation? why?

2. what are the smallest blood vessels called?

vasodilation because they have more skeletal muscle than elastic fibers, which means they can constrict better than they can expand.

2. capillaries

9

1. what do capillary walls consist of?
2. capillaries are wide enough to accommodate the flow of how many RBC's at a time?
3. what are pericytes?

1. only a thin tunica intima
2. one.
3. cells on the outer surface of capillaries that stabilize their walls.

10

1. since capillaries reach all the intimate spots, what is their function once blood reaches those intimate bits?

2. what are the three types of capillaries? which kind is most common?

3. what are intercellular clefts and which capillaries are they found in?

1. gas exchange, hormone exchange, nutrients, etc.
2. continuous, fenestrated, sinusoidal; continuous
3. gaps of unjoined junctions found in continuous capillaries

11

1. which capillaries constitute the blood brain barrier?

2. which capillaries are found wherever active capillary absorption or filtrate formation occurs ( small intestines and kidneys)? why?

1. continuous capillaries
2. fenestrated capillaries. because they are fenestered, which means they have pores that allow solutes to pass through

12

1. highly modified, leaky, fenestrated capillaries with large lumens. allow large molecules (proteins, blood) to pass between blood and surrounding tissues.

2. where are sinusoid capillaries found?

1. sinusoid
2. liver, bone marrow, spleen, and adrenal medulla.

13

1. the sinusoids found in the liver have what kind of cells on their endothelium that remove and destroy any contained bacteria?

2.what are capillary beds?

3. what is microcirculation?

1. hepatic macrophages (kupffer cells)
2. interwoven networks of capillaries
3. flow of blood through a capillary bed.

14

1. what are the two types of vessels found in capillary beds?

2. what is a vascular shunt?

3. describe how vascular shunt works

1. vascular shunt, true capillaries
2. a short vessel that directly connects the arteriole and venule at opposite ends of the capillary bed.
3. the TERMINAL ARTERIOLE that feeds the capillary bed leads into a METARTERIOLE which is a vessel structurally intermediate between an arteriole and a capillary, which connects to the THOROUGHFARE CHANNEL (structurally intermediate between a capillary and a venule) which joins to the POSTCAPILLARY VENULE which drains the bed.

15

1. what are true capillaries?

2. explain true capillaries

3. what is a pre capillary sphincter and what is its function?

1. exchange vessels of capillary beds
2. capillaries that branch off the met arteriole and reconnect at the thoroughfare channel.
3. a cuff of smooth muscle fibers that surrounds the root of each true capillary at the met arteriole. it acts as a valve to regular the blood flow into the capillary.

16

1. describe what happens to blood flow coming from the terminal arteriole when the pre capillary sphincters are open and closed.

1. when they are open, blood from the terminal arteriole flows freely into the true capillaries. when the sphincters are closed, they blood is re routed through the vascular shunt

17

1. what is a venule? what is a post capillary venule?

2. what do venues join to form?

3. veins have the same tunics as arteries. which tunic is the heaviest in veins?

1. a tiny vein formed when capillaries unite. the smallest of all venules.
2. veins.
3. tunica externa

18

1. another name for veins is capacitance vessels or blood reservoirs. why?

2. is the blood pressure in veins high or low?

3. what are venous valves?

1. because up to 65% of the bodes blood is found in the veins at any given time.
2. high.
3. valves formed from folds of the tunica intima. they help keep blood in veins flowing towards the heart because pressure in veins is so low.

19

1. where are venous valves most abundant in the body? why? where are they absent from?

2. do veins have large or small lumens?

1. the veins of limbs because the blood has to flow against gravity to return to the heart. they are absent from the veins in thoracic and abdominal cavities

2. large to limit resistance of flow

20

1. what are varicose veins?

2. what are venoid sinuses?

1. veins that have become tortuous and dilate because of incompetent (leaky) valves.

2. highly specialized, flattened veins with extremely thin walls composed only of endothelium.

21

1. what are vascular anastomoses?

