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Chapter 6: Muscles

Contractility The ability of skeletal muscles to shorten with force.
Excitability The capacity of skeletal muscles to respond to a stimulus.
Extensibility The ability to be stretched.
Elasticity The ability to recoil to their original resting length after they have been stretched.
What do muscles do? They help produce heat essential for maintenance of normal body temperature.
Epimysium Skeletal muscle that is surrounded by a connective tissue sheath.
Fascia Another connective tissue located outside the epimysium.
Perimysium Loose connective tissue.
Endomysium Fiber that is surround by connective tissue.
myofibrils A threadlike structure that extends from one end of the fiber to the other.
What are the two major types of protein fibers? Actin and myosin myofilaments
Actin Myofilaments They are thin myofilaments: they resemble two minute strands of pearls twisted together.
Myosin Myofilaments They are thick myofilaments: they resemble bundles of minute golf clubs.
Sacrcomeres Highly ordered units that are joined end to end to form the myofibrils
Resting membrane potential The change difference across the membrane.
Action potential The brief reversal back of the charge
Motor Neurons They are nerve cells that carry action potentials to skeletal muscle fibers.
Neuromuscular junction Axons that enter the muscles and branch. 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 its innervates.
Presynaptic terminal The enlarged nerve terminal.
Synaptic cleft The space between the presynaptic terminal and the muscle cell.
Postsynaptic terminal Muscle fiber is a.
Synaptic vesicles Presynaptic terminal.
Acetylcholine Secrete neurotransmitter.
Acetylcholinesterase The acetylcholine released into the synaptic cleft between the neuron and muscle cell that 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.
All-or-none-response This phenomenon is called.
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 Where 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 replenish the depleted stores of creatine phosphate stores in muscle cells.
Muscle fatigue Results when ATP is used during muscle contraction faster than it can be produced in the muscle cells.
Isometric Equal distance: holding a ball
Isotonic Equal tension: throwing a ball
Muscle tone Muscle tone refers to 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 muscles.
Insertion Is then end of the muscle undergoing the greatest movement.
Belly The portion of the muscle between the orgin and intersection.
Synergists Muscles that work together to accomplish specific movements.
Antagonists Muscles that work in opposition to one another.
Prime mover Among a group of synergists, if one muscle plays the major role in accomplishing the desired movement.
How are muscles classified? their location, size, orientation of fibers, shape, origin, insertion, and function.
Occipitofrontalis Raises eyebrows
Orbicularis Oculi Closes eyelid: crow's feet
Orbicularis Oris Puckers the lips
Buccinator Flattens the cheeks: trumpeter's muscles
Zygomaticus Smiling
Levator Labili Superioris Sneering
Depressor Anguli Oris Frowing
Mastication Chewing: Masseter(1 Pairs), Temporalis(1 Pairs)
What are the kissing muscles? Orbicularis Oris and Buccinator
Extrinstic Muscle Moves the tongue
Intrinstic Muscle Changes the shape of the tongue
Sternocleidomastoid Prime mover lateral neck muscles. Rotates and abducts the head.
Where does the A Band extend to? The length of the myosin.
What does the H Zone consist of? Only myosin.
When does the muscle contract? It occurs as the actin and myosin myofilaments slide past one another causing the sarcomeres the shorten.
Skeletal Muscles Voluntary
Cardiac Muscles Involuntary
Smooth Muscles Involuntary
What are the functions of muscles? Producing movement, maintaining posture, stabilizing joints, and generating heat.
Where do muscles attach? At it's origin and insertion.
Some muscles have multiple origins or head? True
Where is a neuromusclular junction formed at? An enlarged nerve terminal resting in an indention of the muscle cell membrane.
Platysma Creates a downward sag of the mouth.
Pectoralis Major Adducts and flexes the arm.
Rectus Abdominis Flexes vertebral column
External Oblique Flexes and rotates vertebral column.
Created by: heather1012