A&P Lecture Exam 3 Practice Questions

What triggers activation of ligand-gated Na+ channels at the neuromuscular junction? A. Binding of acetylcholine. B. Depolarization of the postsynaptic membrane. C. Binding of Na+. D. Arrival of an action potential to the presynaptic membrane.

A. Binding of acetylcholine.

Where to find white matter? A. Brain and spinal cord. B. Wherever myelin could be found is considered white matter. C. Myelinated axons of peripheral nerves and ascending and descending tracts in spinal cord. D. Surrounding all myelinated axons

A. Brain and spinal cord.

What is acetylcholine doing at the neuromuscular junction? A. It promotes depolarization at the motor end plate due to activation of Na+ channels. B. It induces degradation of acetylcholinesterase at the synaptic cleft. C. It triggers Ca2+ entry in the presynaptic membrane. D. It promotes K+ entry and depolarization of the presynaptic membrane.

A. It promotes depolarization at the motor end plate due to activation of Na+ channels.

During muscle contraction ______________. A. Muscle fibers become shorter B. Thin (actin) filaments become shorter C. Titin fibers are stretched D. Thick (myosin) filaments become shorter

A. Muscle fibers become shorter

Which one of the following sequences of functional states could be possible for a voltage-gated sodium channel? A. Open > inactivated > closed > open B. Inactivated > open > closed > open C. Closed > inactivated > open > closed D. Open > closed > inactivated > open

A. Open > inactivated > closed > open

What could trigger an action potential in a neuron? A. Summation of multiple graded potentials. B. A rapid repolarization stimulus. C. Activation of voltage-gated potassium channels. D. Diffusion of intracellular potassium ions.

A. Summation of multiple graded potentials.

What should be the effect of completely blocking all voltage-gated Ca2+ channels at the synapse? A. The synapse will stop responding to action potentials. B. The synapse will constantly secrete neurotransmitters. C. The synapse will fire uncontrolled action potentials. D. The synapse will still work, but will slow down.

A. The synapse will stop responding to action potentials.

Which structure is located between the external ear and the middle ear? A. The tympanic membrane B. The petrous portion of the temporal bone C. The vestibule D. The malleus

A. The tympanic membrane

Muscle fibers belonging to the same motor unit______. A. are controlled by the same motor neuron B. take turns to contract, creating a sequence of synchronized movements C. are located in close proximity from each other, so they work more efficiently D. are controlled by different motor neurons whose axons arrive through the same nerve

A. are controlled by the same motor neuron

The muscle fibers that regulate the opening of the pupil ________. A. are smooth muscle under autonomic control B. are voluntary striated muscle located in the iris C. are smooth muscle under autonomic control that inserts in the sclera D. are smooth muscle fibers located in the ciliary body

A. are smooth muscle under autonomic control

When sodium ions are entering the cell via membrane channels, the plasma membrane is said to be__________. A. depolarizing B. repolarizing C. hyperpolarizing D. subpolarizing

A. depolarizing

Saltatory propagation__________. A. is faster than continuous propagation and saves energy B. takes place in unmyelinated axon fibers C. bypasses the nodes of Ranvier D. is faster than continuous propagation and does not require activation of voltage-gated sodium channels

A. is faster than continuous propagation and saves energy

A muscle (organ) is surrounded by_________. A. the epimysium B. the perimysium C. the endomysium D. an aponeurosis

A. the epimysium

Which of the following is NOT considered an accessory structure of the eye? A. the sclera B. the conjunctiva C. the nasolacrimal canal D. the lateral rectus muscle

A. the sclera

At the sarcomere, Ca+2 ions will bind to________. A. troponin B. calsequestrin C. actin D. thick filaments

A. troponin

What is the difference between a graded potential and an action potential? A. A graded potential is simply a "failed" action potential. B. A graded potential may or may not develop into an action potential, depending on the strength of the depolarization. C. Action potentials have nothing to do with graded potentials. D. All graded potentials will eventually become an action potential.

B. A graded potential may or may not develop into an action potential, depending on the strength of the depolarization.

How could the CNS trigger a strong contraction of the biceps brachii? A. By firing a long and sustained action potential. B. By firing multiple action potentials in quick succession C. By firing a stronger than normal action potential D. By firing an action potential via fast and large Type A myelinated axons

B. By firing multiple action potentials in quick succession

In order to reach a muscle fiber, nutrients and blood vessels must go through____________. A. Perimysium and Endomysium B. Epimysium, Perimysium, and Endomysium C. Epimysium and Perimysium D. Muscle is avascular

B. Epimysium, Perimysium, and Endomysium

The macula _________. A. contains only rods B. Is dominated by cones C. provides peripheral vision D. is important for night vision

B. Is dominated by cones

How would a chemical that blocks sodium channels affect a neuron's ability to depolarize? A. It would enhance depolarization. B. It would completely inhibit depolarization. C. It would slow depolarization. D. It would have no effect on depolarization.