2. what are collateral channels? what is the function of them?

3. which organs do not have anastomoses? what happens to them if blood is cut off?

1. areas where vascular channels unite.
2. alternate pathways provided by arterial and vascular anastomoses. to provide area with blood even if one pathway is cut or blocked.
3. retina, kidneys, spleen. they die.

22

CHECK YOUR UNDERSTANDING:
1. name the type of artery that matches each description:
a. major role in dampening the pulsatile pressure of heart contractions
b. vasodilation of constriction determines blood flow to individual capillary beds
c. have the thickest tunica media relative to their lumen size

1. a. elastic arteries
b. dilation or constriction of arterioles
c. muscular arteries

23

CHECK YOUR UNDERSTANDING:
1. what is the function of valves in veins? w hat forms valves?

2. in the systemic circuit, which contains more blood, arteries or veins, or is it the same?

1. valves prevent blood from flowing backwards in veins. they are formed from folds of the tunica intima.
2. in the systemic circuit, veins contain more blood than attires.

24

1. _______ is the volume of blood flowing through a vessel, an organ, or the entire circulation at a given period. (ml/min). equivalent to cardiac output, and under resting conditions, is relatively constant.

2. _____ is the force per unit area exerted on a vessel wall by the contained blood. (mm Hg). systemic arterial blood pressure in the largest arteries near the heart.

1. blood flow

2. blood pressure

25

1. ______ is opposition for flow and is a measure of the amount of friction blood encounters as it passes through the vessels.

2. because the most friction is encountered in the peripheral (systemic) circulation, well away from the heart, the term ______ _____ is used.

1. resistance
2. peripheral resistance

26

1. what are three important sources of resistance?

2. describe blood viscosity. what happens if blood is less viscous?

1. blood viscosity, vessel length, vessel diameter.
2. the internal resistance to flow that exists in all fluids. is related to the thickness or stickiness of a fluid. it has an easier time flowing and getting through areas ( this can be bad sometimes).

27

1. what is the relationship between total blood vessel length and resistance?

2. how does blood vessel diameter play a role in resistance?

1. the longer the vessel, the greater the resistance.

2. the bigger the diameter, the less resistance. the smaller the diameter, the more resistance.

28

1. what is laminar flow? what is turbulent flow? what effect does turbulent flow have on resistance?

2. what is the fourth power of vessel radius?

1. position and speed of fluid remains constant; irregular fluid motion where blood from different laminae mixes. it increases resistance.

2. resistance =1/radius^4. for example, if the radius of a vessel is doubled, the resistance drops to 1/16 of its original value.

29

1. how are flow of blood, blood pressure and resistance all related?

1. blood flow (f) is directly proportional to the difference in blood pressure (DeltaP)between two points in circulation. thus, when BP increases, blood flow speeds up and vice versa. blood flow is inversely proportional to the peripheral resistance (R) in the systemic circulation. if R increases, blood flow decreases.

30

1. what formula can be used to express relationship between flow, pressure and resistance?

1. F= Change in BP/ Resistance

31

CHECK YOUR UNDERSTANDING:
1. list three factors that determine resistance in a vessel. which of these factors is physiologically most important?

2. suppose vasoconstriction decreases the diameter of a vessel to one third its size. what happens to the rate of flow through that vessel? calculate the expected size of change.

1. the three factors that determine resistance are blood viscosity, vessel length, and vessel diameter. vessel diameter is physiologically the most important.

2. the rate of flow will decrease 81 fold from its origin flow. (3x3x3x3=81)

32

1. what is this disease? SNS constricts blood vessels. excessive stimulation of smooth muscles of arterioles of digits. leads to fingers and toes becoming ischemic.

1. reynauds disease.

33

1. where is blood pressure the highest? the lowest? why?

2. blood flows through the vessels along a ______ gradient, always moving from _____ to ______ pressure areas.

1. aorta; right atrium; because the closer you are to the pump, the higher the pressure. the farther away you are, the lower the pressure.

2. pressure; higher; lower.

