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Human Physiology Chapter 10
Terms in this set (77)
Produces heat to warm the body
The ability to respond to certain stimuli by producing electrical signals (muscle action potentials).
The ability to generate tension to do work.
The ability to stretch without damage (Smooth>cardiac>skeletal)
The ability to return to its original shape after contracting or extending.
An individual muscle cell.
A sheet of fibrous C.T. that surrounds muscles and other body organs.
Separates muscle from skin and is composed of adipose and areolar C.T.
Dense irregular C.T. that lines the body wall and also holds muscles with similar functions together.
The outer most layer which surrounds the muscle
Surrounds each fascicle (a bundle of 10-100 muscle fibers).
A thin sheath of areolar C.T. around each muscle fiber.
A cord of dense regular C.T. that attaches muscle to bone periostem
A broad, flat tendon.
Somatic Motor Neurons
Stimulate skeletal muscle to conract.
Neuromuscular junction (NMJ)
The connection between the neuron and the muscle fiber.
Muscle is well supplied with blood so that each muscle fiber is in close contact with blood capillaries.
Cells in mature muscle that retain the capacity to regenerate muscle fibers.
Plasma membrane of a muscle fiber.
T (transverse) Tubules
Tiny invaginations of the sarcolemma that tunnel into each fiber and are filled with extracellular fluid (ECF). These allow the action potential to spread rapidly throughout the muscle cell.
The muscle fiber's cytoplasm. It contains lots of glycogen, and myoglobin which binds oxygen needed for ATP production.
Modified endoplasmic reticulum of muscle fibers that stores Ca2+ and ends in terminal cisterns near T tubules.
Lengthwise threads inside and extend the entire length of the fiber. They contain thin filaments and thick filaments arranged in compartments called sarcomeres. These are connected end-to-end and are the functional units of a myofibril.
Thick and thin filaments overlap each other in a pattern that creates striations.
Light I Bands
Contains only thin filaments
Dark A Bands
Contain entire thick filament.
Makes up the thick filaments and serves as the motor protein to move the thin filaments. It has a golf-club shape with myosin heads that will bind to thin filaments to move them.
Makes up most of the thin filaments and contains myosin binding sites that will bond to the myosin heads to move the actions during contraction.
Covers the myosin-binding sites on actin to prevent contraction in a resting muscle.
Holds the tropomyosin in place.
Gives elasticity and extensibility to myofibrils by stretching and then springing back.
Links thin filaments to the sarcolemma to strengthen it and help transmit force to tendons.
Synaptic End bulbs
Are swellings of axon terminals
Contain vesicles filled with acetylcholine (ACh)
A muscle fiber develops its greatest tension when there is an optimal zone of overlap between thick and thin filaments.
Provides enough energy for maximal contraction for about 15 seconds. It is stored in muscle and then transfers its high energy phosphate group to ADP to make ATP.
Anaerobic Cellular Respiration
Provides enough energy for 30-40 seconds and it occurs when O2 is not available for aerobic cell respiration.
Structure of a Motor Unit
Consists of one somatic motor neuron and all of the muscle fibers that it stimulates.
Function of Motor Unit
Since all of the fibers of one motor unit contract and relax together, we can control the strength of a contraction by the number and size of motor units stimulated.
A brief contraction of all the muscle fibers in a motor unit in response to one action potential (nerve impulse) from a somatic motor neuron.
Time between application of the stimulus and the beginning of contraction. Ca2+ is being released from the sarcoplasmic reticulum and filaments start to exert tension as slack is being removed from elastic components.
Ca2+ is actively pumped back into sarcoplasmic reticulum.
Is the time following a stimulus during which a fiber cannot respond to another stimulus.
Frequency of Stimulation
Is the number of nerve impulses arriving at the NMJ per second and is the main factor that determines a muscle fiber's tension.
If subsequent stimuli arrive before a muscle fiber has finished relaxing, then they will produce a stronger contraction.
