Pracs

Question 1

What does the ECG reveal

Answer 1

Overall spread of electrical activity

Question 2

What information does the ECG provide?

Answer 2

Timing and directional

Question 3

What causes the funny channels to open? Which type of cells contain these channels?

Answer 3

Opened by the hyperpolarisation of the previous action potential. Located in autorhythmic cells

Question 4

Where is the AV node delay on the ECG?

Answer 4

The PR segment

Question 5

TP segment =?

Answer 5

Diastole. In between contractions

Question 6

When is ventricular pressure the highest?

Answer 6

Right before ejection, in between QRS and T

Question 7

How does the SNS change the PT segment?

Answer 7

It doesn’t. Only changes TP

Question 8

Potential causes of a left axis deviation?

Answer 8

Obesity, pregnancy, left ventricular hypertrophy (athletes or hypertension), right heart infarction

Question 9

Right axis deviation causes?

Answer 9

Pulmonary hypertension, tall people, myocardial infarction on left, new borns

Question 10

Best place to hear the 2nd heart sound?

Answer 10

Second intercostal space

Question 11

The fifth intercostal space is where which heart sound is best heard?

Answer 11

First

Question 12

At what stage of the ecg is the ‘lub’ heard?

Answer 12

QRS

Question 13

Is the pulmonary valve more or less compliant than the aorta? Implications of this?

Answer 13

More compliant. Means it takes longer for the pressure to rise, causing later closure of the valve

Question 14

Compare stenosis vs insufficiency in valves

Answer 14

Stenosis = thickening of valve = more narrow opening 
Insufficient = valve doesn’t close tightly = back flow

Question 15

MAP = 2/3 Diastolic pressure + 1/3 systolic pressure. Why?

Answer 15

Because the heart spends 2/3 of its time in diastole

Question 16

Reduced firing of baroreceptors causes what?

Answer 16

Increased activation of cardiovascular centre = causes increase in SNS and decrease in PSNS to increase HR and SV to increase BP

Question 17

High blood pressure causes the baroreceptors to increase or decrease firing rate?

Answer 17

Increase. Stimulates CV centre to reduce BP

Question 18

Metabolites produced by skeletal muscle cause?

Answer 18

Local vasodilation

Question 19

Why does diastolic pressure not rise during exercise?

Answer 19

Vasodilation / vasoconstriction is balanced out across the body to maintain TPR (which is the major determinant of diastolic pressure)