anatomy exam 3

contractibility

ability of a muscle to shorten

excitability

ability of muscle to respond to stimuli

extensibility

ability of a muscle to extend

elasticity

ability of a muscle to return to its resting length

all or none law

individual muscle contract as hard as they can or not at all

functions of muscles

body movement, maintaining posture, regulating elimination of materials, heat production

epimysium

CT that surrounds entire muscle

perimysium

CT surrounding fascicle

endomysium

CT surrounds muscle fiber

origin

muscle tendon that attaches to the bone that remains stationary during contraction

Insertion

at the end of tendon, it attaches to the end of the bone, moves toward origin when muscle contracts

myofibrils

cylindrical structures extending the entire length of the cell, 80% fiber volume, ability to shorten resulting in contraction of muscle fiber, think and thin filaments

A band

everywhere thick filaments are present

H zone/band

only thick filament, no overlap, dark part

M line

center of H zone, middle of the sarcomere, two Z lines pull toward this

I band

only have thin filaments

Isometric

length of muscle remains constant

Concentric

length of the muscle gets shorter

Eccentric

length of the muscle gets longer

sliding filament theory

muscles shorten by thin and thick filaments sliding past each other, filaments increase over lap

Troponin

attached to both actin and tropomyosin, has a binding site for calcium

Tropomyosin

rope like protein, at rest it is in a position to cover binding sites of actin

agonist

main muscle that performs the movement, biggest muscle in the region, prime mover

synergist

help with movement but aren't the biggest muscle

antagonist

opposite side of the body that performs the other movement

Fibromyaligia

chronic muscle pain, unexplainable

muscular dystrophy

progressive deterioration of muscles and tissue (winged scapulae and scoliosis), results in atrophy of the affected muscle, muscle fibers are replaced by fibrous connective and fatty tissue, no cure

Amyotrophic lateral sclerosis (ALS)

neurodegenerative disease affecting motor neurons; loss of function leads to muscle weakness, atrophy, and spastic paralysis; usually leads to death in 5 years from respiratory failure

Myasthenia gravis

autoimmune disease where antibodies attach to the ACh receptors on the sarcolemma, therefore blocking or reducing stimulatory effect on the neurotransmitter

sensory neurons

neurons that transmit sensory info to the CNS

motor neurons

neurons that pass impulses from the CNS to a muscle or gland

Interneuron

neuron that transmits impulses between motor and sensory neurons as part of a reflex arc

Path of nerve impulse

dendrites->cell body->axon

Neurons

transmit nerve impulses

Neuroglial cells

helper cells that support, protect, and nourish neurons

Schwann cells (neurolemmocytes)

PNS axons only, similar in structure and function to oligodendrocytes, myelination

Oligondendrocytes

CNS axons only, wrap themselves around axons, produce myelin

Astrocytes

cells that form the blood-brain barrier, stop toxic substances from entering

Ependymal cells

form and circulate CSF, line ventricles of brain and central canal of spinal cord

Gray matter

motor neuron and interneuron cell bodies, dendrites, myelinated axons

White matter

made up of myelinated axons, deep to the gray matter of the cortex

corpus callosum

largest tract, connecting hemispheres, control of the opposite side of the body

Endoneurium

deepest layer of connective tissue that surrounds each axon

Perineurium

middle layer or connective tissue that surrounds the fascicle

Epineurium

superficial layer of CT that surrounds nerves

Cerebrum

part of the brain that interprets sensory info

Sulcus

grooves of the brain

Gyris

bumps and ridges on the brain

cerebral cortex

covers surface of most of adult brain, superficial in cerebellum

cerebellum

part of brain that coordinates movement and balance

Meninges

CT layers, separate soft brain and tissue, cranium, enclose, protect cerebral blood vessels, circulate cerebral spinal fluid

frontal

lobe of brain in charge of motor control

parietal

lobe of brain in charge of touch

temporal

lobe of brain in chard of hearing

occipital

lobe of brain in charge of sight

insula

lobe of brain in charge of taste

Broca's area (motor speech area)

controls muscular movements necessary for vocalization

Conductivity

the ability to transmit impulses along the cell membrane

individual muscle fibers contain

myofibrils

Myofibrils are composed of

myofilaments

tendon

anchors muscle to the bone

Aponeurosis

a broad tendinous sheet

connective tissue layers are composed mostly of

collagen and elastic fbers

function of CT

protection, site for blood vessel, nerve distribution, attachment to the skeleton

circular

fascicles run in circular pattern

parallel

fibers run straight up and down

convergent

converge into single tendon

pennate

muscle merges down onto tendon

Transverse tubules (T-tubules)

deep invaginations of the sarcolemma that extend into the sarcoplasm, carry impulses from sarcolemma to help stimulate muscle contraction

sacroplasmic reticulum

internal membrane complex

thick filaments

made of myosin

myosin heads

have binding sites

thin filaments

primarily actin

sarcomeres

basic functional unit of muscle, where the shortening occurs, contracts within itself, contain overlapping think and thin filaments, from one Z disc to next

During contraction, thin filaments slide past thick filaments

z discs move closer together so sarcomeres shorten, widths of A bands remain constant, but H zones disappear, I bands narrow

synaptic knob

expanded tip of neuron axon

synpatic vesicles

membrane sacs in synaptic knob, filled with acetylcholine

synaptic cleft

Narrow space separating the synaptic knob and the motor end plate

motor plate end

region of sarcolemma with many folds (increased surface area) under the synaptic knob

ACh receptors

Proteins that bind Ach on the motor end plate

acteylcholinesterase (AChE)

enzyme in synaptic cleft that breaks down ACh (prevents continuous stimulation of muscle)

motor unit

motor neuron and the muscle fibers that it innervates, only some of the muscle fibers in entire muscle

slow oxidative fibers, type I

slow twitch, fatigue resistant

fast oxidative fibers, Type Iia

in between the other two

fast glycolytic fibers, type Iib

fast twitch, maximal contraction, fatigue very quickly

skeletal muscle usually contains

all 3 fiber types

a single motor unit contains

only muscle fibers of the same type, fiber type exclusive

Muscle hyperthrophy

building muscle increases fiber size but not number of fibers, damage the muscle cells, results from repetitive, exhaustive stimulation of muscles

Muscle atrophy

reduced stimulation results in reduced muscle size, tone, and power, decreased cell size results in decrease muscle size

isotonic

muscle length changes as it does work

Treatment for fibromyalgia

antidepressants, exercise, and pain relievers

symptoms of myasthenia gravis

ptosis, muscle weakness, double vision, difficulty swallowing

treatments of myasthenia gravis

steroids, immunosuppressants, surgery

cramps

involuntary painful, sustained contractions of a muscle

cause of cramps

unknown but may be due to lactic acid build-up, dehydration, or calcium deficiencies, severe blow to muscle

treatment of cramps

stretching

Muscle are named according to:

muscle action, specific body regions, muscle attachments, orientation of muscle fibers, muscle shape and size, muscle heads/tendons of origin

Step 1 of muscle contraction

A nerve impulse causes ACh release into the synaptic cleft, ACh binds to receptors on the motor end plate, initiating a muscle fiber impulse

Step 2 of muscle contraction

spread of the impulses down T-tubules causes calcium to leak into sacroplasm

step 3 of muscle contraction

calcium ions bind to troponin, and troponin changes shape, troponin moves tropomyosin exposing active sites on actin, myosin heads bind to actin's active sites to form cross-bridges