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last min > Cardio Physiology > Flashcards

Cardio Physiology Flashcards

1
Q

What causes the rising phase of the action potential (depolarisation) in SA node cells?

A

Opening of Ca++ channels, resulting in Ca++ influx

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2
Q

What causes the falling phase of the action potential (repolarisation) in SA node cells?

A

Opening of K+ channels, resulting in K+ efflux

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3
Q

Which junctions allow cell-to-cell spread of excitation?

A

Gap junctions

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4
Q

Sympathetic stimulation causes increased heart rate. True/False?

A

True

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5
Q

The vagus nerve supplies only the SA node. True/False?

A

False Supplies both SA and AV nodes

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6
Q

Which neurotransmitter acts on which receptor in parasympathetic control of the heart?

A

ACh on M2 receptors

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7
Q

Name a competitive inhibitor of ACh that is used in bradycardia

A

Atropine

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8
Q

What is meant by negative chronotropic effect?

A

Decreased contraction of the heart due to less frequent action potentials

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9
Q

Which areas of the heart does the sympathetic system supply?

A

SA node AV node Myocardium

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10
Q

Which neurotransmitter acts on which receptor in sympathetic control of the heart?

A

Noradrenaline on B1 receptors

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11
Q

Sympathetic stimulation does what to the slope of the action potential?

A

Increases it

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12
Q

Give the name of protein channels that which form electrical communication between neighbouring myocytes

A

Gap junctions

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13
Q

What do desmosomes do in the heart?

A

Provide mechanical adhesion between adjacent cardiac cells Ensure tension is developed

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14
Q

Actin filaments are thick and appear light. True/False?

A

False They appear light but are thin

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15
Q

What is required to generate the force by which sliding of filaments can occur?

A

ATP Calcium

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16
Q

Where does the calcium that activates contractile machinery come from (where is it stored)?

A

Sarcoplasmic reticulum

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17
Q

Describe the Frank-Starling Law of the Heart

A

The greater the EDV (as a result of more venous return), the greater the stroke volume will be during systole

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18
Q

What is meant by positive inotropic effect?

A

Force of contraction increases (due to sympathetic stimulation)

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19
Q

Parasympathetic system has a negative chronotropic and inotropic effect. True/False?

A

False No inotropic effect

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20
Q

What does sympathetic stimulation do to the Frank-Starling curve?

A

Shifts it to the left (increased SV)

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21
Q

What happens in Isovolumetric Ventricular Relaxation?

A

Ventricle is a closed box again (since aortic/pulmonary valves have closed) Pressure falls until Pventricles less than Patria, where AV valves open and whole cycle restarts

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22
Q

What is the 1st Korotkoff sound?

A

Peak systolic pressure

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23
Q

What are the 2nd-3rd Korotkoff sounds?

A

Intermittent sounds of turbulent flow

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24
Q

What is the 4th Korotkoff sound?

A

Last muffled sound heard before sound stops

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25
Q

What is the 5th Korotkoff sound?

A

No sound! Represents diastolic pressure

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26
Q

What is the formula for calculating MAP?

A

[2 x diastolic + systolic]/3

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27
Q

What are the main resistance vessels?

A

Arterioles

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28
Q

Which receptors regulate blood pressure short-term?

A

Baroreceptors

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29
Q

Which CN do the carotid baroreceptors fire through?

A

CN IX

30
Q

Which CN do the aortic baroreceptors fire through?

A

CN X

31
Q

What is the function of renin in the RAAS?

A

Released from kidneys to stimulate conversion of angiotensinogen to angiotensin I

32
Q

What is the function of ACE?

A

Converts angiotensin I to angiotensin II

33
Q

What is the function of angiotensin II?

A

Stimulates release of aldosterone Causes systemic vasoconstriction

34
Q

What is the function of aldosterone in the RAAS?

A

Acts on kidneys to increase Na+ and water retention

35
Q

Where is renin released from?

A

Juxtapulmonary apparatus in the kidney

36
Q

Renal artery hypertension causes renin to be released. True/False?

A

False Hypotension would cause its release

37
Q

Where is ANP stored?

A

Atrial myocytes

38
Q

What does ANP do?

A

Causes excretion of Na+ and water in the kidneys Vasodilates Decreases renin release [counteracts RAAS]

39
Q

When is ADH release stimulation?

