Module 4: Cardiovascular System Flashcards Preview

BM1011 Physiological Systems > Module 4: Cardiovascular System > Flashcards

Flashcards in Module 4: Cardiovascular System Deck (54):
1

What are the layers of the heart

pericardian (outer), myocardian (middle), endocardial (inner most)

2

what are the main arteries

Subclavian artery - arms. carotid artery - head, iliac artery - arms

3

whats the stimulus for a heart beat

the conductile network. automatic, always active and created by specialised cells which make an action potential

4

what are the key parts of the conductile system of the heart

sinoatrial node, atrioventricular node, atrioventricular bundle, bundle branches, endocardial conducting network,

5

what happens in the sinoatrial node(SA)

master controller, depolarises faster than others, depolarises atria

6

what happens in the atrioventricular node (AV)

slower than SA node, controlled by SA, controls ventricular rhythm, sends signals to AV bundle

7

what are the main veins in the body

external jugular vein, internal jugular vein, superior and inferior vena cava, common iliac vein, subclavian vein

8

what happens in the atrioventricular bundle

only electrical connection between atria and ventricles. auto rhythm slower than AV node

9

what happens when cell is at threshold

voltage gated calcium channels open, calcium enters cell and depolarisation occurs.

10

define pressure

total force acting over an area.

11

formula for pressure

pressure=force/area

12

how does a sphygmomanometer work

used to constrict blood flow in a vessel. when the flow returns the brachial artery is very contracted resulting in turbulent and noisy flow. this is the systolic pressure. when the flow returns to continuous, laminar and quiet it is the diastolic pressure

13

what is diffusion

the spontaneous movement of particles in a fluid from a high concentration to low concentration

14

what happens as pressure and densities increase in diffusion

diffusion rates decrease because the material is more closely packed

15

what does the amount of diffusion depend on

surface area and thickness of the membrane

16

what is osmosis

the diffusion of water through a semi-permeable membrane

17

what does the semi-permeable membrane allow

diffusion of water but no other substance or particles

18

what are the effects of osmosis

as diffusion continues, the region into which the water diffuses increases in volume creating excess pressure

19

what is an isotonic solution

cells retain their normal size and shape, water moves in and out

20

what is hypertonic solution

cells lose water by osmosis and shrink, more solute (e.g salt)

21

what is hypotonic solution

cells take in too much water and become bloated and burst. lower concentration of solute

22

what ion causes the muscle cells to start contracting

calcium

23

what components of the muscle cell store calcium

endoplasmic reticulum and sacroplasmic reticulum

24

what two protein bundles are in myofibrils

actin (and troponin) and myosin, contractile units.

25

how does an action potential stimulate muscle contraction

action potential travels along membrane to sarcoplasmic reticulum (SP), and releases calcium. calcium binds to troponin on actin and allows actin and myosin to interact

26

what is the contraction-sliding filament theory

actin can now interact with myosin, myosin pulls past actin, using ATP and the muscle shortens

27

what happens when the muscle shortens in the heart

this makes the muscle smaller, which makes the chamber smaller. pressure increase, blood moves out of chamber into area of lower pressure

28

is the pressure high or low when the atrioventricular valves open

low pressure

29

is the pressure high or low when the atrioventricular valves closes

high pressure

30

is the pressure high or low when the arterial valves open

high pressure

31

is the pressure high or low when the arterial valves close

low pressure

32

name the phases in which the atria and ventricles are filling

passive ventricular filling

33

what happens in atrial contraction

the atria are topping up the ventricles

34

what happens in isovolumetric contraction

the ventricles are in systole but not ejecting blood

35

what happens in ventricular ejection

the ventricles are in systole ejecting blood

36

what happens when the AV valves close

isovol contraction, vent ejection

37

what happens when the AV valves open

passive filling, atrial contraction

38

what happens when the Semilunar valves close

all but ventricular ejection

39

what happens when the semilunar valves open

ventricular ejection

40

summarise the contraction sequence to end of atrial contraction

the passive ventricular filling, heart muscle is relaxed. the contraction starts conductile cells in the SA node generate AP, AP travels to atrial node and AV node. Atrial pressure rises above ventricular pressure, blood passes from atria to ventricles. end of atrial contraction. AV valves close, signal goes from AV node to AV bundle. Start of ventricular contraction.

41

summarise the contraction sequence to end of ventricular contraction

Start of ventricular contraction. Signal goes from AV bundle to bundle branches then to endocardial network. Ventricles start to contract= isovolumetic contraction. pressure in ventricles rises above pressure in arteries to force SL valves open - causing ventricular ejection= blood goes into arteries. pressure in ventricles drops below pressure in arteries so Sl valves shut. ventricular muscle relaxes (repolarising). blood stops moving into arteries. this is isovolumetric relaxation. Finally AV valves open and passive ventricular filling begins again.

42

what is cardiac output

total volume pumped out of the heart in 1 minute= stroke volume * heart rate

43

what is the stroke volume

blood pumped out per beat

44

blood pumped out of heart per beat is the sum of...

end diastolic volume - end systolic volume

45

what to do to increase flow`

either pressure has to increase or resistance has to decrease (blood vessels dilate)

46

what is the pulse pressure

difference between systolic and diastolic pressures

47

where is pulse pressure greatest and least and why

greatest in arteries and zero in veins because pressure drops through the cycle

48

what happens n sympathetic stimulation

increases cardiac contraction, increases heart rate, increases cardiac output

49

what happens in parasympathetic stimulation

doesn't affect cardiac contraction, decreases heart rate, decreases cardiac output

50

how is blood pressure regulated

blood flow to organs depends on the body's requirements, there is a homeostatic set point for rest but gets altered depending on activity.

51

what receptors sense the arterial blood pressure

baroreceptors

52

where are the baroreceptors located

aorta and carotid arteries

53

if baroreceptors sense a fall in BP what will happen

the vasomotor centre will stimulate contraction of arteries (vasoconstriction)

54

if baroreceptors detect rise in BP what will happen

the cardio inhibitory centre will cause the heart rate to decrease