B. It would completely inhibit depolarization.

A key role of astrocytes is to_______. A. Line the central canal and ventricles in the central nervous system, and monitor the composition of the cerebrospinal fluid (CSF) that fills them B. Maintain a selectivity filter or barrier between blood in capillaries and the extracellular fluid that surrounds neurons C. Add layers of electrical insulation, or myelin, to axons in the central nervous system D. Remove cell debris, wastes and pathogens by phagocytosis

B. Maintain a selectivity filter or barrier between blood in capillaries and the extracellular fluid that surrounds neurons

Which one of these elements will shorten following contraction of a muscle fiber? A. Thin filaments B. Myofibrils C. Thick filaments D. Myofilaments

B. Myofibrils

In order to reach a muscle fiber, blood vessels must get through _____. A. The perimysium and Endomysium B. The epimysium, perimysium and endomysium C. The epimysium and perimysium. D. Muscle is avascular.

B. The epimysium, perimysium and endomysium

What would happen if after the sarcomere begins contraction, ATP suddenly becomes unavailable? A. Nothing, the contraction would proceed normally. B. The myosin heads would be unable to detach from actin. C. The myosin heads would detach completely from actin and will not bind again until ATP becomes again available. D. Troponin would bind with the myosin heads.

B. The myosin heads would be unable to detach from actin.

How will a drug that blocks voltage-gated potassium channels affect the ability of a neuron to generate action potentials? A. The neuron will be permanently hyperpolarized, so no action potentials will be generated. B. The neuron will generate action potentials that will last much longer. C. The neuron will stay permanently depolarized. D. Background potassium channels will compensate somehow, so smaller action potentials will take place in that neuron.

B. The neuron will generate action potentials that will last much longer.

Which one of the following types of ion channel would NEVER trigger a graded potential? A. Ligand-gated sodium channels B. Voltage-gated sodium channels C. Chemically-gated sodium channels D. Mechanically-gated sodium channels

B. Voltage-gated sodium channels

At the end of a propagating action potentials the membrane is in a refractory state. This is because ___________________. A. Voltage-gated sodium channels are closed B. Voltage-gated sodium channels are inactivated. C. Voltage-gated sodium channels are open. D. Voltage-gated potassium channels are closed.

B. Voltage-gated sodium channels are inactivated.

An action potential is fired when _______. A. the normal hyperpolarization state of the neuron's soma is disrupted B. a threshold membrane potential is reached at the axon hillock C. calcium channels open at a postsynaptic membrane D. a refractory period ends

B. a threshold membrane potential is reached at the axon hillock

The efferent division of the peripheral nervous system includes _________. A. the spinal cord and peripheral nerves B. axons of motor neurons innervating smooth and skeletal muscle C. nerves that bring sensory information to the CNS D. peripheral nerves and complex sense organs

B. axons of motor neurons innervating smooth and skeletal muscle

These photoreceptors are the only ones present in the macula and provide sharp vision; name them. A. rods B. cones C. maculocites D. foveocytes

B. cones

An action potential ________. A. is an electrical signal generated at the axon. B. is an electrical signal generated at the NS that is transmitted by axons in nerves. C. is the coordinated movement of a muscle fiber. D. is an electrical potential generated by movement of myofibrils and transmitted by nerves.

B. is an electrical signal generated at the NS that is transmitted by axons in nerves.

Action potentials are conducted more rapidly in_____________. A. small-diameter axons than in large-diameter axons B. large-diameter axons than in small-diameter axons C. unmyelinated axons than in myelinated axons D. axons that lack a wrapping of Schwann cells

B. large-diameter axons than in small-diameter axons

A bundle of muscle fibers (or fascicle) is surrounded by_________. A. the epimysium B. the perimysium C. the endomysium D. an aponeurosis

B. the perimysium

During muscle contraction, a "power stroke" follows after__________. A. a myosin head is energized via hydrolysis of ATP B. calcium ions bind to myosin C. ADP and phosphate are released from the myosin head D. ATP binds to myosin

