Muscle System

Skeletal Muscle

Attaches to the skeleton, Voluntary

Smooth Muscle

Lines the blood vessels, stomach, intestines, bladder, and reproductive tract. Involuntary

Cardiac Muscle

Only in the heart, Involuntary

Skeletal Functions

Generates heat, stabilizes joints, protects underlying movement, and values control movement of body fluids

Endomysium

Around the muscles fiber

Perimysium

Connective tissue around fascicles

Fascicles

A bundle of muscle fibers that are surrounded by perimysium

Epimysium

Wraps around entire muscle, becomes part of the tendon and isolates muscle from surrounding muscles

Sarcolemma

The plasma membrane of a muscle cell that surrounds the fibers and facilitates contraction.

Sarcoplasm

Cytoplasm of a muscle fiber that contains myofibrils

Myoglobin

A protein filament inside the muscle fiber (Helps muscle contract)

Sarcomere

Cell membrane, electrically excitable

Contractile Protein

Makes muscle contract

Myosin

Thick filament

Actin

Thin Filament (two beaded strands, twisted together)

Sarcoplasmic Reticulum

Smooth ER that stores calcium

First step of Nerve Muscle relationship

Ach released from somatic motor neuron binds to muscle cell

Second step of the Nerve- Relationship

Opens Na+ channels, Sodium diffuses in and depolarize the membrane

Third step of the Nerve- Relationship

Depolarization triggers release of calcium from sarcoplasmic reticulum

Active Site

Binds to myosin heads causing muscle contraction.

Tropomyosin

Protein the covers the active sites to prevent contraction

Fourth step of the Nerve- Relationship

When calcium binds tropomyosin, it causes it to move off active site

Fifth step of the Nerve- Relationship

Active sites exposed- myosin will bind to actin’s active site

Acetylcholinesterase

Breaks down Ach

Organophosphates

Pesticides that inhibits AchE

What does calcium do to tropomyosin.

When it binds to it, it allows the tropomyosin to move away from actin's binding sites, enabling muscle contraction.