Muscle – CSM 1040Dr. Melanie OsterhouseI. Fxn of m – skeletal m. is about 40% of body mass

a.

b.

c. d.

Typesm. Type Involuntary Voluntary Striated nonstriated

Smooth

cardiac

skeletal

Location and function Smooth – walls of hollow visceral organs like

stomach and bladder Forces fluids thru

Cardiac – only in heart Pumps blood

Skeletal movement

Functional characteristics Excitability Contractility – unique to m. Extensibility elasticity

Histology (slide 127) Bundle of sticks (m. fibers) surrounded by C.T.

called ___________ A cluster of perimysium-surrounded bundles- is

surrounded by dense irregular C.T. called __________

_______ - plasma membrane of m. fiber ________- m. fiber cytoplasm ________- each m. fiber composed of ______ Each m. has 1 n., 1 a., 1 v. – enters center of m. and

branch through the CT sheets

Slide 130 and 129 Explain thick and thin filaments and bands Thick are _______ and thin are ______ (do people demo) Thin filament is troponin and tropomyosin

Tropomyosin blocks myosin heads from binding Troponin binds Ca2+

Slide 133 + 132 Action potential -> Ca2+ release -> C12+

binds to troponin -> troponin exposes binding site for thick filament -> ATP hydrolyzed so myosin head binds -> ADP + P released -> myosin head rotates causing contraction -> ATP binds to myosin -> myosin head released from actin and recocks

Where does all the ATP come from? Regeneration of the hydrolyzed ATP

____________ - high energy molec stored in m ________ +ADP->creatine +ATP

__________- makes lactic acid (m. soreness) After creatine is used up Break down ________ stored in m. For large amts of ATP for moderate periods (40 sec)

______ - prolonged light to moderate exercise Occurs in mitochondria

Aerobic Where does the O2 come from

_____- similar to Hb but in m. ->stores o2 Glucose +o2 -> CO2 +H2O +ATP

36 ATP per glucose but sluggish due to many steps

m. fatigue Cannot contract m. even if still being

stimulated (not just tired) ________ - no ATP to unhook cross bridge =

stays contracted (ex. Rigor mortis – lets go when tissue breaks down, writers cramp)

_______ - extra O2 the body must take in for restorative processes Why you rapidly breathe after stopping exercise

Motor unit Motor unit – Motor n. and all m. fibers it

supplies When motor n. fires, all m. fibers it innervates

contract Fine motor control (eyeball) have few fibers

per n. Large m. that are less precise (hip m.) have

lots of fibers per n.

Where does the Ca2+ come from (slide 128) ____________- stores Ca2+ and releases it on

demand ( during an action potential for ex.) Surrounds each myofibril

______- continuation of sarcolemma that conducts the impulses and orders the release of Ca2+

Terms (slide 137) ______ moving part _______ immovable or less moveable bone _____ same tension (same weight)

Concentric contraction - ________ (picking up book) Eccentric contraction - _________(putting it back)

________- same length (not lenthen or shorten) Adding wt. but not moving

______- even when relaxed, m. are almost always slightly contracted