MUSCULAR SYSTEM Flashcards by 1I - DUBRIA, RAFAEL JOHN F.

Cytoplasm of the muscle cells

Sarcoplasm

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Plasma membrane covering each cell

Sarcolemma

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Contractile protein myosin molecules, shaped like a golf club head.

Thick Filaments

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Contractile protein actin molecules also contains the regulatory proteins tropomyosin and troponin

Thin filaments

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Titin and connectin keep thick and thin filaments aligned over one another for proper contraction to occur; comprise the “Z” line

Elastic filaments

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Energy-storing polysaccharide abundant in muscle

Glycogen

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Oxygen-storing red pigment

Myoglobin

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Tunnel-like extension of the sarcolemma extending from one side of the muscle fiber to the other

T tubule

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Dilated ends of sarcoplasmic reticulum adjacent to a T tubule

Terminal cisternae

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A bundle of protein microfilaments

Myofibril

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A threadlike complex of several hundred contractile protein molecules

Myofilament

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A protein with a long shaftlike tail and a globular head; constitutes the thick myofilament

Myosin

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A fibrous protein made of a long chain of G actin molecules twisted into a helix; main protein of the thin myofilament

F actin

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A globular subunit of F actin with an active site for binding a myosin head

G actin

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Troponin and tropomyosin, proteins that do not directly engage in the sliding filament process of muscle contraction but regulate myosin-actin binding

Regulatory proteins

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A regulatory protein that lies in the groove of F actin and, in relaxed muscle, blocks the myosin-binding active sites

Tropomyosin

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A regulatory protein associated with tropomyosin that acts as a calcium receptor

Troponin

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A springy protein that forms the elastic filaments and Z discs

Titin

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Alternating light and dark transverse bands across a myofibril

Striations

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Dark band formed by parallel thick filaments that partly overlap the thin filaments

A band

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A lighter region in the middle of an A band that contains thick filaments only

H band

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A light band composed of thin filaments only

I band

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A disc of titin to which thin filaments are anchored at each end of a sarcomere; appears as a narrow dark line in the middle of the I band

Z disc

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Functions of muscle

Movement, stability, communication, control of body openings and passages, heat production

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Property of muscle: respond to chemical, mechanical, or electrical stimuli

Excitability(responsiveness)

Property of muscle: initiate events that lead to contraction

Conductivity

Property of muscle: ability to shorten substantially

Contractility

Property of muscle: able to stretch between contractions

Extensibility

Property of muscle: ability to return to original length after stretching

Elasticity

3 muscle tissues

Skeletal, cardiac, smooth

contractile unit of skeletal muscle; defined as the distance between 2 Z discs

Sarcomere

Areolar CT covering each muscle fiber and binding it to its neighbors

Endomysium

Dense irregular CT covering muscle fascicles

Perimysium

Bundles of muscle fibers surrounded by perimysium

Fascicles

Covering of dense irregular CT surrounding the entire muscle

Epimysium

Skeletal muscle fascicle arrangement in which it is thick in the middle and taper at the ends

Fusiform

Skeletal muscle fascicle arrangement in which all muscle fibers are parallel

Parallel

Skeletal muscle fascicle arrangement in which fascicles are short and attach obliquely to a central tendon

Pennate

Skeletal muscle fascicle arrangement spreading out as a fan or converging to a point

Convergent

Skeletal muscle fascicle arrangement in which muscle fibers arranged concentrically

Circular

Type of muscles that are localized to a specific area and function only within that area

Intrinsic muscles

Type of muscles that extend into other areas and are responsible for movements of areas other than where they are attached

Extrinsic muscles

Muscle whose contraction is responsible for a particular movement

Prime mover or agonist

Muscles that assist the movement of the prime mover or agonist

Synergists

Muscle whose action opposes that of the prime mover or agonist

Antagonist

Stabilizes the origin of the prime mover so it can move more efficiently

Fixators

Point of attachment where least movement occurs

Origin

Point of attachment with greatest movement

Insertion

Is controlled by a nerve impulse transmitted by the motor nerve from the brain or spinal cord

Skeletal muscle contraction

Consists of all the muscle fibers controlled by a single motor neuron

Motor unit

Have fewer muscle fibers/nerves(2:1)

Fine control muscles

Initiated by an action potential and followed by the release of a chemical neurotransmitter at the neuromuscular junction

Contraction

Neurotransmitter for skeletal muscle

Acetylcholine

Functional connection between a nerve fiber and its target cell

Synapse

Synapse between a motor nerve and a muscle fiber

Neuromuscular junction

Bulbous swelling at the end of a motor nerve above the motor end plate on the muscle fiber

Synaptic knob, terminal or bouton

Gap between the synaptic knob and the motor end plate

Synaptic cleft

Small packets of neurotransmitter chemical

Synaptic vesicles

Theory in which muscle fibers are composed of many contractile units. Changes in the amount of overlap between thick and thin filaments allows for contraction and relaxation of muscle fibers

Sliding filament theory

Type of muscle contraction where myofilaments are able to slide past each other during contractions; muscle shortens

Isotonic contractions

Type of muscle contraction in which the tension in the muscles increases; muscle unable to shorten

Isometric contractions

A decrease in the angle of a joint

Flexion

An increase in the angle of a joint

Extension

The bicep muscle is shortening while contraction

Concentric muscle contraction

The bicep muscle is lengthening while contracting

Eccentric muscle contraction

A movement that brings the thumb closer to the radial bone of the forearm

Radial deviation or flexion

Draws the little finger closer to the ulnar bone, or outside of the forearm

Ulnar deviation or flexion

Moving a bone away from the midline of the body

Abduction

Moving a bone towards the midline

Adduction

Lifting upward

Elevation

Moving downward

Depression

Movement of the radius around the ulna to turn palm up

Supination

Turning the palm downward

Pronation

Moving a bone around its long axis

Rotation

Function of corrugator supercilii

wrinkles forehead

function of medial rectus

Adducts eye

Function of pelvic muscle

Support of abdominopelvic viscera through their tonic contraction. Resistance to increases in intrapelvic/abdominal pressure during activities such as coughing or lifting heavy objects. chuchu

First described in 1881; deficiency of dystrophin, resulting in progressive loss of muscle fibers

Dystrophinopathy

An autoimmune disease due to an antibody mediated attack directed against nicotinic AchR at neuromuscular junction

Myasthenia gravis

Lack of immunostaining of dystrophin in muscle biopsy specimen; demonstration of deletion in the dystrophin gene

Duchenne muscular dystrophy

The child assumes the hands-and-knees position and then climbs to a stand by walking his hands progressively up his shins, knees, and thighs

Gower's sign

Involuntary twitches of muscles

Tic

Rhythmical, involuntary contractions of opposite groups of muscles

Tremor

Involuntary, short twitches on motor unit visible under the skin

Fasciculations

Spontaneous contractions of fibers of one muscle that aren't visible under the skin

Fibrilace

Involuntary contraction of one muscle

Spasm

Painful spasm

Cramp

Multiple spasms of skeletal muscles

Tetanus

Inherited, muscle enlarge due to increased fat and connective tissue, but fibers degenerate and atrophy

Muscular dystrophy

An autoimmune disease due to an antibody-mediated attack directed against nicotinic AchR at neuromuscular junction

Myasthenia gravis

Functions of the pelvic muscles

Support of abdominopelvic viscera through their tonic contraction. Resistance to increases in intrapelvic/abdominal pressure during activities such as coughing or lifting heavy objects. Urinary and faecal continence

Function of corrugator supercilli

Wrinkles forehead