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Where does the acetylcholine released for muscle contraction bind?
Sarcolema receptors
What is the contractile unit within a myofibril called?
The sarcomere is the contractile unit. It is the space between two Z discs that contains one group of myosin fillaments and two groups of actin fillaments, one group on each end of the myosin fillaments. Z discs join sarcomeres together end-to-end to form myofibrils. A group of myofibrils surrounded by the sarcolema makes up a muscle fiber.
What are the names of some common neurotransmitters?
Acetylcholine or aka ACH is the neurotransmitter that is released from the axon terminal to through the neuromuscular junction across the synaptic cleft which binds to the ACH receptors on the end motor plate of the Sarcolema.
How does muscle contractions?
It would be impossible for you to do anything without your muscles. Absolutely everything that you conceive of with your brain is expressed as muscular motion. The only ways for you to express an idea are with the muscles of your larynx, mouth and tongue (spoken words), with the muscles of your fingers (written words or "talking with your hands") or with the skeletal muscles (body language, dancing, running, building or fighting, to name a few). In order for a muscle fiber to contract there are several steps before getting a response. (obviously they happen at a high speed, so we don't notice it) but first the brain has to send a signal to the nerve, then an electrical impulse travels down the axon to the synapse, and acetylcholine (ACh) is released into the synapse, and goes onto the sarcolema and binds to the ACh receptor sites, then the sarcoplasmic reticulum releases calcium, and the calcium binds to troponin (top of actin) and troponin begins to change shape and tropomyosin slides off of the active sites and the sites then become available for myosin to bind on. Myosin then grabs onto actin and ratchets head to slide actin forward, myosin goes all the way down the line and ratchets all of actin until the muscle fiber is completely contracted.
How do muscles contracts?
Muscles are mainly composed of alternating rows of myosine protein filaments and actin protein filaments. When the muscle is relaxed those rows are least overlapped. When the nervous impulse commands the muscle to contract these rows overlap making the muscle shorter in length and causing a mechanical function.The muscle contraction process first happens by a motor neuron being activated. This produces an action potential that passes outward in a ventral root of the spinal cord where it is conveyed to a motor end plate on each muscle fiber. The action potential causes the release of packets of acetylcholine into the synaptic clefts on the surface of the muscle fiber. The acetylcholine causes the electrical resting potential under the motor end plate to change, and this then initiates an action potential which passes in both directions along the surface of the muscle fiber. At the opening of each transverse tubule onto the muscle fiber surface, the action potential spreads inside the muscle fiber. At each point where a transverse tubule touches part of the sarcoplasmic reticulum, it causes the sarcoplasmic reticulum to release Ca+2 ions. The calcium ions result in movement of troponin and tropomyosin on their thin filaments, and this enables the myosin molecule heads to "grab and swivel" their way along the thin filament. This is the driving force of muscle contraction.in order for a muscle fiber to contract there are several steps before getting a response. (obviously they happen at an unbelievable speed, so we don't notice it) but first the brain has to send a signal to the nerve, then an electrical impulse travels down the synaps, and Acetylcholine (ACh) is released into the synaps, and goes onto the sarcolema (but never touches) and binds to the ACh receptor cites, then the sarcoplasmic reticulum realeases calcium, and the calcium binds to troponin (top of actin) and troponin begins to change shape and tropomyosin slides off of the active cites and the cites then become available for myosin to bind on. Myosin then grabs onto Actin and ratchets head to slide actin forward, myosin goes all the way down the line and ratchets all of actin until the muscle fiber is completely contracted.Read more: [[Q/How does muscle contract#ixzz161moMP5D|How_does_muscle_contract]]
