Question

1. Can cardiac muscle tissue regenerate? What happens to this tissue after a heart attack? When and how does cardiac muscle tissue contract?

2. When and how does smooth muscle tissue contract? Can skeletal muscle tissue regenerate? When and how does skeletal muscle tissue contract?

Answer 1

Question 1:

No the cardiac muscle cannot regenerate. After the heart attack the cardiac muscle cells get damaged and it died and it is replaced by scar tissue. The remaining muscle cells which are not damaged it regulate the functions of heart.

The cardiac muscles consist of two components they are actin and myosin. The muscle contraction is caused initially by the binding of myosin head to the Adenosine triphosphate (ATP). Then the ATP get pulled the the actin filament to the centre of sarcomere it leads to contraction of cardiac muscle.

Question 2:

The smooth muscle contraction is occurs by the Sliding filament mechanism .

Mechanism:

Initially the neurotransmitters or the hormones get activated and it made the calcium to enters into the membrane through the L type voltage gated calcium channels. The calcium which is present outside the cell get activated the sarcoplasmic reticulum to the release of calcium. This process is called calcium induced calcium release. The calcium which enters into the cell membrane it binds with calmodulin which is present inside the cell and it activated the myosin filament. Then it binds with actin filament and they are slide each other and it causes the smooth muscles to contract. This mechanism is called Sliding filament mechanism.

Yes the skeletal muscles can regenerate. The skeletal muscle contraction is also occurs by Sliding filament mechanism. The action potential from the motor neuron reaches the sarcomere and it causes the sliding of actin and myosin filament and it leads to contraction of skeletal muscle.