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Chapter 6
Muscles
| Term | Definition |
|---|---|
| 1. Contractility | the ability of skeletal muscle to shorten with force. |
| 2. Excitability | the capacity of skeletal muscle to respond to a stimulus. |
| 3. Extensibility | the ability to be stretched |
| 4. Elasticity | ability to recoil to their original resting length after they have been stretched. |
| Muscles help to produce... | heat essential for maintenance of normal body temperature. |
| epimysium | 1. Each skeletal muscle is surrounded by a connective tissue sheath |
| 2. Fascia | is another connective tissue located outside the epimysium. It surrounds and separates muscles. |
| perimysium. | 3. A muscle is composed of numerous visible bundles called muscle fasciculi (fascicle), which are surrounded by loose connective tissue |
| fibers | 4. The fasciculi are composed of single muscle cells |
| endomysium. | 6. Each fiber is surrounded by a connective tissue sheath |
| myofibrils | a threadlike structure that extends from one end of the fiber to the other. |
| a. actin myofilaments | thin myofilaments. They resemble 2 minute strands of pearls twisted together. |
| b. myosin myofilaments | thick myofilaments. They resemble bundles of minute golf clubs. |
| sarcomeres | 9. Actin and myosin myofilaments form highly ordered units |
| I band | 13. On each side of the Z line is a light area it consists of actin. |
| A band | extends the length of the myosin. It is the darker central region in each sarcomere. |
| Z line | is an attachment site for actin |
| resting membrane potential. | The charge difference across the |
| action potential. | The brief reversal back of the charge |
| 1. Motor neurons | are nerve cells that carry action potentials to skeletal muscle fibers |
| neuromusclular junction, or.... | synapse |
| Each branch that connects to the muscle forms.... | neuromusclular junction |
| near the center of the cell | synapse |
| motor unit | 3. A single motor neuron and all the skeletal muscle fibers it innervates |
| presynaptic terminal | 5. The enlarged nerve |
| the space between the presynaptic terminal and the muscle cell is the... | synaptic cleft |
| the muscle fiber is the | postsynaptic terminal |
| 6. Each presynaptic terminal contains | synaptic vesicles |
| synaptic vesicles secrete a neurotransmitter called | acetylcholine |
| The acetylcholine released into the synaptic cleft between the neuron and muscle cell is rapidly broken down by an enzymes | acetylcholinesterase |
| sliding filament mechanism | 2. The sliding of actin myofilaments past myosin myofilaments during contraction |
| The H and I bands shorten, but the A bands do not change | in length. |
| 3. Muscle twitch | is a contraction of an entire muscle in response to a stimulus that causes the action potential in one or more muscle fibers. |
| 4. A muscle fiber will not respond to stimulus until that stimulus reaches a level called | threshold |
| the muscle fiber will contract maximally. This phenomenon is called the | all-or-none response. |
| 5. The time between application of a stimulus to a motor neuron and the beginning of a contraction is the | lag phase |
| 6. The time of contraction is | contraction phase |
| 7. The time during which the muscle relaxes is the | relaxation phase |
| 8. If successive stimuli are given you get successive twitches that occur so frequently the muscle doesn’t have time to | fully relax. |
| 9. Tetany | where the muscle remains contracted without relaxing |
| 10. The increase in number of motor units being activated is called | recruitment. |
| is needed for energy for muscle contraction. | 1. ATP (adenosine triphosphate) |
| is produced in the mitochondria | ATP |
| is short-lived and unstable | ATP |
| When at rest they can’t stockpile ATP but they can store another high-energy molecule, called | creatine phosphate. |
| 6. Anaerobic respiration | without oxygen |
| 7. Aerobic respiration | with oxygen (more efficient). |
| 3. ATP is short-lived and unstable. It degenerates to the more stable | ADP (adenosine diphosphate) plus phosphate |
| 4. It is necessary for muscle cells to constantly produce | ATP |
| oxygen debt | is the amount of oxygen needed in chemical reactions to convert lactic acid to glucose and to replenish the depleted stores of creatine phosphate stores in muscle cells. |
| 9. Muscle fatigue | results when ATP is used during muscle contraction faster than it can be produced in the muscle cells. |
| 10. 2 types of muscle contractions: | a. isometric,b. isotonic |
| a. isometric (equal distance) | the length of the muscle does not change, but the amount of tension increases during the contraction process. |
| b. isotonic (equal tension) | the amount of tension produced by the muscle is constant during contraction, but the length of the muscle changes. |
| 11. Muscle tone | Muscle tone refers to constant tension produced by muscles of the body for long periods of time |
| 11. Muscle tone keeps | Keeps head up and back straight. |
| 12. Fast-twitch fibers | contract quickly and fatigue quickly |
| Ex. white meat of a chicken’s breast. | 12. Fast-twitch fibers |
| 13. Slow-twitch fibers | contract more slowly and are more resistant to fatigue |
| . Ex. dark meat of a duck’s breast or the legs of a chicken | 13. Slow-twitch fibers |
| 1. The points of attachment of each muscle are | its origin and insertion |
| At these attachment points the muscle is connected to the bone | by a tendon. |
| 2. The origin (head) | is the most stationary end of the muscle. |
| 3. The insertion | is the end of the muscle undergoing the greatest movement. |
| 4. The portion of the muscle between the origin and the insertion is the | belly. |
| 6. Muscles that work together to accomplish specific movements are called | synergists. |
| 7. Muscles that work in opposition to one another are called | antagonists. |
| 8. Among a group of synergists, if one muscle plays the major role in accomplishing the desired movement, it is the | prime mover. |
| Some are named according to their | location, size, orientation of fibers, shape, origin, insertion, and function, etc. |
| Occipitofrontalis | raises the eyebrows |
| Orbicularis oculi | closes the eyelids and causes “crows feet” wrinkles in the skin at the lateral corners of the eye. |
| Orbicularis oris | puckers the lips |
| Buccinator | flattens the cheeks. Trumpeter’s muscle. |
| Zygomaticus | smiling muscle. |
| Levator labii superioris | sneering |
Created by:
tiffanykane
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