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physiology > cardio vascular > Flashcards

cardio vascular Flashcards

1
Q

what is blood flow determined by?

A

pressure and resistance.
p/r

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2
Q

what side of the heart has oxygenated blood?

A

left side

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3
Q

what does the myocardium do?

A

contracts to generate force and pump blood.

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4
Q

what side of the heart wall is thicker?

A

the left, because it needs to pump blood around the body.

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5
Q

what do heart valves do?

A

keep the blood flowing one way.

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6
Q

where does the semilunar sit?

A

between the ventricles and arteries. pulmonary valve (right) and aortic valve (left)

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7
Q

what are the two atrioventricular valves called?

A

Bicuspid/mitral valve (left) * Tricuspid (right).

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8
Q

what is the SA node

A

the pacemaker of region of the heart, produces action potentials to generate heart beat. on right artium.

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9
Q

what does the P-wave represent.

A

Action potential spreading through atria and depolarising of atria.

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10
Q

what does the QRS represent?

A

action potential spreading through the AV bundle then to the ventricles. causing contraction of ventricles, having ventricular depolarisation.

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11
Q

what does the T-wave represent?

A

the repolarisation of the ventricles.

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12
Q

how is the ECG measured?

A

electrocardiogram

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13
Q

what is diastole?

A

relaxation of the ventricles, 2/3 of the cardiac cycle. ventricles relax and fill with blood.

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14
Q

what is systole?

A

1/3 cardiac cycle. Ventricle contract and pump blood out of the heart.

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15
Q

what does the start of the cardiac cycle look like?

A

all four chambers of the heart relaxed. SA node generates action potential. AV valves are open with blood flowing into the ventricle as the pressure is higher in the atria. Whereas the pressure in the arteries is higher then the ventrcile causing the semilunar valves to be shut.

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16
Q

step 2

A

isovolumetric contraction - systole.
- action potential spreads down the AV bundle and ventricles = ventricle depolarise causing them to contract. increasing the pressure in the ventricles becoming higher then the atria. AV valve closes. no volume change = isovolumetric.

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17
Q

step 3

A

ventricular ejection - systole.
ventricles depolarise; continue to contract.
Semilunar valves open allowing blood to pass through to the arteries.

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18
Q

stroke volume

A

the amount of blood being pushed out of the ventricle is known as the stroke volume.
In healthy adult SV is around 70mL at rest. 50-60% pumped out.

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19
Q

step 4

A

Isovolumetric relaxation – diastole
Ventricles repolarise = T-wave.
Ventricles relax.
Pressure in the ventricles decreases as blood is ejected.
- Ventricle pressure drops lower than the arteries and the semilunar valves close.
Pressure drops in ventricles with no volume change = isovolumetric.

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20
Q

step 5

A

Ventricular filling 1 – diastole.
All chambers are repolarised/relaxed.
Pressure in the ventricles drop back below pressure in atria.
- AV valves open. Semilunar valves closed.
Ventricles start to fill with blood, passive filling of ventricle.

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21
Q

what is heart beat sound 1

A

The first sound “lub” happens with closing of the AV valves as the ventricles contract.
- This happens following the QRS complex on the ECG.

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22
Q

heart beat sound 2

A

The second heart sound “dub” happens with closing of the semilunar valves as the ventricles relax.
- This happens following the T-wave on the ECG.

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23
Q

cardiac output

A

Amount of blood we pump in one minute.
Heart rate x stroke volume.
In an average adult CO is around 5L/min at rest.

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24
Q

what is flow determined by?

A

F= P/R. P = pressure. R = resistance.

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25
Q

where is pressure higher venous system or arteries?

A

arteries. blood has further to travel and has to pass through smaller blood vessles.

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26
Q

how is pressure gradient determined?

A

p1-p2.

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27
Q

what is resistance proportional to?

A

fluid viscosity (n) how thick blood is
blood vessel length (l)

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28
Q

what is resistance inversely proportional to?

A

blood vessel radius (r) (big difference with the power of 4)

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29
Q

different blood flow in vessels.

A

laminar flow = smooth
turbulent flow = distructued, plaque developing on vessel walls.
Turbulence increases resistance and reduces flow.

30
Q

arteries anatomy

A

carry blood away from heart. carry both deoxygenated and oxygenated blood. have thick walls and large diameters. combination of elastic tissue and smooth muscle. low resistance.

31
Q

what do elastic arteries do?

A

allow for change in blood flow. reduce fluctuation. to provide steady blood flow to the body. this happens by the aorta getting a large volume of blood and being able to stretch like a balloon to always have blood to pump out. highly compliant.

32
Q

muscular arteries.

A

contain smooth muscle. distribute blood to skeletal muscle and internal organs through arterioles.

33
Q

arteriole anatomy

A

contain smooth and endothelim. change size and diameter to maintain blood flow.

34
Q

how does pulse pressure chnage around the body?

A

decrease as you get further away from the heart. pressure gradient. peaks because of the pumping of the heart.

35
Q

how to get pulse pressure (PP)

A

SP - DP.

36
Q

mean arterial blood pressure

A

(MABP) = DP + 1/3 x PP. Why 1/3? Since more of the cardiac cycle is spent more in diastole. Mean pressure is closer ot DP.

