Lecture 22 Cardiovascular system 3 vessels, flow & pressure

Question 1

Arteries

Answer 1

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

Question 2

Arterioles

Answer 2

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)

Question 3

Capillaries

Answer 3

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

Question 4

Veins

Answer 4

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

Question 5

Overall circuit is arranged in

Answer 5

series

pressure drops continuously from arteries to capillaries to veins

Question 6

Blood supplies to different organs are arranged in

Answer 6

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

Question 7

Blood flow and blood pressure

Answer 7

Flow = deltaP/R

Cardiac output, blood pressure, resistance

Question 8

Cardiac output

Answer 8

CO= total blood flow 
CO= SV X HR

Question 9

Blood pressure

Answer 9

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

Question 10

Mean arterial pressure (MAP)

Answer 10

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

Question 11

Resistance

Answer 11

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

Question 12

Vessel radius

Answer 12

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

Question 13

Total Peripheral Resistance

Answer 13

TPR

is the resistance of ENTIRE systemic circuit

Question 14

Vasodilation is _ while vasoconstriction is _

Answer 14

locally controlled

sympathetic alpha adrenergic

Question 15

Arterial BP

Answer 15

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

normal MAP is about 90 mm Hg

Question 16

Factors that affect arterial blood pressure

Answer 16

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

Question 17

Blood volume is determined by

Answer 17

fluid intake vs fluid loss

Question 18

Homeostatic control of blood pressure

Answer 18

Cardiovasular control center

arterial baroreceptors

Question 19

Cardiovasular control center

Answer 19

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

Question 20

Arterial baroreceptors

Answer 20

stretch receptors located in aorta and carotid arteries

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

Question 21

sympathetic nervous system effects

Answer 21

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

Question 22

Negative feedback control examples

Answer 22

hemorrhage

exercise

Question 23

Negative feedback for arterial blood pressure

Answer 23

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