Muscle HIstology/ Cytology

which is the longest cells in the body

nerve cells (neurons)

general characteristics of muscle

excitable

contractile

extensibility

elasticity

excitable

respond to stimulation

allows control

contractile

Can shorten forcefully - movement and load carrying

extensibility

they can be stretched passively

allows flexibility

increased by range of motion

elastcity

muscles recoil when stretched

prevents injury and provides force

general uses of muscle

tone and movement

tone

smooth muscle in arteries

maintains blood pressure

skeletal muscle - joint stability and posture

movement

smooth muscle in arteries -> movement in blood

digestive tract -> movement in food

skeletal muscle -> movement in body

muscle tissue is mostly made of

cells

intermixed with

connective tissue

myoblasts

what muscle cells start out as

releases the proteins that make up muscle

blasts = create

smooth muscle

non striated

spindle shaped cells

single nucleus (per cell)

Involuntary

functions of smooth muscle

lines our blood vessels

lines gastrointestinal tract

cardiac muscle

striated

cylindrical and branched

single nucleus

involuntary

functions of cardiac muscle

pump blood

create blood pressure

skeletal muscle

striated

striped

long cylinders (for making proteins throughout the cell)

voluntary

functions of skeletal muscle

body movement, maintenance of posture, protection and support, regulating elimination of materials, heat production

all energy breakdown from ATP is lost as heat

when you are exercising, you are using ATP to break down and release heart

ex: shivering

skeletal muscle cells are

surrounded by the endomysium

- areolar CT

thick cells

Skeletal Muscle Membrane (Sacrolemma)

Motor End Plate

Motor end plate

specialized region for communication with the nerves (neurons interact with the skeletal muscle

motor end plate has many

many acetylcholine (neurotransmitter) receptors

highly folded for more surface area

transverse tubules (T-Tibules)

part of the membrane

cylindrical indentations of sacolema

outer membrane "pokes in"

function of the t-tibules

allows action potential (stimulus from nerve) to spread deep into the thick cells

sarcoplasmic reticulum (non apart of membrane)

in muscle cells

sarcoplasmic reticulum function

calcium storage

important for muscle contraction

interacts with tubules to get stimulation from them

Multinucleate (multiple nuclei)

can produce proteins all throughout fiber

prevents cell proliferation (muscle cells don't divide much)

functional unit of muscle: Sarcromere

from one z-disk to the next

made up of myofilaments

z- line filaments together

different myofilaments

myosin

actin

troponin

tropomyosin

titin

myosin

thick filament

tail portion bundled into rope

head sticks out and crates sliding of filaments

actin

thin filament

globular units string together

what does the sliding

troponin

calcium binding site

changes shape with calcium

tropomyosin

wound around actin

strengthes actin, blocks myosiiin head from binding

titin

spring shaped

elastic component of muscle

what is the 3-d relationship with myosin

6 actins surround each mysoin

if there was to many it would overlap