Muscular system

stuff about muscles openstax+video notes combination

excitability

plasma membranes can change their electrical states (from polarized to depolarized) and send an electrical wave called an action potential along the entire length of the membrane.

three types of muscle tissue

skeletal muscle, cardiac muscle, and smooth muscle

cardiac muscle and smooth muscle can respond to:

other stimuli, such as hormones and local stimuli

elasticity

It can recoil back to its original length due to elastic fibers

extensibility

it can stretch or extend

Contractility

allows muscle tissue to pull on its attachment points and shorten with force

striations (viewable from longitudinal section of muscle)

actin and myosin proteins are arranged very regularly in the cytoplasm of individual muscle cells (referred to as fibers) in both skeletal muscle and cardiac muscle, which creates a pattern, or stripes, called ________

Skeletal muscle fibers

multinucleated structures that compose the skeletal muscle

Cardiac muscle fibers

one to two nuclei and are physically and electrically connected to each other so that the entire heart contracts as one unit (syncytium)

smooth muscle

Because the actin and myosin are not arranged in such regular fashion in ________, the cytoplasm of a smooth muscle fiber (which has only a single nucleus) has a uniform, nonstriated appearance (resulting in the name smooth muscle).

Smooth muscle in the walls of arteries

critical component that regulates blood pressure necessary to push blood through the circulatory system; and smooth muscle in the skin, visceral organs, and internal passageways is essential for moving all materials through the body

cardiac (muscle fibers)

The fibers of this muscle have one to two nuclei

skeletal (muscle fibers)

The fibers of this muscle are multinucleated

sarcolemma

The plasma membrane of muscle fibers

Skeletal muscle (contractions)

contracts forcefully along a set path, so it has big bundles of parallel fibers

smooth muscle (squeezing)

just needs to squeeze, so it’s organized into broad sheets

cardic muscle is found

ONLY in the heart

Skeletal muscle is found

in the muscles attached to the skeleton; (biceps, quads, etc)

Smooth Muscle is found

in different organs that need to constrict and expand (blood vessels, sphincters, uterus)

functional unit of the cell

sarcomere

Type 1 muscle

relies mostly on aerobic-stains darker due to more myoglobin and mitochondria (slow twitch)

Type 2 muscle

relies mostly on anaerobic-stains lighter due to less myoglobin and mitochondria (fast twitch)

striations refer to

stripes along the muscle cell itself (visible sarcomeres)

intercalated discs

allow cardiac muscle to send transmission signals super quickly between cells.

epimysium

sheath of dense, irregular connective tissue, which allows a muscle to contract and move powerfully while maintaining its structural integrity