Questions

Myoglobin

(A) has ATPase activity;

(B) is found in thick but not thin filaments;

(C) accounts for some of the excitability of muscle tissue;

(D) binds oxygen within red myofibers;

(E) binds calcium

Rigor mortis occurs after death because

(A) of the fusion of sarcolemmas;

(B) calcium is no longer available for the release of myosin-actin crossbridges;

(C) ATP is no longer available for the release of myosin-actin crossbridges;

(D) of the intracellular digestion of actin and myosin;

(E) nerve stimulation stops after death.

The function of calcium ions in skeletal muscle contraction is to:

(A) bind to receptors on the sarcolemma at the neuromuscular junction to

stimulate muscle contraction;

(B) cause a pH change in the sarcoplasm to trigger

muscle contraction;

(C) bind to the myosin binding sites on actin so that myosin

will have something to attach to;

(D) bind to troponin on the thin filament

myofilaments so that myosin binding sites on actin can be exposed;

(E) bind oxygen to fuel cellular respiration in oxidative myofibers.

If the overall length of a muscle increases during a contraction, the

contraction is referred to as a(n):

(A) concentric isometric contraction;

(B) eccentric isometric contraction;

(C) concentric isotonic contraction;

(D) eccentric isotonic contraction;

(E) muscle spasm.

The sustained partial contraction of a portion of skeletal muscle is called

(A) treppe;

(B) incomplete tetany;

(C) a simple twitch;

(D) tonus;

(E) a spasm.

Which of the following is found in skeletal muscle but not in smooth

muscle?

(A) actin;

(B) myosin;

(C) ATP;

(D) sarcoplasmic reticulum;

(E) troponin

The sarcolemma is a specialized form of

(A) endoplasmic reticulum;

(B) fibrous protein;

(C) plasma membrane;

(D) nucleus;

(E) connective tissue fascia

Creatine-phosphate is a

(A) myofiber waste product excreted into urine;

(B) high-energy compound that can generate ATP;

(C) component of myofiber

thin filaments;

(D) source of calcium;

(E) substance that binds oxygen in red muscle tissue.

Which of the following is the SMALLEST unit?

(A) myofilament;

(B) myofibril;

(C) myofiber;

(D) fascicle;

(E) motor unit.

The function of calsequestrin is to:

(A) bind calcium ions within the sarcoplasmic reticulum;

(B) provide a means by which calcium ions can attach to myosin heads;

(C) actively transport calcium ions into the transverse tubules;

(D) break down the ATP on the myosin cross bridges;

(E) open calcium channels in the sarcoplasmic reticulum so that calcium ions can diffuse into the sarcoplasm.

During an isometric contraction, a muscle

(A) shortens and exhibits greater and greater tension;

(B) lengthens and exhibits constant tension;

(C) relaxes and moves by gravity;

(D) shortens by maintaining nearly constant tension;

(E) remains the same length but exhibits increasing tension.

The function of intercalated discs in cardiac muscle cells is to:

(A) separate the sarcomeres from each other;

(B) generate the appropriate

neurotransmitters to regulate heart rate;

(C) store calcium;

(D) provide a mechanism by which all the cells in a network can contract as a functional unit;

(E) store ATP.

A motor unit is defined as

(A) a single neuromuscular junction;

(B) a single motor axon and all the myofibers it innervates;

(C) a single myofiber and all the motor axons which innervate it;

(D) a single muscle which contracts as a unit, such as the biceps;

(E) a single muscle spindle (intrafusal) fiber and the motor neuron which innervates it.

Myasthenia gravis is sometimes treated with drugs that block

acetylcholinesterase. The purpose of this treatment is to

(A) increase acetylcholine concentrations to offset the partially blocked Ach receptors;

(B) decrease acetylcholinesterase from abnormally high levels to normal levels;

(C) inactivate abnormal acetylcholinesterase because the enzyme interferes with

the Ach receptors;

(D) depolarize the postsynaptic membrane which is

hyperpolarized by acetylcholinesterase;

(E) inhibit ATP production.

When calmodulin binds calcium ions in smooth muscle tissue, it causes

troponin to move away from the myosin binding sites on the actin filament.

(A) True;

(B) False.

Which is NOT a risk factor for osteoporosis

(A) menopause;

(B) moderate exercise;

(C) diets deficient in calcium and vitamin D;

(D) decrease in estrogen;

(E) smoking

Secondary ossification centers form

(A) in diaphyses;

(B) in epiphyses of

cartilaginous templates;

(C) along marrow cavity borders;

(D) at edges of primary ossification centers;

(E) along perichondrium inner surfaces.

During normal homeostasis, blood calcium rapidly decreases in response to

(A) parathyroid hormone;

(B) the active metabolite made from vitamin D;

(C) calcitonin;

(D) thyroid hormone;

(E) vitamin C.

All of the following are true for bone remodeling EXCEPT

(A) it continues throughout life;

(B) it allows the release of calcium to the blood;

(C) it allows growing bone to respond to mechanical forces;

(D) it results in the formation of new osteons;

(E) it is found only in fetuses.

Osteoarthritis appears to be related to

(A) meat in the diet;

(B) vitamin C

deficiency;

(C) increased physical activity;

(D) systemic metabolic disease;

(E) degeneration of articular cartilage

Which of the following is NOT true of red bone marrow:

(A) consists of adipose cells;

(B) is found in spongy bone;

(C) produces blood cells;

(D) is not found in the medulla of long bones.

The procedure for examining and repairing the interior of a joint with

minimal incisions is known as:

(A) arthroplasty;

(B) plastic surgery;

(C) arthroscopy;

(D) adduction;

(E) supination