C. ADP and phosphate are released from the myosin head

Where in a skeletal muscle fiber could you find Nebulin? A. In thin filaments, masking the active site of actin B. In thick filaments C. At the core of thin filaments D. At the M line of the sarcomere

C. At the core of thin filaments

Which type of neuron is found controlling movement of skeletal muscle fibers? A. Unipolar B. Bipolar C. Multipolar D. Anaxonic

C. Multipolar

Multipolar neurons have __________. A. Multiple dendrites and axons B. One dendrite and many axons C. One axon and many dendrites D. More than one axon and a variable number of dendrites

C. One axon and many dendrites

Upon arrival of an action potential, the terminal cisternae release Ca2+ into the______. A. Transverse tubules B. Endoplasmic reticulum C. Sarcoplasm D. Sarcoplasmic reticulum

C. Sarcoplasm

Which one of these structures is absent in cardiac muscle cells? A. T-tubules B. Sarcoplasmic reticulum C. Triads D. Myofibrils

C. Triads

Which of the following is a component of thin filaments in skeletal muscle fibers? A. Titin B. Collagen C. Troponin D. Myosin

C. Troponin

Where could you find Schwann cells? A. In white matter. B. In gray matter. C. Wrapping the axons of motor neurons. D. Providing insulation to anaxonic neurons.

C. Wrapping the axons of motor neurons.

In cardiac muscle cells, action potentials are triggered______. A. by neuromuscular junctions with neighboring pacemaker cells B. by acetylcholine released by a nearby cell or neuronal synapsis C. by ions moving between neighboring cells, via gap junctions D. by acetylcholine entering via gap junctions

C. by ions moving between neighboring cells, via gap junctions

A voltage-gated sodium channel may change from inactivated state to _______. A. closed state, once the cell membrane depolarizes B. open state, if the cell membrane depolarizes once more C. closed state, after the refractory period passes D. open state, after the cell membrane hyperpolarizes

C. closed state, after the refractory period passes

What tissue layer surrounds sympathetic nerves? A. dura mater B. arachnoid mater C. epineurium D. perineurium

C. epineurium

The space between the cornea and the iris ______. A. is known as the posterior cavity and contains mostly vitreous humor B. is known as the anterior cavity and contains vitreous humor. C. is known as the anterior chamber and contains mostly aqueous humor D. is known as the posterior chamber, and is filled with aqueous humor

C. is known as the anterior chamber and contains mostly aqueous humor

At +30mV, voltage-gated potassium channels in a neuron's axon will be__________. A. absent B. inactivated C. open D. closed

C. open

Repolarization of an axon during an action potential is produced by_______. A. inward diffusion of sodium ions B. exit of potassium ions from the cell by active transport C. outward diffusion of potassium ions D. inward diffusion of calcium ions

C. outward diffusion of potassium ions

These two structures are in close apposition and are responsible for transferring vibrations to the inner ear; identify them! A. tympanic membrane/stapes B. malleus/round window C. stapes/oval window D. auditory tube/cochlea

C. stapes/oval window

A structure made of dense fibrous connective tissue that shapes the eye is the _______. A. the conjunctiva, rich in elastic and collagen fibers B. the cornea, rich in collagen C. the sclera, rich in collagen and elastic fibers D. the lens; centrally located, it provides a solid frame for the eyeball

C. the sclera, rich in collagen and elastic fibers

Where are special senses located?

Cephalic region

What are the Ca2+ concentrations in the lumen of T-tubules and at the sarcoplasm? A. 0.1 µM / 2 mM B. 2 µM / 0.1 mM C. 2 µM / 1 µM D. 2 mM / 0.1 µM

D. 2 mM / 0.1 µM

In a typical neuron, what part of the soma is located closest to the axon? A. Dendrites B. Nucleus C. Telodendria D. Axon hillock

D. Axon hillock

How does a mechanoreceptor neuron communicated a strong pressure applied to the dermis? A. By transmitting one strong action potential along its axon. B. By transmitting a very long action potential along its axon. C. By breaking a routine of sequential action potentials and going silent. D. By firing multiple action potentials within a short time.

