CIRCULATION QUESTIONS

1.

This table shows the state of the valves and heart muscle at different stages of the heart cycle
(a)

Fill in the gaps in the table

 

Phase

SL Valves

AV Valves

Atria

Ventricles

Isometric Relaxation

closed

closed

diastole

diastole

Rapid Filling

closed

open

diastole

i

Diastasis

closed

open

diastole

diastole

Atrial Systole

closed

ii

systole

diastole

Ejection

iii

iv

diastole

systole

 

(2)

(b)

In which part of the heart is the SAN (pacemaker) located?

(1)

(c) Describe and explain the functions of the SAN

(2)