leture test 3

Which of the following is the correct sequence of events for muscle contractions?

• neurotransmitter release, muscle cell action potential, motor neuron action potential, release of calcium ions from SR, sliding of myofilaments, ATP-driven power stroke

• neurotransmitter release, motor neuron action potential, muscle cell action potential, release of calcium ions from SR, ATP-driven power stroke

• • muscle cell action potential, neurotransmitter release, ATP-driven power stroke, calcium ion release from SR, sliding of myofilaments

• motor neuron action potential, neurotransmitter release, muscle cell action potential, release of calcium ions from SR, ATP-driven power stroke, sliding of myofilaments

What is the role of calcium ions in muscle contraction?

• form hydroxyapatite crystals

• • bind to regulatory sites on troponin to remove contraction inhibition

• reestablish glycogen stores

• increase levels of myoglobin

1.) Once a motor neuron has fired, all the muscle fibers in a muscle contract.

   2.) A contraction in which the muscle does not shorten but its tension increases is called     

    isometric contraction.

• Both statements are true

• Both statements are false

• Statement one is true and statement two is false

• Statement one is false and statement two is true

Muscle tissue has all the following properties except:

• contractility

• secretion

• elasticity

• excitability

Muscle tone is ________.

• the ability of a muscle to efficiently cause skeletal movements

• a state of sustained partial contraction

• the feeling of well-being following exercise

• the condition of athletes after intensive training

.Hypothetically, if a muscle were stretched to the point where thick and thin filaments no longer 

   overlapped, ________.

• maximum force production would result because the muscle has a maximum range of travel

• cross bridge attachment would be optimum because of all the free binding sites on actin

• • ATP consumption would increase because the sarcomere is "trying" to contract

• no muscle tension could be generated

During vigorous exercise, there may be insufficient oxygen available to completely break

   down pyruvic acid for energy. As a result, the pyruvic acid is converted to ________.

• hydrochloric acid

• a strong base

• lactic acid

• stearic acid

During muscle contraction, myosin cross bridges attach to which active sites?

• actin filaments

• thick filaments

• myosin filaments

• Z discs

What is the role of tropomyosin in skeletal muscles?

• Tropomyosin is the receptor for the motor neuron neurotransmitter.

• Tropomyosin serves as a contraction inhibitor by blocking the myosin binding sites on the actin molecules.

• • Tropomyosin serves as a contraction inhibitor by blocking the actin binding sites on the myosin molecules.

• Tropomyosin is the chemical that activates the myosin heads.

Schwann cells are functionally similar to ________.

• ependymal cells

• astrocytes

• microglia

• oligodendrocytes