Which of the following is/are applicable to cardiac muscles? (T/F )
a) Are multinucleate
b) Action potential last about 200 ms
c) Behave as a functional syncytium
d) Refractory period is 100ms
e) Hyperkalemia affects the ECG
Answer
a.T
b.T
c.T
d.T
e.T
Discussion
a. Cardiac myocyte has many mitochondria
To see more morphological features of cardiac muscle and difference between cardiac and skeletal muscle click here
b. Click here to see duration action potential of cardiac and skeletal muscle
c. What is functional sysnsitum
d. Cardiac muscle absolute refractory period is 100 ms
Why skeletal muscle has Ability for Tetanization ?
e. Hyperkalemia
Hyperkalemia is elevated serum potassium level more than 5.0 mmol/L ( normal 3.5 - 5 mmol/l).Due to increase extracellular K+ level, resting membrane potential of the cell is reduced .Therefore muscle fiber become unexcitable . These produce following ECG changes
1. Tall tented T wave
2. Flattening of P wave
3. Prolong PR interval
3. Wide QRS complexLabels: CVS, CVS MCQ, Physiology MCQ