Hole's Anatomy & Physiology Chapter 8 - Muscular System

fascia

a band or sheet of fibrous connective tissue that covers, supports, and separates muscle

myofibrils

play a fundamental role in muscle contraction, composed of 2 types of protein, myosin and actin.

myosin

protein that makes up the thick filaments in striations in skeletal muscle cells

sacromeres

the smallest contractile unit of muscle: striations form a repeating of units along each muscle fiber.

motor neurons

neurons that carry outgoing information from the central nervous system to the muscles and glands

synapse

the junction where one neuron can transfer an impulse to another structure

neurotransmitters

chemicals that transmit information from one neuron to another

sliding filament model

states that the thick and thin filaments slide past each other so that their degree of overlap increases.

acetylcholine

the neurotransmitter released by the neuromuscular junction

muscle impulse

an impulse, generated as a result of the stimulus, passes in all directions over the surface of the muscle fiber

threshold stimulus

The minimal strength required to cause a contraction

twitch

the contractile response of a single muscle fiber to a muscle impulse

origin

the fixed attachment of a muscle that serves as a basis for action

insertion

movable end of the muscle

prime mover/agonist

muscle responsible for a particular body movement

antagonist

muscles that resist a prime mover muscle.

myology

the branch of physiology that studies muscles

Striations

alternate dark and light bands found on skeletal and cardiac muscle

voluntary

Muscles you can control

involuntary

Muscle contractions that are not controlled

muscle fibers

skeletal and smooth muscles; are elongated; multiple nuclei

fascicles

Bundle of muscle fibers

neuromuscular junction

the point of contact between a motor neuron and a skeletal muscle cell

motor unit

A single neuron and all the muscle fibers it stimulates

hypertrophy

increase in muscle size

atrophy

shrinking of muscle size

intercalated disc

band located where two cardiac muscle cells join

cardiac muscle

the muscle tissue of the heart

smooth muscle

a muscle that contracts without conscious control and found in walls of internal organs such as stomach and intestine and bladder and blood vessels (excluding the heart)

skeletal muscle

Voluntary, striated muscle that moves bones, works in pairs and is attached to bones by tendons

synergist

muscle that aids a prime mover in a movement and helps prevent rotation

tetanic contraction (tetanus)

results if a muscle is stimulated so rapidly that it does not have a chance to relax at all between stimuli

recruitment

an increase in the number of motor units being activated

muscle tone

the state of balanced muscle tension that makes normal posture, coordination, and movement possible

contracture

a condition in which a muscle shortens its length in the resting state and remains that way.

actin

Protein that makes up the thin myofilaments in skeletal muscle

aponeuroses

broad fibrous sheets of connective tissue that attach muscles to the coverings of adjacent muscles

sarcoplasmic reticulum

The smooth ER of a muscle cell, enlarged and specialized to act as a Ca2+ reservoir. The SR winds around each myofibril in the muscle cell.

transverse tubules (T tubules)

A system of tubules that provides channels for ion flow throughout the muscle fibers to facilitate the propagation of an action potential.

motor end plate

The portion of the cell membrane at the neuromuscular junction; essentially the postsynaptic membrane at the synapse.

troponin

The binding of calcium to which molecule causes the myosin binding sites to be exposed

tropomyosin

A regulatory protein that, on a resting muscle fiber, covers myosin binding sites along the thin filament, preventing actin and myosin from interacting

ATPase

an enzyme that breaks down ATP molecules to transfer the energy stored in the phosphate bonds

acetylcholinesterase

the enzyme that breaks down acetylcholine in the synaptic cleft

creatine phosphate

An energy storage molecule used by muscle tissue. The phosphate from creatine phosphate can be removed and attached to an ADP to generate ATP quickly.

hemoglobin

Iron-containing protein in red blood cells that binds oxygen and transports it to the body

myoglobin

An oxygen-storing, pigmented protein in muscle cells.

oxygen debt

Respiration in the absence of sufficient oxygen leads to a build up of lactic acid that has to be cleared when sufficient oxygen is available.

latent period

the period elapsing between the application of a stimulus and the contraction of a muscle is the _____.

summation

contractions combine and become stronger and more prolonged

peristalsis

Involuntary waves of muscle contraction that keep food moving along in one direction through the digestive system.

tetanic contraction