UNIT 2

concept 3: the muscular system (PAGE 26-29)

what is the main function of the muscular system

movement (voluntary)

how do muscles produce movement

the contract

(PULL NEVER PUSH)

what is insertion

muscle attached to a moveable bone

what is origin

muscle attached to an immovable bone

whatever one muscle can do…

another can undo

what are the other functions of the muscular system

maintain posture

stabilize joints

generate heat

how is ATP used in muscles (and cellular respiration)

muscles need it to contract

what kind of reaction occurs when muscles contract

exothermic

what is a byproduct of muscle contractions

giving off heat

why do muscles give off heat during muscle contractions

maintains homeostasis and regulate constant body temperature

how are muscles classified FUNCTIONALLY

agonists

antagonists

synergists

prime mover (agonist)

muscles most responsible for producing certain movement

antagonists

muscles that oppose or do the reverse of a certain movement

what happens when a prime mover is active in antagonists

usually stretched or relaxed

how do antagonists regulate prime movers

adding resistance

where are antagonists located

on the opposite side of a joint from the prime mover

what are synergists

muscle that help the prime mover

such as stabilizing across a joint adding some “oopmh”

what are fixators

they are a synergist muscle that specifically immobilize he muscles origin bone

why do fixators immobilize the muscles origin bone

to increase the prime movers effectiveness

what else do fixators do

help maintain an upright posture

in a bicep curl, what is the prime mover In forearm flexion

biceps brachii

what is the antagonist in a bicep curl

triceps brachii

what is the synergist in forearm flexion

brachioradialis and brachialis

how can myosin touch actin

energy from ATP and access

what is blocking the actin

regulatory protein tropomyosin

how does myosin gain access

neuron signals an action potential in a muscle cell that triggers Ca +2 channels in the sarcoplasmic reticulum to open and release stores Ca +2

whats the next step in gaining access for myosin

Ca +2 grabs troponin which grabs tropomyosin and pulls it out the way (access is granted)

how does myosin get energy to touch actin

myosin grabs an ATP and rips a phosphate off, releases the energy it needs to bind to the acti (power stroke), muscle contraction

how does myosin relax

ADP and the free P unbind to the myosin, allowing fresh ATP to bind

what does this cause? (ADP and the free P unbind to the myosin, allowing fresh ATP to bind)

myosin releases from acting until the new ATP is broken down to release energy needed to grab actin again

whats the next step in relaxing myosin

when Ca +2 unbinds from troponin the actin gets blocked again by tropomyosin, and it all has to be repeated

what are the 3 types of muscle tissue

cardiac

smooth

skeletal

what is cardiac muscle tissue

striated muscles of the heart that contract involuntarily to pump blood throughout the body

what is smooth muscle tissue

nonstriated muscles in the walls of visceral organs that contract involuntarily

what is skeletal muscles tissue

striated muscles generally attached to bones that contract voluntarily to produce movement

every muscle is its own…

organ

what are muscles mainly composed of

skeletal muscles tissue BUT also blood vessels, nerves, and connective tissues

what are myofibrils

organelle that makes up most of muscle cells

what runs the length of each myofibril

thin filaments called myofilaments (actin and myosin)

myofibrils are subdivided lengthwise into…

sarcomeres

what are sarcomeres

the contractile unit of the muscle

what makes up muscle cells

myofibrils, tiny threads bunched together that make up muscle fibers which make up…

what do muscles fibers contain

multiple mitochondria, nuclei, specialized ER (sarcoplasmic reticulum), cytoplasm (sarcoplasm), and a cell membrane (sarcolemma), in addition to the myofibrils

how are fascicles formed

muscle fibers bundle together

each one is a bundle of muscle cells

how is the muscle organ formed

fascicles bundle together

made of hundreds to thousands of muscle cells, plus connective tissues, blood vessels, and nerve fibers

what are the 3 types of connective tissue

epimysium, perimysium, and endomysium

what do the 3 connective tissues in the skeletal muscle do

wrap around different parts of the muscle to support it

what is the epimysium

wraps around the entire outside of the muscle

what is the perimysium

surrounds each fascicle

what is the endomysium

surrounds each muscle fiber