D4 Heart

Question 1

Describe cardiac muscles

Answer 1

Branched (to allow faster signal propagation)
Contract in 3D
Not fused but connected by inercalated discs
Mitochondria rich

Question 2

How does cardiac muscle avoid fatigue?

Answer 2

Longer periods of contraction and refraction

Question 3

How does the heart muscle cells ensure the atria and ventricles contract separately?

Answer 3

Interconnected networks separated between them allowing each set of chambers to contract independently
Separated by fibrous cardiac fibres

Question 4

What triggers the atrial contraction?

Answer 4

SA node sends out a signal

Question 5

How does atrial systole occur?

Answer 5

Signal sent from the SA node propagates through the intercalated discs and the cardiac muscles contract simultaneously

Question 6

What creates the delay between the two contractions?

Answer 6

AV node takes longer to propagate the signal than the SA node

Question 7

How does ventricular contraction occur?

Answer 7

AV node sends a signal down the septum to the Bundle of His which innervated the Purkinje fibres in the ventricular wall causing contractions

Question 8

Where does the ventricular contraction begin?

Answer 8

From the bottom up to push blood towards the arteries

Question 9

What is the Bundle of His?

Answer 9

Bundle of cardiomyocytes

Question 10

What causes the Lubb?

Answer 10

AV valves shutting after atrial systole

Question 11

What causes the Dupp?

Answer 11

Semilunar valves shutting after the ventricular systole

Question 12

What is an electrocardiogram (ECG)?

Answer 12

A map of the electrical activity of the heart with each contraction

Question 13

Describe the P wave of an ECG

Answer 13

Small initial wave

Question 14

What occurs in the P wave (ECG)?

Answer 14

Depolarisation of the atria in response to signalling from the SA node

Question 15

Describe the QRS complex on an ECG

Answer 15

A large spike and fall

Question 16

What occurs during the QRS complex (ECG)?

Answer 16

Depolarisation of the ventricles triggered by the AV node

Question 17

Describe the T wave on an ECG

Answer 17

Small wave (similar to the P wave)

Question 18

What occurs during the T wave?

Answer 18

Repolarisation of the ventricles

Question 19

What is the order of sections on an ECG?

Answer 19

P wave
PR interval
QRS complex
ST segment
T wave

Question 20

Equation for cardiac output?

Answer 20

Cardiac output (CO) = Heart rate (HR) x Stroke volume (SV)

Question 21

Describe hypertension

Answer 21

Abnormally high blood pressure

Question 22

What can be used to help bradycardia or arrhythmias?

Answer 22

Artificial pacemaker