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Human Physiology > The Cardiovascular System 4 > Flashcards

The Cardiovascular System 4 Flashcards

1
Q

what are the three layers of a blood vessel

A

tunica intima, tunica media, and tunica externa

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2
Q

what is the tunica intima

A

innermost layer of blood vessel
endothelium made of simple squamous epithelium
also has a layer of areolar connective tissue

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3
Q

what is the tunica media

A

middle layer of circular smooth muscle and elastic fibers
performs vasoconstriction and vasodilation

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4
Q

what is the tunica externa

A

outermost layer of blood vessel
made of areolar connective tissue with elastic and collagen fibers
anchors vessel to other structures

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5
Q

what are vasa vasorum

A

smaller arteries coming off of a blood vessels
required to supply very large vessels

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6
Q

what are the three types of arteries

A

elastic (conducting)
muscular (distributing)
arterioles

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7
Q

what are elastic (conducting arteries)

A

largest type of artery
arteries that exit from heart chambers
made of little smooth muscle fibers but lots of elastic fibers stretch and recoil to propel blood

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8
Q

what are muscular (distributing arteries)

A

medium arteries that have more smooth muscle
vasodilation and vasoconstriction
mostly named arteries

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9
Q

what are arterioles

A

smallest arteries
smallest ones have thin endothelium and single smooth muscle layer
regulates systemic blood pressure and flow

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10
Q

what is atherosclerosis

A

thickening of tunica intima due to the buildup up atheroma; narrowing of lumen
caused by: trauma, high blood pressure, hypercholesterolemia (too much blood cholesterol)

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11
Q

define rouleau

A

erythrocytes move in a single file line in capillaries

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12
Q

what are the three types of capillaries

A

continuous
fenestrated
sinusoid

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13
Q

explain the components of a capillary bed

A

arteriole on one end and postcapillary venule the other
metarteriole: branch off of arteriole; proximal portion has smooth muscle
thoroughfare channel: branch off venule
true capillaries: branches off metarteriole and thoroughfare channel; where gas exchange happens

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14
Q

define perfusion

A

amount of blood entering capillaries per unit time per gram of tissue

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15
Q

where is most of the blood found in vessels

A

veins
they act as blood reservoirs (70%)

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16
Q

what is an arterial or venous anastomosis

A

two or more arteries or veins converge to supply same region

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17
Q

what is an arteriovenous anastomosis

A

shunt that transports blood from artery directly to vein
found in areas like fingers

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18
Q

what is a portal system

A

two capillary beds separated by a portal vein

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19
Q

what is a cross-sectional area

A

area of cross section of one vessel

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20
Q

what is total cross-sectional area

A

sum of diameters of all vessels of a certain type

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21
Q

why is it good that blood flow is slow in capillaries

A

so there is time for exchange between blood and tissue fluid

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22
Q

how does diffusion in capillaries work

A

substances leave or enter blood depending on concentration gradient
oxygen, hormones, and nutrients move from blood into interstitial fluid
wastes diffuse from tissues to blood
small particles will go through endothelial cells
large particles will go through gaps in sinusoids

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23
Q

how does vesicular transport in capillaries work

A

substances are taken in by pinocytosis and transported across cell
substances are secreted by exocytosis
used for substances that are too big to move through membranes

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24
Q

how does bulk flow in capillaries work

A

fluids flow down pressure gradient
includes filtration and reabsorption

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25
Q

how does filtration in a capillary work

A

occurs at arterial end
fluid moves down its pressure gradient: out of blood and into interstitial fluid
blood hydrostatic pressure is greater than net osmotic pressure (net pressure out)

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26
Q

how does reabsorption in a capillary work

A

occurs at venous end
fluid moves down its pressure gradient: from interstitial fluid back into blood
net osmotic pressure is greater than blood hydrostatic pressure (net pressure in)

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27
Q

define hydrostatic pressure

A

forced exerted by a fluid
two types: blood and interstital pressures

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28
Q

define blood hydrostatic pressure

A

force exerted per unit area by blood on vessel wall
high at arterial end which promotes filtration

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29
Q

define interstitial fluid hydrostatic pressure

A

force of interstitial fluid on outside of blood vessel
around 0 usually

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30
Q

define colloid osmotic pressure

A

pull on water due to presence of proteins (colloid)
two types: blood and interstitial fluid colloid pressures

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31
Q

define blood colloid osmotic pressure (oncotic pressure)

A

draws fluid into blood due to blood proteins
higher than hydrostatic pressure which promotes reabsorption at venule end

