haemodynamics

Question 1

what is serum

Answer 1

plasma without clotting factors

Question 2

what are plasma viscosity changes used to measure

Answer 2

inflammation

Question 3

modern way of measuring inflammation

Answer 3

measure number C reactive proteins

Question 4

what is laminar flow

Answer 4

smooth and silent flow

Question 5

what is turbulent flow

Answer 5

noisy and disorganised flow. usually happens when pressure is disrupted e.g in ventricles or when branching occurs.

Question 6

where within the vessel is the velocity the greatest

Answer 6

in the centre of the vessel due to the least resistance present here

Question 7

what is pressure

Answer 7

force per unit area. e.g mmHg

Question 8

what is the flow of the blood and why does pressure decrease.

Answer 8

moves down pressure gradient from high to low. decreases due to the cross-sectional area of the capillaries being the largest. this explains the drop in pressure

Question 9

what is flow

Answer 9

volume transferred per unit of time

Question 10

what is resistance and what is the calculation triangle to go with it

Answer 10

the measure of difficulty of flow (not ease like conductance therefore it is the reciprocal inverse of k) and the equation triangle is change in pressure over flow times resistance

Question 11

what is conductance

Answer 11

it is the ease of flow (K)

Question 12

how do you find TPR (total peripheral resistance)

Answer 12

add together the resistances in each vessel. more vessels means more resistance

Question 13

changes in resistance in the CVS

Answer 13

resistance in the aorta is low because vessel is wide and short and is much higher in the arteries and arterioles. much lower resistance in the pulmonary system as vessels are wide and blood only needs to travel to lungs

Question 14

what is velocity

Answer 14

distance of fluid moved in a given time (cm/s). low velocity in capillaries to allow material exchange die to the sudden increase in cross sectional area

Question 15

calculation for flow

Answer 15

velocity x cross sectional area(pi r squared)

Question 16

explain the pulse pressure change and how to calculate it

Answer 16

on graph pressure increases during systole and then decreases during diastole. pulse pressure is calculated by systolic BP-diastolic BP. it is the force produced every time the heart beats

Question 17

how to calculate mean arteriole pressure

Answer 17

diastolic blood pressure + 1/3(pulse pressure) . it is the mean arterial pressure is an average blood pressure in an individual during a single cardiac cycle

Question 18

reasons/ why pulse pressure increases

Answer 18

exercise due to increased stroke volume or bradycardia due to more diastolic run off meaning increased PP or vasodilation which decreases resistance increasing pulse pressure

Question 19

reasons/ why pulse pressure

Answer 19

haemorrhage causes lower pressure due to lower volume of blood

Question 20

how to calculate cardiac output

Answer 20

Stroke volume x heart rate

Question 21

how to calculate mean arterial pressure from the cardiac output

Answer 21

cardiac output x total peripheral pressure.

Question 22

why doesnt the mean arteriole pressure not increase during exercise

Answer 22

because it is very heavily regulated even though the systolic blood pressure increases.

Question 23

how to measure blood pressure indirectly

Answer 23

increase pressure of brachial artery using cuff to prevent blood dole. when it is released the blood moves through in a turbulent style producing korotokoff sounds. when this starts it is the systolic BP and when these stop and flow goes back to laminar is the diastolic BP

Question 24

how to measure blood pressure directly

Answer 24

canulation. however this is an invasive and dangerous technique

Question 25

what makes a blood pressure measurement accurate

Answer 25

sitting relaxed with both feet on floor and reassuring several times with arm rested on table at heart level. this is because gravity affect BP. if you lift arm up then there is lower blood pressure and below heart it is higher. this is why you get dizzy when you stand up quickly because the blood pools in the venous system.

Question 26

what does vessel diameter affect

Answer 26

it has huge effect on flow and resistance due to the 4th power relationship