Circulation of blood

Question 1

function of cardiovascular system

Answer 1

to maintain an ADATPTABLE supply of blood to tissues to supply nutrients and signalling molecules
and to remove waste products

Question 2

how are nutrients exchanged in the cardiovascular system

Answer 2

via capillary exchange
pressure differentals are generated across tissues to allow exchange

Question 3

what is haemodynamics

Answer 3

the physics of blood flow

Question 4

what are the 2 major factors blood flow is dependant on?

Answer 4

pressure diff between point A and B (driving force)

resistance to flow (also controls rate)

Question 5

equation for blood flow

Answer 5

change in pressure/resistance
basically darcy’s law

Question 6

what are 3 things that affect resistance

Answer 6

viscosity
vessel length
vessel radius (most important out of these 3 factors)

Question 7

why does vessel radius cause sm of a difference in flow

Answer 7

flow proportional to r^4
so small diff in radius hugely affects the flow

e.g. is the radius in a vessel is 2x bigger than the other
then resistance = 16x less
so flow = 16x greater

Question 8

how does vessel length increase resistance

Answer 8

more vessel coming into contact w/ blood
more of it to get through
so if vessel length = 1
flow = 1

if vessel length = 2
flow = 1/2

Question 9

how does blood viscosity affect resistance

Answer 9

more viscous = more resistant = less flow

e.g. if haematocrit or protein content is quite high, then more viscous blood

Question 10

what does the hagen-poiseuille formula tell us?

Answer 10

flow is directly proporional to r^4
and that resistance is affected by blood viscosity, vessel length and vessel radius

dw dont need to know formula

Question 11

ehich vessel is rate of blood flow highest in?

Answer 11

elastic arteries

Question 12

if lumen is biggest in vena cava, then why is blood flow highest in the aorta?

Answer 12

flow not only dependent on radius, even tho flow DP to r^4

but, pressure vry important

Question 13

if pressure in venae cava is the lowest, the how is the rate of blood flow high?

Answer 13

vry little rsistance, vry large lumen

Question 14

which part of the heart has the ability to generate most pressure (how much in mmHg) and why is this important

Answer 14

left ventricle (100-140mmHg)

needs to pump to rest of body

Question 15

how is blood pressure maintained in the systemic circ

Answer 15

elastic arteries can act as ‘pressure resovoirs’

Question 16

how can elastic arteries act as pressure reservoirs

Answer 16

when heart pumps, arteries fill with blood
when heart relaxes and blood moves through, theres elastic recoil that helps push the blood further

Question 17

to see how pressure differs in each part of the CV system see onenote for diagram

Answer 17

:)

Question 18

which artery is BP measured at

Answer 18

brachial artery

Question 19

what is the top and bottom numbers in a BP reading representing

Answer 19

top = systolic pressure = max pressure
bottom = diastolic pressure = min pressure

Question 20

what is considered ideal blood pressure

Answer 20

systolic= 90-120
diastolic = 60-80

Question 21

what is considered ideal blood pressure

Answer 21

systolic= 90-120 (120-140 GP might advise excersice etc)
diastolic = 60-80

Question 22

what is mean arterial pressure

Answer 22

mean pressure over course of one contraction
not jsut average of the two numbers cuz the heart is in diastole for longer, so value skewed towards diastolic BP

diastolic pressure + 1/3 of pulse pressure

see onenote for BP values diagram

Question 23

what is pulse pressure

Answer 23

diff between systolic and diastolic pressure

Question 24

what type of cells are at the sinoatrial node, and how do they work?

Answer 24

pacemaker cells
spontaneously depolarise w/o need for oustside nerve input

Question 25

what does the 100msec delay through the AV node allow for?

Answer 25

atrial contraction

Question 26

pathway of the electrical impulse

Answer 26

sinoatrial node
via internodal pathways
atrioventricular node
AV bundle
down the septum
through bundle branches
into ventricular myocardium through Purkinje fibres

see onenote

Question 27

what does an ECG detect

Answer 27

electrical activity across the heart

an amalgamation of all the action potentials occuring in the heart

Question 28

what does the P wave represent

Answer 28

atrial depolarisation (systole)
memb potential goes up, +ve deflection

Question 29

what does the QRS complex represent

Answer 29

ventricular depolarisation (systole)

(during this time, repolarisation of atria also happenening, but cant see it as is masked by ventricular events)

Question 30

what does T wave show

Answer 30

ventricular repolarisation - (diastole)

see onenote for all diagrams in comparison to heart activity

Question 31

what are 3 mechanical events taht happen during the cardiac cycle

Answer 31

contraction inc chamber pressure

blood flows from high pressure to low pressure

valves open and close due to pressure gradients

Question 32

what is isovolumic contraction

Answer 32

when it contracts but volume stays the same

happens in ventricle during ventricular systole, until the pressure surpasses the aortic pressure, blood will stay in ventricles

Question 33

what causes the dicrotic notch

Answer 33

elastic recoil when the aortic valve shuts which causes pressrue to rise slightly

Question 34

pressure and volume relations, see all notes in onenote

Answer 34

:)