Heart 3 A

Question 1

Electrical conduction system of the heart composed

Answer 1

Sino atrial node
Internodal conduction tracts and interact rial conduction tracts
Atrioventricular junction
Right bundle branch
Left bundle branch
Purkinje network

Question 2

Cardiac cells

Answer 2

Myocardial cells

Pacemaker cells

Question 3

Myocardial cells function

Answer 3

Primary function contraction and relaxation

Question 4

Myocardium consist of

Answer 4

Interlacing bundles of cardiac muscles fibres arranged spirally around the circumference of the heart

Question 5

Contractility

Answer 5

Myocardial cells shorten and return to their original length when stimulated by an electrical impulse

Question 6

Conductivity

Answer 6

The ability for cardiac cells to conduct electrical impulses

Question 7

Myocardial cells are

Answer 7

Working cells of the heart

Question 8

Function of pcemaker cells

Answer 8

Generation and conduction of electrical impulses

Question 9

Pacemaker cells

Answer 9

Cannot contract

Contain more gap junctions that allows them to conduct electrical impulses rapidly

Question 10

Automacity

Answer 10

They are capable of generating impulses spontaneously

Question 11

Autonomic nervous system

Answer 11

Heart is under the constant control

Question 12

Regulation occurs

Answer 12

In medulla oblongata

Question 13

Ecg

Answer 13

Is a graphic record of the changes in magnitude and direction of electrical activity of the heart
It records depolarisation and repolarisation of the atrial and ventricular myocardial cells

Question 14

The ecg paper

Answer 14

Grid allows measurement of time in seconds ( along the horizontal axis) and voltage (amplitude) in mm along the vertical axis

Question 15

Lead placement

Answer 15

12 lead ecg lead placement

Electrodes need to be placed in the correct position to ensure accurate ECG recording

Question 16

Limb leads

Answer 16

L ( left)
R (right)
F (foot)
N (neutral)

Question 17

Chest leads

Answer 17

V1,
V2
V3
V4
V5
V6

Question 18

P wave onset and end

Answer 18

Onset is first abrupt or gradual deviation from the baseline. The end is marked were the wave flattens out to return to the baseline

Question 19

P wave direction

Answer 19

Upright in lead 11 (upright in most lead)

Question 20

P wave duration

Answer 20

Between 0.08 and .10 seconds

Question 21

P wave amplitude
Shape
P wave - qrs relationship

Answer 21

0.5 -2.5 mm
Smooth and rounded
1:1

Question 22

Pr interval
Onset and end
Pr interval - qrs relationship

Answer 22

Begins with the onset of the p wave and ends with the onset of qrs complex

0. 12 -.20 seconds
   1: 1

Question 23

Qrs complex
Onset and end
Components 
Direction 
Duration
Amplitude 
Shape

Answer 23

At the point where the first wave of the complex just begins to deviate, abruptly or gradually from the baseline
Consist of one or more of the ff: upright deflection ( r wave) and inverted deflection (q, s waves)
May be predominantly upright, inverted or equiphasic
0.06-0.12 or 0.08 seconds
Vary from 1-15 mm in lead 11 for r and s wave. Q wave is less than 25% of the r wave
Narrow and sharply pointed

Question 24

Qt interval
Onset and end
Duration

Answer 24

The point where the first wave of the qrs complex begins to deviate