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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
how does filtration in a capillary work
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)**
26
how does reabsorption in a capillary work
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**)
27
define hydrostatic pressure
forced exerted by a fluid two types: blood and interstital pressures
28
define blood hydrostatic pressure
force exerted per unit area by blood on vessel wall **high at arterial end which promotes filtration**
29
define interstitial fluid hydrostatic pressure
force of interstitial fluid on outside of blood vessel around 0 usually
30
define colloid osmotic pressure
pull on water due to presence of proteins (colloid) two types: blood and interstitial fluid colloid pressures
31
define blood colloid osmotic pressure (oncotic pressure)
draws fluid into blood due to blood proteins **higher than hydrostatic pressure which promotes reabsorption at venule end**
32
define interstitial fluid colloid osmotic pressure
draws fluid into interstitial fluid relatively small becuase only small amount of proteins in interstitial fluid
33
define net filtration pressure and give equation
difference between net hydrostatic pressure and colloid osmotic pressure NFP = (HPb - Hpif) - (COPb - COPif) **higher at arterial end (filtration) lower at venous end (reabsorption)**
34
what is the role of the lymphatic system in capillary exchange
lymphatic system picks up excess fluid not reabsorbed at venous end and returns it to venous circulation 15%
35
what is local blood flow and what are the four things it is dependent on
some capillaries are filled, some are not degree of tissue vascularity myogenic response local regulatory factors altering blood flow total blood flow
36
define degree of vascularization
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
define angiogenesis
formation of new vessels to increase perfusion ex. in adipose tissue during weight gain
38
define regression
returning to previous state of blood vessels ex. when adipose tissue is lost
39
what is the myogenic response
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
what is autoregulation
how the tissue controls local blood flow based on need if tissue activity increases, stimuli signal inadequate perfusion and act has vasodilators
41
which local substances act as vasodilators to increase blood flow
increased CO2, hydrogen, potassium, lactate decrease in oxygen and nutrient levels bradykinin nitric oxide
42
what are vasodilators
a type of vasoactive chemical that dilates arterioles and relax precapillary sphincters to **increase flow to capillary beds**
43
what is the local, short term regulation for inflammed tissue
tissue, leukocytes, and platelets release vasoactive chemicals like **histamine, bradykinin, and nitric oxide which cause arterioles to dilate**
44
define total blood flow and give equation
amount of blood transported through vasculature per unit of time equal to cardiac output F = changeP / R changeP = systemic blood pressure gradient
45
define blood pressure
force of blood against vessel wall
46
define pulse pressure
pressure in arteries added by heart contraction difference between systolic and diastolic blood pressure ex. 120/80 = 40 PP
47
define mean arterial pressure and give equation
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
what are the three things that affect resistance (peripheral resistance)
blood viscosity (n), vessel length (L), and vessel lumen diameter (r^4)
49
what is the resistance equation
R = 8 x n x L / pie x r^4
50
define peripheral resistance
resistance of blood in blood vessels
51
define viscosity
resistance of fluid to its flow goes up due to more particles in blood goes down due to anemia
52
what are the three areas of the cardiovascular control center in the medulla
cardioinhibitory center, cardioacceleratory center, and vasomotor center
53
what are companion vessels
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
what are some unique functions of ateries
thick tunica media, smaller lumen more elastic and collagen fibers that make them springy and resilient
55
what are some unique features of veins
have a thicker tunica externa, wider lumen less elastic and collagen fibers so they're flat in the absence of blood
56
what are some unique features of capillaries
only have a tunica intima (endothelelial and basement membrane layer) **thin to allow for rapid gas exchange**
57
define vasomotor tone
smooth muscle is arterioles is usually somewhat constricted
58
explain an angioplasty
used to treat atherosclerosis catheter put artery, balloon is inflated, stent is placed
59
what is an aneurysm
part of an arterial wall thins and balloons out can rupture risk increases with age most common around brain
60
what is a precapillary sphincter
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
define vasomotion
cycle of contracting and relaxing precapillary sphincters
62
define net hydrostatic pressure
difference between hydrostatic pressure of blood and interstitial fluid
63
define net colloid osmotic pressure
difference between blood and interstital fluid osmotic pressures
64
define tumor angiogenesis
tumors trigger new growth of blood vessels to feed their cells
65
what are vasoconstrictors
a type of vasoactive chemical that constricts arterioles and cause contration of precapillary sphincters to **decrease flow into capillary beds**
66
what is the local, short term regulation for damaged tissue
**leukotrines and thromboxanes are released which vasoconstrict vessels** to prevent blood loss through damaged vessel
67
define cerebral edema
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
what are some features of capillary blood pressure
no systolic and diastolic - flow and pressure are smooth arterial end: 40 mmHg venous end: 20 mmHg
68
what are the three things venous return depends on
pressure gradient (small) skeletal muscle pump respiratory pump
69
explain the skeletal muscle pump in terms of venous return
muscle contracts, vein is squeezed blood is pushed towards the heart valves in veins prevent backflow
70
explain respiratory pump in terms of venous return
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
explain vericose veins
dilated and tortuous, nonfunctional veins blood pools here usually in lower legs called hemorrhoids if they're in the anorectal region
72
explain circulatory shock
insufficient blood flow to prefuse tissues causes: impaired heart, low venous return
73
define resistance
the friction blood encounters
74
what are the three things that blood pressure is dependent on
cardiac output resistance to blood flow blood volume **(all directly related)**
75
how does the vasomotor center affect blood pressure
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
explain how baroreceptors affect regulation of blood pressure
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
give an example of how chemoreceptors affect blood pressure
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
how does the hypothalamus regulate blood pressure
increases cardiac output and resistance
79
how does the limbic system affect blood pressure
alters blood pressure in response to emotions or memories
80
explain the renin-angiotensin-aldosterone system (RAAS)
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
how does angiotensin 2 raise blood pressure
vasoconstricts stimulates thirst center decreases urine formation stimulates release of aldosterone and antidiuretic hormone
82
how does aldosterone work to maintain blood volume and pressure
released from adrenal cortex due to angiotensin 2 increases absorption of ions and water in kidney to decrease urine output
83
how does antidiuretic hormone help to elevate blood pressure
released from posterior pituitary because of signals from hypothalamus increases water reabsorption in kidney stimulates thirst center vasoconstriction
84
how does atrial natriuretic peptide (ANP) decrease blood pressure
released from atria when they are stretching stimulates vasodilation increases urine output
85
what is hypertension
elevated blood pressure greater than 140/90 can damage vessels
86
what is hypotension
low blood pressure less than 90/60
87
define orthostatic hypotension
drop in blood pressure upon standing suddenly

Human Physiology (19 decks)

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