34

1 .blood pressure is produced by the _______ of muscles of the heart and the ____ _____ of walls of vessels.

1. contractions; elastic recoil.

35

1. what is systolic pressure? diastolic pressure?

2. what is pulse pressure?

1. the pressure speak of the aorta when expelling blood. it is normally 120 mm/Hg. Diastolic pressure is the lowest level of pressure in the aorta, when blood is returning to the heart. it is normally 70-80 mm/Hg.

2. the difference between systolic and diastolic pressure.

36

1. what is mean arterial pressure (MAP)?

2. whats the equation for finding MAP?

1. the pressure that proper the blood to the tissues. it is roughly equal to diastolic pressure plus one third of the pulse pressure.

2. MAP = diastolic pressure + (Pulse pressure/3)

37

1. if systolic pressure is 143, and diastolic pressure is 98, whats the MAP?

1. first, find the difference between systolic and diastolic (pulse pressure). 143-98= 45. now MAP = diastolic + (Pulse pressure/3)

so MAP = 98 + (45/3) -> 98+15= 113

38

if someone had a BP of 110/70, their pulse pressure would be.......

40. (110-70)

39

1. why is low pressure in capillaries desirable?

2. what is the range of capillary blood pressure?

1. increased pressure would rupture them cause thy are fragile. the pressure would force even more solutes and stuff out than the already low pressure does.

2. 20-40 mm/Hg

40

1. venous BP is ____ and changes ______ (a lot/ a little) during the cardiac cycle.

2. a cut vein has ______ blood flow while a lacerated artery ______.

1. steady, little

2. steady; spurts

41

1. what three things aid venous blood return?

2. what is the respiratory pump and how does it help?

1. respiratory pump, muscular pump, and layer of smooth muscle around veins.

2. pressure changes that occur during breathing create the respiratory pump that mods blood up toward the heart. as we inhale, abdominal pressure increases, squeezing local veins and forcing blood up to the heart.

42

1. what is the muscular pump and how does it work

2. how does smooth muscle around veins help venous return?

1. its just skeletal muscles around the deep veins contracting and relaxing, thus 'milking' the blood up towards the heart.

2. they constrict under SNS control, increasing venous return.

43

1. What is cardiac output and what is it the product of?

2. What is SV?

3. what is the function of the parasympathetic cardio inhibitory located in the medulla? the sympathetic cardio acceleratory?

1. its the amount of blood pumped by each ventricle in one minute. it is the product of HR and Stroke volume (SV).

2. the amount of blood pumped out by a ventricle with each beat.

3. decreases HR, contractility; increases HR

44

1. what do short term controls of BP do, and what are they mediated by?

2. what is the function of the vasomotor center? is it neural or chemical?

1. they counteract moment to moment fluctuations in BP by altering peripheral resistance and CO. they are mediated by the nervous system and bloodborne chemicals.

2. it oversees changes in the diameter of blood vessels. it is neural, more precisely, a cluster of neurons in the medulla.

45

1. what is the cardiovascular center made of and what is its function?

2. how are impulses from the vasomotor center transmitted? what parts of the body do they innervate?

3. based on the last question, what effect does this have on the innervated body parts? what is this effect called?

1. made of vasomotor center plus cardiac centers. this center integrates blood pressure control by altering CO and blood vessel diameter.

2. they are transmitted at a steady rate along sympathetic efferents called vasomotor fibers. they innervate smooth muscle of blood vessels, mainly arterioles.

3. arterioles are almost always in a state of moderate constriction called vasomotor tone.

46

1. what three factors modify vasomotor activity (short term control of BP, neural controls)?

CHEMORECEPTOR INITIATED REFLEXES

2. what are baroreceptors and where are they located?

1. baroreceptors, chemocreceptors, higher brain centers.

2. they are pressure sensitive neuroreceptors that are located in the carotid sinuses, aortic arch, and walls of nearly every large artery of neck and thorax.

47

CHEMORECEPTOR INITIATED REFLEXES

1. what happens when baroreceptors are stretched?

