"Study Guide" muscle system

What makes up muscle tissue (ie organ)?

-nerves

-blood vessels

-various connective tissue

what does every muscle have attached to it?

motor neuron

what does every muscle have to have the capability of

-ability to contract

-ability to conduct action potential

Muscle functions (Production of...)

-movement of body parts and environment

-movement of blood thru vessels and heart and lymphatic vessels and food thru GI tract, etc

-movement of bile out of gallbladder, child thru birth canal, urine from urinary system, etc

Muscle functions (maintenance of...)

Posture. Muscle contraction is constantly allowing us to sit upright

Muscle functions (generation of...)

Thermogenesis (heat). Moderates body temp via shivering

Muscle functions (stabilization at...)

tendons (connect bone to muscle)

3 types of muscle tissue

-skeletal

-cardiac

-smooth

Skeletal Muscle

-striated

-multiple nuclei

-long striated fibers in bundles

-voluntary

-grow quickly, slow to regenerate

cardiac muscle

-striated

-one nuclei

-short and thick cells with branches

-involuntary

-don't regenerate

Smooth Muscle

-nonstriated

-one nuclei, centrally located

-spindle shaped, thick in middle

-involuntary

-regenerates the best

excitability

ability to receive stimulus (neurotransmitters and hormones) and identify potential stimuli. the responce is the generation of an electrical impulse

contractility

ability to get shorter (defining ability of muscle)

Extensability

ability to stretch

elasticity

ability to recoil and resume original length arfter being stretched

connective tissue membrane of muscle

Epimysium

perimysium

endomysium

levels of muscle (alphabetical)

fassicles

fibers

fibrils

filaments

artery

carries o2 in blood, carries blood away from heart

vein

carries blood to heart, and holds "waste" blood

neuron

motor neuron tells muscle to moves

how do the arteries, veins, and neurons enter the muscle

connective converings and branch extensively

epimysium

whole muscle and perimysium is held together by this ct

perimysium

holds fassicles, inside epimysium

fassicles

bundles of cells inside perimysium. holds endomysium and fibers

endomysium

inside fassicles, holds muscle fibers

muscle fibers

muscle cell

myofibrils

make up muscle cells

filaments

make up fibryls, thin and thick. Cause contraction

Skeletal muscle attachment

most span joints and are attached to bones

Origin of muscle

attachment of muscle to immovable bone

insertion

attachment of muscle to movable bone

direct muscle attachment

less common, epimysium is fused to a peristeum o pericerondrium

indirect attachment

typical, ct extends and forms tendon or aponeurosis, which attaches to peristeum or perichondrium

why are muscle cells known as muscle fiber?

they are very long (30cm)

sarcolemma

muscl fiber's memebrane

sarcoplasm

muscle fiber cytoplasm

transverse tubules

sarcolemma's tubes that penitrate through cell. encircles myofibril at each A-I junstion

sarcoplasmic reticulum

stores Ca2+, surrounds the tubules and myofibrils

Thick filaments

myosin, with tail and head.

thin filaments

actin, tropomyosin, and troponin

actin

myosin binding site

tropomyosin

blocks myosin binding site

troponin

moves tropomyosin so there will be a binding.

sacromeres

functional unit of contraction between 7 disks

a band

Length of thick filaments, dark under microscope. Stands for anisotropic

h zone

Area of only thick filaments between the thin

M line

center of thick filaments

I band

stands for iliotibial, appears light under micro, apart of two sacromeres. only thin filaments and z disc

Z disc

center of thin filaments

terminal cisternae

enlarged ends of sarcolpastmic reticulum, surrounds t tubules more directly

triad

t tubules and 2 term cisterna

muscle contraction

thin and thick filaments slide over each other, pulling z discs closer, shortening fiber and pulls on attached tendon (pulls on endomysium, perimysium, and epimysium

distance between z discs

shortens

length of A band

stays same

Lenght of H zone

shortens

Length of I band

shortens

muscle contractions are instigated by

nerve impulses

motor neurons and muscles meet at the

neuromuscular junction (NMJ)

where does the message btwn neuron and muscle

synapse

At the axon terminal (the end of the motor neuron) there are

vesicles filled with a neurotransmitter, Acetylcholine (ACh).

the cell membrane and releases the ACh by

exocytosis

Active transport, in the form of the Na+/K+ pump, is used by the

myofibers (muscle cells) to maintain a higher concentration of Na+ outside the cell membrane.

On the sarcolemma (muscle cell membrane) there are ACh receptors that will open up a channel when

ACh attaches, allowing the Na+ to flood into the cell through facilitated diffusion.

Inside the myofibers are

sarcoplasmic reticula that store Ca2+ ions by active transport

The change in Na+ concentration due to the ACh causes the SR to release

Ca2+ in the same flood-like fashion

the contraction of the sarcomere involves the binding

of the proteins Actin (thin filament) and Myosin (thick filament)

Contraction btwn actin and myosin is prevented by the

protein molecules Troponin and Tropomyosin, which wrap around the Actin molecules, covering the Myosin-binding site on the Actin molecule.

The Ca2+ ions bind to the

troponin molecules, thus causing them to change shape, and in turn cause the Tropomyosin to change shape, thus exposing the Myosin-binding sites.

Heads on the Myosin molecule, then bind with the Actin. This is called

a cross bridge and causes the rigidity of the muscles. The binding also changes the shape of the molecules thus moving the thin filament closer to the center of the sarcomere.

Rigor mortis

the release of Ca2+ ions from the SR once the active transport stops due to lack of ATP, always flexing

When ATP is present it is needed to break

the bond between the Actin and the Myosin filaments. The Myosin heads contain the enzyme ATPase, which breaks ATP down into ADP and a phosphate, and releases energy.

break btwn myosin and actin forms

a power-stroke that moves the thin filament closer to the center and allows the Myosin-binding site to bind to the next Myosin head.

Relaxation is

ach removal from the synapse.

Acetylcholinesterase (AChE)

breaks down the ACh, thus closing the ACh receptors and allowing the high concentration of Na+ ions to be reestablished by active transport and remain on the outside of the sarcolemma.

Active transport pumps in the

SR then work toward keeping the concentration of Ca2+ ions 10,000 times higher in the SR than in the sarcoplasm

This uptake of Ca2+ ions is facilitated by the binding of Ca2+ ions to a protein called

calsequestrin in the SR.

The lack of Ca2+ ions in the sarcomere causes

the Troponin and Tropomyosin to block the Myosin-binding sites on the Actin, thus preventing the cross bridges from forming

relaxation alone will not

return a muscle to its previous length, but that it requires the contraction of an antagonistic muscle