Week 1 Part 1

Question 1

Where does the excitation of the heart normally originate?

Answer 1

Sino-atrial node

Question 2

Where is the SA node located?

Answer 2

Upper right atrium

Question 3

What happens to the ions during the slow depolarisation of the membrane potential (pacemaker) to threshold?

Answer 3

Decrease in K+ efflux

Na+ and K+ influx

Transient Ca++ influx

Question 4

The rising phase of action potential depolarisation in pacemaker cells is caused by what?

Answer 4

Calcium influx

Question 5

The falling phase of action potential in pacemaker cells is caused by what?

Answer 5

Potassium efflux

Question 6

How does cardiac excitation spread across the heart?

Answer 6

SA node
AV node
Bundle of His
Left and right branches
Purkinje fibres

Question 7

What type of cell:cell junctions allow excitation to spread through the heart?

Answer 7

Gap junctions

Question 8

In the ventricular muscle action potential, what is the steep rise in membrane potential (phase 0) caused by?

Answer 8

Fast Na influx

Question 9

In ventricular muscle action potential, what is the small decline in membrane potential after the steep incline due to?

Answer 9

Closure of the Na channels and transient K efflux

Question 10

What is the horizontal part of the ventricular muscle action potential graph due to (phase 2)?

Answer 10

Calcium influx

Question 11

What is the fall in action potential of the ventricular muscle action potential graph due to?

Answer 11

Closure of Ca++ channels and K+ efflux

Question 12

What is the resting membrane potential of ventricular muscle?

Answer 12

-90mV

Question 13

Stimulation of which nervous system increases the heart rate?

Answer 13

Sympathetic

Question 14

Stimulation of which nervous system decreases the heart rate?

Answer 14

Parasympathetic

Question 15

What is considered a normal resting heart rate?

Answer 15

60-100bpm

Question 16

What is the neurotransmitter for parasympathetic stimulation of the heart?

What muscarinic receptors does it act on?

Answer 16

Acetyl choline

M2 receptors

Question 17

What drug can be used in extreme bradycardia to speed up the heart rate?

Answer 17

Atropine

Question 18

What does vagal stimulation of the heart do to the electrical impluses running through the heart?

Answer 18

Increases AV nodal delay

Question 19

What is the neurotransmitter for sympathetic stimulation of the heart and what adrenoceptors does it act on?

Answer 19

Noradrenaline

Beta-1 adrenoceptors

Question 20

True/False

Cardiac muscle is striated

Answer 20

TRUE

Question 21

Muscle fibres are made up of many…

Answer 21

Myofibrils

Question 22

Myofibrils are made up of 2 components. What are they?

Answer 22

Myocyin

Actin

Question 23

What ion is essential for muscle contraction?

Answer 23

Extracellular calcium

Question 24

What does actin bind to in order to allow contraction?

Answer 24

Troponin

Question 25

Where is calcium released from in the cell to allow contraction of muscle fibres?

Answer 25

Sacroplasmic reticulum

Question 26

What is a refractory period?

Answer 26

A period following an action potential in which it is not possible to produce another action potential

Question 27

What is stroke volume?

Answer 27

The volume of blood ejected by each ventricle per heart beat

Question 28

What is an intrinsic mechanism?

Answer 28

Mechanism from within the heart

Question 29

What is an extrinsic mechanism?

Answer 29

Nervous/hormonal control

Question 30

What is the Frank-Starling Mechanism or Law of the Heart?

Answer 30

The more the ventricle is filled with blood during diastole, the greater the volume of ejected blood will be during the resulting systolic contraction

Question 31

What increases the affinity of troponin for Ca++?

Answer 31

Stretch

Question 32

What is afterload?

Answer 32

The resistance into which the heart is pumping

Question 33

What type of nerves supply the ventricular muscle?

Answer 33

Sympathetic

Question 34

What is a positive inotropic effect?

Answer 34

Increase in the force of contraction

Question 35

What is a positive chronotropic effect?

Answer 35

Increase in the heart rate

Question 36

What does sympathetic stimulation do to the Frank-Starling curve?

Answer 36

Shifts it to the left

Question 37

What does the heart failure do to the Frank Starling curve?

Answer 37

Shifts the curve to the right

Question 38

What does vagal stimulation of the heart do to: A: The heart rate B: The force of contraction

Answer 38

Slows rate No influence on force of contraction

Question 39

Where are adrenaline and noradrenaline hormonesreleased from?

Answer 39

Adrenal medulla

Question 40

What makes up cardiac output?

Answer 40

SV x HR

Question 41

What is cardiac output?

Answer 41

Volume of blood pumped by each ventricle per minute

Question 42

What events occur during the cardiac cycle?

Answer 42

Passive filling Atrial contraction Isovolumetric ventricular contraction Ventricular ejection Isovolumetric ventricular relaxation

Question 43

What does the P wave signal in an ECG?

Answer 43

Atrial depolarisation

Question 44

When do the atria contract on an ECG?

Answer 44

Between the P-wave and the QRS

Question 45

When does ventricular contraction occur on an ECG?

Answer 45

After the QRS

Question 46

What is an isovolumetric contraction?

Answer 46

When the tension rises around a closed volume (just before diastole)

Question 47

What does the T wave on an ECG represent?

Answer 47

Ventricular repolarisation

Question 48

What causes the dicrotic notch on the aortic pressure curve?

Answer 48

Second heart sound, aortic/pulmonary valves closing

Question 49

On the jugular venous pulse graph, what do the following letters represent? A C V

Answer 49

A - atrial contraction C - bulging of tricuspid valve into atrium during ventricular contraction V - is rise of atrial pressure during atrial filling: release as AV valves open