MUSCLEPHYSIOLOGY

By: Megan WhiteAndSilver King

What is a muscle twitch?What is a muscle twitch?A response of motor unit to a single action potential of its motor neuron.

What induces a skeletal muscle fiber to contract?A. action potentialB. thin filaments slide past the thick onesC i i i t ll l l i i l lC. rise in intracellular calcium ion levelsD. both C&A

What are the nerve Cells that activate What are the nerve Cells that activate skeletal muscle fibers?

Somatic motor neuronsWhat is a neuromuscular junction?

A tiny space between the end of nerve and the surface of a muscle.

What contains the neurotransmitter What contains the neurotransmitter acetyl choline (Ach)?A. sarcoplasmic reticulum (SR)B. junctional foldsC. cross bridges D. synaptic vesicles

4.

5.

Answer Key:Axon terminal

1.

Axon terminal of motor neuronSarcolemmaf l fib

2.

of muscle fiberJunctionalfolds of sarcolemma 2.

3.Synaptic vesicle containing AchAchSynaptic cleft

4. Synaptic vesicle containing ACh

5. Synaptic cleft

1. Axon terminal of

motor motor neuron

2. Sarcolemma

3. Junctional folds of sarcolemma

of muscle fiber

AP travels across the entire sacrolemma

AP travels along T tubules

SR releases Ca^2+; Ca^2+ binds to troponin; myosin-binding sites (active sites) on binding sites (active sites) on actin exposed

Myosin heads bind to actincontraction begins

A transient change in membrane A transient change in membrane potential that occurs in the interior of the sarcolemma becomes less negative is called?A. end plate potentialB. depolrizationC. action potentialD e ola i tioD. repolariztion

When a muscles fiber cannot be When a muscles fiber cannot be stimulated again until repolarizationis called the_____ period?A. latentB. relaxationC. contractionD. refractory

What is (E-C) coupling (excitation What is (E C) coupling (excitation coupling)?

A sequence of events by which transmission of an action potential along the sarcolemma leads to the sliding of myofilamentsmyofilaments.

Put the E-C coupling steps in orderPut the E C coupling steps in orderA. action potential is propagated along the

sarcolemma and down the T-tubules.B. calcium binds to troponin and removes

the blocking action of tropomyosin.C calcium ions are released C. calcium ions are released D. contraction begins

Answer: a , c, b, d

What is the cross bridge cycle?What is the cross bridge cycle?Series of events during which myosin heads pull thin filaments toward the center of the sarcomere.

How can muscle contraction be How can muscle contraction be graded?

By changing the frequency of a stimulationBy changing the strength of stimulation.

The temporal or wave summation The temporal or wave summation occurs because ?A. second contraction occurs before the

muscle has completely relaxed.B. vigorous muscle activity cannot

continue continue C. all evidence of muscle relaxation

disappears and the contractions fuse into ppa smooth, sustained contraction plateau.

MATCH THE WORDS TO THEIRDEFINITIONS:

1 Concentric A Muscle generates 1. Concentric contractions

2. Isotonic

A. Muscle generates force as it lengthens

contractions3. Eccetric

B. Muscle shortens and does not work

contractions4. Isometric

C. The muscle neither shortens

l hcontractions nor lengthensD. Tension

i l ti l irrelatively constantAnswers: 1-b 2-d 3-a 4-c

What is glycolysis?What is glycolysis?Initial phase of glucose breakdown.

What occurs during anaerobic glycolysis?g y y

Lactic acid is the end product of cellular metabolism of glucose without oxygen.

I bi i i h i ?In aerobic respiration what transpires?A. Glucose + O2 -> CO2 +H2O + ATPB Gl + O2 > CO + H2O3 + ADPB. Glucose + O2 -> CO + H2O3 + ADPC. Glucose +O2 -> CO2 + H2O + Lactic acidD Glucose+O2 -> CO+HOH+ CreatineD. Glucose+O2 -> CO+HOH+ Creatine

Phosphate

A total lack of ATP results in:A. Internal tensionB. RecruitmentC. ContracturesD. External tension

The greater the load… The greater the load… A. The slower the contractionB. The greater the atrophyg p yC. Less the muscle shortens and the

shorter the durationC& AD. C& A

What are the chemical factors that What are the chemical factors that cause smooth muscle contraction or relaxation without an action potential?

Certain hormones, lack of oxygen, hi t i CO2 d l Hhistamine, excess CO2, and low pH.

What does it mean by stress-What does it mean by stressrelaxation response?

A brief tension occurs on the muscle that persist only momentarily, and the muscle will begins to adapt to its new state(length) and relaxesstate(length) and relaxes.

What is hyperplasia?What is hyperplasia?A. Increase in cell sizeB. Smooth muscle fibers can divide and

increase their numbersC. Overactive creatine kinsae

M l fib d hi h D. Muscle fibers expand at a high rate

Why are single-unit smooth muscle Why are single unit smooth muscle are commonly called visceral muscle?

It is in the walls of all hollow organs except the heart

How does the binding sites of calcium diff i k l l d h l differ in skeletal and smooth muscle fibers?

Calcium binds to troponin on the actinCalcium binds to troponin on the actinfilaments in skeletal muscle.In smooth muscle, binds to a cytoplasmic, y pprotein called calmeduin.

What are myoblasts?What are myoblasts?They are embryonic mesoderm cells from which all muscle fibers develop.