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32
Q

define interstitial fluid colloid osmotic pressure

A

draws fluid into interstitial fluid
relatively small becuase only small amount of proteins in interstitial fluid

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33
Q

define net filtration pressure and give equation

A

difference between net hydrostatic pressure and colloid osmotic pressure
NFP = (HPb - Hpif) - (COPb - COPif)
higher at arterial end (filtration)
lower at venous end (reabsorption)

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34
Q

what is the role of the lymphatic system in capillary exchange

A

lymphatic system picks up excess fluid not reabsorbed at venous end and returns it to venous circulation
15%

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35
Q

what is local blood flow and what are the four things it is dependent on

A

some capillaries are filled, some are not
degree of tissue vascularity
myogenic response
local regulatory factors altering blood flow
total blood flow

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36
Q

define degree of vascularization

A

extent of vessels in a tissue
tissues that are more metabollically active have more vessels to get them more nutrients and vise versa
ex. brain tissue has more vasculature than tendons

37
Q

define angiogenesis

A

formation of new vessels to increase perfusion
ex. in adipose tissue during weight gain

38
Q

define regression

A

returning to previous state of blood vessels
ex. when adipose tissue is lost

39
Q

what is the myogenic response

A

smooth muscle of a vessel and its ability keep local blood flow constant by dilating and constricting as need be
if blood pressure rises, vessels will stretch (vasoconstriction to return it to its normal size)
if blood pressure decreases, vessels will stretch less (relaxation to return to normal size)

40
Q

what is autoregulation

A

how the tissue controls local blood flow based on need
if tissue activity increases, stimuli signal inadequate perfusion and act has vasodilators

41
Q

which local substances act as vasodilators to increase blood flow

A

increased CO2, hydrogen, potassium, lactate
decrease in oxygen and nutrient levels
bradykinin
nitric oxide

42
Q

what are vasodilators

A

a type of vasoactive chemical that dilates arterioles and relax precapillary sphincters to increase flow to capillary beds

43
Q

what is the local, short term regulation for inflammed tissue

A

tissue, leukocytes, and platelets release vasoactive chemicals like histamine, bradykinin, and nitric oxide which cause arterioles to dilate

44
Q

define total blood flow and give equation

A

amount of blood transported through vasculature per unit of time
equal to cardiac output
F = changeP / R
changeP = systemic blood pressure gradient

45
Q

define blood pressure

A

force of blood against vessel wall

46
Q

define pulse pressure

A

pressure in arteries added by heart contraction
difference between systolic and diastolic blood pressure
ex. 120/80 = 40 PP

47
Q

define mean arterial pressure and give equation

A

average arterial blood pressure across entire cardiac cycle
MAP = diastolic pressure + 1/3rd PP
provides index of perfusion
higher in arteries, lower in veins

48
Q

what are the three things that affect resistance (peripheral resistance)

A

blood viscosity (n), vessel length (L), and vessel lumen diameter (r^4)

49
Q

what is the resistance equation

A

R = 8 x n x L / pie x r^4

50
Q

define peripheral resistance

A

resistance of blood in blood vessels

51
Q

define viscosity

A

resistance of fluid to its flow
goes up due to more particles in blood
goes down due to anemia

52
Q

what are the three areas of the cardiovascular control center in the medulla

A

cardioinhibitory center, cardioacceleratory center, and vasomotor center

53
Q

what are companion vessels

A

vessels that lie next to each other and supply the same region
ex. an atery and vein supplying the same area will run together but will flow in opposite directions typically

54
Q

what are some unique functions of ateries

A

thick tunica media, smaller lumen
more elastic and collagen fibers that make them springy and resilient

55
Q

what are some unique features of veins

A

have a thicker tunica externa, wider lumen
less elastic and collagen fibers so they’re flat in the absence of blood

56
Q

what are some unique features of capillaries

A

only have a tunica intima (endothelelial and basement membrane layer)
thin to allow for rapid gas exchange

57
Q

define vasomotor tone

A

smooth muscle is arterioles is usually somewhat constricted

58
Q

explain an angioplasty

A

used to treat atherosclerosis
catheter put artery, balloon is inflated, stent is placed

59
Q

what is an aneurysm

A

part of an arterial wall thins and balloons out
can rupture
risk increases with age
most common around brain

60
Q

what is a precapillary sphincter

A

rings of smooth muscle at base of true capillaries coming off metarteriole
relaxation: allows blood to flow through for gas exchange
constriction: sends blood through metarteriole to thoroughfare channel

