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Chapter 6 (Muscles)
| Question | Answer |
|---|---|
| Contractility | the ability of skeletal muscle to shorten with force |
| Excitability | the capacity of skeletal muscle to respond to a stimulus |
| Extensibility | the ability to be stretched |
| Elasticity | ability to recoil to their original resting length after they have been stretched |
| Endomysium | a connective tissue sheath that surrounds muscle fiber |
| Perimysium | loose connective tissue that surround muscle fascicle |
| Fascia | connective tissue located outside the epimysium that surrounds and separates muscles |
| Epimysium | connective tissue sheath that surrounds each skeletal muscle |
| Myofibrils | a threadlike structure that extends from one end of the fiber to the other |
| Actin Myofilaments | thin myofilaments that resemble two strands of pearls twisted together |
| Myosin Myofilaments | thick myofilaments that resemble bundles of golf clubs |
| Sarcomeres | formed by actin and myosin myofilaments that create highly ordered units which are joined end to end to form myofibril |
| Z Line | attachment site for actin |
| I band | thin filaments that only consists of actin |
| A band | the darker central region of each sarcomere and extends the length of the myosin |
| H Zone | another light area located in the center of each sarcomere that only consists of myosin |
| M Line | a dark staining band that myosin myofilaments are anchored to in the center of the sarcomere |
| Resting membrane potential | the charge difference across the cell membrane |
| Action potential | the brief reversal back of the charge of a stimulated muscle cell |
| motor neurons | nerve cells that carry action potentials to skeletal muscle fibers |
| Neuromusclular junction (synapse) | what the muscle forms when the axon branch connects to it |
| Motor unit | a single motor neuron and all the muscle fibers it innervates |
| Presynaptic terminal | the enlarged nerve terminal |
| Synaptic cleft | the space between the presynaptic terminal and the muscle cell |
| Postsynaptic terminal | Membrane region of a cell containing receptor sites for neurotransmitters. The muscle fiber. |
| Synaptic vesicles | located in each presynaptic terminal that secretes a neurotransmitter called acetylcholine |
| When an action potential reaches the nerve terminal what does it do? | it causes the synaptic vesicles to release acetylcholine into the synaptic cleft by exocytosis |
| The acetylcholine released into the synaptic cleft between the neuron and muscle cell is rapidly broken down by an enzymes called | acetylcholinesterase |
| Muscle contraction | occurs as actin and myosin myofilaments slide past one another causing the sarcomeres to shorten |
| Sliding filament mechanism | the sliding of actin myofilaments past myosin myofilaments during contraction |
| What happens to the bands during sliding filament mechanism | the H and I bands shorten but the A bands do not change in length |
| 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 |
| A muscle fiber will not respond to a stimulus until that stimulus reaches the | threshold |
| What is it called when the muscle fiber contracts maximally once it reaches the threshold? | all-or-none response |
| Lag phase | the time between application of a stimulus to a motor neuron and the beginning of a contraction |
| Tetany | where the muscle remains contracted without relaxing |
| Anaerobic respiration | without oxygen |
| Aerobic respiration | with oxygen |
| Muscle fatigue | results when ATP is used during muscle contraction faster than it can be produced in the cells |
| isometric | (equal distance) the length of the muscle does not change, but the amount of tension increases during the contraction process |
| Isotonic | (equal tension) the amount of tension produced by the muscle is constant during contraction, but the length of the muscle changes |
| Muscle tone | muscle tone refers to constant tension produced by muscles of the body for long periods. keeps head up and back straight |
| Fast-twitch fibers | contract quickly and fatigue quickly |
| Slow-twitch fibers | contract more slowly and are more resistant to fatigue |
| Origin | (head) is the most stationary end of the muscle |
| insertion | is the end of the muscle undergoing the greatest movement |
| Belly | the portion of the muscle between the origin and the insertion |
| Synergists | muscles that work together to accomplish specific movements |
| Antagonists | muscles that work in opposition to one another |
| Among a group of synergists, if one muscle plays the major role in accomplishing the desired movement, it is the | prime mover |
| 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 (part of the kissing muscles) |
| Zygomaticus | smiling muscle |
| Levator labii superioris | sneering |
| Depressor anguli oris | frowning |
| Mastication | chewing |
| Sternocleidomastoid | lateral neck muscle and prime mover |
| Erector spinae (trunk muscle) | group of muscles on each side of the back. Responsible for keeping the back straight and the body erect |
| Trapezius | rotates scapula |
| serratus anterior | pulls scapula anteriorly |
| Pectoralis major | adducts and flexes the arm |
| Latissimus dorsi | medially rotates, adducts, and powerfully extends the arm |
| Deltoid | attaches the humerus to the scapula and clavicle, and is the major abductor of the upper limb |
| triceps brachii | extends the forearm |
| biceps brachii | flexes the forearm |
| brachialis | flexes forearm |
| brachioradialis | flexes and supinates the forearm |
| Flexor carpi | flexes the wrist |
| extensor carpi | extends the wrist |
| flexor digitorum | flexes the fingers |
| extensor digitorum | extends the fingers |
| Gluteus maximus | buttocks |
| Quadriceps femoris | extends the leg |
| Sartorius | "tailors muscle" flexes the thigh |
| Hamstring muscles | posterior thigh muscles; flexes the leg and extends the thigh |
| Peroneus | the lateral muscles of the leg |
Created by:
korie.noble
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