study guide 111

skeltal functions

movement,posture,protection,elimination of materials,heat production

charcteriscs of skeltal system

excitability- respond to stimulus by changing electric membrane potiental

conductivity-sending electric activity to cell membrane

contractivity-filaments slide past each other

extensibility- strech

elasticity- return to original length

3 connective tissue layers

epimysium (dense irregular wraps whole muscle),perimysium(dense irregular wraps fascicle),endomysium(areolar wrapping individual fiber)

tendon

tendon- cordlike structure of dense regular connective tissue

aponeurosis-thin flattend sheets of dense regular connective tissue

microscopic

sacroplasm- (cytoplasm) typical organelles and contractile proteins

sacroemma-(plasma membrane) tranverse tubes extend deep in cell and voltage senstive calciumm chanels responds to electric signals

salcrum recitum-internal membrane similar to smooth ER

mybrofibris-bundles of myofilaments enclosed in sacroplasmic rectelum

myofilaments-contractile proteins w myofibrils

triad-terminal cisterna

multinucleated

cell is formed in embryo when multiple myoblasts fuse

thin vs thick filaments (sarcomere)

thick- myosin protein molecules

thin-actin protein molecules

repeating dark/light bands

myogoblin

energy stored production

creatine phosphate

quickly gives up its phosphate for ATP

motor unit

a motor neuron and all the muscle fiber controls it

neoromuscular junction

location where motor neuron innervates muscle

usually mid region of muscle fiber

synaptic knob ,syanthic cleft, motor end plate

resting membrane potiental

muscle fibers exihbit RMP

negative

exicitation contraction coupling

-stimulation of fiber is coupled with filaments

-coupling includes end plate potiental and release of ca2 from sacroplasmic

crossbridge cycling

ca2 binds to troponin , it triggers crossbridge cycling

exiciation of skeltal muscle fiber

1.calcium entry at a synaptic knob

2.release of ACh from synaptic knob

3.binding of ACh at motor end plate

skeltal muscle relaxtion

-termination of nerve signal and ACh release from motor neuron

-closure of ACh end of plate potiental

-closure of calcium channels in sacroplasmic reticulum

-ca2 and troponion to original state

energy is supplied for muscle metabolism

myokinase-additional ATP rapidly produced

creatine kinese- contains a high-energy bond between creatine and phosphate

glycolysis- does not require oxygen

aerobic cellular respiration- requires energy happens in mitochondria

oxygen debt

amount of oxygen needed after exercise

2 main criteria for muscle fiber

1. type of contraction generated

2. means for supplying ATP

Muscle fibers

1.slow oxidative-high endurance since ATP required red in color contractions are slower

2.fast oxidative-aerobitic respirationj but delivery of oxygen lower , red in color,powerful contractions

3.fast glycolic -white in color lack of myoglobin

muscle tension

force generated when a muscle is stimulated to contract

motor unit requirement

-muscle is stimulated repeatedly

-above a certain voltage , all units are recruited and maximum contractions occurs

-explains how exihbit varying degrees of force

changes in stimulus fequency

wave summation-relaxation is not complete

incomplete tetany and tetany- if frequency is increased further it exibits incomplete tetany and then tetany

muscle tone

-resting tension in muscle

-generated by involuntary muscle

-do not generate enough tension for movement

-changes constantly

isometric vs isotonic

isometric contraction- tension is increased but insufficient to overcome resistance (muscle length stays the same)

isotonic contraction- muscle overcomes resistance resulting in movement

muscle fatigue

reduced ability to produce muscle tension caused by decrease in glycocse stores

-resistance exercise leads to hypertrophy

-atrophy- decrease in size

effects of exercise

-endurance exercise leads to better ATP prodcuction

effcts of aging

-loss of muscle mass

-reduced capacity to recover from injury

-fibrosis- muscle mass often replaced by dense regular connective tissue