Exam 3 iClicker Animal Phys

BIOL3800 Lisa Welch UNT spring 2026

Which characteristic differentiates skeletal muscle from both cardiac and smooth muscle?

multinucleated fibers; stimulated by somatic motor neurons

Which allows action potentials to move rapidly from the cell surface into the interior?

t-tubules

In hyperkalemia, the resting membrane potential of a muscle fiber is ___ negative and ___ likely to depolarize.

less; more

Acetylcholine receptor-channels allow diffusion of ___ when open.

both Na+ and K+

Which phases of a muscle twitch requires ATP?

Contraction and relaxation period

Which about sarcomere shortening is FALSE?

The length of the I band remains constant.

When skeletal muscles lengthen, sarcomeres

lengthen

Drug “X” inhibits acetylcholinesterase in the neuromuscular junction. What effect drug “X” have on the membrane potential of the muscle fiber?

It would remain depolarized.

Which is a potential energy source for an athlete sprinting the 40-yard dash?

phosphocreatine

How do the skeletal muscle fibers in the legs of a marathon runner differ from those of an sprinter who runs the 100- meter dash?

All of the above

Which about smooth muscle contraction is FALSE?

Troponin plays the same role as in skeletal muscle.

In smooth muscle, Ca2+ for contraction comes from:

extracellular fluid and sarcoplasmic reticulum

The right ventricle pumps ____ blood into the ____ circulation.

deoxygenated; pulmonary

Which of the following is not important in preventing backflow of blood?

endocardium

Which valve separates the left atrium from the left ventricle?

mitral

Which of the following lists the valves in the order through which the blood flows from the vena cava through the heart?

tricuspid, pulmonary semilunar, bicuspid, aortic semilunar

Which chamber initially receives blood from the systemic circuit?

right atrium

In which septum is it normal to find openings in the adult?

atrioventricular septum

In the myocardium, voltage-gated K+ channels in ____ cells and contribute to the ____ phase of the action potential.

autorhythmic and contractile; repolarization

In cardiomyocytes action potentials, voltage-gated Na+ channels are in _____ cells open during _____.

contractile; depolarization

T/F: The refractory period in a cardiac muscle fiber lasts almost as long as the entire muscle twitch.

True

If the SA node stopped functioning what result would you see on the EKG?

P waves absent, hrt- 50 bpm

During ventricular fibrillation, there is no coordinated ventricular contraction. What effect does this have on cardiac output?

no cardiac output.

Which about diastole (filling of the heart) is false?

Pressure in the ventricles is greater than in the atria.

During the T wave, which is TRUE?

Both ventricles are repolarizing.

During the P wave, which is TRUE?

None of the above

Isovolumic ventricular contraction is most closely associated with:

QRS complex

The PR interval represents which phase of the cardiac cycle?

ventricular filling

Which statement is FALSE?

The action potentials of cardiac contractile and skeletal

muscle cells are the same.

Decreased parasympathetic activity has which effect?

increases heart rate

Ouabain, a specific inhibitor of the Na+-K+ ATPase pump, is applied to a neuron. What effect will this have on the next action potential fired by that neuron?

There will be no effect.

What causes the repolarization phase of the action potential?

K+ exiting the cell through voltage-gated ion channels.

Which is TRUE about one of the two gates in Na+ channels

in axons?

The closing of the inactivation gate stops the depolarization during an action potential.

The conduction of an action potential along an axon ____.

is faster for a strong stimulus than a weak one.

Which of the following neurons would have the fastest conduction?

Myelinated axon, diameter 20 um.

Which of the following neurons would have the slowest conduction?

Unmyelinated axon diameter, 20 um.

Release of a neurotransmitter requires ___.

an action potential and Ca2+ entry into the cell.

If a neuron releases norepinephrine, it is part of which division of the peripheral nervous system?

sympathetic

Which physiological responses results from sympathetic action?

All of the above

The two branches of the autonomic nervous system have which properties?

All of the above

The sympathetic nervous system originates in the ___ region(s) of the spinal cord.

thoracic and lumbar

The parasympathetic nervous system has

long preganglionic and short postganglionic nerve fibers.

The neurotransmitter in the synapse between pre- and postganglionic autonomic neurons is

acetylcholine.

The neurotransmitter norepinephrine is made from ___.

tyrosine.

The receptor found on most parasympathetic target cells is ___.

muscarinic cholinergic.

Which pairings between ligand and receptor is NOT correct?

norepinephrine: muscarinic cholinergic

Which is an example of a parasympathetic response?

increased secretion of digestive enzymes.

Which plasma proteins is NOT correctly matched with its function?

fibrinogen; collagen formation

Which is the most common leukocytes in a healthy human?

neutrophils

Which does not have a nucleus?

erythrocytes and platelets

Which is the main plasma protein that helps pull water from

the interstitial fluid into capillaries?

albumins

The production of blood cells is ____.

hematopoiesis

Thrombopoietin (TPO) regulates the growth and maturation of

megakaryocytes.

An athlete using erythropoietin (EPO) is hoping to increase ___.

erythrocytes.

A patient has a yellow color to their skin and the whites of their eyes. Which is a possible clinical explanation?

all of the above

A person with a elevated hematocrit of 65% may have which condition?

polycythemia vera

A person with hemolytic anemia may present with ___.

all of the above

Following injury to the vessel, what role does tissue factor (factor III) play in coagulation?

activates the extrinsic pathway

Which is needed for the synthesis of factors II, VII, IX, and X?

vitamin K

The end product of the coagulation cascade is____.

cross-linked fibrin polymer