Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

RC Test 4 > B4.064 Prework 2: Regional Circulations > Flashcards

B4.064 Prework 2: Regional Circulations Flashcards

1
Q

flow =

A

pressure gradient / resistance in organ

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

when vasoconstrictor nerves are cute and arterioles are maximally vasodilated, how does flow increase in the skeletal muscle

A

over 20 fold

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

when vasoconstrictor nerves are cute and arterioles are maximally vasodilated, how does flow increase in the heart

A

5 fold

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

when vasoconstrictor nerves are cute and arterioles are maximally vasodilated, how does flow increase in the brain and liver

A

2 to 3 fold

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

when vasoconstrictor nerves are cute and arterioles are maximally vasodilated, how does flow increase in the kidneys

A

only 16%

high resting blood flow

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

what is the pressure gradient driving blood flow to systemic organs

A

MAP-RAP

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

does the pressure gradient differ between systemic organs?

A

no, all the same

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

what determines the variance in resting blood flow to organs?

A

differences in vascular resistances between organs

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

what is the primary determinant of organ vascular resistance

A

changes in metabolic needs, primarily changes in tissue O2 levels

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

which organ systems have the most sophisticated mechanisms for local control of blood flow

A

heart and brain

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

O2 uptake in an organ =

A

blood flow * (a-v)O2

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

what is (a-v)O2

A

O2 extraction

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

what determines ability of an organ to extract O2

A

total surface area of perfused capillaries

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

fick equation

A

CO = O2 consumption/ (a-v)O2

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

how much O2 does the heart extract from oxygen?

A

as much as 75% even at rest
systemic organs only 25% at rest
coronary sinus blood content = 5 ml O2

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

what controls O2 uptake in heart

A

all capillaries perfused at rest, SA cannot be increased

increased O2 uptake is dependent on changes in blood flow only

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

what controls O2 uptake in kidneys

A

increase capillary surface area by opening pre capillary sphincters
renal blood flow cant increase very much (max 16%)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

what is autoregulation

A

the ability of an organ to maintain blood flow relatively constant in response to changes in systemic arterial pressure
occurs over arterial pressures from 70-180 mmHg

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

which organs exhibit autoregulation

A

brain and heart

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

how is flow maintained in the heart and brain

A

at low MAP, arteriolar dilation
at high MAP, arteriolar constriction
limited by maximal dilation or maximal constriction of arterioles

21
Q

what happens in systemic arterioles with changes in arterial pressure?

A

at low MAP, arteriolar constriction due to increased SYM firing via baroreflex
at high MAP, arteriolar dilation due to decreased SYM firing via baroreflex

22
Q

what is the myogenic response?

A

change in arteriolar diameter after a sudden increase in intravascular pressure
high pressure > increased stretch of vessel wall > increased frequency of action potentials in vascular SM > Ca2+ channels open > Ca2+ influx > constriction

23
Q

what is the purpose of the myogenic response?

A

increases resistance in an arteriole to minimize an increase in flow while pressure is high

24
Q

what determines interstitial concentration of vasodilator metabolites?

A

rate of formation (proportional to organ metabolic rate)

rate of removal (proportional to organ blood flow)

25
Q

describe the effects of increased metabolism or decreased blood flow in an organ

A

increased concentrations of vasodilator metabolites > local arteriolar dilation > decrease in vascular resistance > improved O2 delivery to organs

26
Q

do changes in vascular resistance in one organ affect TPR?

A

nah gurl

27
Q

what are some examples of vasodilator metabolites

A 
adenosine
K+
lactic acid
H+
CO2
28
Q

how is adenosine formed

A

levels rise when ATP formation is impaired

freely diffuses out of the cell

29
Q

how is K+ increased

A

when frequency of action potentials increases, interstitial concentration of K+ rises

30
Q

how does K+ cause relaxation

A

local hyperkalemia causes hyperpolarization of arterioles > decreases Ca2+ influx to vascular SM > relaxation

31
Q

how are lactic acid, H+, and CO2 increased

A

increase when O2 demand exceeds O2 availability

32
Q

actions of all vasodilator metabolites

A

decrease Ca2+ levels within vascular SM > relaxation > increased arteriolar radius > decreased vascular resistance > increased blood flow

33
Q

what is active hyperemia?

A

as metabolic rate increases, blood flow increases due to local arteriolar dilation caused by increased interstitial levels of vasodilator metabolites
increase in blood flow is proportional to increase in metabolic activity

34
Q

what is reactive hyperemia?

A

blood flow is transiently increased following a brief period of ischemia
degree and duration of increased flow are proportional to duration of occlusion

35
Q

why does arteriolar dilation occur during the period of occlusion in reactive hyperemia?

A
  1. decreased stretch of arterioles (myogenic)

2. accumulation of metabolic vasodilators in interstitial fluid due to a decreased rate of removal w/ no blood flow

36
Q

what length of ischemia does it take to get a reperfusion injury?

A

30 min

37
Q

why does reperfusion injury occur?

A

during ischemia, enzymatic changes occur in the tissue which cause reactive oxidants to be formed when oxygen delivery increases at the time of reperfusion
ROS inactivate NO, increase endothelin 1, and damage endothelial cells

38
Q

what is the result of reperfusion?

A

microvascular inflammation

arteriolar constriction

39
Q

how does PCO2 affect cerebral blood flow (CBF)

A

increased PCO2 = increased CBF

highly sensitive to small changes in PCO2

40
Q

how does PO2 affect CBF

A

CBF changes very little when arterial PO@ changes over normal range 80-120 mmHg

41
Q

at what PO2 is cerebral arteriolar dilation triggered to increase flow

A

below 50 mmHg

begins to drop rapidly after this pt due to shape of oxygen dissociation curve

42
Q

why does CO2 have such an effect on cerebral arterioles?

A

importance of maintaining pH in brain nearly constant as to not depress neuronal activity

43
Q

how is CO2 removed from brain

A

blood flow

is CO2 is low, arteriolar constriction occurs to reduce blood flow and thus rate of removal of CO2

44
Q

determinants of myocardial O2 demand

A

contractility
intraventricular pressure
heart rate
EDV

45
Q

which determinant of myocardial O2 demand is most costly?

A

contractility

100% increase = 200% increase in O2 consumption

46
Q

which determinant of myocardial O2 demand is least costly?

A

EDV

100% increase = <5% increase in O2 consumption

47
Q

why is the splanchnic bed unusual?

A

the portal circulation transports blood from one capillary bed (stomach, spleen, intestine, pancreas) to another capillary bed (liver)

48
Q

discuss the blood supply to the liver

A

dual supply
oxygenated blood through hepatic artery 20%
deoxygenated blood through portal vein 80%

49
Q

what regulated GI blood flow

A

hormones and neural reflexes
increased parasympathetic activity = increased blood flow
increased sympathetic = decreased blood flow (due to constriction)

RC Test 4 (22 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions