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Uponmuscle contraction
, the A-bands do not change their length (1.85 micrometer in mammalian skeletal muscle) whereas the I-bands and the H-zone shorten.
The protein tropomyosin covers the myosin binding sites of the actin molecules in the muscle cell. To allow the muscle cell to contract, tropomyosin must be moved to uncover the binding sites on the actin. Calcium ions bind with troponin-C molecules (which are dispersed throughout the tropomyosin protein) and alter the structure of the tropomyosin, forcing it to reveal the cross bridge binding site on the actin. The concentration of calcium within muscle cells is controlled by thesarcoplasmic reticulum
, a unique form of endoplasmic reticulum. Muscle contraction ends when calcium ions are pumped back to the sarcomere. Once Calcium goes back into the sarcoplasmic reticulum, muscle relaxation starts.
During stimulation of the muscle cell, themotor neuron
releases the neurotransmitter acetylcholine which travels across the neuromuscular junction (the synapse between the terminal bouton of the neuron and the muscle cell). Acetylcholine binds to a post-synaptic nicotinic acetylcholine receptor. A change in the receptor conformation allows an influx of sodium ions and initiation of a post-synaptic action potential. The action potential then travels along T (transverse) tubules until it reaches the sarcoplasmic reticulum; the action potential from the motor neuron changes the permeability of the sarcoplasmic reticulum, allowing the flow of calcium ions into the sarcomere. The outflow of calcium allows the myosin heads access to the actin cross bridge binding sites, permitting muscle contraction.
Source(s):wikipedia "sarcomere"the sarcomere is the functional unit of the muscle cell
utube "sarcomere" would give you a visual
Do actin and myosin shorten during muscle contraction?
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What does myosin attach to?
During muscle contraction, myosin cross bridges attach to active sites of ACTIN FILAMENTS.
When do you see glycerinated muscle shorten?
Glycerinated muscle can shorten when ATP is present, allowing myosin cross-bridges to form and generate force. However, once ATP is depleted or unavailable, glycerinated muscle cannot shorten as it lacks the energy to power the cross-bridge cycling.
Neurotransmitter that triggers muscle contraction?
Acetylcholine (ah-Seh-til-KO-leen) is the organic molecule that triggers muscle contractions in humans. Acetylcholine acts on both the central nervous system (CNS) and on the peripheral nervous system (PNS). It is also the principal neurotransmitter in autonomic ganglia.
When you feel like urinating when does it pass out?
When you relax the muscle at the base of the bladder. The control of this muscle is learnt as a child, during potty training.
Where is ATPase enzyme needed for muscle contraction located?
It is in the mitochodria and speeds up the formation of ATP by breaking down ATP into ADP + energy. Muscle cells have many more mitochrondia than other cells.
What band shortens during skeletal muscle contraction?
during skeletal muscle contraction ,I band and H zone shortens. Sarcomeres
Is it true The more a muscle shortens during a contraction then the greater the power of the muscle?
No it is not true.
Which region of a sarcomere shortens during contraction?
During a contraction, the I bands and H zone of a sarcomere contract. The A bands remain unchanged.
What shortens muscle contraction?
myofibrils
What is a concentric contraction?
concentric contraction is atype of muscle contraction which the muscle shortens while genrating aforce The muscle shortens to produce movement. A muscle contraction in which shortening occurs.
A contraction in which the muscle shortens and work is done?
B. isotonic contraction
What contraction that shortens the muscle but does not increase tension is called?
It is called concentric isotonic contraction.
What shortens contraction?
The interaction between actin and myosin filaments in muscle cells shortens the sarcomere during a contraction. Calcium ions released from the sarcoplasmic reticulum trigger this interaction, leading to the sliding of actin filaments over myosin filaments and shortening of the muscle fiber.
In an isotonic contraction the muscle?
shortens while maintaining constant tension.
When a muscle shortens it means what?
It is called a concentric contraction. The muscle gets shorter in preparation to do work.
What does contraction mean in medical terms?
contract or "contraction" is when a muscle fiber lengthens or shortens
What is an example of an isotonic contraction?
An Isotonic contraction is when a muscle becomes longer or shorter to produce force and therefore an example is a bicep curl. During the downward phase your muscle (bicep) lengthens and during the upward phase your muscle (bicep) shortens.
