1. Properties of heart muscle Flashcards
What is the myocardium composed of?
Cardiac myocytes
How is cardiac muscle similar to skeletal muscle?
Striated
How does cardiac muscle differ?
Branched and is automatic in nature
What are the three layers of the heart?
Epicardium
Endocardium
Myocardium
What are intercalated discs?
Discs that link cells mechanically though folds and electrically through gap junction
Why is the cardiac muscle branched?
So it contracts in a specific order and may contract in a different direction due to the shape of the heart pulling in many different directions and serves the pumping function very well
What are features of cardiac muscle cells?
Single nucleus
Many mitochondria
Lots of capillaries
What is the reason for having many mitochondria in the cardiac muscle?
Aerobic metabolism
efficient
Economic
What is the meant by the heart being an obligate organ?
Aerobic organ and therefore lots of mitochondria
Why are cells negative on the inside?
Large negative ions on the inside of cell
K+ leaks out but Na+ doesn’t leak in
How does depolarisation occur?
Excitable cells are activated by allowing the positive ions in making the cell temporarily positive
What is the difference in a non-pacemaker v pacemaker cardiac action potential?
Pacemaker- varying prepotential
SA and AV nodes
Setting and carrying the rhythm
Non pacemaker- longer lasting
-92 mV RMP
In atrial and ventricular myocardium
Force development
What is meant by the refractory period?
Time after an initial stimulation during which a muscle or nerve is unstimulable
What does the long plateau of the refactory period indicate?
So no summation and tetanus like in skeletal muscle
What does the long plateau of the refactory period indicate?
So no summation and tetanus like in skeletal muscle
