Term
| How many types of muscles are there? |
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Definition
3 Skeletal, Smooth, and Cardiac.
They differ in structure, function, location and means of function |
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Term
| What are the muscle similarities? |
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Definition
| Skeletal and smooth muscles are elongated(long) and called muscle fibers. |
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Term
| What does contraction depend on? |
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Definition
| Actin(thin) and myosin(thick) |
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Term
| what are sarcolemma, sarcoplasm, and the prefixes? |
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Definition
| sarcolemma is muscle plasma membrane, sarcoplasm is the cytoplasm of a muscle cell. and prefixes is myo, sarco, and mys |
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Term
| what are the muscle characteristics? |
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Definition
| excitability where it receives and responds to stimulation. contractility - to shorten the muscle forcibly. extensibility is the ability to stretch. elasticity the ability to recoil and resume the original resting length |
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Term
| what are the muscle functions? |
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Definition
| the muscle is responsible for all locomotion. muscle generates posture, heat and stabilizes joints. cardiac muscle is responsible for coursing blood throughout the body. smooth muscle is responsible to maintain blood pressure , and squeezes or propels substances through organs. |
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Term
| what are the nerve and blood supplies to muscle |
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Definition
| each muscle has an artery, one nerve and one or more veins. each skeletal muscle is supplied with a nerve ending that controls contraction. contracting fibers require continuous deliver of oxygen and nutrients via arteries. waste is removed via veins |
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Term
| give me a brief explanation of the myofibril. |
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Definition
| the myofibril is a rod like that runs parallel to its length and is responsible for 80% of muscle volume. |
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Term
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Definition
| the smallest contractile unit of a muscle. the region of a myofibril with two z discs and made up of myofilaments with a thin and thick structure |
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Term
| what are the myofilament banding patterns like? |
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Definition
| the thick filament runs through the whole A band. the thin filaments extends through the i and fals slightly into the a band and the z disc are protein sheets that connect the myofibrils togheter and connects thin filaments |
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Term
| Give the ultra structure of the thick myofilaments |
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Definition
| The thick filaments are composed of the protein myosin. Each myosin molecule has a rodlike tail and two globular heads. the tails are made of two interwoven polypeptide chains, and the heads are two smaller, light polypeptide chains called cross bridges |
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Term
| give me the ultra structure of the thin myofilaments |
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Definition
| thiin structure is composed of actin. each actin molecule is composed of helical polymer of globular subunits called g actin. the subunits contains the active sites which myosin heads attach during contraction. tropomyosin and troponin are regulatory subunits bound to actin |
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Term
| explain sarcoplasmic reticulum |
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Definition
| sarcoplasmic reticulum is a long smooth endoplasmic reticulum that runs longitidunally and surrounds each myofibril. functions in the regulation of intracellular calcium levels. t tubules pair with the terminal cisternae to form triads |
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Term
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Definition
| t tubules run continousoly with the sarcolemma. they conduct impulses to the deepest regions of the muscle . these impulses release signal for the release of Ca2 from the terminal cisternae |
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Term
| sliding filament of contraction |
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Definition
thin filaments slide past the thick filament to overlap eachother to a greater degree. 2. in the relaxed state , thin and thick filaments overlap eachother slightly. 3.upon stimulation, myosin heads bind to the active sites of actin. 4. each myosin head attaches and detaches several times to cause tension and propel thin filaments to the center of the sarcomere.
as this event occurs throughout the sarcomeres, the muscle shortens |
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Term
| How does skeletal muscle contraction work? |
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Definition
| It needs to stimulated by a nerve ending. Needs an electrical impulse or action potential through its sarcolemma. Have a rise in intracellular Calcium ions, the final level of contraction. |
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Term
| _________ is linking the electrical signal to the contraction. |
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Definition
| Excitation-contraction coupling |
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Term
| how are nerves stimulated of the skeletal muscle? |
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Definition
skeletal muscles are stimulated by motor neurons from the somatic nervous system. axons in these nerves travel to muscle cells.
each axonal branch forms a neuromuscular junction for a single muscle cell. |
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Term
| how are neuromuscular junctions formed? |
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Definition
from axonal endings , membranous sacs(synaptic vessicles) that have neurotransmitter ach. the motor end plate of a muscle, part of the sarcolemma which have ach receptors and forms the neuromuscular junction.
though exceedingly close, axonal ends and muscle cells are seperated by the synaptic cleft |
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Term
| what happens when the nerve impulses reach the end of the axonal terminal? |
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Definition
calcium channels open allowing calcium ions to enter the axon
calcium ions fuse with the axonal membrane
This fusion releases ACh into the synaptic cleft via exocytosis
ACh diffuses across the synaptic cleft to ACh receptors on the sarcolemma
Binding of ACh to its receptors initiates an action potential in the muscle |
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Term
| what are the electrical conditions of a polarized sarcolemma? |
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Definition
| the outside face is postive and the inside face is negative. the difference in charge is the resting membrane potential. the predominant extracelular ion is sodium, and the predominant ion is potassium(K). the sarcolemma is relatively impermeable to both ions. |
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Term
| describe the depolarization and generation of the action potential. |
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Definition
an axon terminal of the motor neuron releases ach and causes a patch of sarcolemma to become permeable sodium. open sodium channels
Na+ enters the cell, and the resting potential is decreased (depolarization occurs)
If the stimulus is strong enough, an action potential is initiated |
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