tendons

muscles get bigger, but no new muscle fibers are created

you have as many muscles now as you were born with

cylindrical bundles in muscle fibers

thick filaments are made of ________

thin filaments are made of _________

myosin

actin

wide band of myosin

narrow region in center of A band, space between 2 sets of thin filaments

in center of H zone, proteins that link central regions of adjacent thick filaments

2 sets of thin filaments anchored to a network of proteins at this paint

2 successive Z lines make a sarcomere

contains portions of thin filaments that do not overlap thick filaments

which two portions of the sarcomere shorten during muscle contraction?

H zone

I band

6 protein subunits combine to form a protein with 2 heads and a long tail

each head has binding site for actin and ATP

release of inorganic phosphate causes crossbridge to move towards the H zone

no ATP left in the body. muscle decomposes and myosin heads detaches and muscle relaxes

rod-shaped molecule composed of 2 intertwined proteins

in absence of calcium, it covers the myosin-binding sites

smaller protein bound to both tropomyosin and actin

binds Ca2+ and drags tropomyosin off of myosin binding site and contraction begins

ligand-gated ion

1. action potential propagates along plasma membrane and down T-tubules

2. Depolarization opens Ca²⁺ channels in membrane of SR

3. Ca²⁺ enters cells, binds to tropomyosin

4. ATP used to pump Ca²⁺ back into SR by ion-pumps

5. Muscle relaxes

trophic factors

aka oxidative or red fibers

color due to large amounts of myoglobin

high # of mitochondria

use reserves of fat and gylcogen for energy

aka glycolytic fibers (use glycolysis and CP for quick energy)

white (contain little myoglobin)

high concentration of glycolytic enzymes and large store of glycogen

muscles don't have much readily available ATP, but they do have CP which stores energy in a phosphate bond

energy it provides is limited but immediate. it enables fast-twitch fiber to create a lot of force quickly

involves oxidative phospohorylation in the mitchondria of slow-twitch fibers

becomes fully active in about a minute, producing huge amounts of ATP

protein that combines with Ca²⁺ after it enters the sarcoplasm

the calmodulin-calcium ion complex activates enzyme myosin kinase (responsible for phosphorylating myosin heads)

smaller than skeletal muscle cells, usually long and spindle-shaped, mononucleate, cells connected by gap junctions like in cardiac muscle, so action potential can spread to all cells in the tissue

plasma membranes are sensitive to strech. the more forcefully they are stretched, the more they contract

In the heart, ryanodine receptors are ion-gated Ca²⁺ channels that are sensitive to Ca²⁺. When an action potential spreads down T-tubules, these channels open and let in calcium ions, which opens more voltage-gated channels.

Result: tons of Calcium ions and contraction

1. one binds actin

2. one binds calcium ion

3. one binds tropomyosin

True The SR has calcium ion pumps that remove calcium from the sarcoplasm when the muscle is at rest

voltage-sensitive channel on T-tubule that changes conformation when the action potential reaches it and causes ryanodine receptor to allow Ca²⁺ to leave the sarcoplasmic reticulum

releases Ca²⁺ from the sarcoplasmic reticulum into the sacroplasm when activated by DHP receptor

largest protein in the body

runs full length of the sarcomere (Z to Z)

bound to thick filaments

in relaxed muscle, resistance to stretch is mostly due to elasticity of titin

activation of this gene enables to burn fat more efficiently

transgenic "Marathon mice" gained less weight and had dramatic shift to slow-oxidative muscle fibers

muscles that straighten a limb are called ______________.

muscles that bend a limb are called _____________.

extensors

flexors

improper mineral deposition

due to inadequate dietary calcium intake or inadequate absorption of calcium in small intestine

prevented or treated with vitamin D

both the mineral and organic portions of bone are reduced

caused by disruption in balance of bone remodeling

can be minimized with adequate calcium and vitamin D intake and weight-bearing exercises

immune system produces antibodies for ACh receptors on skeletal muscle

skeletal muscle fatique and weakness

treatment: plasmapheresis to remove antibodies from blood or drugs that target acetylcholinesterase

results from mutation in dystrophin

natural loss of muscle tissue as part of aging process

True

False hinge pivot

hinge, pivot, ball and socket

saddle

condyloid

gliding

1. a myosin cross-bridge bound to Pi and ADP binds to an actin molecule on a thin filament

2. release of Pi causes the cross-bridge to move and the thin filaments to slide past thick filaments

3. ADP is released, a new ATP binds to myosin, and then myosin detaches

4. ATP is hydrolyzed, providing energy to move the crossbridge

I band

slow-oxidative fibers

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