physio muscle physiology 1

oct 1

3 types of muscle tissue

skeletal tissue, cardiac muscle, smooth muscle

skeletal muscle

muscle attached to bones, striated, innervated by somatic motor neurons

skeletal muscle requires ____ to contract

nervous stimulation

functions of skeletal tissue

movement of body, maintenance of posture, stabilize joints

cardiac muscle

located in heart, striated, possesses autorhythmicity

autorhythmicity

does not require nervous stimulation to contract

smooth muscle

non striated, found in walls of internal organs / blood vessels, some have autorhythmicity

functions of smooth muscle

moves material in and out of body, and within body

What are the 4 characteristics of muscle

electrical excitability, contractility, Extensibility, Elasticity

Electrical Excitability

respond to stimulus and generate AP, in response to AP, muscle contracts

Contractility

ability to generate tension (force) in response to AP, tension generated > load placed on muscle = movement occurs

extensability

stretch without being damaged

Elasticity

return to original shape & length after extension

structure of skeletal muscle

structure of skeletal muscle

Epimysium

connective tissue that encases one muscle

bundles of fascicles

what one single muscle is made out of

Muscle fibers =

muscle cells

myofibril

muscle fiber = bundle of these

myofibril are made of:

myofilaments

cell membrane muscle fiber

sarcolemma

cytoplasm muscle fiber

sarcoplasm

two important parts of muscle fibers

multinucleate (more than one nuclei), contain myoglobin

myoglobin

red pigment similar to hemoglobin, contains iron that binds and stores O2

sarcoplasmic reticulum

modified smooth endoplasmic reticulum, stores calcium, surrounds each myofibril

cross channels of sarcoplasmic reticulum

terminal cisternae

Myofibril

contain thick and thin filaments, majority of muscle fibers are myofibril

thick and thin filaments (myofibril)

contractile and elastic proteins that run the length of the fiber (in a cross section)

Sarcomere

unit of contraction in skeletal and cardiac muscle, made of proteins, thick filaments and thin filaments

thick filaments of sarcomere:

myosin

thin filaments of sarcomere

actin, troponin, tropomysin

regions of sarcomere

regions of sarcomere

5 regions of sarcomere

I band, Z disk, A band, H zone, M line

I band

region occupied by thin filaments only, appears light under microscope

Z disk

dark areas (middle of I band), proteins that anchor thin filaments

A band

dark colored under microscope, runs entire length of thick filaments

H zone (heavy only)

thick filaments that dont overlap with thin, only seen in relaxed fibers

M line

dark line in middle of A band, proteins that anchor thick filaments

which areas shorten during contraction

I band & H zone