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BIOL 125 > Lecture 6 > Flashcards

Lecture 6 Flashcards

1
Q

Does aortic and arterial pressure rise or fall in diastole/early systole?

A

Falls.

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2
Q

What name refers to the minimum pressure?

A

Diastolic pressure. (DP)

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3
Q

Does the pressure rise or fall when the aortic valve opens?

A

Rise.

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4
Q

What name refers to the maximum pressure?

A

Systolic pressure. (SP)

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5
Q

How do you measure systolic blood pressure?

A

Place cuff above elbow, and pump up to the point you can’t hear sounds any more using stethoscope on lower arm.

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6
Q

How do you measure diastolic blood pressure?

A

Release pressure in cuff, until you can’t hear pulse any more in lower arm.

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7
Q

Normal blood pressure?

A

120/80 mm Hg.

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8
Q

Hypertension levels?

A

140-159/90-99 mm Hg.

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9
Q

Severe hypertension levels?

A

> 159/>99 mm Hg.

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10
Q

What 4 main causes increase the risk of hypertension?

A

Obesity, high cholesterol, smoking, genetic disposition.

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11
Q

What is atherosclerosis, and which condition does it relate to?

A

Build up of fatty deposits in walls of arteries, causing narrowing of the lumen.
Relates to hypertension.

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12
Q

Why does blood pressure tend to rise with age?

A

Reduced elasticity of the arterial system.

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13
Q

Is heart muscle neurogenic or myogenic, and why?

A

Myogenic.

Signals to contract arise from the heart itself.

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14
Q

What word can be used to describe the heart’s ability to regulate its beat?

A

Autorhythmicity.

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15
Q

What two types of cells make up the heart, and how do they differ?

A 
Myocardial cells (contractile muscle).
Pacemaker cells (not contractile, generate electrical impulses).
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16
Q

The pacemaker cells are concentrated in two regions of the myocardium. Where are these and what are they called?

A 
Sinoatrial node (SA node), upper right atrium.
Atrioventricular node (AV node), near tricuspid valve.
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17
Q

What do conduction fibres do?

A

Spread electrical signals from SAN and AVN throughout the heart muscle.

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18
Q

What is the interatrial pathway?

… is it quick or slow?

A

SA node -> right atrium -> left atrium.

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19
Q

What is the internodal pathway?

A

SA node -> AV node.

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20
Q

Is AV node transmission quick or slow?

A

Slow - 0.1s.

21
Q

In the interatrial pathway, do the right and left atria contract simultaneously?

A

Yes.

22
Q

Is there a steady membrane potential in pacemaker potentials?

A

No, because action potential triggered, before membrane slowly depolarises, and another action potential is initiated.

23
Q

Which ions are required to generate pacemaker potentials?

… Is the concentration of these ions particularly different to other cells?

A

Na+, K+, Ca2+.

Similar concentration to other cells.

24
Q

What is the slow depolarisation due to?

A

The funny channels controlling movement of K+ and Na+.

25
Q

What is the cardiac action potential mainly due to?

A

Ca2+.

26
Q

What happens during slow depolarisation?

A

K+ channels close.
Funny channels open.
Slower efflux of K+.
Influx of Na+.

27
Q

What happens just before cardiac threshold?

A

Ca2+ channels open.

Slow influx of Ca2+.

28
Q

What happens at the threshold?

A

Rapid Ca2+ influx.

29
Q

What happens at repolarisation?

A

Ca2+ influx decreases.

K+ efflux increases.

30
Q

On average, how often does the cardiac cycle occur over a lifetime?

A

100,000 times/day.
36.4 X 10^6 times/year.
3000 X 10^6 times/lifetime.

31
Q

What type of ion channels are the calcium channels that open before rapid depolarisation?

A

T-type voltage gated calcium channels.

32
Q

What type of ion channels are the calcium channels that open after rapid depolarisation?

A

L-type voltage gated calcium channels.

33
Q

What is cardiac output, and what is it determined by?

A

Volume of blood pumped out of each ventricle in one minute.
Determined by:
- Heart rate (HR) (bpm)
- Stroke volume (SV) (cm3)

34
Q

What is the formula for Cardiac Output?

A

CO = HR * SV

35
Q

Average HR and SV?

A

Average HR = 72bpm.

Average SV = 70cm3.

36
Q

What is the average cardiac output (approximately?

A

~5 litres/minute.

37
Q

What neurotransmitter does the vagus nerve (parasympathetic) use? And what does it connect?

A

Acetylcholine.

Connects medulla oblongata to SA and AV nodes.

38
Q

What neurotransmitter does the sympathetic cardiac nerve use? And what does it connect?

A

Noradrenaline.

Medulla oblongata to spinal cord, to sympathetic trunk, to SA, AV nodes and ventricular myocardium.

39
Q

What 3 effects does sympathetic input have on the heart?

A

Increases action potential frequency at SA node (heart rate increases).
Decreases delay at AV node (ventricular contraction starts sooner).
Increases contractile force of cardiac muscle.

40
Q

What effect does parasympathetic have in relation to the sympathetic system?

A

The opposite effect.

41
Q

What hormone enhances sympathetic input?

A

Adrenaline.

42
Q

What 3 factors is stroke volume affected by?

A
  • Ventricular contractility.
  • End-diastolic volume (EDV).
  • Afterload.
43
Q

What effect does sympathetic input and adrenaline have on ventricular contractility?

A

Gives increased force.

44
Q

What affects the degree of stretching of cardiac muscle?

A

The volume of blood in the heart at the end of diastole.

45
Q

What is afterload?

A

The back-pressure in the arteries.

46
Q

What is Starling’s Law of the Heart?

A

When the rate at which blood flows into the heart from the veins changes, the heart automatically adjusts its output to match the inflow.

47
Q

If an increase in end-diastolic volume occurs, what happens to the force of ventricular contraction, and why?

A

Force of ventricular contraction rises, producing increase in stroke volume and cardiac output.

48
Q

Does the stretching of muscle fibres increase or decrease contraction force?

A

Increase.

BIOL 125 (11 decks)

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