unit 3

3 types of Muscle

skeletal cardiac and smooth

function of muscles

locomotion

facial expression

posture and body positioning

control of body openings/passage

regulation of body temp

metabolism and endocrine func

skeletal muscle contraction

requires nervous system input

origin

place where muscle starts on a bone

insertion

place where muscles end on bone

flexion

movement to reduce the angle of a joint

extension

movement to inc the angle of a joint

abduction

away from the middline

adduction

toward the midline

agonist

muscle primarily responsible for movement

antagonist

opposes the action of the agonist

synergist

muscle which assists the agonist in making the action more efficient

fixator

stabilizes the origin of the agonist to help the agonist produce more effective movement (a special type of synergist )

tendon

collagenous band or cord associated with a muscle usually attaching it to a bone and transferring muscular tension to it

first class lever

fulcrum in middle like seesaw

second class

resistance in the middle

like lifting wheelbarrow

third class lever

resistance at the end effort middle and fulcrum last

articular cartilage

layer of hyalin cartilage covering the articular surface of a bone at a synovial joint reduce friction and ease movement

synovial fluid

A lubricating fluid similar to egg white in consistency, found in the synovial joint cavities and bursae.

ligament

attaches bone to muscle

elevation

raised body part vertically

depression

lowers body part vertically

supination

rotational movement of forearm that turns the palm so faces up

pronation

rotational movement of the forearm that turns palm down

skeletal muscle

striated and voluntary

sarcolemma

plasma membrane of the muscle fiber

sarcoplasm

cytoplasm of the muscle

myofibrils

long protein cord that occupies the sarcoplasm

glycogen

glucose polymer that serves as an energy storage polysaccharide

myoglobin

supplements hemoglobin in providing o for aerobic muscle metabolism

sarcoplasmic reticulum

smooth endoplasmic reticulum of a muscle cell serving as a ca reservoir

t tubules

provides the stability required during muscle contraction, and facilitates repair upon damage

what does the sarcolemma do

conduction of electircal signals

who controls the muscle contraction

sarcoplasmic reticulum

what performs contraction

myofibrils

a band

thick filament remains constant during contraction

z lines

move closer together as sarcomere shortens

i band

narrows as actin filaments are pulled toward the center of sarcomere

h zone

shortens as myosin filaments pull actin filaments toward the center of sarcomere

actin

thin filament and interacts with myosin during muscle contraction

myosin

thick filaments with binding sites for actin and atp

troponin

regulatory protein attached to tropomyosin binds ca ions

tropomyosin

covers myosin binding sites on actin molecules in resting muscle

titin

stabilizes thick filament

dystrophin

links actin filaments to protein on inner face of the sarcolemma

cross-bridge cycling

event that occur between actin and myosin for contaction

where does cross-bridge cycling take place

the zone of overlap

contraction cycle step 1

myosin binding sites on actin become exposed with ca binds to troponin

cc step 2

myosin heads bind to actin forming cross bridges

cc step 3

myosin head pivot toward center of sarcomere ( power stroke)

cc step 4

atop binds to myosin head - detachment of myosin head from acin

cc step 5

atp is hydrolyzed and the energy released is used to re-energize the myosin head back to its start position so a new cross-bridge can form

cc step 6

contraction cycle repeats until myosin binding sites on actin are no longer available

motor unit

motor neuron and all skeletal muscle fibers innervated by it

axon

propagate info

axon terminals

form synapses with other cells

NMJ

synapse between nerve fiber and muscle fiber

synapse

junction at end of axon where it sim another cell

ACh

neurotransmitter released by somatic motor fibers parasympathetic fibers and some other neurons

depolarization

shift in electrical potential across the plasma membrane to a value less negative than the resting potential

associated with excitation of a nerve or muscle cell

repolarization

reattainment of the resting membrane potential after a nerve or muscle has depolarized

excitation

process in which ap in nerve fiber lead to action potentials

excitation step 1

nerve signal arrives at the axon terminal and opens voltage-gated ca channels. ca ions enter terminal

excitation step 2

ca stim the synaptic vesicles to release ach into the synaptic cleft

excitation step 3

ACh diffuses across synaptic cleft and binds to receptors on the sarcolemma

excitation step 4

opening of ligand-regulated ion gate creation of end-plate potential

excitation step 5

opening of voltage regulated ion gates creating action potentials

excite step 6

action potentials propagated down t tubules

exit step 7

ca released from terminal cisterns

excite step 8

binding of ca to troponin

excite step 9

shifting of tropomyosin exposure of active sites on actin

excite step 10

hydrolysis of atp into adp

activation and cocking of myosin head

excite step 11

formation of myosin-actin cross bridge

excite step 12

powerstroke sliding of thin filament over thick filament

excite step 13

binding of new atp

breaking of cross bridge

excite step 14

cessation of nervous stimulations and ACh release

excite step 15

ach breakdown by AChE

excite step 16

reabsorption of ca ions by sarcoplasmic reticulum

excite step 17

loss of ca ions from troponin

excite step 18

return of tropomyosin to position blocking active sites of actin

ATP sources

anaerobic and aerobic

cardiac muscle

it pumps blood

what do intercalated discs have

gap junctions and desmosomes

every cardiac muscle cell contracts with

every hearth beat

which has the highest action potential

cardiac muscle

what does smooth muscle do

it controls the diameter of tissue tubes

structural features

small mononucleated cells

lacks a clearly organized structure

no sarcomeres

no extensive t tubule

smooth muscle appearance

contain thick and thin filaments with a rudimentary. overlapping organization

in smooth muscle what does ca do

activate regulatory enzyme

myosin heads and crossbridge formation

slow fibers

slowly contracting aerobic metabolsim

fast fibers

rapidly contracting

anaerobic metabolism

intermediate fiber

relatively fast

primarily anaerobic

low speed

slow myosin ATPase activity

what is a key feature of slow fibers

high resistance of fatigue

many mitochondria

high speed

fast myosin ATPase activity

fast fibers special characteristic

low resistance to fatigue and relies on anaerobic glycolis

intermediate fibers

moderate speed and intermediate resistance to fatigue

moderate speed

intermediate myosin ATPase activity

special char of intermediate fibers

intermediate resistance to fatigue that rely on glycolysis but can have some aerobic capabilities

myoglobin

amino acids that contain iron and bind and release O2