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The sarcolemma is the capsule of fibrous tissue contianing striated muscles.
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∙ 13y ago
The sarcolemma is the cell membrane of a muscle fiber. It surrounds and protects the muscle fiber and controls the movement of substances into and out of the cell. The sarcolemma plays a crucial role in muscle contraction and the transmission of nerve impulses to the muscle fiber.
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T tubules are invaginations of the?
Sacrolemma
What is a sacrolemma?
sarcolemma is the plasma membrane of the muscle fiber (muscle cell)
What are the muscle fibers of a plasma membrane called?
I think it is the sacrolemma.
What is the sequence of electrical changes that occurs along the sacrolemma when a muscle fiber is stimulated?
action potential
Does muscle cell have cell wall?
Yes, it most certainly does. It is known as the sacrolemma
Microscopic anatomy of skeletal muscle?
1. Muscle2. Strands/Bundles3. Muscle Fibers (a.k.a. cells)4. Sacrolemma (plasma membrane)5. Sacroplasmic Reticulum (modified ER of cell / stores calcium / tubules that surround myofibrils)6. Myofibrils (have striations)7. Sacromeres (parts of Miofibils)8. Myofillaments~ Thick Myofilaments~ ~ Thin Myofilaments~- contain Myosin - contain Actin
Why is muscle excitable tissue?
Muscle is excitable because it can be stimulated in order to cause contraction. Stimulation comes from the nervous system via electric signals/action potential that travels from neuron through axon to muscle tissue.In-depth Details:Neuron sends action potential down its axonOnce reaching the muscle tissue, the action potential stimulates release of Ach (acetylcholine)Ach crosses the synapse and binds to a muscle fiber (cell of muscle tissue),This stimulates action potential on the sacrolemma (plasma membrane of muscle cell)Action potential travels on the sacrolemma until it reaches a T-tubuleAction goes down the T-tubule and into the muscle fiberThis stimulates release of Ca2+ (calcium) from the sarcolemmaCa2+ binds with troponinWhich stimulates tropomyosin to move out of the way so that actin and myosin can interactIf ATP is available from mitochondria in muscle fiber, cross-bridge cycle occursContraction of muscle stops when the muscle is no longer stimulated from the nervous system
When a muscle contracts what happens to it?
When our skeletal muscles in our bodies contract they shorten by a process known as the Sliding Filament Theory proposed by Huxley in the 1960's. What happens on a microscopic level is that short sections inside the muscle cells called sacromeres are arranged in long parallel rows and bundled together as long cords called myofibrils. As an action potential, electrical impulse, travels down the cell membrane of the muscle cell, the sacrolemma, the impulse causes calcium to be released and unlock binding sites on the actin filaments so that the myosin heads can attach and pull the actin filaments closer together. These actin and myosin filament are inside all the sarcomeres. When the energy stored in the ATP (adenosine triphosphate) molecule is released, the result is muscle contraction. On a larger scale the muscle has an origin, a an attachment to a more stable structure, usually to bone. And another end that is attached to a structure that is less satble and can move more easily. This is usually another bone and called the insertion site. When the muscle contracts, the joint between the two attachments acts as a lever and causes motion that moves that part of the body. *copied from a different question to help you out*
What happens when the cardiac muscles contract?
Cardiac muscle contracts and relaxes automatically without you having to think about it. When you take exercise your heart beats faster and with a bigger volume. This increase in cardiac output (how fast the blood is pumped around your body) is produced by a hormone called adrenaline. The vagus nerve can make the heart go slower; this happens when you are sitting or lying down.
What are the steps in sliding filament theory?
Before contraction:1) no nerve impulse to myoneural junction.2) Ca++ in the sarcoplasmic reticulum3) combining of actin and myosin is prevented by a tropomyosin-troponin complex that attatches to the actin.Contraction:1) an action potential (nerve impulse) travels along a neural axon to a myoneural junction (synapse)2) Acetylcholine (neurotransmitter) is released from the synaptic vesicles of the neuron.3) acetylcholine diffuses over into the sacrolemma and the t-tubules.4) Ca++mis released from the sarcoplasmic reticulum.5) the Ca++ then binds to the actin degrading the tropomyosin-troponin complex to expose myosin attatchment sights6) the heads of the myosin myofilaments attatch to the exposed attatchment sights on actin filament7) ATP binds to the heads of the myosin filaments. breakdown of the ATP to ADP+p releases energy and causes a bending of myosin heads.8) another ATP binds to the myosin head causing it to release the actin filament then attatch again with the head unbent. again the ATP breaks down and the process continues.To relax:1) nerve impulse stops2) active transport returns Ca++ to the sarcoplasmic reticulum3) ATP's are reformed (ADP+P+energy=ATP)4) Tropomyosin-troponin complex reforms causing the myosin to release the actin5) when the filaments release each other they slide back to the resting position.
