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KIN 407 > 1 > Flashcards

1 Flashcards

1
Q

Name the four coronary arteries

A

1) Right Coronary Artery
2) Left Main Coronary Artery
3) Left Anterior Descending Coronary Artery
4) Left Circumflex Coronary Artery

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2
Q

How does the heart get its blood supply?

What phase of the cardiac cycle does the heart get blood?

A

Cardiomyocytes supplied by Coronary arteries during diastole
Coronary ostia is located behind aortic valve leaflets so cannot flow while blocked during systole. Micro-vasculature is also compressed during systole which further reduces blood flow

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3
Q

Explain the automaticity of the SA node

A

Slow inward flow of Na “pacemaker current” results in spontaneous depolarization

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4
Q

What is the function of the intercalated discs

A

Allow ions to pass through cells, allowing for rapid transmission of AP

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5
Q

What are the main differences between cardiac myocyte and skeletal muscle

A

Cardiac has a longer duration: allowing for prolonged Ca entry and muscle contraction
Cardiac has a longer refractory period: allowing sufficient time for ventricles to empty
Cardiac has low resistant gap junctions - intercalated discs

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6
Q

What specific isoforms of regulatory proteins are used to diagnose a myocardial infarction

A

Troponin I and Troponin T are unique for cardiac muscle vs skeletal muscle
TnC is the same for cardiac and skeletal

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7
Q

Resting values of BP, HR, SV, Q, and VO2

A 
BP: 120/80 mmHg
HR: 60-80 bpm
SV: 70mL/beat
Q (cardiac output): 5L/min
VO2: 250mL/min
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8
Q

Chronotropy

A

Rate of contraction

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9
Q

Ionotropy

A

Force of contraction

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10
Q

Dromotropy

A

Velocity of contraction

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11
Q

How does the autonomic nervous system decrease heart rate

A

Through the PNS:
acetylcholine acts on muscarinic receptors (M2) at the SA and AV nodes to decreasing chronotropy (rate of contraction)
Intrinsic Control (100bpm) + PNS = 60-80bpm resting HR

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12
Q

How does the autonomic nervous system increase heart rate

A

Through the SNS:
norepinephrine (NE) acts on beta receptors (mainly B2) to increase chronotropy
As well stimulates the adrenal cortex to release the catecholamine epinephrine (E) which also acts on beta 1 and beta 2 receptors to increase chronotropy
During Exercise: PNS withdrawal + SNS Activation = 110-220bpm

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13
Q

How does SNS and catecholamines affect ionotropy and chronotropy

A

SNS –> Epinephrine
Catecholamines –> Norepinephrine
Act on beta 2 receptors on SA and AV node to increase chronotropy (rate of contraction) - increasing HR
Act on beta 1 receptors on cardiomyocytes to increase inotropy (force of contraction) - increasing SV by decreasing ESV

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14
Q

At submaximal exercise, which has a bigger impact: increasing HR or increasing SV?

A

At sub-maximal exercise, largely influenced by increasing in SV since there is a more rapid increase initially and then plateaus

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15
Q

At maximal exercise, which has a larger impact on blood flow: increasing HR or increasing SV?

A

At maximal exercise, increase in blood flow is most influenced by an increase in HR as there is consistent linear increase

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16
Q

What intrinsic factors increase venous return

A

increasing blood volume
venoconstriction (mostly done by SNS (NE) and catecholamines (E))
skeletal muscle pump
respiratory pump
This increases the length-tension relationship described by Frank-Sterling mechanism which increases SV

17
Q

What’s the passive force in Frank-Sterling mechanism?

A

Blood filling the ventricles causes a stretch in the sarcomeres, causing an increase in tension - increasing the force

18
Q

What’s the active force in the Frank-Sterling mechanism?

A

Refers to the ability of the crossbridges to produce force. At the optimal sarcomere length (Lo) there is the maximal amount of thick and thin filament overlap producing the largest amount of force

19
Q

How is ejection fraction calculated and what does it represent?

A

(SV/EDV) x 100
Represents the amount of blood ejected from the left ventricle as a percentage of the total blood in the l. ventricle prior to contraction

20
Q

What is a typical EF of a healthy individual?

A

50-70%

21
Q

What is a typical EF of a person with systolic dysfunction?

A

35-40%

22
Q

What is the typical EF of a person with diastolic dysfunction?

A

50-70% - able to eject the available blood in the ventricle, but the amount of blood available is diminished (% the same, volume is lowered)

23
Q

How does the automatic nervous system control blood pressure

A

PNS: release of Ach, acts on muscarinic M2 receptors to cause vasodilation
SNS: release of NE, acts on alpha 1 and alpha 2 receptors to cause vasoconstriction

24
Q

How do hormones control blood pressure

A

Epinephrine: acts on alpha receptors to cause vasoconstriction, acts on beta 2 receptors to cause local vasodilation seen in active skeletal muscle
Angiotensin II: vasoconstrictor
Vasopressin: antidiuretic that increases blood volume through reabsorption at kidneys. Acts on alpha receptors to cause vasoconstriction
Atrial Natriuretic Factor: released in atria during stretch caused by the increase in blood volume. Acts to decrease blood volume by inhibiting renin. Causes vasodilation

25
Q

What is the function of Renin

A

Convert Angtiotensinogen to Angiotensin I

26
Q

What is the role of ACE

A

ACE (Angiotensin Converting Enzyme) converts Angiotensin I to Angiotensin II

27
Q

How does the kidney control blood pressure

A

Renin converts Angiotensinogen into Angiotensin I. ACE converts Angiotensin I into Angiotensin II. Angiotensin II acts on the blood vessels to cause vasoconstriction. Angiotensin II also acts on the adrenal cortex to release aldosterone and the brain to release vasopressin. Both cause sodium and water retention to increase blood volume

28
Q

What does the release of endothelium NO cause

A

local vasodilation

29
Q

What does the release of endothelium endothelin cause

A

local vasoconstriction

30
Q

What does VO2 describe

A

The energy expended by the body in meeting the demands to perform work

31
Q

What occurs in phase 4 of the pacemaker cell AP

A

Phase 4 = the upward slope representing the spontaneous depolarization of the cell
This is called the pacemaker current and is caused by the influx of Na from channels that were opened during the repolarizing phase when the lowest voltage was reached

32
Q

What occurs in phase 0 of the pacemaker cell AP

A

Upstroke of the AP is less rapid and reaches a lower amplitude than cardiac muscle cells
Ca influx is responsible for the polarization in the cell

33
Q

How do you know there’s a Right Bundle Branch Block

A

Wide QRS = >0.12s

RSR’ in V1

34
Q

How do you know there’s a Left Bundle Branch Block

A

Wide QRS = >0.12s

RR’ in V6 (bunny ears)

35
Q

What areas would pathological Q waves be in an inferior MI?

A

Lead II, Lead III, aVF

36
Q

What areas would pathological Q waves be in a lateral MI?

A

Lead I, aVL, V5, V6

37
Q

What areas would pathological Q waves be in an anterior MI

A

V1, V2, V3, V4

KIN 407 (2 decks)

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