Control Of Heart Rate

Question 1

Describe how the heart beats on its own

Answer 1

• heart is myogenic
• can beat w out any nervous stimulation
• muscle cells are able to generate their own electrical impulses

Question 2

Describe the pathway of an electrical impulse through the heart

Answer 2

• internal pacemaker starts at sinoatrial node (SAN), located near wall of right atrium
• pulse then causes atria to contract, this is atrial systole
• pulse then reaches the atrioventricular node (AV)
• and pauses for 0.01 s to allow blood in atria to empty into ventricles before ventricles pump out the blood
• then spreads to walls of ventricles
• pulse then enters bundles of his from left to right branch then to the septum
• finally it reaches the purkinje fibres that conduct the impulse up to the ventricles, causing them to contract, this is called ventricuar systole

Question 3

What is observed when using an electrocardiogram (ECG)?

Answer 3

the electrical impulses in the heart that produce electrical currents that flow thru the body

Question 4

What is the average bpm?

Answer 4

70 bpm

Question 5

Why is it important that the heart rate can be altered in response to the needs of the body during exercise?

Answer 5

so the heart rate will increase to supply more oxygen to muscles