Organisms Exchange Substances with their Environment: Mass Transport in Animals - Control of the Heart Beat

Question 1

Define the term myogenic

Answer 1

• The heart is myogenic

- This means that it can generate its own contractions without nervous impulses from outside

Question 2

What is the role of the sinoatrial node (SAN)?

Answer 2

• Acts as a pacemaker
• Small group of cells located in the wall of the right atrium
• Works by sending out regular waves of electrical activity to the atrial walls
• This causes the right and left atria to contract simultaneously

Question 3

What is the role of the non conducting collagen tissue?

Answer 3

• Prevents the waves of electrical activity from being passed directly to the atria to the ventricles
• Instead these waves are transferred from SAN to the atrioventricular node

Question 4

What is the role of the atrioventricular node (AVN)?

Answer 4

• Located between two atria
• The AVN passes waves of electrical activity to the bundle of His
• There is a slight delay before the AVN reacts, to ensure the atria have emptied before the ventricles contract

Question 5

What are the bundle of His and purkyne fibres?

Answer 5

• Group of muscle fibres
• That conduct waves of electrical activity through atrioventricular septum to base of ventricles
• Bundle of His split into finer muscle fibres called Purkyne fibres
• The Purkyne tissue carries waves of electrical activity into walls of right and left ventricle
• This causes ventricles to contract simultaneously, from the bottom up