37
Q

what is the main way to alter flow and resistance?

A

change the radius of the vessel.

38
Q

vasodilation

A

blood vessels become wider.

39
Q

Physiological vasodilators: (4)

A

Adrenaline acting on beta (β) receptors in vessels * Increased nitric oxide (NO) release by endothelium * Atrial natriuretic peptide (ANP) * Local increases in CO2 levels.

40
Q

Vasoconstriction

A

blood vessels become narrower.

41
Q

Physiological vasoconstrictors: (3)

A

Adrenaline acting on alpha (α) receptors in vessels * Endothelin-1 (ET-1) release by endothelium * Vasopressin (ADH) and angiotensin II * Local increases in O2 levels

42
Q

what is filtration and what is it determined by?

A

movement of fluids. Determined by the balance of
- Capillary hydrostatic pressure (CHP)
- Blood colloid osmotic pressure (BCOP)

43
Q

what is CHP?

A

blood pressure within the capillaries. the driving force to push fluid out of the blood stream.

44
Q

what is BCOP?

A

osmotic pressure within the blood. force pulls fluid into the bloodstream to even it out.

45
Q

what is net filtration pressure (NFP)

A

The balance between BCOP and CHP. starts at the arteriole and ends at the venules.

46
Q

what happens when CHP>BCOP,

A

filtration occurs = positive NFP. Out of the blood.

47
Q

what happens when CHP<BCOP

A

reabsorption occurs = negative NFP. Into the blood.

48
Q

When CHP = BCOP

A

no net movement occurs. Things do move in and out but they balance out.

49
Q

diffusion in the blood is determined by…

A

concentration gradient - from high to low concentration.
solubility and size - Lipid-soluble molecules can diffuse through the cell membrane (co2 or o2).
Small non-lipid soluble molecules can pass through pores (e.g.) ions. Still down concentration gradient.
Large non-lipid soluble molecules must be transported in vesicles (e.g. proteins).

50
Q

venules

A

collect blood from the capillary beds. smallest venous vessels.

51
Q

veins.

A

carry blood back to the heart. highly distensible - can change their volume easily. can release or store blood in response to pressure change.

52
Q

how much blood does the average adult have?

A

5L.

53
Q

how is our blood broken up?

A

55% plasma. 45% solids.

54
Q

red blood cells.

A

the largest component of formed elements. major function is to carry oxygen-bound to haemoglobin. average lifespan is 120 days.

55
Q

white blood cells.

A

account for 0.1% of all blood. critical in the bodys immune.

56
Q

five types of white blood cells.

A

neutrophils 50-70% engulf pathogens and debris.
lymphocytes 20-40% - defend against specific pathogens or toxins.
monocytes 2-8% - become macrophages.
eosinophils 2-4% - engulf foreign material.
basophils <1% - release chemicals in damaged tissue.

57
Q

platelets

A

<0.1% of formed elements in blood.
Clump together and stick to damaged blood vessel walls.
Release chemicals to trigger blot clotting
Key component of haemostats.

58
Q

where does the innervation for both the parasympathetic and sympathetic pathways originate?

A

the medulla oblongata of the brainstem. The sympathetic pathway originates in the cardio accelerator centre.
Parasympathetic pathways originate in the cardioinhibitory centre.

59
Q

how does the sympathetic nerve system effect heart rate?

A

increases it. By releasing noradrenaline which binds to B receptors in the heart. which then reduces the resting repolarisation of the cells. cells reach the threshold faster which makes more action potentials. increasing the heat rate.

60
Q

how does the sympathetic nerve system effect the stroke volume?

A

b receptors activation increases the amount of force produced during contraction. atria and ventricles contract harder. stroke volume increases.

61
Q

parasympathetic nerve activity - Release acetylcholine which causes potassium channels to open. how does this effect the SA Node

A
  • K channel activation hyperpolarisation the nodal cells
  • Cells reach threshold slower = fewer action potentials
  • Heart decreased.
62
Q

parasympathetic nerve activity - Release acetylcholine which causes potassium channels to open. how does this effect the Atrial myocardium.

A
  • Atria contracts less
  • Less filling of the ventricles
  • Stroke volume decreases.
63
Q

how does the Sympathetic vasomotor nerves innervate arterioles?

A
  • Release noradrenaline onto the smooth muscle cells of the blood vessel.
  • Activate a-adrenergic receptors.
    = Vasoconstriction
64
Q

what is postural hypotension

A

when your blood pressure drops when you go from lying down to sitting up, or from sitting to standing. less blood to fill the ventricles = lower stroke volume and reduced cardiac output.

65
Q

Responding to exercise.

A

To meet increased metabolic demand during exercise, cardiac output must increase.
Heart rate x stroke volume.

66
Q

what is our heart rate at rest

A

60-100bpm

67
Q

how does our heart rate react to exercise?

A

increases to 3x, beacuse increase in sympathetic and decrease in para to SA node.

68
Q

stroke volume at rest

A

around 70mL

69
Q

what happens to stroke volume during exercise.

A

increases 2x. because: increase sympathetic to ventricle and increase venous return more filling.

70
Q

resting cardiac output

A

around 5L/min

71
Q

what happens to cardiac output during exercise

A

increases by 6x.

physiology (11 decks)

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