movement of blood and fluid

Question 1

explain the difference in pressure in the systemic circulation compared to the pulmonary circulation

Answer 1

systemic (left) is a high pressure system due to the pump being much stronger to overcome the pressure and push blood to the extremities and pulmonary circulation is low pressure due to a much weaker pump.

Question 2

define bulk flow

Answer 2

the movement of fluid (blood) by means of pressure difference

Question 3

define diffusion

Answer 3

tendency for solutes to move along a concentration gradient from an area of high concentration of the solute to an area of low concentration of the solutes until the concentrations are equalised.

Question 4

explain how perfusion pressure can be generated and how it can be affected

Answer 4

generated by the pumping actions of the ventricles
the difference between 2 points in a blood vessel

Question 5

describe how variation of transmural hydrostatic and oncotic pressures affect the movement of fluid across the capillary wall

Answer 5

osmotic pressure = high oncotic pressure inside vessel draws water in, fluid moves from an area of low osmotic pressure to an area of high oncotic pressure.
transmural hydrostatic pressure = expels fluid if perforated - pressure exerted by fluid inside of vessel - outside of vessel

Question 6

source of energy for bulk flow

Answer 6

derived from hydrostatic pressure difference

Question 7

what is hydrostatic pressure

Answer 7

the pressure that fluid exerts on its container

Question 8

what is perfusion pressure

Answer 8

the pressure needed for blood to move through blood vessels

Question 9

what is osmotic pressure

Answer 9

the drive for water to move into a solution by osmosis

Question 10

explain how cardiac output is generated and varied in the normal animal

Answer 10

stroke volume x heart rate
only altered by these 2 variables

Question 11

what is preload

Answer 11

the filling pressure of the ventricle

Question 12

what is afterload

Answer 12

resistance overcome to let the blood out

Question 13

what is oedema

Answer 13

leaking fluids

Question 14

how to increase preload

Answer 14

increase in pressure in the atria and veins

Question 15

what does increasing preload also increase

Answer 15

end diastolic ventricular volume

Question 16

why does exercise increase preload

Answer 16

increased action of the respiratory and skeletal muscle pumps compresses veins thereby increases venous return to the heart.

Question 17

what is heterometric autoregulation

Answer 17

increase in stroke volume on one side of the heart leads to increase blood flow through the tissues, an increase venous return and hence preload to the other side of the heart and therefore an increased stroke volume on that side too.

Question 18

what are the phases of the cardiac cycle

Answer 18

isovolumetric contraction
rapid ejection
reduced ejection
isovolumetric relaxation
rapid filling
reduced filling

Question 19

how is arterial pressure generated

Answer 19

pressure of blood within a vessel

Question 20

what is compliance

Answer 20

measure of how readily the ventricular walls stretch during diastolic filling

Question 21

how does diastolic filling time impact EDVV

Answer 21

if too little time, it will prevent the ventricle from filling optimally and hence reduce stroke volume

Question 22

what does the heart rate govern

Answer 22

length of systole and diastole

Question 23

what is atrial systole responsible for

Answer 23

higher percentage of ventricular filling at higher heart rates.

Question 24

what is atrial fibrillation

Answer 24

disease where the atria doesn’t contract properly

Question 25

clinical presentation of atrial fibrillation

Answer 25

exercise intolerance

Question 26

what will a higher afterload increase

Answer 26

end systolic ventricular volume

Question 27

why does a higher afterload increase ESVV

Answer 27

heart has to work harder to maintain the same CO when afterload increases - more pressure must be generated during isovolumetric contraction to overcome arterial pressure, open the semilunar valves and allow blood to exit.

Question 28

what can an increase in end systolic wall stress lead to

Answer 28

myocardial hypertrophy (thickening of the heart muscle)

Question 29

what control vasoconstriction and vasodilation

Answer 29

autonomic nervous system

Question 30

what is the total peripheral resistance

Answer 30

net resistance of the whole circulation

Question 31

what is systolic pressure

Answer 31

during systole, ventricles eject blood into the aorta and pulmonary artery under high pressure, pressure rises to systolic pressure

Question 32

what is diastolic pressure

Answer 32

pressure in the aorta drops as blood flows out into the circulation when entering diastole - this is the lowest point.