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Stack #2644220

Muscle Cells Muscle Fibers
M -Line A dark band that anchors the myosin myofilaments in the center of the sarcomere
H- zone - Light area in the center of sacomere - consists of only myosin
A-band -extends the length of the myosin -darker central region in each sarcomere
I-band -each side of Z-line - consists of actin
The arrangement of actin and myosin give a _______ appearance. banded
basic structural and functional unit of the muscle sarcomeres
sarcomeres joined end to end to form the myofibril. (Z-line to Z-line)
myosin myofilaments thick myofilaments
actin myofilaments thin myofilaments
myofilaments consist of 2 major kinds of protein fibers -actin myofilaments - myosin myofilaments
minute small
four major functional characteristics -contractility -excitability -extensibility -elasticity
contractility the ability of skeletal muscle to shorten with force
excitability the capacity of skeletal muscle to respond to stimulus
extensibility the ability to be stretched
elasticity the ability to recoil to their original resting length after they have been stretched
epi upon
epimysium connective tissue that wraps the entire muscle
fascia another connective tissue located outside the epimysium. It surrounds and separates muscles.
fasciculi (fascicle) bundles of muscle
perimysium surrounds the fascicle
muscle fibers (fibers) single muscle cell
endomysium surrounds muscle fibers
myofibrils a thread-like structure that extends from one end of the fiber to the other
motor unit a single motor neuron and all skeletal muscle fibers it innervates
presynaptic terminal enlarged nerve terminal
synaptic cleft the presynaptic terminal and the muscle cell
postsynaptic terminal muscle fiber
synaptic vesicles secretes neurotransmitter called acetylcholine
acetylcholine a neurotransmitter
acetylcholinesterase enzymes that rapidly break down neuron and muscle cells
sliding filament mechanism the sliding of actin myfilaments past myosin myofilaments during contraction
muscle twitch a contraction of an entire muscle in response to a stimulus
threshold the point where muscle fibers contract maximally
all-or-none response when threshold is reached
lag phase time between application of a stimulus to a motor neuron and the beginning of a contraction
contraction phase time of contraction
relaxation phase the tie during which the muscle relaxes
tetany the muscle remains contracted without relaxing
recruitment the increase in number of motor units being activated
ATP -needed for energy for muscle contraction -produced in mitochondria -short-lived and unstable
creatine phosphate another high-energy molecule
anaerobic respiration without oxygen
aerobic respiration with oxygen (more efficient)
oxygen debt the amount of oxygen needed in chemical reactions to convert lactic acid to glucose
muscle fatigue results when ATP is used during muscle contraction faster than it can be produced in the muscle cells
2 types of muscle contractions - isometric -isotonic
isometric the length of the muscle doesn't change, but the amount of tension increases during the contraction process
isotonic 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 the muscle is constant during contraction
fast-twitch fibers contract quickly and fatigue quickly
slow-twitch fibers contract more slowly and are more resistant to fatigue
the points of attachment of each muscle are its _____ and ______ - origin - insertion
origin (head) the most stationary end of the muscle
insertion the end of the muscle undergoing the greatest movement
neuromuscular junction - each branch that connects to the muscle - near the center of the cell
platysma a sheet-like muscle that covers the anterolateral neck
sternocleidomastoid lateral neck muscle and prime mover
extrinsic tongue muscles move the tongue
intrinsic tongue muscle change of shape of the tongue
4 pairs of mastication 2 pairs of pterygoids, temporalis, and masseter
mastication chewing
depressor anguli oris frowning
levator labii superioris sneering
zygomaticus smiling muscle
buccinator flattens the cheeks
orbicularis oris puckers the lip
orbicularis oculi closes the eyelids and causes wrinkles to form
occipitofrontalis raises the eyebrow
prime mover one muscle playsa major role in accomplishing the desired 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
muscles are named according to their ____, ____, ____, ____, ____, ____, and ____ - location -size - orientation of fibers - shape - origin - insertion - function
motor neurons nerve cells that carry action potentials to skeletal muscle fibers
action potential the brief reversal back of the charge
resting membrane potential the charge difference across the membrane
Created by: hannah.workmannn