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Chapter 6 - Muscles
flash cards
| Term | Definition |
|---|---|
| four major functional characteristics | contractility, excitability, extensibility, elasticity |
| contractility | ability of skeletal muscle to shorten with force |
| excitability | capacity of skeletal muscle to respond to a stimulus |
| extensibility | ability to be stretched |
| elasticity | ability to recoil to their original resting length after they have been stretched |
| muscles do what ? | help to produce heat essential for maintenance of normal body temperature |
| epimysium | connective tissue sheath surrounding each skeletal muscle |
| fascia | connective tissue located outside the epimysium. it surrounds & separates muscles. |
| muscle is composed of ? | numerous visible bundles |
| perimysium | loose connective tissue surrounding fascicle |
| fasciculi composed of ? | single muscle cells |
| fibers | single muscle cells |
| muscle fiber | single cylindrical cell containing several nuclei |
| endomysium | connective tissue sheath surrounding each fiber |
| myofibrils | thread like structure that extends from one end of the fiber to the other. also the cytoplasm of each fiber is filled with it |
| 2 major kinds of protein fibers in myofibrils | actin myofilaments, myosin myofilaments |
| actin myofilament | thin myofilaments, resemble 2 minute strands of pearls twisted together |
| myosin myofilaments | thick myofilaments, resemble bundles of minute gold clubs |
| sarcomeres | highly ordered units formed by actin & myosin myofilaments |
| myofibril made how ? | sarcomeres joined end to end |
| sarcomere is ? | basic structural & functional unity of the muscle |
| motor neurons | nerve cells that carry action potentials to skeletal muscle fibers |
| resting membrane potential | charge difference across a membrane |
| action potential | brief reversal back of a charge |
| neuromuscular junction | chemical synapse formed by the contact between a motor neuron and a muscle fiber. |
| motor unit | single motor neuron and all the skeletal muscle fibers it innervates |
| synaptic cleft | space between the presynaptic terminal |
| presynaptic terminal | enlarged nerve terminal |
| postsynaptic terminal | muscle fiber |
| synaptic vesicles | store various neurotransmitters that are released at the synapse. |
| acetylcholine | neurotransmitter |
| acetylcholinesterase | enzyme |
| sliding filament mechanism | sliding of actin myofilaments past myosin myofilaments during contraction |
| muscle twitch | contraction of an entire muscle in response to a stimulus that causes the action potential in one or more muscle fiber |
| threshold | which point the muscle fiber will contract maximally |
| all or none response | phenonmenon |
| lag phase | time between application of a stimulus to a a motor neuron an the beginning of a contraction |
| contraction phase | time of contraction |
| relaxation phase | time during which the muscle relaxes |
| tetany | where the muscle remains contracted without relaxing |
| recruitment | increase in number of motor units being activated |
| ATP | adenosine triphosphate |
| ATP is produced where | mitochondria |
| ADP | adenosine diphosphate |
| creatine phosphate | high energy molocule |
| anaerobic repsiration | without oxygen |
| aerobic respiration | with oxygen |
| oxygen debt | 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 |
| muscle fatigue | results of when ATP is used during muscle contraction faster than it can be produced in the muscle cells |
| isometric | length of muscle does not change, but the amount of tension increases during the contraction process |
| isotonic | 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 of time |
| fast twitch fibers | contract quickly & fatigue quickly |
| slow twitch fibers | contract more slowly & are more resistant to fatigue |
| origin ( head ) | most stationary end of the muscle |
| insertion | end of the muscle undergoing the greatest movement |
| belly | portion of the muscle between the origin& the insertion |
| muscles have multiple.. | origins or heads |
| synergists | muscles that work together to accomplish specific movements |
| antagonists | muscles that work in opposition to one another |
| prime mover | muscle that plays the major role in accomplishing the desired movement |
| glucose | simple sugar which is an important energy source in living organisms and is a component of many carbohydrates. |
| molecules | group of atoms bonded together |
| how to describe muscles | location, size, orientation of fibers, shape, origin, insertion, & function |
| Occipitofrontalis | moves 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 |
| Zygomaticus | smiling muscle |
| Levator labii superioris | sneering |
| Depressor anguli oris | frowning |
| Intrinsic Tongue Muscles | change the shape of the tongue |
| Extrinsic Tongue Muscles | move the tongue. |
| Sternocleidomastoid | lateral neck muscle and prime mover |
| Erector spinae | group of muscles on each side of the back |
Created by:
lynzie.rae
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