pressure and flow in arteries

Question 1

what is the main method used for measurement of arterial pressure?

Answer 1

auscultation of Korotkoff sounds using sphygmomanometer and stethoscope

Question 2

what sound is heart when cuff pressure is just less than systolic pressue?

Answer 2

tapping

Question 3

what sound is heard when cuff pressure is between diastolic and systolic pressure?

Answer 3

a thumping sound

Question 4

what sound is heard when cuff pressure is the same as diastolic pressure?

Answer 4

a muffled sound, often inaudible though

Question 5

what is the function of elastic arteries?

Answer 5

act as a pressure reservoir to dampen down pressure variations. (prevents pressure getting too high in systole and too low in diastole

Question 6

what factors affect the pressure wave for blood in arteries?

Answer 6

-stroke volume
-velocity of stroke volume
-elasticity of arteries
total peripheral resisitance

Question 7

what happens to arterial pressure with age?

Answer 7

it increases as blood vessels lose elasticity

Question 8

what happens to pressure in blood vessels moving from the arteries all the way through to the veins?

Answer 8

it decreases

Question 9

between which two types of vessels is the decrease in pressure the greatest? why is this?

Answer 9

arteries and arterioles.
moving into these resistance vessels the area increases dramatically as the diameter of the vessels decreases, this increase in area means that pressure decreases dramatically too.

Question 10

what is the systemic filling pressure?

Answer 10

the pressure of blood exiting the circulatory system

Question 11

what is the pressure drop through the arteries?

Answer 11

~ 95 to 90 mmHg

Question 12

what is the pressure drop through the arterioles?

Answer 12

~ 90 to 40 mmHg

Question 13

what is the pressure drop through the veins ?

Answer 13

~ 20 to 5 mmHg

Question 14

what is the main determinant of blood velocity?

Answer 14

total cross-sectional area, higher it is the lower the velocity is

Question 15

why do external influences affect flow in veins?

Answer 15

they are distensible and collapsible

Question 16

does gravity affect the driving pressure from arteries to veins?

Answer 16

no

Question 17

what does gravity cause in the veins of the legs?

Answer 17

distension

Question 18

how does the distension in the veins on the legs affect the mean arterial pressure?

Answer 18

pooling of blood means that there is a greater volume of blood in them, this blood is drawn from the centre of the body. This causes EDV to decrease and so preload decreases, this causes a decrease in stroke volume and so a decrease in cardiac output, this decreases mean arterial pressure

Question 19

what is orthostatic (postural) hypotension?

Answer 19

a sudden drop in blood pressure from standing up suddenly, it is caused by the effect of gravity on veins

Question 20

what can jugular collapse be used to estimate?

Answer 20

central venous pressure`

Question 21

explain the concept of jugular venous collapse.

Answer 21

moving up the jugular vein the the pressure decreases. At the point where the venous pressure becomes less than the outside pressure the vein collapses. this usually happens within the thorax, but when there is high CVP the collapse occurs further up the neck.

Question 22

what are the external factors that affect the pressure and flow in veins?

Answer 22

gravity
skeletal muscle pump
respiratory pump
systemic filling pressure

Question 23

how does the skeletal muscle pump work?

Answer 23

skeletal muscle contracting in a rhythmic fashion helps pump blood back from the peripheries. as valves prevent blood moving away from the heart. static contraction of muscle does not act as a pump

Question 24

describe how the respiratory pump changes the flow in veins?

Answer 24

the descent of the diaphragm on inspiration causes a decrease in pressure in the thoracic region of the body. on expiration the opposite is true. so by moving between inspiration and expiration the flow in the veins increases

Question 25

how does venomotor tone affect pressure and flow in veins?

Answer 25

contraction of smooth muscle round the veins helps to mobilise capacitance and increase EDV

Question 26

how does systemic filling pressure affect blood flow in veins?

Answer 26

an increase in the pressure created by ventricles is transmitted through the vascular tree