Muscle Physio Flashcards by Adrian Gamo

•Striated- a striped or banded pattern due to the arrangement of contractile proteins (actin and myosin) within the cells.

•Voluntary-This means that the contraction of skeletal muscles is under conscious control, meaning you can decide when to move them.

Skeletal muscle tissue

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•Striated
•Involuntary
•Autorhythmicity-This is the unique ability of cardiac muscle to generate its own rhythmic electrical impulses, independent of external nerve stimulation

Cardiac muscle tissue

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Involuntary

Smooth muscle tissue

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ability to respond to certain stimuli by producing electrical signals/action potentials

Electrical excitability

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ability of muscular tissue to contract forcefully when stimulated.

Contractility

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ability of muscular tissue to stretch within limits, without being damaged.

Extensibility

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ability of muscular tissue to return to its original length and shape after contraction or extension.

Elasticity

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main component of thin filaments

Actin

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main component of thick filaments

Myosin

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compenent of thin filament

Tropomyosin

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component of thin filament

Troponin

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has strong affinity to actin

Troponin I

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has strong affinity to tropomyosin

Troponin T

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has strong affinity to calcium

Troponin C

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connects & aise to M mne of sarcomere

Titin

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Helps stabilize thick filament

Titin

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Accounts for the elasticity and extensibility of myofibrils

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Accounts for the elasticity and extensibility of myofibrils

Titin

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Prevents overstretching of the sarcomere

Titin

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attaches to actin molecules of thin filaments and to titin molecules

A-actinin

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forms M line of sarcomere

Myomesin

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Binds to titin molecules and connects thick filaments to one another

Myomesin

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wraps around entire length of each thin filament

Nebulin

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Helps anchor thin filaments of Z discs and regulate length of thin filaments

Nebulin

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links thin filaments of sarcomere to integral membrane proteins in sarcolemma

Dystrophin

Help reinforce sarcolemma and transmit tension generated by sarcomere to tendons

Dystrophin

separates one sarcomere from the next.

Z disc

dark, middle part of sarcomere that extends entire length of thick filaments; and those parts of thin filaments that overlap the thick

A band

lighter, less dense area of sarcomere that contains the remainder of thin filaments but no thick filaments

I band

narrow region in center of each A band

H zone

region in center of H zone that contains proteins that hold thick filaments together

M line

contain only actin filaments

Light bands/I bands

WIDTH OF THE A BAND IS

Constant

Z lines move _____

Closer together

Lies between two successive Z discs

Sarcomere

actin filaments completely overlap the

Myosin filaments

The side-by-side relationship between the myosin and actin filaments is

Difficult to maintain

This is achieved by a large number of filamentous molecules of a protein called

Titin

is the repeating sequence of events that causes sliding of the filaments:

CONTRACTION CYCL

the cross-bridge generates force as it swivels or rotates toward the center of the sarcomere

Power stroke

myosin ATPase splits ATP and becomes energized

Splitting ATP

the myosin head attaches to actin, forming a cross-bridge

Forming cross-bridges

Nerve Resting Membrane Potential=

-70mV

Threshold potential=

-55 mV

Overshoot=

+30mV

•Overshoot= +30mV •Skeletal Muscle Resting Membrane Potential=

-90 mV

Cardiac Muscle Resting Membrane Potential=

-80 mV

When the muscle fiber contracts _______, the tension developed is proportional to the number of cross-bridges between the actin and the myosin molecules

Isometrically

When muscle is _______, the overlap between actin and myosin is ______ and the number of cross-linkages is therefore reduced.

Stretched, reduced

Conversely, when the muscle is _______ than resting length, the distance the thin filaments can move is _______.

Shorter,reduced

The velocity of muscle contraction varies _______, with the load on the muscle

Inversely

At a given load, the velocity is _______ at the resting length and declines if the muscle is shorter or longer than this length

Maximal

Carries high-energy phosphate bond similar to the bonds of ATP

Phosphocreatine/ Anaerobic lactic system

Release of ________ causes bonding of a new phosphate ion to ADP to reconstitute the ATP

Phospocreatine

Doesn't require oxygen to function and lactic because it doesn't produce lactic acid.

Phospocreatine

Used to reconstitute ATP and phosphocreatine

Glycolysis of glycogen

Rapid enzymatic breakdown of the glycogen to ________ and l liberates energy that is used to convert ADP to ATP

Pyruvic, lactic acids

The _____can then be used directly to energize additional muscle contraction and also to re-form the stores of phosphocreatine

ATP, glycolysis

The contribution of the fast glycolytic system to energy production _______ rapidly after the initial ten seconds of intense exercise. This coincides with a drop in power output as the immediately available phosphagens, ATP and PC begin to _____

Increases, run out

of sustained activity the majority of energy comes from the anaerobic glycolytic system

30 seconds

Combining oxygen with the end products of glycolysis and with various other cellular foodstuffs to liberate ATP.

Oxidative metabolism

More than 95 percent of all energy used by the muscles for sustained, long-term contraction is derived from this source.

Oxidative metabolism

If the energy demands of exercise cannot be met by oxidative phosphorylation, an ______ is incurred.

Oxygen debt

After completion of exercise, respiration remains above the resting level in order to ______this oxygen debt. The extra oxygen consumption during this recovery phase is used to restore metabolite levels (such as creatine phosphate and ATP) and to metabolize the lactate generated by ______.

Repay,glycolysis

The increased ________ work during recovery also contributes to the increased oxygen consumption seen at this time and explains why more oxygen has to be “repaid” than was “borrowed.”

Cardio,respiratory,

•Some ________occurs even with low levels of exercise because ______ motor units consume considerable ATP, derived from creatine phosphate or glycolysis, before oxidative metabolism can increase ATP production to meet steady-state requirements.

Oxygen debt,slow oxidative

is much greater with strenuous exercise, when fast glycolytic motor units are used

Oxygen debt

is approximately equal to the energy consumed during exercise minus that supplied by oxidative metabolism

Oxygen debt