Cardiovascular: Cardiac Excitation and Contraction

Question 1

What part of the heart controlls the sinus rhythm?

Answer 1

S.A. node

Question 2

What happens if signals propegate from outside the the S.A. node?

Answer 2

This can refract and interfere with the S.A. node and can cause it to not signal properly

Question 3

Describe the excitation pathway in the heart?

Answer 3

• S.A. node controls sinus rhythm
• Action potential activates atria
• Atrial A.P. activates A.V. node
• A.V. node is poorly conductive causing a 0.1s delay
• A.V. node activates Bundle of His and Purkinje fibres
• Purkinje fibres activates ventricles

Question 4

What is the difference in the way that skeletal and cardiac muscle are stimulated?

Answer 4

Question 5

What has a longer action potential muscle or cardiac?

Answer 5

Cardiac

Skelletal: action potial triggers short contraction
Cardiac: action potential lasts and causing a long contraction therefor length of action potential controls duration of contraction as well as stimulation

Question 6

Difference in calcium release involved in muscle and cardiac contraction?

Answer 6