A

Reduced extracellular fluid Increased extracellular fluid osmolarity (solute)

40
Q

What does ADH do?

A

Causes reabsorption of water, i.e. concentrates urine, to increase plasma volume Vasoconstriction (small degree)

41
Q

Resistance to blood flow is directly proportional to what?

A

Thickness and length of blood vessel

42
Q

There is no parasympathetic innervation of vascular smooth muscle. True/False?

A

False There is in the penis and clitoris

43
Q

Adrenaline acting on alpha receptors causes what?

A

Vasoconstriction

44
Q

Adrenaline acting on beta receptors causes what?

A

Vasodilation

45
Q

Alpha receptors are predominant in skeletal and cardiac muscle arterioles. True/False?

A

False Beta receptors are predominant here

46
Q

Where are alpha receptors predominately found?

A

Skin, gut and kidney arterioles

47
Q

What is the effect of angiotensin II on vascular smooth muscle?

A

Vasoconstriction

48
Q

What is the effect of decrease in local PO2 in pulmonary circulation arterial smooth muscle?

A

Vasoconstriction

49
Q

Name some humoral agents that are potent vasodilators

A

Histamine Bradykinin Prostaglandins Nitric oxide

50
Q

Name some humoral agents that are potent vasoconstrictors

A

Serotonin Thromboxane A2 Leukotrienes Endothelin

51
Q

Describe myogenic response to stretch

A

If MAP falls, resistance vessels in brain and kidneys dilate to increase flow (i.e. not in line with normal baroreceptor reflex)

52
Q

Sympathetic stimulation increases during exercise. What does this do to the HR, SV and CO?

A

Increases all of them

53
Q

Systolic and diastolic murmurs coincide with the carotid pulse. True/False?

A

False Only systolic murmurs coincide with carotid pulse

54
Q

How does tension pneumothorax lead to obstructive shock?

A

Increased intrathoracic pressure leads to decreased venous return leads to decreased stroke volume leads to decreased CO + BP = low perfusion and oxygenation

55
Q

Compensatory mechanisms exist to deal with blood volume loss until greater than 40% is lost. True/False?

A

False Mechanisms only compensate until greater than 30% volume is lost

56
Q

What are the first branches/arteries that come off the aorta?

A

Right + left coronary arteries

57
Q

How is the oxygen supply to the heart increased, if not by increasing oxygen extraction?

A

Increase coronary blood flow

58
Q

Describe the mechanism by which sympathetic stimulation (indirectly) causes coronary vasodilation

A

Sympathetic tone causes increased HR + SV and hence CO (which itself dilates coronary arteries); This increases cardiac work and metabolism, consuming O2 (leading to decreased PO2, increased ADP) and releasing metabolites, all of which cause vasodilation; Adrenaline also acts on B2 to cause vasodilation

59
Q

What effect do K+, H+ and CO2 have on coronary arteries?

A

Vasodilation

60
Q

When does peak coronary flow occur?

A

Diastole

61
Q

Which arteries supply the brain?

A

Internal carotid arteries Vertebral arteries

62
Q

Which arteries make up the Circle of Willis?

A

Internal carotids + basilar artery (formed by both vertebral arteries joining)

63
Q

The baroreceptor reflex affects the brain. True/False?

A

False

64
Q

When does autoregulation of cerebral blood flow fail?

A

When MAP is less than 60 or greater than 160 mm Hg

65
Q

Decreased O2 does what to pulmonary arterioles? Why?

A

Vasoconstriction (opposite to systemic circulation) Redirects blood to alveoli to get more oxygen

66
Q

What are the forces favouring filtration?

A

Capillary hydrostatic pressure (Pc) Interstitial fluid osmotic pressure (πi)

67
Q

What are the forces favouring absorption?

A

Capillary osmotic pressure (πc) Interstitial fluid hydrostatic pressure (Pi)

68
Q

What is the main contributor to capillary hydrostatic pressure (Pc)?

A

Blood flow Tends to force blood out of capillary

69
Q

What is the main contibutor to capillary osmotic pressure (πc)?

A

Presence of plasma proteins Tends to force blood into capillary

70
Q

How is net filtration pressure calculated using forces described previously?

A

(Pc + πi) - (πc - Pi)

71
Q

Pulmonary capillary hydrostatic pressure is high compared to systemic hydrostatic pressure. True/False?

A

False

last min (15 decks)

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