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Ch6 Muscles

the ability of skeletal muscle to shorten with force Contractility
the capacity of skeletal muscle the respond to a stimulus Excitability
the ability to be stretched Extensibility
Ability to recoil to their original resting length after they have been stretched Elasticity
Four major skeletal muscle characteristics Contractility, Excitability, Extensibility, and Elasticity
Each skeletal muscle is surrounded by a connective tissue sheath called the Epimysium
Connective tissue located outside the epimysium Fascia
A muscle is composed of numerous visible bundles called Muscle Fasciculi
Muscle fasciculi are surrounded by loose connective tissue called the Perimysium
Muscle cells Fibers
Each fiber is surrounded by a connective tissue sheath called the Endomysium
The cytoplasm of each fiber is filled with Myofibrils
Myofibrils consist of 2 major kinds of protein fibers Actin and myosin myofilaments
Thin myofilaments, pearls twisted together Actin
Thick myofilaments, bundles of golf clubs Myosin
Actin and myosin myofilaments form highly ordered units called Sarcomeres
Basic structural and functional unity of the muscle Sarcomere
Z line to Z line Sarcomere
Light area on each side of the z line I band
i bands consist of actin
darker region in each sarcomere a band
the a band extends the length of the myosin
the light area in the middle of the sarcomere h zone
h zone consists of myosin
dark staining band in the center of the sarcomere m line
charge difference across the membrane resting membrane potential
the brief reversal back of the charge action potential
nerve cells that carry action potentials to the skeletal muscle fibers motor nuerons
each branch that connects to the muscle forms a neuromuscular junction
another term for neuromuscular junction synapse
a single motor neuron and all the skeletal fibers it innervates motor unit
many motor units single muscle
formed by an enlarged nerve terminal resting in an identification of the muscle cell membrane neuromuscular junction
enlarged nerve terminal presynaptic terminal
space between the presynaptic terminal and the muscle cell synaptic cleft
muscle fiber postsynaptic terminal
each presynaptic terminal contains synaptic vesicles
synaptic vesicles secrete a neurotransmitter called acetylcholine
enzymes that break down acetocholine acetylcholinesterase
Occurs as actin and myosin myofilaments slide past one another causing the sarcomeres to shorten Contraction
The sliding of actin myofilaments past myosin myofilaments during contraction Sliding filament mechanism
A contraction of an entire muscle in response to a stimulus that causes the action potential in one or more muscle fibers Muscle twitch
A muscle fiber will not respond to stimulus until that stimulus reaches a level called Threshold
The muscle fiber will contract maximally All-Or-None Response
The time between application of a stimulus to a motor neuron and the beginning of a contraction Lag phase
The time of the contraction Contraction phase
The time during which the muscle relaxes Relaxation Phase
Where the muscle remains contracted without relaxing Tetany
The increase in number of motor units being activated Recruitment
Needed for energy for muscle contraction ATP (adenosine triphosphate
ATP is produced in the Mitochondria
ATP degenerates to the more stable plus phosphate ADP (adenosine diphosphate)
High energy molecule muscle cells store Creatine phosphate
Without oxygen Anaerobic respiration
With oxygen Aerobic respiration
The amount of oxygen needed in chemical reactions to convert lactic acid to glucose and to replenish the depleted stores of creatine phosphate store in muscle cells. Oxygen debt
Results when ATP is used during muscle contraction faster than it can be produced in the muscle cells. Muscle fatigue
2 types of muscle contractions Isometric and isotonic
Equal distance, tension increases Isometric
Equal tension, length changes Isotonic
Refers to constant tension produced by muscles of the body for long periods of time. Muscle tone
Contract quickly and fatigue quickly. Ex. white meat of chicken breasts Fast-twitch fibers
Contract more slowly and are more resistant to fatigue. Ex. dark meat of a duck's breast. Slow-twitch fibers
Muscle connects to bone Tendons
Most stationary end of the muscle Origin
The end of the muscle undergoing the greatest movement. Insertion
he portion of the muscle between the origin and the insertion Belly
Muscles that work together to accomplish specific movemens Synergists
Muscles that work in opposition to one another Antagonists
If one muscle plays the major role in accomplishing the desired movement it's the Prime mover
Muscles named according to their Location, size, orientation of fibers, shape, origin, insertion, and function.
Raises the eyebrows Occipitofrontalis
Closes the eyelids and causes “crows feet” wrinkles in the skin at the lateral corners of the eye. Orbicularis oculi
Puckers the lips Orbicularis oris
Flattens the cheeks. Trumpeter’s muscle. Buccinator
smilinh muscle zygomaticus
Created by: MikieB



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