PSIO411 - Cardiovascular system

Question 1

What are the 4 layers that lines the heart layers?

Answer 1

• Pericardium
• Epicardium
• Myocardium
• Endocardium

Question 2

What is the primary pace maker node?

Answer 2

Sinoatrial node (SA node)

Question 3

Question 4

How are myocytes connected?

Answer 4

gap junctions

Question 5

Answer 5

Because of the plateau phase the cardiac muscle contraction stays contracted for longer than skeletal muscles

Question 6

What is the absolute refractory period for AP in cardiac muscle?

Answer 6

• 250 msec

(compared to 1msec on SM)

Question 7

Question 8

Question 9

Question 10

The heart is located in the centre of the … what?

Answer 10

thoracic cavity. The apex (pointy end) angles
downwards to the left-hand side of the body. The base of the heart is at the top and
lies just behind the breastbone (or sternum).

Question 11

List the main functions of the cardiovascular system.

Question 12

Describe the components that comprise the cardiovascular system: the heart and blood vessels.

Question 13

Draw a diagrammatic representation of the circulatory system showing the systemic circulation and the pulmonary circulation.

Question 14

Demonstrate a sound understanding of the principles of pressure, volume, flow and resistance as they apply to the cardiovascular system.

Question 15

Give a detailed description of the heart, its chambers and valves.

Question 16

Describe the structure and function of cardiac muscle.

Question 17

Describe, in detail, the functioning of the heart as a whole, including how the contraction of the heart is coordinated.

Question 18

Draw and explain an electrocardiogram.

Question 19

Question 20

Question 21

Question 22

Question 23

Question 24

Question 25

Question 25

Question 26

Question 27

Question 28

Answer 28

1) Arrival of action potential from an adjacent cell
2) This triggers opening of voltage gated (L-type) calcium channels.
3) The small amount of calcium entry stimulates the release of a much larger
amount of calcium from the sarcoplasmic stores. This released calcium is
extruded through the the ryanodine channels
4) The local calcium release triggers a calcium spark
5) Summed calcium sparks create a calcium signal
6) The calcium ions then bind to troponin and contraction is initiated
7) Relaxation is initiated when calcium is released from troponin
8) The calcium is pumped back into the SR through the Ca-ATPase
9) Calcium is also extruded from the cell in exchange for Na+.
10) The sodium is rec-cycled via the Na+ pump
Sodium balance is maintained by extruding the Na+ which is exchanged for calcium
at the sarcolemmal membrane on the Na+ pump.

Question 29

Question 30

a) The pacemaker potential gradually becomes less negative until it reaches
threshold, triggering an action potential.

b) Ion movements during an action and pacemaker potential

c) State of various ion channels
If channels are permeable to Na and K. When these channels open at –ve membrane
potentials Na influx exceeds K efflux and the net influx of positive charge
depolarises the cell.

At a certain point the If channels close and calcium channels
open and calcium rushes in.

Calcium channels close at the peak of the action
potential when K channels open which enable repolarisation.

Question 31

a) The pacemaker potential gradually becomes less negative until it reaches
threshold, triggering an action potential.

b) Ion movements during an action and pacemaker potential

c) State of various ion channels
If channels are permeable to Na and K. When these channels open at –ve membrane
potentials Na influx exceeds K efflux and the net influx of positive charge
depolarises the cell.

At a certain point the If channels close and calcium channels
open and calcium rushes in.

Calcium channels close at the peak of the action
potential when K channels open which enable repolarisation.

Question 32

What happens with respiratory sinus arrhythmia?

Answer 32

• HR increases during inspiration
• Slows down during expiration

Question 33

What happens with respiratory sinus arrhythmia?

Answer 33

• HR increases during inspiration
• Slows down during expiration

Question 34

What is cardiac output?

Answer 34

CO = stroke volume (SV) x heart rate (HR)

e.g.
SV - 70ml
HR = 72 bpm
Cardiac output = 70 x 72

Question 35

What is a dipole?

Answer 35

Positive or negative deflections on ECG

Question 36

How many electrodes on a standard ECG?

Answer 36

10

Question 37

the heart rate can be calculated by counting the number of
large squares between two consecutive R waves, and dividing this number into 300.

Question 38

Question 39

Question 40

Question 41

Question 42

Question 43