Question

Give a brief detail of the physiologic steps to muscle contraction. Explain with support of the appropriate chapters in your book.

We have multiple important muscles or muscle groups in the body. Chose one of the following and detail its attachment, insertion, the part of the body it moves, and anything else of particular importance: quadriceps; biceps; triceps; hamstrings; gluteus maximus; gluteus minimus; gastrocnemius; Sartorius; rotator cuff; pectorals; wrist flexors; wrist extensors; or tibialis anterior. Explain with support of the appropriate chapters in your book.

There are multiple types of cells in the nervous system. Choose one and detail its functions, shape, and anything special or particular about that type of cell. Explain with support of the appropriate chapters in your book.

Answer 1

Answer 1:)

Muscle contractions are divided into the following steps:

1. Muscle activation: The motor nerve rouses an action potential (impulse) to clear down a neuron to the neuromuscular junction. This activates the sarcoplasmic reticulum to discharge calcium into the muscle cell.

As excitation happens, contraction is also caused. This happens due to the release of Ca2+ ions inside the cells. It has the following steps:

1. The signal is augmented by the CICR (Calcium-induced calcium release) mechanism that initiates greater discharge of Ca2+ from the sarcoplasmic reticulum.
2. As Ca2+ arrives at the cells via L-type channels, the ryanodine receptors alter conformation and tempt a larger discharge of Ca2+ from plentiful SR stores.
3. Bulky levels of intracellular Ca2+ perform on tropomyosin complexes to prompt myocyte contraction.

Now, Ca2+ binds to TnC → TnI is inhibited → conformational change in tropomyosin that exposes active site between actin and myosin.

2. Muscle contraction: Calcium deluges into the muscle cell tie with troponin letting actin and myosin to bind. The actin-myosin cross-bridges attach and contract using ATP as energy. It includes the following steps:

1. Adenosine triphosphate (ATP) binds with the actin-myosin bridge. The bridge then is dissociated. This can be show as the given equation: (Actin = A, Myosin= M, actin-myosin bridge= A-M, inorganic phosphate= pi, Adenosine diphosphate = ADP)

A-M + ATP === A + M + ADP + Pi + Energy.

2. Now, Myosin Bridge moves towards actin for reattachment. This requires energy, during this step, myosin hydrolyzes the ATP to release ADP, Pi, and energy.

M + ATP ==== M+ ADP + Pi + Energy

3. Now all three products; actin, myosin, and ATP hydrolyzed products attached to each other and form a rigor complex.

3. Recharging: ATP is re-manufactured letting actin and myosin to uphold their strong binding state.

4. Relaxation: Relaxation happens when stimulation of the nerve halts. Calcium is then drove back into the sarcoplasmic reticulum breaching the link amid actin and myosin. Actin and myosin come back to their unbound state affecting the muscle to relax. Instead, relaxation will also happen when ATP is no longer obtainable.