Ch. 6 Muscles

Ch. 6 Muscles

Question Answer
Contractility shorten with force
Excitability the capacity of skeletal muscle to respond to a stimulus.
Extensibility the ability to be stretched
Elasticity ability to recoil their original resting length after they have been stretched
epimysium A connective tissue sheath
fascia A connective tissue (located outside the epimysium) that surrounds and separates muscle
perimysium A loose connective tissue that surrounds the fasciculi muscles (numerous bundles that make up muscle)
fibers single muscle cells
endomysium Connective tissue sheath that surrounds each fiber
myofibrils fills the cytoplasm of each fiber and it is a threadlike structure that extends from one end of the fiber to another,
actin myofilaments thin myofilaments
myosin myofilaments thick myofilaments
sarcomeres actin and myosin myofilaments form highly ordered units
resting membrane potential the charge difference across the membrane
action potential the brief reversal back of the charge
motor neurons nerve cells that carry action potentials to skeletal muscle fibers
neuromuscular junction Each branch that connects to the muscle
synapse near the center of the cell
motor unit a single motor neuron and all the skeletal muscle fibers it innovates
presynaptic terminal the enlarged nerve terminal
synaptic cleft the space between the presynaptic terminal and the muscle cell
postsynaptic terminal the muscle fiber
synaptic vesicles they secrete a neurotransmitter called acetylcholine
acetylcholine a neurotransmitter
acetylcholinesterase The acetylcholine released into the synaptic cleft between the neuron and muscle cell is rapidly broken down by an enzymes
sliding filament mechanism The sliding of actin myofilaments past myosin myofilaments during contraction
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.
threshold A muscle fiber will not respond to stimulus until that stimulus reaches a level called threshold
all-or-none response the muscle fiber will contract maximally
lag phase The time between application of a stimulus to a motor neuron and the beginning of a contraction
contraction phase The time of contraction
relaxation phase The time during which the muscle relaxes
tetany the muscle remains contracted without relaxing
recruitment The increase in number of motor units being activated
creatine phosphate When at rest they can’t stockpile ATP but they can store another high-energy molecule
anaerobic respiration without oxygen
aerobic respiration with oxygen
oxygen debt 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.
muscle fatigue ATP is used during muscle contraction faster than it can be produced in the muscle cells.
isometric muscle contraction the length of the muscle does not change, but the amount of tension increases during the contraction process.
isotonic muscle contraction the amount of tension produced by the muscle is constant during contraction, but the length of the muscle changes.
Muscle tone constant tension produced by muscles of the body for long periods of time
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 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
prime mover one muscle plays the major role in accomplishing the desired movement
occipitofrontalis raises the eyebrows
orbicularis oculi closes the eyelids and causes 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
mastication chewing
intrinsic tongue muscles change the shape of the tongue
extrinsic tongue muscles move the tongue
sternocleidomastoid lateral neck muscles and prime mover
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
Triceps brachii extends the forearm
Biceps brachii flexes the forearm. Occupies the anterior compartment of the arm
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
Gluteus medius hip muscle and common injection site.

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