A sustained contraction.
Fused (complete) tetanus
Shows no discernible twitches.
Unfused (incomplete) tetanus
Shows discernible twitches.
Motor Unit Recruitment
Is the process in which the number of motor units activated increases. It helps produce smooth fine movements. Also if some units are activated and some are not this allows units to rest between contractions.
Size of motor units activated
The larger the motor unit that is activated, the stronger the contraction. But smaller units can give more precise movements.
Small amount of tension in muscle due to weak, involuntary contractions. When this is lost, the muscle become flaccid.
Muscle does not shorten, but develops tension.
Tension stays almost constant while muscle shortens to move a load.
Slow Oxidative Fibers (SO)
ATP is generated especially aerobically. Contain many mitochondria and lots of myoglobin and have many blood capillaries. Split ATP slowly and are very resistant to fatigue. E.g. in neck muscles to hold up the head.
Fast Oxidative-Glycolytic fibers (FOG)
ATP is generated especially aerobically but also by anaerobic cell respiration (glycolysis). Also contain many mitochondria, blood capillaries and contain lots of myoglobin. Split ATP very rapidly and are moderately resistant to fatigue. E.g. In leg muscles of sprinters.
Fast Glycolytic Fibers
Generate ATP anaerobically (by glycolysis). Relative few mitochondria, blood capillaries, and have relatively low amounts of myoglobin. Split ATP rapidly but have the lowest resistance to fatigue. E.g. in arm muscles.
Visceral (single unit) Smooth Muscle Tissue
Occurs in walls of small arteries, veins, and hollow viscera (organs); the fibers are arranged in a network. An impulse to contract spreads to neighboring cells, which contract together (as a single unit).
Multiunit Smooth Muscle Tissue
It occurs in airways, large artery walls, arrestor pili muscles, and eye muscles that adjust pupil diameter and focus. The fibers operate singly rather than as a unit.
Sarcoplasm of smooth muscle fibers contains both thick and thin filaments which filaments which are not organized into orderly sarcomeres. Smooth muscle fibers contain intermediate filaments which are attached to dense bodies.
Regernartion is limited due to replacement of damaged muscle fibers by fibrous scar tissue (fibrosis). Satellite cells help in regeneration.
Lacks satellite cells and therefore has low regeneration capability. Stem cells may migrate from blood to form new muscle fibers.
Has the greatest power of regeneration of all muscle types. Some retain the capacity to divide. Also there are some stem cells (pericytes) that can form new smooth muscle.
Is an inherited disease characterized by degeneration of muscle fibers leading to atrophy of skeletal muscle. The gene that codes dystrophin is mutated.
A weakness of skeletal muscles caused by a partial blockage of impulse transmission at the neuromuscular junction. An autoimmune disease most often affects the face and neck with difficulty in swallowing and double vision. Seventy five% are associated with a tumor or hyperplasia of the thymus.
Affects fibrous C.T. of muscles, tendons, and ligaments. Gentle pressure at "tender points" produces pain. Also severe fatigue, poor sleep, headaches, and depression may occur.
Is a sudden involuntary contraction in a single muscle in a large group of muscles.
A painful spasm.
A spasmodic, involuntary twitching of muscles under voluntary control.
A rhythmic involuntary contraction of opposing muscle groups.
Involuntary brief twitch of a motor unit visible under the skin.
Involuntary twitches of a single muscle fiber but is not visible under the skin. It can be recorded by electromyography.
Pain in or associated with muscles.
Pathological softening of muscle tissue.
Inflammation of muscle fibers (cells).
Increasing muscular excitability and contractibility with decreasing power of relaxation; tonic spasm of a muscle.
Permanent shortening (contracture) and lack of extensibility of a muscle due to replacement of destroyed muscle fibers by fibrous connective tissue. Usually occur if a bandage or cast is on too tight (typically forearm flexors).
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