Question

What role does the motor neuron play in stimulation of muscle contraction?

What role does the sarcoplasmic reticulum play in muscle contraction?

What is the difference between aerobic and anerobic muscle contraction?

What happens in a reflex response?

Answer 1

1. Muscle contraction begins when the nervous system generates a signal . This signal is called as action potential , travel through a type of nerve called a motor neuron . At the neuromuscular junction motor neuron reaches a muscle . A chemical called neurotransmitter (acetylcholine) is released at the neuromuscular junction which binds with the receptor on the outside of the muscle fibre. This start the chemical reaction within the muscle .

2. Sarcoplamic reticulum store intracellular calcium ion . When the muscle is stimulated , calcium ions are released from its store inside the sarcoplamic reticulum , into the sarcoplasm .

3. With adequate fuel and oxygen (aerobic) , muscle cell can contract repeatedly without fatigue . During anaerobic condition (higher intensity exercise) , muscle cells must rely on other reactions that donot require oxygen to fuel muscle contraction . The anaerobic metabolism in cells produce waste molecule that can impair muscle contractions (fatigue) .

4. In reflex action , when receptors of sensory organ sense the danger , they send signal through sensory neuron to spinal cord which passes the signal to other interconnected neurons . It is then received by relay neuron which is present in spunal cord . Immediately, spinal cord sends back signals to the muscle through motor neuron . And the muscle aatached to sense organ move the organ away from danger .