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Cardio Vascular Year 1 > Review of Physiology from Foundations > Flashcards

Review of Physiology from Foundations Flashcards

1
Q

Where does excitation of the heart originates from?

A

Pacemaker cells in the Sino-Atrial Node

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2
Q

Where is the SA Node located

A

Upper right Atrium close to where the superior vena cava enters

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3
Q

What is a heart called that is controlled by the SA node

A

Sinus Rhythm

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4
Q

Phase 0 of cardiac action potential

A

fast Na+ influx causing reversal of resting membrane potential from -90mV to +30 mV

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5
Q

Phase 1 of cardiac action potential

A

Pacemaker potential, closure of Na+ channels and transition of K+ efflux causes some depolarisation

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6
Q

Plateau phase (phase 2) of cardiac potential

A

rising phase, Ca++ influx

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7
Q

Falling phase (phase 3) of cardiac potential

A

K+ efflux, closure of Ca++ channels, depolarisation of membrane potential back to -90mV

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8
Q

Which drugs slows the heart rate in the sinus rhythm

A

Drugs which Block HCN (funny current (If)

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9
Q

How does the signal travel from the SA node to the AV node

A

mainly cell-to-cell conduction via gap junctions but also internal pathways

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10
Q

Why is the conduction to the AV node delayed

A

Allows atrial systole to proceed ventricular systole

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11
Q

What allows rapid spread of action potential to the ventricles

A

Bundle of His and network of Purkinje fibres

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12
Q

The effect of Sympathetic nervous system on the heart rate

A

Noradrenaline increases slope of pace maker potential -> increases pacemaker cell Na+ and Ca++ influx -> decreases AV node delay -> increases heart rate

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13
Q

The effect of Parasympathetic (vagel) nervous system on the heart rate

A

Acetyl-choline decreases the slope of the pacemaker potential -> decreases the pacemaker cell Na+ and Ca++ influx -> increases AV node delay -> decreases heart rate

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14
Q

What do Beta Blockers do

A

Block sympathetic action, decrease slope of pacemaker potential in SA and increases AV delay , slow heart rate, reduces force of contraction, reduces myocardial oxygen consumption

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15
Q

What nerve supplies the Heart with parasympathetic supply

A

Vagus nerve

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16
Q

What does Atropine do

A

Competitive binding to acetylcholine receptors, increases slope of pacemaker potential in SA and decreases AV delay -> increases heart rate

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17
Q

What does Atropine do

A

Competitive binding to acetylcholine receptors, increases slope of pacemaker potential in SA and decreases AV delay -> increases heart rate

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18
Q

What happens during Systole - ventricular muscle contraction

A

When action potential has passed, Ca++ influx ceases, Ca++ re-sequestered in SR by Ca++-ATPase, heart muscle relaxes

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19
Q

What are calcium channel blockers

A

Interact with L-type calcium channels, can reduce heart and conduction via AV node, reduce force of conduction

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20
Q

What do Dihydropyride Ca+2 blockers act on

A

Smooth muscles - decrease blood pressure

21
Q

What does intrinsic mean

A

within the heart muscle

22
Q

What does extrinsic mean

A

nervous and hormonal control

23
Q

Stroke volume

A

the volume of blood ejected by each ventricle per heart beat, regulated by intrinsic and extrinsic mechanisms

24
Q

SV calculation

A

SV=End diastolic volume (EDV) - End systolic volume (ESV)

25
Q

Cardiac output

A

Volume of blood pumped by each ventricle per minute, Healthy adult = 5 litres per minute

26
Q

CO calculation

A

CO=SV x HR

27
Q

Systemic Vascular Resistance

A

Sum of Resistance of all vasculature in the systemic circulation

28
Q

Mean arterial pressure calculation

A

Mean arterial Pressure = Stroke volume x Heart Rate x Systemic Vascular Resistance

29
Q

Resistance to blood flow:

A

directly proportional to blood viscosity and length of blood vessels; inversely proportional to radius of blood vessel

30
Q

What does the Baroreceptor do

A

Short-term regulation of mean arterial blood pressure

31
Q

what nerve fibres are the smooth muscles supplied by? What is the neurotransmitter? What receptor do they act on?

A

Sympathetic, Noradrenaline, Alpha

32
Q

What is the partial constriction of the vascular smooth muscles at rest called

A

Vaosmotor tone

33
Q

Where does adrenaline come from

A

adrenal medulla

34
Q

Adrenaline acting on Alpha receptors causes … and are predominant in …

A

Vasoconstriction
Skin, gut, kidney arterioles

35
Q

Adrenaline acting on Beta 2 receptors cause … and are predominant present in …

A

Vasodilation
Cardiac and skeletal muscle arterioles

36
Q

What factors cause relaxation of arteriolar smooth muscles resulting in vasodilation

A

Decreased local PO2
Increased local PCO2
Increased local H+ (decreased pH)
Increased extra-cellular K+
Adenosine

37
Q

the use of Organic Nitrates

A

Relaxes smooth muscles via their metabolism if nitric oxide
Decreases preload (dilation of veins) and after load (dilation of arterioles)
Increases coronary blood flow
Treats angina
Examples: GTN, ISMN

38
Q

SV consists of

A

Venous return->Preload, Myocardial contractility, Afterload

39
Q

What is Postural Hypotension

A

Results from failure of Baroreceptor response to gravitational shifts in blood

40
Q

Postural Hypotension is indicated by a drop within 3 minutes of standing from lying position

A

In systolic blood pressure of at least 20 mmHg
A drop in diastolic blood pressure of at least 10mmHg (with symptomes)

41
Q

What are symptoms of Postural Hypotension

A

Lightheadedness, dizziness, blurred vision, faintness and fall

42
Q

Hormones regulating extracellular fluid volume include

A

RAAS, NPs, ADH

43
Q

What are ACEIs and ARBs

A

Treatment of hypertension and heart failure
ACEIs inhibits conversion of Angiotensin 1 to 2
ARBs blocks action of Angiotensin 2

44
Q

What are NPs

A

Cause excretion of salt and water in the kidneys thereby reduce blood volume and blood pressure

45
Q

The first heart sound is caused by … it sounds like … and heralds the beginning of …

A

closure of mitral and tricuspid valves
lub
systole

46
Q

The second heart sound is caused by … it sounds like a … heralds the end of … and beginning of …

A

closure of aortic and pulmonary valves
dub
systole
diastole

47
Q

what causes the 3rd heart sound

A

early-diastolic rapid distension of the left ventricle that accompanies rapid ventricular filling and abrupt deceleration of the atrioventricular blood flow

48
Q

what causes the 4th heart sound

A

ontraction of the atria pushing blood into a stiff or hypertrophic ventricle, indicating failure of the left ventricle.

Cardio Vascular Year 1 (23 decks)

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