61
Q

define vasomotion

A

cycle of contracting and relaxing precapillary sphincters

62
Q

define net hydrostatic pressure

A

difference between hydrostatic pressure of blood and interstitial fluid

63
Q

define net colloid osmotic pressure

A

difference between blood and interstital fluid osmotic pressures

64
Q

define tumor angiogenesis

A

tumors trigger new growth of blood vessels to feed their cells

65
Q

what are vasoconstrictors

A

a type of vasoactive chemical that constricts arterioles and cause contration of precapillary sphincters to decrease flow into capillary beds

66
Q

what is the local, short term regulation for damaged tissue

A

leukotrines and thromboxanes are released which vasoconstrict vessels to prevent blood loss through damaged vessel

67
Q

define cerebral edema

A

excess interstitial fluid in the brain
occurs if mean arterial pressure is greater than 160 mmHg
high pressure increases filtration (more fluid is leave the blood for the tissues; leads to excess fluid)

67
Q

what are some features of capillary blood pressure

A

no systolic and diastolic - flow and pressure are smooth
arterial end: 40 mmHg
venous end: 20 mmHg

68
Q

what are the three things venous return depends on

A

pressure gradient (small)
skeletal muscle pump
respiratory pump

69
Q

explain the skeletal muscle pump in terms of venous return

A

muscle contracts, vein is squeezed
blood is pushed towards the heart
valves in veins prevent backflow

70
Q

explain respiratory pump in terms of venous return

A

brings blood back towards the heart
inspiration: diaphragm contrats, abdominal pressure increases and drives blood towards thoracic cavity
expiration: diaphragm relaxes, abdominal pressure decreases, blood is driven towards heart

71
Q

explain vericose veins

A

dilated and tortuous, nonfunctional veins
blood pools here
usually in lower legs
called hemorrhoids if they’re in the anorectal region

72
Q

explain circulatory shock

A

insufficient blood flow to prefuse tissues
causes: impaired heart, low venous return

73
Q

define resistance

A

the friction blood encounters

74
Q

what are the three things that blood pressure is dependent on

A

cardiac output
resistance to blood flow
blood volume
(all directly related)

75
Q

how does the vasomotor center affect blood pressure

A

sympathetic: increase in blood pressure
increased peripheral resistance: blood vessels constrict
larger circulating blood volume: blood moves from venous reservoirs
redistribution of blood flow: more blood to heart and skeletal muscle

opposite for parasympathetic

76
Q

explain how baroreceptors affect regulation of blood pressure

A

located in aortic arch and carotid sinus
arch: communicates to cv center through vagus nerve
carotid sinus: communicates to cv center through glossopharyngeal nerve (more sensitive to changes than arch)
blood pressure decrease: baroreceptors fires less, signals sympathetic pathways in cv center to increase cardiac output and blood pressure
blood pressure increase: baroreceptor fires more (more stretch), more signals along parasympathetic pathways , less cardiac output and blood pressure

77
Q

give an example of how chemoreceptors affect blood pressure

A

if too much CO2 is detected, they will signal to the cv center, cv center will increase blood pressure to get the blood to the lungs to breath it off

78
Q

how does the hypothalamus regulate blood pressure

A

increases cardiac output and resistance

79
Q

how does the limbic system affect blood pressure

A

alters blood pressure in response to emotions or memories

80
Q

explain the renin-angiotensin-aldosterone system (RAAS)

A

low blood pressure detected:
angiotensinogen made by the liver is released into blood
renin made by kidneys released into blood
renin converts angiotensinogen into angiotensin 1
angiotensin-converting enzyme (ACE) converts angiotensin 1 to angiotensin 2
angiotensin 2 raises blood pressure

81
Q

how does angiotensin 2 raise blood pressure

A

vasoconstricts
stimulates thirst center
decreases urine formation
stimulates release of aldosterone and antidiuretic hormone

82
Q

how does aldosterone work to maintain blood volume and pressure

A

released from adrenal cortex due to angiotensin 2
increases absorption of ions and water in kidney to decrease urine output

83
Q

how does antidiuretic hormone help to elevate blood pressure

A

released from posterior pituitary because of signals from hypothalamus
increases water reabsorption in kidney
stimulates thirst center
vasoconstriction

84
Q

how does atrial natriuretic peptide (ANP) decrease blood pressure

A

released from atria when they are stretching
stimulates vasodilation
increases urine output

85
Q

what is hypertension

A

elevated blood pressure
greater than 140/90
can damage vessels

86
Q

what is hypotension

A

low blood pressure
less than 90/60

87
Q

define orthostatic hypotension

A

drop in blood pressure upon standing suddenly

Human Physiology (19 decks)

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