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Chapter 6 - Muscles

flash cards

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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