1. when arterial BP rises, it stretches baroreceptors. when they're stretched, they send a rapid stream of impulses to vasomotor center. this input inhibits the vasomotor center, resulting in vasodilation of not only arterioles but also veins, and a decline in BP. long story short, baroreceptors are stretched when theres an increase in BP. when stretched, they decrease BP

48

CHEMORECEPTOR INITIATED REFLEXES

1. are baroreceptors effective in long term (chronic) or short term (acute) changes in BP?

2. what events can stimulate chemoreceptors? how do chemoreceptor initiated reflexes happen?

1. short term

2. increased CO2, pH falls, o2 drops sharply, etc. when affected by any of those chemical imbalances, chemoreceptors in the aortic arch and large arteries of the neck transmit impulses to cardioacceleratory center which causes reflex vasoconstriction. the rise in BP that follows speeds the return of blood to heart and lungs.

49

CHEMORECEPTOR INITIATED REFLEXES

1. what are the most prominent chemreceptors?

1. carotid and aortic bodies. they're located close to the baroreceptors in the carotid sinuses and aortic arch.

50

INFLUENCES OF HIGHER BRAIN CENTERS

which areas of the brain influence blood pressure?

medulla and hypothalamus. hypothalamus indirectly.

51

SHORT TERM MECHANISMS: HORMONAL CONTROL

1. which 7 hormones as listed in the book regulate BP?

2. how do dpi and norepi regulate BP?

1. epinephrine; norepinephrine, angiotensin II, atrial natriuretic peptide, antidiuretic hormone, aldosterone, and cortisol.

2. released during periods of stress. both hormones enhance SNS fight or flight response. promote vasoconstriction and increase CO.

52

1. how does angiotensin II affect BP?

2. how does ANP affect BP?

1. stimulates vasoconstriction by increasing peripheral resistance in arterioles.

2. causes bp to decline by stimulating kidneys to excrete more NA+ and H2O from body, causing blood volume to drop, this lowering BP

53

1. how does ADH affect BP?

2. how do aldosterone and cortisol effect bp?

3. can alcohol affect BP? how?

1. stimulates kidneys to conserve H20. causes intense vasoconstriction.

2. both increase blood volume by decreasing water and salt loss. happens in kidney tubule cells.

3. yes. decreases BP by inhibiting ADH

54

LONG TERM MECHANISMS: RENAL REGULATION

1. which mechanisms mediate long term BP controls? how?

2. what is the direct renal mechanism?

1. renal mechanisms. they do it by altering blood volume instead of altering peripheral resistance like short term mechanisms do.

2. a mechanism that alters blood volume depending on blood pressure. increased BP or increased blood volume stimulates the kidneys to filter water faster than normal, meaning more water leaves the body, thus decreasing BP because BV is decreased.

55

1. what is the indirect renal mechanism (also known as renin angiotensin mechanism)? which three ways does angiotensin II increase BP?

1. when arterial blood pressure declines, the kidneys release renin which triggers reactions that produce angiotensin II, which increases BP in three ways. the three ways in which it increases BP is by vasoconstriction, secretion of aldosterone which enhances renal reabsorption of Na+, and by prodding posterior pituitary to release ADH, which helps retain water.

56

MONITORING CIRCULATORY EFFICIENCY:

1. how can efficiency be assessed?

2. what is a pulse? which area is used most often for pulse?

1. taking pulse and BP measurements. referred to as vital signs.

2. the alternating expansion and recoil of arteries during each cardiac cycle. radial

57

1.what happens if you put pressure on a pressure point? give an example

2. what is the first sound read when using a sphygmomanometer?

3. what are the sounds of kororkoff?

1. bleeding will stop. for example, if you severely cut your hand, you can slow or stop bleeding by compressing radial or brachial artery.

2. systolic pressure (first point at which a small amount of blood)

3. the sounds heard after the initial sound (systolic pressure sound)

58

1. when is diastolic pressure heard?

2. what is hypotension? what is the typical range of hypotention?

