the cardiovascular system

Question 1

functions of cv system

Answer 1

-transportation of oxygen, nutrients and metabolites
-removal of metabolic waste products
-distribution of hormones
-involvement in controlling body tempurature

Question 2

how is the systemic system connected?

Answer 2

in parallel
there is a choice of which parts of the body receives more or less blood volume

Question 3

how is the pulmonary system connected

Answer 3

in series
entire blood volume has to pass through pulmonary system every time blood circulates the body

Question 4

what is Darcy’s law?

Answer 4

regulates where in the body blood goes
flow= pressure difference/ resistance

Question 5

how to work out velocity of blood

Answer 5

velocity= flow rate/ cross-sectional area
the narrower the vessel the faster the flow

Question 6

role of pericardium

Answer 6

protects heart by providing lubrication during constant movement
helps anchor heart against diaphragm and spine

Question 7

which node conducts the heart

Answer 7

sino atrial node initiates action potential that spreads throughout the heart

Question 8

describe systole

Answer 8

-occurs as soon as ventricles have stopped filling
-bicuspid and tricuspid valves close so no movement of blood
-as ventricular contraction continues, pulmonary and aortic valves open so blood flows out

Question 9

describe diastole

Answer 9

-isovolumetric ventricular relaxation
-all 4 valves closed
-when pressure in ventricles drop, bicuspid and tricuspid valves open so ventricles start to fill due to gravity
-atria contract

Question 10

what is driving pressure

Answer 10

flow created by the pressure difference between two points
flow requires a pressure difference and for resistance to be overcome

Question 11

what is poiseuille’s law

Answer 11

resistance is inversely proportionate to radius of a blood vessel
doubling vessel radius reduces resistance by a factor of 16

Question 12

what is the intrinsic rate of the SA node

Answer 12

100bpm without the influence of the ANS

Question 13

how does SA node initiate action potential

Answer 13

due to unstable membrane potential that is continuously drifting towards the threshold
action potential is generated when threshold is reached

Question 14

what does rate of firing depend on

Answer 14

-initial value of the membrane potential
-the gradient of the slope drifting towards the threshold

Question 15

what effect does sympathetic stimulation have on rate of firing

Answer 15

leads to an increase in gradient the drift sue to increased permeability of Na+ current

Question 16

what effect does parasympathetic stimulation have on rate of firing

Answer 16

leads to decrease in slope gradient

Question 17

how does conduction travel through the heart

Answer 17

-stimulation of atria by SA node spreads from fibre to fibre through gap junctions
-stimulus spreads through atria almost simultaneously
-ventricular stimulation spreads initially via a network of conduits beginning at AV node and terminates via purkinje fibres
-AV node and bundle of His are only pathway for electrical stimulus to travel from atria to ventricles
-signal delayed at AV node to allow atria to empty
-ventricle contract upwards, depolarising muscle fibres via purkinje fibres

Question 18

when does the tricuspid valve open

Answer 18

when right atrium pressure is greater than right ventricle pressure

Question 19

when does bicuspid valve open

Answer 19

when left atrium pressure is greater than left ventricle pressure

Question 20

when does pulmonary valve open

Answer 20

when right ventricle pressure is greater than pulmonary artery pressure

Question 21

when does aortic valve open

Answer 21

when left ventricle pressure is greater than aortic pressure

Question 22

what is cardiac output

Answer 22

volume of blood pumped out by the heart every minute

Question 23

how is heart rate controlled

Answer 23

-regulated by ANS
-under sympathetic control, heart rate slows down as membranes become depolarised
-under parasympathetic control heart rate increases due as membranes become hyperpolarised

Question 24

sympathetic nervous system innervation

Answer 24

thoracic spinal nerves (by noradrenaline)

Question 25

parasympathetic nervous system innervation

Answer 25

vagus nerve (by acetylcholine)

Question 26

how can sympathetic nervous system control heart rate

Answer 26

-slow heart rate by depolarising membranes
-shorten av node delay
-shorten myoctye action potential
-increase speed of relaxation

Question 27

how is stroke volume regulated

Answer 27

-by force of heart contraction
-by atrial pressure against which the ventricles eject blood

Question 28

what is starlings law of the heart

Answer 28

the more the heart stretches, the stronger it will contract

Question 29

which hormones increase contractility of the heart

Answer 29

adrenaline and noradrenaline

Question 30

what is blood pressure

Answer 30

the driving force for flow in the cv system
must be maintained at all times

Question 31

how does blood pressure work in arteries

Answer 31

pulsatile, reflects oscillations from heart

Question 32

how does blood pressure work in veins

Answer 32

continuous, reflecting loss of forward energy due to friction

Question 33

what factors affect blood pressure

Answer 33

-gender. women have lower blood pressure than men
-age. arteries become stuffer due to loss of elasticity
-location in body. pressure higher in foot and lower in head due to hydrostatic pressure

Question 34

how does dynamic exercise affect blood pressure

Answer 34

mean blood pressure remains relatively steady

Question 35

how does static exercise affect blood pressure

Answer 35

mean blood pressure rises dramatically

Question 36

how can mean arterial blood pressure be calculated?

Answer 36

cardiac output x total peripheral distance