Human Biology Chapter 8: Definitions

Fascia

Fibrous connective tissue; separates muscle and holds them in place

Tendon

Cord like structure that attaches muscle to bone

Aponeroses

Sheet of fibrous connective tissue that attaches muscle to bone

Actin

Protein that with myosin, contracts muscle fibers, thin

Myosin

Protein that with actin, contracts muscle fibers, thick

Sarcolemma

Cell membrane

Sarcomere

Structural and functional unit of myofibril (between striations)

Sarcoplasmic Reticulum

ER

Sarcoplasm

Cytoplasm

T-Tubles

Transverse Tubules = canal system for extra-cellular fluids

Motor Neuron

Nerve fiber that stimulates muscle fiber

Neuromuscular Junction

Site where muscle and nerve meet

Neurotransmitter

Stores chemicals at ends of nerve fibers

Motor End Plate

Special muscle fiber; membrane forms with lots of mitochondria and many fluids

Acetylcholine

Type of neurotransmitter; transmits nerve messages across synapses

Ca++

Reacts with active filaments and forms cross-bridges between actin and myosin

ADP

Adenosine Diphosphate - molecule produced when ATP loses terminal phosphate

Cholinesterase

Enzyme at neuromuscluar junction that prevents a single nerve impulse from causing a continued stimulation of muscle (decomposes acetylcholine)

Myoglobin

Pigment in muscle cells that loosely bonds oxygen for temporary storage; reduces need for continuous blood supply

Hemoglobin

Loosely bonds oxygen within RBC

Oxygen Debt

Inadequate function of respiratory and circulatory system

Liver

Lactic acid to liver by blood where it can change back into glucose, but this requires ATP

ATP

Adenosine Triphosphate - organic molecule that stores and releases energy for use in cellular processes

Skeletal Muscle

Type of voluntary muscle tissue in muscles attached to bones

Fatigue

Lose of ability to contract

Creatine Phosphate

Primary source of engery to regenerate ATP from ADP+P --> stores mitochondria and engergy

Cramp

Painful condition in which muscle contracts spasmodically but doesn't relax completely

Myogram

Muscular response - "picture" of muscle contracting

All-or-none Resonse

Muscle fibers are stimulated either responds to its fullest or no contraction

Twitch

Single contraction that lasts 1/10 of a second

Threshold Stimulus

Minimal stimuli strength to cause a contraction

Impulse

Wave of depolarization conducted along a nerve or a muscle fiber

Latent Period

Time lag between application of stimulus to time muscle responds

Period of Contraction

Muscle pulls at its attachments (shortens)

Period of Relaxation

Returns to former length

Tone/Tonus

Partial contraction of small numbers of muscle fibers; maintaining posture if lost the body will collapse (unconscious)

Smooth Muscle

Single nucleus/fiber - look at section D in notes

Cardiac Muscle

Striated cells joined end to end - look at section E in notes

Origin

Immovable end to which skeletal muscle is attached

Insertion

Movable part on the other side of a joint

Prime Mover

Muscle responsible for most movement

Synergists

muscles that assist prime movers

Antagonists

Muscle capable of resisting prime mover's action; movement in opposite direction

Isotonic

Tone remains the same but length of muscle changes; work and movements is produced; moving a heavy box

Isometric

Muscle length remains same but the tension increase; no work is done; pushing the wall

Spastic

Result of forceful exercise that increases size of individual muscle fibers not an increase in number of fibers (spastic)

Flaccid

Muscle decreases in size, strength and number of cell organelles due to lack of use (flaccid)

Epimysium

A layer of connective tissue at the muscle; at an entire skeletal muscle

Perimysium

A layer of connective tissue at the muscle; at bundle of muscle fibers

Endomysium

A layer of connective tissue at the muscle; at each muscle fiber cell

Motor Unit

Motor neuron + muscle fibers

Muscle Fiber

Muscle cell - shape of a fiber