3. what is orthostatic hypotension? who is usually more prone to it?

1. when the last korotkoff sound is heard

2. low blood pressure. its a systolic pressure of below 100 mmHg.

3. temporary low BP and dizziness when they rise suddenly from a reclining or sitting position. old people

59

1. what is hypertension and what is its normal range? what are the two types of hypertension?

2. what is primary or essential hypertension? what factors can influence hypertension?

1. high blood pressure. can be transient or persistent. transient is normal adaptations during fever, exercise or emotional upset. persistent is common in obese people for a variety of reasons. usually above 140/90 or higher

2. hypertension in which no underlying cause is known. diet, age, heredity, obesity, diabetes, stress, smoking, etc. accounts for 90% of hypertensive people

60

1. what is secondary hypertension?

1. found in 10% of hypertensive people. due to unidentifiable disorders like obstruction of renal arteries, kidney disease, endocrine disorders.

61

CHECK YOUR UNDERSTANDING:
1. describe the baroreceptor initiated reflex changes that occur to maintain BP when you rise from a lying down to a standing position.

2. the kidneys play an important role in maintaining MAP by influencing which variable? explain how renal artery obstruction could lead to secondary hypertension.

1. when you first stand up, mean arterial pressure temporarily decreases and this is sensed by aortic and carotid baroreceptors. medullary cardiac and vasomotor center reflexes increase sympathetic and decrease parasympathetic outflow to the heart. HR and contractility increase, increasing CO and therefor MAP. sympathetic constriction also occurs, increasing MAP.

2. the kidneys help maintain MAP by influencing blood volume. in renal artery obstruction, row BP in kidneys is lower than rest of body. low renal BP triggers borth direct and indirect renal mechanisms to increase pressure by increasingblood volume. this can cause secondary hypertension.

62

BLOOW FLOW THROUGH TISSUES:

1. what is tissue perfusion?

2. what 5 things is tissue perfusion involved in?

1. blood flow through body tissues.

2. delivery of O2 and nutrients and removal of wastes from tissue cells, gas exchange in the lungs, absorption of nutrients in digestive tract, and urine formation by kidneys.

63

1. is blood flow slower in capillaries or arteries/veins? why?

1. slower in capillaries because they have a total cross sectional area that is larger than the large veins/arteries. this allows more time for blood to serve the tissues in that area.

64

1. what is auto regulation? how does it work?

1. the automatic adjustment of blood flow to each tissue in proportion to the tissues requirements at any instant. it works by modifying the diameter of local arterioles feeding its capillaries. Pressure is the same, it just adjusts diameter

65

1. what are metabolic and myogenic controls? are they intrinsic or extrinsic?

2. the net result of this kind of auto regulation is immediate vasodilation of arterioles serving capillary beds of needy tissues, usually with Nitric oxide, a potent vasodilator. this causes temporary increase in blood flow to the area. endothelins are the most potent vasoconstrictors.

3. what is the most potent vasoconstrictors?

1. metabolic= chemical, myogenic = physical. intrinsic

2. metabolic control

3.endothelins are the most potent vasoconstrictors.

66

1. which of these metabolic controls dilate or constrict
- nitric oxide, adenosine, prostaglandins, K+, CO2, decreased pH, decreased O2, endothelins

1. all dilate except endothelins constrict

67

1. which control, metabolic or myogenic, uses vascular smooth muscle to help control blood pressure of certain organs. increased stretch in vessels stimulates _______ while decreased vessel stretch stimulates ______.

1. myogenic; vasoconstriction; vasodilation

68

1. what is angiogenesis? why does it occur?

1. vessels enlarge and become more numerous. this occurs during long term auto regulation of blood flow, usually when tissue demands are not met my short term controls.

69

1. in skeletal muscles, is capillary density and blood flow greater in red (slow oxidative) or white (fast glycolytic) fibers?

2. what is exercise hyperemia?

1. red.

2. increased blood flow to skeletal muscles when they've become active. blood flow is in direct proportion to their greater metabolic activity.


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