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Cardio Physiology Flashcards

(71 cards)

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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
What is the 5th Korotkoff sound?
No sound! Represents diastolic pressure
26
What is the formula for calculating MAP?
[2 x diastolic + systolic]/3
27
What are the main resistance vessels?
Arterioles
28
Which receptors regulate blood pressure short-term?
Baroreceptors
29
Which CN do the carotid baroreceptors fire through?
CN IX
30
Which CN do the aortic baroreceptors fire through?
CN X
31
What is the function of renin in the RAAS?
Released from kidneys to stimulate conversion of angiotensinogen to angiotensin I
32
What is the function of ACE?
Converts angiotensin I to angiotensin II
33
What is the function of angiotensin II?
Stimulates release of aldosterone Causes systemic vasoconstriction
34
What is the function of aldosterone in the RAAS?
Acts on kidneys to increase Na+ and water retention
35
Where is renin released from?
Juxtapulmonary apparatus in the kidney
36
Renal artery hypertension causes renin to be released. True/False?
False Hypotension would cause its release
37
Where is ANP stored?
Atrial myocytes
38
What does ANP do?
Causes excretion of Na+ and water in the kidneys Vasodilates Decreases renin release [counteracts RAAS]
39
When is ADH release stimulation?
Reduced extracellular fluid Increased extracellular fluid osmolarity (solute)
40
What does ADH do?
Causes reabsorption of water, i.e. concentrates urine, to increase plasma volume Vasoconstriction (small degree)
41
Resistance to blood flow is directly proportional to what?
Thickness and length of blood vessel
42
There is no parasympathetic innervation of vascular smooth muscle. True/False?
False There is in the penis and clitoris
43
Adrenaline acting on alpha receptors causes what?
Vasoconstriction
44
Adrenaline acting on beta receptors causes what?
Vasodilation
45
Alpha receptors are predominant in skeletal and cardiac muscle arterioles. True/False?
False Beta receptors are predominant here
46
Where are alpha receptors predominately found?
Skin, gut and kidney arterioles
47
What is the effect of angiotensin II on vascular smooth muscle?
Vasoconstriction
48
What is the effect of decrease in local PO2 in pulmonary circulation arterial smooth muscle?
Vasoconstriction
49
Name some humoral agents that are potent vasodilators
Histamine Bradykinin Prostaglandins Nitric oxide
50
Name some humoral agents that are potent vasoconstrictors
Serotonin Thromboxane A2 Leukotrienes Endothelin
51
Describe myogenic response to stretch
If MAP falls, resistance vessels in brain and kidneys dilate to increase flow (i.e. not in line with normal baroreceptor reflex)
52
Sympathetic stimulation increases during exercise. What does this do to the HR, SV and CO?
Increases all of them
53
Systolic and diastolic murmurs coincide with the carotid pulse. True/False?
False Only systolic murmurs coincide with carotid pulse
54
How does tension pneumothorax lead to obstructive shock?
Increased intrathoracic pressure leads to decreased venous return leads to decreased stroke volume leads to decreased CO + BP = low perfusion and oxygenation
55
Compensatory mechanisms exist to deal with blood volume loss until greater than 40% is lost. True/False?
False Mechanisms only compensate until greater than 30% volume is lost
56
What are the first branches/arteries that come off the aorta?
Right + left coronary arteries
57
How is the oxygen supply to the heart increased, if not by increasing oxygen extraction?
Increase coronary blood flow
58
Describe the mechanism by which sympathetic stimulation (indirectly) causes coronary vasodilation
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
What effect do K+, H+ and CO2 have on coronary arteries?
Vasodilation
60
When does peak coronary flow occur?
Diastole
61
Which arteries supply the brain?
Internal carotid arteries Vertebral arteries
62
Which arteries make up the Circle of Willis?
Internal carotids + basilar artery (formed by both vertebral arteries joining)
63
The baroreceptor reflex affects the brain. True/False?
False
64
When does autoregulation of cerebral blood flow fail?
When MAP is less than 60 or greater than 160 mm Hg
65
Decreased O2 does what to pulmonary arterioles? Why?
Vasoconstriction (opposite to systemic circulation) Redirects blood to alveoli to get more oxygen
66
What are the forces favouring filtration?
Capillary hydrostatic pressure (Pc) Interstitial fluid osmotic pressure (πi)
67
What are the forces favouring absorption?
Capillary osmotic pressure (πc) Interstitial fluid hydrostatic pressure (Pi)
68
What is the main contributor to capillary hydrostatic pressure (Pc)?
Blood flow Tends to force blood out of capillary
69
What is the main contibutor to capillary osmotic pressure (πc)?
Presence of plasma proteins Tends to force blood into capillary
70
How is net filtration pressure calculated using forces described previously?
(Pc + πi) - (πc - Pi)
71
Pulmonary capillary hydrostatic pressure is high compared to systemic hydrostatic pressure. True/False?
False

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