Lecture 22 Cardiovascular system 3 vessels, flow & pressure Flashcards Preview

Physiology > Lecture 22 Cardiovascular system 3 vessels, flow & pressure > Flashcards

Flashcards in Lecture 22 Cardiovascular system 3 vessels, flow & pressure Deck (23)
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1
Q

Arteries

A
conducting vessels 
high pressure 
thick walls
elastic arteries 
"pressure reservoirs" 
muscular arteries 
smooth muscle, endothelium, elastic tissue, fibrous tissue
2
Q

Arterioles

A

resistance vessels
small diameter
smooth muscle in walls
vasoconstriction/vasodilation regulates blood flow to capillaries
endothelium, smooth muscle
pressure decreases steeply because of high resistance to blood flow (biggest P drop)

3
Q

Capillaries

A
exchange vessels 
microscopic 
very thin walls 
fluid filters out/in
permeability: continuous< fenestrated <sinusoid 
Endothelium
4
Q

Veins

A

low pressure conducting vessels
thin walls
high compliance (“volume reservoir”)
valves ensure one-way flow back to heart
endothelium, smooth muscle, elastic tissue, fibrous tissue
Pressure lowest in venules and veins

5
Q

Overall circuit is arranged in

A

series

pressure drops continuously from arteries to capillaries to veins

6
Q

Blood supplies to different organs are arranged in

A

parallel
high pressure, oxygenated blood delivered to all organs
independent regulation of blood flow to different organs

7
Q

Blood flow and blood pressure

A

Flow = deltaP/R

Cardiac output, blood pressure, resistance

8
Q

Cardiac output

A
CO= total blood flow 
CO= SV X HR
9
Q

Blood pressure

A
difference (deltaP) between arteries and veins is the driving force for blood flow 
MAP
P high in arteries 
P low in veins and venules 
P intermediate in Pulmonary arteries 
biggest P drop in arterioles
10
Q

Mean arterial pressure (MAP)

A

total deltaP of the systemic circuit
MAP = diastolic P + 1/3 (systolic P - diastolic P)
s=120 d=75 answer=90

11
Q

Resistance

A

factors that oppose or reduce blood flow:
blood viscosity (high RBCs -> high viscosity)
length (L) of blood vessel - longer = more resistance
radius (r) of blood vessel: R a 1/r4

12
Q

Vessel radius

A

diameter
is the major factor that determines resistance
small change in vessel radius results in large change in resistance and flow
if diameter is 2 times higher then resistance is down 16x and flow is increased 16x

13
Q

Total Peripheral Resistance

A

TPR

is the resistance of ENTIRE systemic circuit

14
Q

Vasodilation is _ while vasoconstriction is _

A

locally controlled

sympathetic alpha adrenergic

15
Q

Arterial BP

A

MAP= CO x TPR (relationship of factors that determine BP)

normal MAP is about 90 mm Hg

16
Q

Factors that affect arterial blood pressure

A

hear rate: increase HR -> increase CO -> increase BP
stroke volume: increase SV -> increase CO ->increase BP
blood volume: increase BV -> increase SV -> increase CO ->increase BP
vascular resistance: increase TPR -> increase BP

17
Q

Blood volume is determined by

A

fluid intake vs fluid loss

18
Q

Homeostatic control of blood pressure

A

Cardiovasular control center

arterial baroreceptors

19
Q

Cardiovasular control center

A

located in the medulla oblongata
increases inputs from sensory receptors and higher brain centers
activates autonomic NS to regulate BP

20
Q

Arterial baroreceptors

A

stretch receptors located in aorta and carotid arteries

low BP ->decreased stretch of artery walls -> frequency of APs -> increase in sympathetic NS activation

21
Q

sympathetic nervous system effects

A
high HR (B1)  -> increase CO
high contractility (B1) -> increase CO
increased vasoconstriction (a1) -> increase TPR
 ALL INCREASE BP
22
Q

Negative feedback control examples

A

hemorrhage

exercise

23
Q

Negative feedback for arterial blood pressure

A

variable - arterial blood pressure
sensor - baroreceptors (stretch receptors)& carotid and aortic arteries
input - 9th & 10th cranial nerves
integrating center - medulla oblongata
effectors - heart (CO) and vascular smooth muscle (TPR)
response