CVS review

Question 1

what does the right coronary artery supply

Answer 1

inferior aspect of the heart and right atrium

Question 2

An increase in intracellular calcium ion concentration causes contraction in cardiac myocytes. What do calcium ions bind to to initiate contraction?

Answer 2

Troponin C

Question 3

If cells in the SA node cease to function what rhythm will likely result?

Answer 3

If cells of the SA node cease to fire the AV node will take over as the pacemaker. These cells fire more slowly, hence bradycardia. It will not be sinus bradycardia as this implies the sino-atrial node is driving the electrical activity.

Question 4

If cells in the SA node fire too quickly what rhythm will result?

Answer 4

sinus tachycardia

Question 5

An increase in intracellular calcium ion concentration causes contraction in vascular smooth muscle cells. What do calcium ions bind to to initiate contraction?

Answer 5

Calcium ions bind to calmodulin and the Ca2+-calmodulin complex activates myosin light chain kinase.

Question 6

How is electrical activity in the heart initiated?

Answer 6

spontaneous depolarisation

Question 7

In the isovolumetric phases of the cardiac cycle, which valves are open?

Answer 7

none

Question 8

In which phase of the cardiac cycle can the first heart sound be heard?

Answer 8

The first heart sound is caused by the shutting of the mitral valve, and this occurs in the isovolumetric contraction phase.

Question 9

What causes the second heart sound?

Answer 9

The snapping shut of the aortic valve in the isovolumetric stage of the cardiac cycle causes the second heart sound.

Question 10

In which phase of the cardiac cycle can the QRS complex be seen on an ECG?

Answer 10

isovolumetric contraction

Question 11

What is the correct path of the electrical impulse through the cardiac tissue?

Answer 11

SA node -> AV node -> Bundle of His -> Purkinje fibres

Question 12

If a patient’s blood pressure is 120/75 mmHg, what is their mean arterial blood pressure?

Answer 12

diastolic + 1/3 (pulse pressure) = diastolic + 1/3 (systolic - diastolic) = 75 + 1/3 (120 - 75) = 75 + 1/3 (45) = 75 + 15 = 90

Question 13

Where do you find the femoral pulse?

Answer 13

just inferior to the mid-inguinal point (this is halfway between the ASIS and the pubis)

Question 14

action of adrenaline in coronary muscle, skeletal muscle and in the liver’s vasculature

Answer 14

At physiological (normal body) levels = vasodilation (β2 receptors)/

At pharmacological levels = vasoconstriction (α1 receptors)

Question 15

The opening of which channel is responsible for the upstroke of the action potential in the ventricular myocytes?

Answer 15

Voltage-gated Sodium ion channels

Question 16

Calcium can bind to a protein on the surface of the sarcoplasmic reticulum to cause calcium release from inside the sarcoplasmic reticulum into the cell cytoplasm. What is the name of this protein

Answer 16

ryanodine receptors. This is called Calcium Induced Calcium Release.

Question 17

What causes the inactivation of the voltage-gated sodium channels in hyperkalaemia?

Answer 17

The membrane potential becoming less negative and the cell depolarising

Question 18

Which of these is classified as stage 2 hypertension?

Answer 18

The margins for stage 2 hypertension are between 160/100 mmHg (clinic) or 150/95 mmHg (home) and 180/110 mmHg.

Question 19

Which part of the brain stimulates the thirst reflex, an important accompaniment for ADH release?

Answer 19

hypothalamus

Question 20

What is the typical resting membrane potential in ventricular myocytes?

Answer 20

-85mV

The cell membrane of ventricular myocytes is permeable to potassium ions at rest and there is only a very small permeability to other ions. Therefore the resting membrane potential is close to the equilibrium potential for potassium ions.

Question 21

What is the effect of hyperkalaemia on the spread of action potentials though out the myocardium?

Answer 21

Cardiac myocytes depolarise causing inactivation of sodium channels and slowing down the spread of action potentials

Question 22

Left atrial pressure is being assessed in a patient using a specialised catheter with a balloon and pressure sensor at the tip. The patient’s left atrial pressure is elevated and ranges from 5 - 20 mmHg throughout the cardiac cycle, whilst the patient’s arterial blood pressure is 140/80 mmHg. What will be the pressure in the patient’s left ventricle in diastole?

Answer 22

5-20