Anatomical Basis Of The Cardiac Cycle

Question 1

Contraction =

Answer 1

Systole

Question 2

Relaxation =

Answer 2

Diastole

Question 3

Why does contraction takes place?

Answer 3

Due to the intrinsic conducting system

Question 4

What is the conducting system made up of?

Answer 4

Specialised cardiac muscle cells

Question 5

What is the extrinsic conducting system controlled by?

Answer 5

Nerves

Question 6

What does the extrinsic conducting system control?

Answer 6

Heart rate, contraction and force

Question 7

What two nodal tissues does the intrinsic conducting system consist of?

Answer 7

Sinoatrial node and the atrioventricular node

Question 8

Describe the SA node

Answer 8

The pacemaker of the heart, is a cluster of cells situated on the posterior wall of the right atrium

Question 9

What sets the rhythm of the heartbeat?

Answer 9

Automatic depolarisation

Question 10

Where is the SA node found?

Answer 10

Close to the superior vena cava

Question 11

How is the SA node modified?

Answer 11

By autonomic input

Question 12

What is autonomic input?

Answer 12

Sympathetic increasing heart rate and parasympathetic decreasing heart rate

Question 13

Describe a pacemaker

Answer 13

A group of cells or a body part (such as the sinus node of the heart) that serves to establish and maintain a rhythmic activity

Question 14

What does bifurcate mean?

Answer 14

To cause a divide into branches or parts

Question 15

Where do the impulses pass along after the AV node?

Answer 15

Through the insulating Annulus fibrosus

Question 16

What is the annulus fibrosus?

Answer 16

Cardiac/fibrous skeleton

Question 17

After the annulus fibrosus where do the impulses go?

Answer 17

Down the interventricular septum of the heart where it bifurcates into the right and left bundle branches

Question 18

What do the right and left bundle branches comprise?

Answer 18

Narrow slow-conducting fibres (modified cardiac muscle cells) which terminate

Question 19

Where do the cardiac muscle cells terminate?

Answer 19

At an extensive network of fibres in the subendocardium called purkinje fibres

Question 20

Describe purkinje fibres

Answer 20

Fast conducting fibres that spread the impulse throughout the ventricular myocardium

Question 21

What do the purkinje fibres cause when spreading an impulse through the ventricular myocardium?

Answer 21

Cause an upward wave of contraction

Question 22

Where is the moderator band found?

Answer 22

In the right ventricle

Question 23

What does the moderator band provide?

Answer 23

A shortcut for electrical impulses of the right bundle branch from the interventricular septum to the anterior papillary muscle of the right ventricle