CH 10- muscle tissue

function of muscular system

movement

generate heat

venous return

smooth muscle function

maintain blood pressure

movement within visceral organs encourage transport

cardiac muscle function

pump blood throughout the body

muscle tissue types

smooth

cardiac

skeletal

all muscle tissue characteristics

excitability

contractility

elasticity

extensibility

contractility

muscle contrast to create force by shortening when actin protein pulled by myosin protein

extensibility

muscle can stretch/extend beyond

excitability

muscle need to “depolarize”

undergo change of electrical state of membrane

send electrical wave down membrane

action potential

send electrical wave down membrane

elasticity

muscle can recoil to original length

all muscles require what to contract

calcium

all muscles require what to relax

ATP

cardiac cells

branched and joined by intercalated disc

gap junction allows calcium flow rapidly across cells for entire heart depolarize as one

fiber arrangement skeletal

actin/myosin arranged in parallel bundles

overlapping pattern make it appear stripes

sacromeres

actin and myosin arranged in parallel bundles

striation

overlapping pattern; stripe

epimysium

wrap entire muscle

hold fascicles together and separate muscle from other body structure

muscles nuclei

smooth: uni-nucleated

skeletal: multi-nucleated

cardiac: uni-nucleated

tendon

collagen of 3 Mysia layer melt into collagen of tendon

collagen tendon meld into collagen of periosteum

fascia

connective tissue sheets beneath skin

help anchor and separate muscle

skeletal muscle

muscle tissue proper

epimysium

perimysium

endomysium

muscle tissue proper

delicate and must be protected/separate by connective tissue wrapping

fiber arrangement cardiac

striation similar to skeletal

fiber arrangement smooth

actin/myosin criss-cross (smooth appearance)

aponeurosis

some muscles connect to broad, flat tendons instead directly to bone

embryonic development

tiny, indv myoblast fuse together to form one long component cell for contraction

• nuclei remain; muscle fiber is multi-nucleated

perimysium

separate muscle fiber into bundles (fascicles)

fascicles

separate muscle fiber into bundles

endomysium

surround each indv muscle fiber for protection and integrity

sarcolemma

cell membrane of muscle cell

sacroplasm

cytoplasm of muscle cell

sarcoplasmic reticulum

endoplasmic reticulum of muscle cell

store, release, retrieve calcium ions for muscle contraction

sarcomere

functional contractile unit of muscle cell

sarcomere structure

span from one Z disc to next

Z disc

zigzag line that attach actin (thin) filament

A band

dark stripe

actin-myosin overlapped

M line

middle sarcomere

line attach myosin (thick) filament

I band

light color

thin actin

H zone

only myosin

NO overlap of actin

action potential

electrical signal that travel across membrane as wave

70mV

membrane potential

electrical gradient (voltage) across cell membrane

70mV

what does a muscle to contract need to be

excited

stimulate to fire an action potential

neuromuscular junction NMJ

nerve/skeletal muscle to contract

release acetylcholine (ACh)

T-tubules

invagination of cell membrane that connect to sarcoplasmic reticulum

pass action potential all around myofibrils

terminal cisterna

portion of SR; join T-tubules

motor neuron

nerve that originate in spinal cord or brain stem to give signal to muscle

acetylcholine

ACh

diffuse across synaptic cleft

bind to receptor on motor endplate of muscle cell

synaptic cleft

space between nerve/muscle

voltage-gated sodium channel

depolarization triggers it

open along membrane

spread action potential to muscle

ATP in contraction

creatine phosphate

glycolysis

aerobic respiration

triad

TC: terminal cisternae

TT: t-tubules

1 TC + 1 TT 1 TC = 3

excitation-contraction coupling goal

calcium to filaments of myofibrils; to attach to each other and contract

tail

large protein

rope

head

binding site for actin and ATP

muscle contractions requires

calcium

ATP

thin filament

actin

protein present

actin

small

globular protein chain

troponin

attach tropomyosin to actin

binding site for calcium

trompomyosin

long

thin protein

thin protein

hide binding site on actin

thick filament

myosin

myosin strand intertwined

eccentric contraction

load moved under constant muscle tension and angle joint INCREASE

concentric contraction

load move under constant muscle tension and angle of joint DECREASE

Isotonic

under constant muscle tension, load is moved

• concentric contraction

• eccentric contraction

isometric

under constant muscle tension

load is NOT moved and angle of joint does NOT change

muscle tension

force generated by shortening sarcomeres

type muscle tension

isotonic

isometric

contraction of muscle fiber

cross-bridge form between actin and myosin head trigger contraction

muscle to shorten

muscle to shorten

calcium ion remain sarcoplasm bind to troponin

ATP always available

creatine phosphate

fast

store extra phosphate for fast transfer back to ATP when needed

muscle fiber relaxation

calcium ion pump back to SR

• tropomyosin to reshield binding site on actin strand

muscle STOP contracting when ATP run out/fatigued

glycolysis

slow/anaerobic

break one molecule of sugar down to 2ATP/2 pyruvic acid

myoglobin

store small O2 for absence of sufficient O2

quickly available

aerobic respiration

best way

use oxygen to convert pyruvic acid to ATP

water/CO2 in mitochondria

1 glucose = 36 ATP

myoglobin

rigor mortis

3rd post-mortem stage of death

sarcoplasmic reticulum disintegrate, calcium release into cytosol

muscle contraction occur…

neural stimulus ceases

neural stimulus ceases

release ACh ceases

membrane repolorize

calcium pump return calcium to sarcoplasmic reticulum

skeletal muscle contraction

1. active site actin exposed (calcium bind to troponin)

2. myosin bind actin at actin-binding site (cross-bridge)

3. power stroke

4. new ATP attach myosin head (cross-bridge detach)

5. myosin head hydrolyze ATP to ADP/Phosphate

power stroke

phosphate generated in post contraction cycle is released

contraction/relaxation

1. myosin binds with actin

2. calcium bind to troponin; troponin pull tropomyosin

3. myosin head “flexes” to pull actin closer to M-line; sacromere shorten

   • filament slide

     • each pull myosin head req. ATP

muscle strength

number of muscle fibers (cells)

disuse

lifestyle or immobility

hypertrophy

muscle growth (Bulk)

atrophy

muscle loss/reduction (disuse)

Duchenne muscular dystrophy DMD

gene mutation on X chromosome

muscle contraction cause sacrolemma to tear and cause accumulated damage/weak

mutation affect protein “dystrophin”

dystrophin

attaches the myofibrils to the sarcolemma

motor unit

motor neuron and all muscle fibers it controls

• small

• large

small motor unit

each motor neuron only innervate s a few fibers

fine motor

large motor unit

motor unit may innervate thousands of fibers for simple but powerful movement

gross motor

muscles wide range of motor unit size

small motor: light task to elicit small amount of muscle tension

larger motor: recruited for more challenging task

muscle tone

skeletal muscle never relaxed

slight contraction is maintained to keep protein in regulation

flaccid

never relax

hypotonia

decrease muscle tone

hypertonia

increased muscle tone

rigidity or spactic

nervous system control of tension

muscle tone

hypotonia

hypertonia

tetany

tetany

involuntary

sustained muscle contraction, spasms, cramps

• overstimulated nerves

• calcium issue

• tetanus

tetanus

clostridium tetani bacteria

type of muscle fibers

slow oxidative

fast oxidative

fast glycolytic

oxidative

glycolytic

slow oxidative

most myoglobin for oxygen storage

sustain activity for long period of time w/o fatiguing

low tension

fast oxidative

intermediate fibers

less myoglobin

produce powerful, more controlled movement