WEEK 3 PCA - up to midterm 1 content

types of muscle

skeletal, cardiac, smooth

skeletal muscles

Attached to bones & enables movement

cardiac muscles

Makes up heart muscle & Pumps blood

smooth muscles

Around blood vessels/internal organs & contraction of GI tract / control of blood vessel diameter / uterine contractions

joints

where one bone attaches to another bone.

tendons

where muscles attach to bones

flexor muscles

decrease the angle between the bones when contracting

extensor muscles

increase the angle between the bones when contracting

antagonistic pairs

movable joints come in these pairs of opposing flexors and extensors

→ biceps / triceps

muscle fibers

The individual cells that make up skeletal muscle

fasicle

muscle fibers are bundled together

Structures of skeletal muscle fiber

sarcoplasm, sarcolemma, t tubules, myofibril, sarcoplasmic reticulum

sarcoplasm

cytoplasm

sarcolemma

plasma membrane

t tubule

invagination of sarcolemma

myofibril

bundle of contractile proteins

sarcoplasmic reticulum

stores ca 2+

sarcomeres

contractile units that chain up to make myofibril

basis of muscle contraction

sarcomeres shortening

thick filament

made of the protein myosin.

• Each thick filament is a bundle of many parallel myosin molecules

thin filament

made of the protein actin.

• Each thin filament is a helix of actin molecules.

organization of sarcomere

thick filament binding sites

binding sites for actin, binding site for ATP (with ATPase activity)

thin filament binding sites

binding sites for myosin, hidden under tropomyosin

During contraction, troponin helps move the tropomyosin away, enabling

actin-myosin crossbridges.