Cardiovascular physiology I

Question 1

What are the functions of the cardiovascular system?

Answer 1

• Transport and exchange gasses
• Transport nutrients
• Transport metabolic waste
• Transport hormones

Question 2

Describe the route from SA node to AP:

Answer 2

Starts negative –> AP –> hyperpolarisation –> pacemaker potential

Question 3

Describe the difference between AV node –> AP from SA node

Answer 3

There is a slower depolarisation which means it takes longer to reach threshold, which causes a pause in signal conduction: latent pacemaker

Question 4

What is an electrocardiogram?

Answer 4

A non invasive way to measure heart rate through signal conduction in heart tissue

Question 5

What heart cells show intrinsic autonomy?

Answer 5

SA, AV nodes and purjunke cells - generate heartbeat

Question 6

Outline the Sinoatrial node

Answer 6

A specialised structure that sends electrical impulses to the artia and ventricles - gap junctions allow signals to flow
It has the fastest pacemaker potential (action potential) which means it is the primary pacemaker driving the heart

Question 7

How are signals initiated?

Answer 7

1) Slow depolarisation
2) Seep AP
3) Steep hyperpolarisation
4) Back to depolarisation
NO stimulus is required because of PMP

Question 8

How is the ANS involved with modulation of heart rate?

Answer 8

SYMPATHETIC: fight or flight response, heart rate is increased so noradrenaline is released. Calcium and IF levels are increased
PARASYMPATHETIC: rest and digest, PMP rate is reduced meaning there is a lower heart rate. Increase in potassium, decrease in calcium

Question 9

Where does blood enter and exit?

Answer 9

Enters through superior venavava and does through the right atrium and ventricle, then pumped through the left pulmonary arteries, back into left pulmonary veins and into left atrium and ventricle

Question 10

How is the pump coordinated?

Answer 10

Gap junctions allow signals to spread which allows synchronisation through an electrical signal conduction system. The signal is spread in a way that allows the chambers to contract in the right order.

Question 11

List the 6 steps to electrical signal flow

Answer 11

1) SA node initiates electrical signal and atriuses are activated - calcium enters
2) Stimulus spreads across atriuses and reaches the AV node
3) AV node causes delay which allows atriuses to contract before signal travels further
4) Impulse travels along interventriciular septum in the AV bundle, through purjunke fibres to the right ventricle
5) Purjunke fibres spread the signal and relay through ventricular myocardium
6) Atrical contraction completes, ventricular contraction begins