physio lab skeletal muscle

What are the 3 different types of muscle tissue?

smooth, skeletal, and cardiac

Involuntary/Voluntary: smooth muscle?

involuntary

Involuntary/Voluntary: skeletal muscle?

voluntary

Involuntary/Voluntary: cardiac muscle?

involuntary

Non-striated/striated: smooth muscle?

non-striated

Non-striated/striated: skelatal muscle?

striated

Non-striated/striated: cardiac muscle?

striated

epimysium surrounds ________

muscle groups

perimysium surrounds ____

fascicle

endomysium surrounds

fibers/cell

Tendon

muscle to bone

Ligament

bone to bone

thick filament

myosin

thin filament

actin

A band

dark region of the sarcomere, myosin filaments plus some overlapping actin

I band

light region of the sarcomere, containing only actin filaments

H zone

in the center of each A band is a portion of the myosin filament with no overlap of actin

Z line

how sarcomeres are divided from each other, found in the center of each I band

M line

in the center of each A line

what are the 2 additions proteins located on the actin molecule itself

troponin and tropomyosin

Excitation-Contration Coupling: step 1

action potential generated is propagated along the sarcolemma and down the T tubules

Excitation-Contration Coupling: step 2

action potential triggers Ca2+ release from terminal cisternae of SR

Excitation-Contration Coupling: step 3

calcium ions bind to troponin; troponin changes shape, removing the blocking action of tropomyosin; actin active sites exposed

Excitation-Contration Coupling: step 4

contraction; myosin cross bridge alternately attach to actin and detach, pulling the actin filaments toward the center of the sarcomere; release of energy by ATP hydrolysis powers the cycling process

Excitation-Contration Coupling: step 5

removal of Ca2+ by active transport into the SR after the action potential ends

Excitation-Contration Coupling: step 6

tropomyosin blockage restored blocking actin active site; contraction ends and muscle fiber relaxes

when Ca2+ is low

tropomyosin blocks the myosin binding site on actin and contraction will NOT occur

when Ca2+ is present

Ca2+ binds to troponin complex, conformational change of tropomyosin allows myosin to bind to actin, contraction can occur

Sliding Filament Theory: released

ATP binds to myosin causing the dissociated of the actin-myosin complex

Sliding Filament Theory: cocked

ATP is hydrolyzed, causing myosin heads to return to thier resting conformation

Sliding Filament Theory: cross bridge

myosin head binds to actin monomer forming cross bridge

Sliding Filament Theory: power stroke

P is released. Myosin heads change conformation; the filaments slide past each other

Sliding Filament Theory: attached

ADP is released

True or False: filaments don't shorten; they slide

true

the sarcomere shorten and the muscle fibers shorten

what shorten in the sliding filament therory

motor unit

comprises a single motor neuron and the muscle fibers it innervates

small motor units are involved with _____ motor activities

fine

large motor units are involved with ___ motor activities

gross

motor units are recruited from _____ to ______; your body always uses the minimum force necessary before recruiting more

smallest; largest

axon of motor neuron

• branch of efferent motor neuron - carries wave of depolarization to muscle

axon terminal

• distal port of a motor neuron - forms neuron side of neuromuscular junction

synaptic vesicles

• located at tip of axon terminal - contain neurotransmitters, acetylcholine (ACh)

motor end plate

-specialized region of sarcolemma -forms muscle side of neuromuscular junction -highly folded -contains membrane receptor proteins that bind acetylcholine -when ACh is bound to receptors, Na+ rushes into muscle fiber which may depolarize the sarcolemma

synaptic cleft

• narrow space - between axon terminal and motor end plate - contains molecules of the enzyme acetylcholinesterase (AChE) - AChE breaks down ACh to remove it from the synaptic cleft

isometric action

muscle contract and length remains; the force generated is insufficient to overcome the load

isotonic action

the contraction tension remain constant and the muscle changes in length and moves the load

concentric action

muscle contracts and shortens

eccentric action

muscle contracts and lengths

agonist

the primary mover

synergistic

muscles that assist the agonist group

antagonistic

muscle that oppose the agonist

myoglobin

the oxygen binding molecule that facilitates oxygen transport into myocytes

slow twitch type 1

• myoglobin rich - contain large numbers of oxidative enzymes - high mitochondrial volume - surrounded by more dense capillary networks - fatigue resistant - slower maximal shortening velocity - highly efficient

fast twitch type IIX

• small number of mitochondria - less resistant to fatigue - rich in glycolytic enzymes - generate the hgihest power output

fast twitch type IIA

• intermediate fibers - mixture of type I and type IIX

hypertrophy

an increase in muscle fiber diameter due to an increase in myofibril size

opposite of hypertrophy

atrophy

physiological adaptation of hypertrophy

increase in muscle size, not muscle number

muscle soreness

result from microscopic injury to the muscle fibers

Delayed Onset Muscle Scoreness (DOMS)

appears 24-48 hours post microscopic injury NOT a result of lactic acid accumulation

sex differences in exercise physiology

when absolute strength is compared in untrained men and women, men are typically stronger. absolute strength differs, but relative strength per unit muscle mass is similar.

rigor mortis

postmortem muscle stiffness resulting from rigid cross bridge in the absence of ATP

sarcopenia

age related decline in muscle mass begins around age 25 and occurs across the lifetime

slow phase sarcopenia

10% of muscle mass is last from 25 to 50 years

rapid phase sarcopenia

an additional 40% of muscle mass is lost from 50-80 years

characterized by defects in muscle proteins or lack of protein called ____ that result in a progressive muscle weakness and a loss of muscle fibers

dystrophin

Muscular Dystrophy: mutated gene is expressed on the X chromosome. thus are more men or women affect? why?

Men; if women get the gene it stays recessive and since men only have 1 X chromosome there is no "genetic backup" so its presented more dominant