Question

Physiology

- Describe excitation-contraction coupling.

-Compare and contrast electrical synapses with chemical synapses, including advantages and disadvantages for each.

-Compare and contrast smooth, skeletal and cardiac muscles

Thank YOU!

Answer 1

1. Excitation-contraction Coupling
Excitation-contraction coupling is the process that occurs in between the excitation and contraction of the muscle. This process involves series of activities, which are responsible for the contraction of excited muscle.
Stages of excitation-contraction coupling
When a muscle is excited (stimulated) by the impulses passing through motor nerve and neuromuscular junc­ tion, action potential is generated in the muscle fiber.
Action potential spreads over sarcolemma and also into the muscle fiber through the ‘T’ tubules. The ‘T’ tubules are responsible for the rapid spread of action potential into the muscle fiber. When the action potential reaches the cisternae of ‘L’ tubules, these cisternae are excited. Now, the calcium ions stored in the cisternae are released into the sarcoplasm .The cal- cium ions from the sarcoplasm move towards the actin filaments to produce the contraction.
Thus, the calcium ion forms the link or coupling material between the excitation and the contraction of muscle. Hence, the calcium ions are said to form the basis of excitation-contraction coupling.

2.

Chemical synapses	electrical synapses
Use neurotransmitters as chemical mediator for transmission of impulse.	impulse is transmitted through gap junctions or law resistance bridges.
Transmission is one way.	transmission is two way
They are seen at most of the synaptic junction in ghe body .	they are found only in special areas like retina, olfactory bulb ,cerebral cortex etc,

3.

Cardiac muscle	skeletal muscle	smooth muscle
Found only in heart	attached to bone and skin	lines walls of internal organs
Involuntary movements	voluntary movements	Involuntary movements
Responsible for pumping blood from heat to all the prte of body	power the joints aiding the movement	move internal organs to facilitate their functions
Striated with many myofibrils in orderly arrangements.	striated with orderly arranged myofibrils	Not striated, fewer, myofibrils are found in varying lengths.