1. Define responsiveness, conductivity, contractility, extensibility, and elasticity. State why each of these properties is necessary for muscle function. a. Responsiveness- is a property of all living cells- Muscle and nerve cells have developed this property to the highest degree. When stimulated by chemical signals, stretch, and other stimuli, muscle cells respond with electrical changes across the plasma membrane. b. Conductivity- Stimulation of a muscle cell produces more than a local effect- The local electrical change triggers a wave of excitation that travels rapidly along the cell and initiates processes leading to contraction. c. Contractility-Muscle cells are unique in their ability to shorten substantially when stimulated.-This enable them to pull on bones and other organs to create movement. d. Extensibility- In order to contract, a muscle cell must alson be extensible able to stretch again between contractions.- Most cells rupture if they are stretched even a little, but skeletal muscle cells can stretch to as much as three times their contracted length. e. Elasticity- When a muscle cell is stetched and then released, it recoils to a shorter length.- If it were not for this elastic recoil, resting muscles would be too slack. 2. How is skeletal muscle different from the other types of muscle? f. Skeletal muscle may be defined as voluntary striated muscle that is usually attached to one or more bones. A skeletal muscle exhibits alternating light and dark transverse bands, or striations that result from an overlapping arrangement of their internal contractile proteins. Skeletal muscle is called voluntary because it is usually subject to conscious control. The other types of muscle are involuntary (not usually under conscious control ), and they are never attached to bones. 3. Name and define the three layers on collagenous connective tissue in a skeletal muscle. g. Endomysium-that surrounds each muscle fiber
h. Perimysium- that bundles muscel fibers together into fascicles i. Epimysium- that encloses the entire muscle.
4. What special terms are given to plasma membrane, Cytoplasm, and smooth ER of a muscle cell? j. Plasma membrane-Sarcolemma
k. Cytoplasm- Sarcoplasma
l. Smooth ER- Sarcoplasic Reticulum (SR)
5. What is the difference between a myofilament and a myofibril? m. The myofibril is a bundle of parallel protein microfilaments call myofilaments. So the myofilaments are bundle inside of the mypfibril 6. List five proteins of the myofilaments and a myofibril. n. Myofilament proteins- 1. Myosin, 2 Fibrous(F) actin, 3 Tropomyosin, 4 Troponin, 5 Titin o. Myofibril protein- Cystoskeletal proteins.
7. Sketch the overlapping pattern of myofilaments to show how they account for the A bans, Ibands, H bands, and Z discs.
8. What differences would you expect to see between a motor unit where muscular strength is more important than fine control and another motor unit where fine control is more important? p. Between a motor unit where muscular strength is more important than fine control-where strength is more important than fine control, we have a large motor units, example muscle of the calf q. Where fine control is needed we have small motor units, example eyemovements 9. Distinguish between acetylcholine, and acetylcholine receptor, and acetylcholinesterase. State where each is found and describe the function it serves. r. Acetylcholine-The synaptic knob contains spheroidal organells called synaptic vesicles, which are filled with a chemical called acetylcholine (Ach) one of the many neurotransmitters. The electrical signal (nerve impulse) traveling down a nerve fiber cannot cross the synaptic cleft like a spark jumping between two electrodes-rather, it cause the synaptic vesicles to undergo exocytosis, releasing Ach into the cleft. Ach functions as...
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