Question

1.) What is the importance of acetylcholinesterase in the neuromuscular junction?

A. it breaks down acetylcholine immediately after the neurotransmitter signals a contraction

B. it breaks down acetylcholine to signal the muscle fiber to extend

C. it ensures that multiple twitches are produced from a single stimulation

D. it prevents stimulation of muscle fibers

2.) In a sarcomere, the thin filaments are ______.

A. composed of slow oxidative fibers

B. the central part of an A band

C. the portion of a sarcomere that creates the dark-staining portions of the striations

D. the region made of myosin filaments

E. the region where calcium ions bind

3.) Rhabdomyolysis is ______.

A. an inherited sex-linked recessive disorder of muscle weakness leading to death

B. a mysterious chronic pain syndrome of unknown cause that results in fatigue

C. a condition in which myoglobin pours crushed muscle tissue into the bloodstream, causing renal failure

D. a common pain syndrome by tightened bands of muscle fiber

Answer 1

1. it breaks down acetylcholine immediately after the neurotransmitter signals a contraction.

Acetyl choline is a neurotransmitter release from pre synaptic neuron into the synaptic cleft,which bindes to the Acetyl choline receptors in the post synaptic neuron.This binding is essential for depolarisation of post synaptic membrane and occurance of muscle contraction.

Acetyl choilne esterase are the Enzymes that breakdown acetyl choline,Soon after the Muscle contraction occur,SO that repeated stimulation of post synaptic neuron by same acetyl choline molecule will not occur.

2.Option E-The region where calcium ions bind

In a Relaxed muscle,Tropomyosin molecules masks the Myosin binding Site on actin molecule.But During Stimulus,When action potential Reach the Motor End plate,the released ca2+ Binds to Troponin molecules on the Actin molecules.This troponin molecules are in contact with Tropomyosin molecule,so Binding of Ca2+ on troponin molecule induces Change in shape of Troponin molecule so that Tropomyosin gets moved from the myosin binding sites on Actin molecule.

In a sarcomere Thin filaments are Made up of Actin molecules & thick filaments are made of Myosin molecules.

H zone is The central part of A band-This is the region of thick filaments which is not overlapped by the actin filaments.

Dark-staining portions of the striations are formed by thick filaments,Thin filaments forms light staining region.

3.C. a condition in which myoglobin pours crushed muscle tissue into the bloodstream, causing renal failure

Rhabdomyolysis is the condition in which there is breakdown of damaged skeletal muscle. Muscle breakdown will lead to the release of myoglobin((the protein that stores oxygen in your muscles) into bloodstream. Too much myoglobin in the bloodcan lead to kidney damage.