Muscles Flashcards
How many muscles in body
400-500
Skeletal, smooth and cardiac muscle, voluntary or involuntary?
Skeletal- voluntary
Smooth-involuntary
Cardiac- involuntary
Prefix referring to muscle
Myo
Muscles are made of bundles of muscle fibers made of
Myofibrils
Myofibril bundles in muscle are made of
Myofilaments (actin and myosin)
The “__” lines make up the striations in skeletal muscles
“Z” lines
Actin and myosin are arranged in
Sacromeres
Which myofilament is thin, which is thick
Actin is thin, myosin is thick
How contraction happens
Actin and myosin interlock, shortening the sacromeres, myofibrils shorten, muscle fibers shorten
The the actin and myosin “unlock” and the muscle
Lengthens and relaxes
Proximal end of muscle is the _____
Distal end is the ______
Origin
Insertion
What causes flexion and extension in limbs
Contraction and relaxation of muscles
Nerves release a chemical messenger to send information to contract muscles. This messenger is called
Acetylcholine (Ach)
The acetylcholine sent by the nerves to the muscle cells does what
Stimulates sarcoptic (endoplasmic) reticulum of muscle cells to release calcium (Ca++) into cytoplasm
What Ca++ does when it is released by the sarcoptic reticulum
Ca++ exposes a binding site on the actin so that myosin can bind to it
Once actin and myosin bind, they need this to contract and shorten
ATP (energy)