Normal healthy muscles.Not weak or overly bulgy. resting tension in a skeletal muscle.

 muscle with low tone is limp and flaccid. Moderate toned muscles is firm and solid.

muscles stiffness tightening muscles, contraction

Incomplete tetanus: almost at peak tension cycling btwn contraction and relaxation.

Complete tetanus: continuous contraction.

increase in peak tension with each successive stimulus delivered shortly after completion of the relaxation phase of the preceding twitch.

warming up process

ex:warming up b4 exercise

staircase like rise

smooth but steady increase in musclur tension produced by increasing the the number of active motor units.

mental decision about how many muscles fibers are required for a task

when succesive stimuli arrive b4 relaxation phase has been completed, then a more powerful powerful contraction occurs. Contractions build on one another in waves

adding to load withouth resting in btwn

dense irregular connective tissue

in and around muscles packages

include epi-,peri-, and endomysium

outermost layer of connective tissue around entire muscle.

dense layer of collagen fibers that seperates the muscles from surrounding tissues

connected to deep fascia

divides muscle fibers into fascicles

possesses collagen and elastic fibers and blood vessles and nerves that branch out for each fascicle

delicate connective tissue that surrounds individual skeletal muscle cells or fibers and loosely connects with adjacent muscle fibers

flexible elastic network contains capillaries and myosatellite cells

all the muscle fibers controlled by a single motor neuron.

size of motor unit is an indication of how fine the control of movement is. The fewer the # of fibers per neuron the finer the control. ie eye muscles (4-6)vs leg muscles(1000-2000).

neuromuscular junction

NMJ

connection and  btwn nervous system and skeletal muscle fiber that occurs at specialized intercellular connection---actually little space btwn called synapse.

narrow space btwn nerve cell and muscle cell

more specifically space btwn motor end plate on nerve cell  and sacrolemmal surface of muscle cell

spot on muscle cell where nerve cell touches it.

ex: door bell on door.

contains membrane receptors for acetylcholine

nucleus toward outside

mitochondia: randomly scattered

ER also on outside of cell

narrow tubes that are continuous with the sarcolemma and extend into the sarcoplasm at right angles to the cell surface.

conducts electrical impulses into cell interior

has same properties as sarcolemma

single repeating contractile unit of muscle filamentsfrom Z line to Z line

I-band: only thin filaments, light colored band

A-band:thick filaments,has thin in zone of overlap in contracted state

H-band: central A band in resting state that contain only thick filaments

thin myofilaments

do the moving

thick myofilaments

do the pulling

myosin molecule:head,hinge,tail

elastic myofilaments associated with myosin/thick filaments

coiled spring

membrane complex related to smooth ER

tubular network around each individual myofibril

when myosin heads interact with thin filaments of actin during a contraction only in the presence of calcium

physical movement of the myosin head toward the M line after the cross bridge is fomed

the myosin is the doing the work but the actin is doing the moving

ATP is required

made by nerve cell at motor endplate

changes permeability of sarcolemma and triggers the contraction of the muscle fiber

breaks down Ach

found in synaptic cleft and ssarcolemma

combination of a pair of terminal cisternae (bulges) of sacroplasmic reticulum  (SR) on either side of a T-tubule

function to release calcium

a protein that reversibly binds Calcium

sequesters the calcium

collects the calcium gets it away from the thin filament and puts it back in the SR until the next contraction

stored in SR

released Ca binds to troponin to expose actin active sites

gets reabsorbed by SR

takes place in mitochondria

glucose + O₂ yields CO₂ +H₂O +36 (17) ATP

via Krebs cycle

resting muscles use aerobic process

glucose (no oxygen)yields CO₂ +lactic acid

incomplete breakdown of glucose

also called glycolysis

lactic acid irratates muscles,nerves

produces 2 ATP

(yeast produces CO₂ +alcohol by fermentation)

when muscles run out of oxygen

rising lactic levels lower tissue pH levels then muscles can no longer function normally

muscles needs enough energy supplysupplies,blood flow, normal oxygen levels,and normall pH levels

by-product of anaerobic respiration

build up lowers pH and interferes with contraction

recycled back to pyruvic acid when O₂ available

during a contraction, each myosin head breaks down ATP producing ADP and a phosphate group. Energy stored in CP is used to "recharge" ADP back to ATP

ADP +CP --> ATP + creatine

graphic illustration of muscle contraction

gap:latent period

rising slope:contraction phase

decling slope:relaxation phase

resting phase: flat line b4 stimulus

Latent period:gap after stimulus and before contraction when Na+ changes permeability of membrane,action potential sweeps across sarcolemma,SR releases Ca and diffuses to thin filament

Contraction phase: occurs in 5 steps

1.exposure of active sites as Ca binds to troponin

2.formation of cross-bridges--myosin head binds active site on actin

3.pivoting of myosin heads toward M line requiring ATP--ie power-stroke

4.cross-bridge detachment

5.myosin reactivation--re-cocking of myosin head away from M-line. Requires ATP.

process repeats if suffient ATP and Ca ions

Relaxation phase: Ca levels fall,active site covered, cross-bridges detach,tension falls

myogram line has downward slope

period after contraction that muscles is busy and can't be stimulated again

UNLESS the second signal is so much stronger

General characteristics of:

Skeletal Muscle Tissue

largest type of muscle cell

striated:alternating thin and thick filaments

multinucleated,nuclei on outside

voluntary

General characteristics of :

Smooth Muscle Tissue

found in respiratory,digestive,urinary,repro sys

relatively long n slender:spindle-shaped

non-striated..no myofibrils or sacromeres

thick filaments scattered in cytoplasm

involuntary: can't control

not striated

has actin,myosin organized in criss-cross pattern

single nucleus in center

General characteristics of:

Cardiac Muscle

myofibrils  in sacromeres like skeletal muscle

striated like skeletal muscle

relatively small cell size

single cental nucleus like smooth muscle

joined to intercalated discs at Zlines to give strength and stability

contracts w/o neural stimulation:automaticity