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Chapter 6 Muscles

Four major characteristics of skeletal muscle Contractility, excitability, extensibility, and elasticity.
What do muscles help to produce that is essential for maintenance of normal body temperature? Heat
Connective tissue sheath that surrounds each skeletal muscle Epimysium
Located outside epimysium, that surrounds & separates muscles. Fascia
A muscle is composed of numerous visible bundles called Fasciculi
Fasciculi are surrounded by loose connective tissue called the Perimysium
Each muscle fiber is surrounded by a connective sheath called Endomysium
A threadlike structure that extends from one end of the fiber to the other, the cytoplasm of each fiber is filled with this Myofibrils
2 major kinds of protein fibers Actin myofilaments, and myosin myofilaments
Thin myofilaments, resemble 2 minute strands of pearls twisted together. Actin myofilaments
Thick myofilaments, they resemble bundles of minute golf clubs. Myosin myofilaments
Actin and myofilaments form highly ordered units, which are joined end to end to form the myofibril Sarcomeres
Extends from one Z line to anoher Z line Sarcomere
The light area on each side of Z line I band
Darker central region of sarcomere A band
Nerve cells hat carry action potentials to skeletal muscle fibers Motor neurons
Neurotransmitter that diffuses across the synaptic cleft and binds to the postsynaptic terminal causing a change in the postsynaptic cell. Acetylcholine
The acetylcholine released into the synaptic cleft between the neuron and muscle cell is rapidly broken down by an enzyme Acetylcholinesterase
The sliding of actin myofilaments past myosin myofilaments during contraction is called 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 new level called ________, at which point the muscle fiber will contract maximally. This phenomenon is called the ___________. Threshold. All or none response.
The time between application of a stimulus to a motor neuron and the beginning of a contraction is the Lag phase
The time of contraction is called the Contraction phase.
Time during which muscle relaxes Relaxation phase
Where the muscle remains contracted without relaxing Tetany
The increase in number of motor units being activated is called Recruitment
Occipitofrontalis Raises 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. kissing muscle
Buccinator flattens cheeks. Trumpeter's muscles. kissing muscle.
Zygomaticus smiling muscle
Levator labii superioris sneering
Depressor anguli oris frowning
Mastication chewing. 4 pairs of mastication muscles. 2 pair of pterygoids, temporalis, and masteer.
Intrisic Tongue Muscles change the shape of the tongue
Extrinsic tongue muscles move the tongue
Thoraic muscles muscles that move the thorax
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. "swimmer muscles"
Deltoid attaches the humerus to the scapula and clavicle, and is the major abductor of the upper limb
Triceps brachii extends the forearm
Biceps brachii flexes the forearm
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
Quadriceps femoris extends the leg; anterior thigh muscles
Sartorius tailors muscle; flexes the thigh
Hamstring muscles posterior thigh muscles; flexes the leg and extends
Gastrocnemius and soleus form the calf muscle, join the calcaneal tendon. flex the foot and toes.
Basic structural and functional unit of the muscle Sarcomere
Each branch that connects to the muscle forms a __________ , or ________ , near the center of the cell. neuromusclular junction synapse
Needed for energy for muscle contraction. Produced in Mitochondria. Short-lived and unstable. ATP (adenosine triphospate)
ATP degenerates to the more stable ADP (adenosine diphosphate) plus phospate
When at rest, muscles can't stockpile ATP but they can store another high-energy molecule called Creatine phospate
Without oxygen anaerobic respiration
With oxygen (more efficient) Aerobic respiration
When ATP is used during muscle contraction faster than it is produced in the muscle cells Muscle fatigue
The length of the muscle does not change, but the amount of tension increases during contraction process Isometric
The amount of tension produced by the muscle is constant during contraction, but the length of the muscle changes Isotonic
Refers to constant tension produced by muscles of the body for long periods of time. Keeps head up and back straight muscle tone
Contract quickly and fatigue quickly, well adapted to to perform anaerobic metabolism fast-twitch fibers
Contract more slowly and are more resistant to fatigue. They are better suited for aerobic metabolism. slow-twitch fibers
most stationary end of the muscle origin
end of the muscle undergoing the greatest movement. insertion
portion of muscle between the origin and the insertion is the belly
Muscles that work together to accomplish specific movements are called synergists
muscles that work in opposition to one another are called antagonists
among a group of synergists, if one muscle plays the major role in accomplishing the desire movement, it is the prime mover
Erector spinae group of muscles on each side of the back, responsible for keeping the back straight and body erect
External intercostals elevate ribs during inspiration
Internal intercostals contract during forces expiration
Diaphragm accomplishes quiet breathing.
Dome-shaped muscle Aids in breathing.
Created by: Kassidymathis



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