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Biomed 2 > Int 4: Cardiovascular System > Flashcards

Int 4: Cardiovascular System Flashcards

1
Q

What are the two main circulatory circuits

A

Pulmanory
Systemic

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2
Q

Name the 4 valves of the heart

A
  • pulmonary semilunar valve
  • aortic semilunar valve
  • left AV (bicuspid) valve
  • right AV (tricuspid) valve
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3
Q

Cardiac muscles are a)______ meaning they will only contract along their long axis. They wrap around the heart to contract in 2 axis

A

a) striated

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4
Q

Name some things that a healthy endothelium regulates

A
  • vessel tone
  • movement of fluid into tissues
  • leukocyte adhesion, platelet aggregation
  • structure of endothelium varies in different locations depending on its function
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5
Q

What does the term myogenic mean and how does cardiac muscle pull it off

A

generates its own action potential - action potential conducted from cell to cell via intercalated discs which have gap junctions.

skeletal muscle is neurogenic

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6
Q

What is the function of the Purkinje fibres

A

To coordinate contraction of the muscles in the ventricles

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7
Q

Explain the process of cardiac excitation

A

1) AP depolarises atria while impulse is delayed at AV-node ~100ms
2) AV-node the activate Purkinje fibres via Bundle of His
3) Purkinje fibres activate ventricles

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8
Q

Explain the processes behind the following steps in terms of Na+, K+ and Ca++:

1) Depolarisation of cardiac muscles
2) Repolarisation (3 sub-steps)
3) refractory period

A

1) Fast influx of Na+
2a) Steep initial decrease from the efflux of K+.
2b) Ca2+ is also released from intracellular stores to cause contraction (enters vi a Ca channels)
2c) Further repolarisation from K leaving
3) Hyperpolarisation, heart still contracted because of high calcium. Na+ removed and K+ returned via Na+/K+ ATPase. Also a Na/Ca exchanger

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9
Q

When measuring the electrical activity of the heart you can measure 4 things:

a) automaticity
b) conductivity
c) hypertrophy
d) ischemic damages

What is being measured in each case

A

a) HR, rhythmicity
b) pathway
c) -
d) location, size and progress

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10
Q

Below are the ECG events of the cardiac cycle. Describe the events that are occurring / causing these ECG features
- P wave (small bump)
- Q wave (small, sharp downwards divot)
- R wave (sharp, large upwards spike)
- S wave (sort of like hyperpolarisation, small downward divot)
- T wave (rounded bump)
Repeat

A
  • P wave: Atrial depolarisation, atria contract after
  • Q wave: Signal goes through sinoatrial node to Purkinje fibres
  • R wave: Purkinje fibre depolarisation, ventricle contraction
  • S wave: Ventricles still contracted
  • T wave: Repolarisation
  • AORTIC valve CLOSES a bit after T wave
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11
Q

What is bradycardia and what is tachycardia

A

Bradycardia - Slow HR
Tachycardia - fast HR

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12
Q
A
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13
Q

Define the following:
- Cardiac Output
- Stroke Volume
- Ejection Fraction

A
  • Cardiac Output: amount of blood pumped out by each side of the heart in 1 minute
  • Stroke Volume: Vol of blood pumped out by each ventricle in one contraction
  • Ejection Fraction: % of blood vol that is pumped out by the ventricle can increase to 80% during exercise
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14
Q

The ANS (sympathetic and parasympathetic) can modify 2 things to do with the heart, what are they?

A

Rate of activation (thru effects on the S.A node) and contraction force

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15
Q

Two branches of the ANS are involved in heart modulation, the parasympathetic (PSNS) and the sympathetic nervous system (SNS). What type of nerves does each system use?

A

PSNS: Cholinergic
SNS: Noradrenergic

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16
Q

What are the respective functions of the PSNS and SNS on heart activity? (hint = 1 decreases and 1 increases)

A

Sympathetic: Fight or Flight
- Increases HR
- Increases rate of conduction and overall excitability
- Increases force of contraction
- Dilates coronary arteries

Parasympathetic: Rest
- Decreases HR
- Reduce the force of contraction

17
Q

What is considered normal BP and what is considered hypertension

A

Normal: 120/80mmHg
Hypertension: 140/90mmHg

18
Q

Outline the foundations of measuring BP and how it can be measured

A
  • SBP and DBP
  • Pulse pressure = SBP-DPB
  • 2/3 cycle is in diastole, 1/3 in systole
  • Can be measured invasively (arterial cannulation) or indirectly (cuff sensor)
19
Q

What is mean arterial blood pressure and why do we use it?

A
  • Is the average arterial pressure through 1 cardiac cycle
  • Used because it accounts for flow, resistance, and pressure within arteries.
  • MAP = DP + 1/3(pulse pressure)
20
Q

What does stroke volume depend on? (2 things - pretty obvious)

A
  • Contractility (force of contraction)
  • End diastolic volume (amount of blood in ventricles)
21
Q

What is Starling’s Law of the heart (hint = elastic one)

A
  • Venous return to the heart gives ‘preload’. this refers to the stretching of the heart muscle during filling.
  • Higher venous return increases volume –> increases stretch of the ventricle –> increases elastic recoil
22
Q

What is Laplace’s Law? (hint = blood pressure one)

A

Force acting on blood vessel wall is proportional to: Diameter of vessel x BP

Large diameter = thick walls to withstand pressure
Capillaries = thin walls = low pressure

Hypertension induces stiffness of arteries so can lose their elastic properties

23
Q

What is Ohm’s Law? (hint = flow one) and Poiseuille’s adaptation

A

Flow = Pressure gradient / Resistance

Poiseuille found that a 2 fold change in radius produces a 16 fold change in flow rate. I.e. small changes in arteriole diameter exert large changes in tissue perfusion.

24
Q

How do kidneys control blood volume?

A

1) Blood pressure increases
2) Kidney excretes more salt and water
3) Extracellular fluid volume falls
4) Blood pressure falls

25
Q

Given a normal ECG record, what would be the approximate duration of the P-R interval, the QRS complex and the Q-T and the S-T intervals?

a) 0.4s
b) 0.08s
c) 0.32s
d) 0.12-0.2s

  • P-R interval
  • QRS complex
  • Q-T interval
  • S-T interval
A

a) Q-T
b) QRS complex
c) S-T
d) P-R

26
Q

Note:
At a state of rest (75bpm), systole lasts 0.27s and diastole 0.53s

A
27
Q

Which fibres are where in the heart:

a) Ordinary myocardial fibres
b) Bachmann’s bundle
c) Purkinje fibres
d) Bundle of His

A

a) Right atrium
b) Left atrium
c) Ventricles
d) Upper ventricles

Biomed 2 (16 decks)

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