D. By firing multiple action potentials within a short time.

The Sarcoplasmic Reticulum _____. A. Is similar to the cytoplasmic membrane. B. Surrounds groups of myofibrils C. Is composed of many sarcomeres D. Contains high calcium concentration

D. Contains high calcium concentration

The Sarcoplasmic Reticulum ______________. A. Is similar to the cytoplasmic membrane B. Surrounds groups of myofibrils C. Is composed of many sarcomeres D. Contains high calcium concentration

D. Contains high calcium concentration

Once Ca2+ is removed from the sarcolemma, myosin heads in thick filaments come to a complete stop. Which one of the following statements best describes the status of those myosin heads? A. Myosin heads are inactive because their ADP binding sites are vacant. B. Myosin heads are inactive but keep binding ATP C. Myosin heads are inactive because their Ca2+ binding sites are vacant. D. Myosin heads remain energized, with their ADP and phosphate binding sites occupied.

D. Myosin heads remain energized, with their ADP and phosphate binding sites occupied.

Which one of these elements will shorten following contraction of a muscle fiber? A. Thin filaments B. Thick filaments C. M line D. Sarcomeres

D. Sarcomeres

How will a drug that temporarily extends the opening time of voltage-gated potassium channels affect the ability of a neuron to generate action potentials? A. The neuron will be permanently hyperpolarized, so no action potentials will be generated. B. The neuron will generate action potentials that will last much longer. C. The neuron will stay permanently depolarized. D. The neuron will go through an extended hyperpolarization period after each action potential.

D. The neuron will go through an extended hyperpolarization period after each action potential.

How will a drug that blocks voltage-gated sodium channels affect the ability of a neuron to generate action potentials? A. The neuron will be permanently hyperpolarized, so no action potentials will be generated. B. The neuron will generate action potentials that will last much longer. C. The neuron will stay permanently depolarized. D. The neuron will never depolarize, so no action potential will be generated.

D. The neuron will never depolarize, so no action potential will be generated.

What should be the effect of partially blocking voltage-gated Ca2+ channels at the synapse? A. The synapse will stop responding to action potentials B. The synapse will constantly secrete neurotransmitters C. The synapse will fire uncontrolled action potentials D. The synapse will still work, but will secrete less neurotransmitter in response to action potentials

D. The synapse will still work, but will secrete less neurotransmitter in response to action potentials

Which one of these structures is present in smooth muscle cells? A. Myofibrils B. Sarcomeres C. T-tubules D. Thin filaments

D. Thin filaments

One of these proteins prevents binding of actin to myosin in the absence of calcium. Which one is it? A. ATP B. Titin C. Troponin D. Tropomyosin

D. Tropomyosin

Which of the following is a component of thin filaments in skeletal muscle fibers? A. Titin B. Collagen C. Myosin D. Tropomyosin

D. Tropomyosin

Muscle fibers undergoing intense and frequent contractions ______. A. will not use the citric acid cycle B. will use primarily the citric acid cycle C. will accumulate creatine, acidifying the intracellular pH and destroying important enzymes D. Will produce large amounts of pyruvate and lactate from glucose

D. Will produce large amounts of pyruvate and lactate from glucose

Motor unit refers to______. A. individual muscle fibers B. muscle fiber bundles or fascicles C. a set of muscle fibers, innervated by one or more motor neuron, that contract at the same time. D. a more or less large group of muscle fibers that is controlled by the same motor neuron.

D. a more or less large group of muscle fibers that is controlled by the same motor neuron.

If the membrane potential of a neuron changes from -70mV to -55mV, it is said to be _____________. A. polarizing B. hyperpolarizing C. repolarizing D. depolarizing

D. depolarizing

When the membrane potential (i.e. -70 mV) becomes less negative or in other words, approaches zero, the membrane is said to be_____________. A. polarizing B. hyperpolarizing C. repolarizing D. depolarizing

D. depolarizing

Aqueous humor ______. A. predominates the posterior cavity B. fills the anterior chamber, but not the posterior one. C. is secreted at the scleral venous sinus D. is secreted at the ciliary body

D. is secreted at the ciliary body

During moderate activity a skeletal muscle fiber will_________. A. produce glycogen B. use creatine phosphate to generate ATP C. use only anaerobic metabolism (i.e., glycolysis) to produce ATP D. use both anaerobic and aerobic metabolic pathways (i.e., glycolysis and citric acid cycle) to produce ATP

D. use both anaerobic and aerobic metabolic pathways (i.e., glycolysis and citric acid cycle) to produce ATP

Damage to which root of a spinal nerve would interfere with motor function? A. posterior root B. dorsal root ganglion C. dorsal root D. ventral root

D. ventral root

Following the propagation of an action potential, the axon membrane is in a refractory state. This is because___________. A. voltage-gated sodium channels are closed B. voltage-gated sodium channels are open C. voltage-gated potassium channels are closed D. voltage-gated sodium channels are inactivated

D. voltage-gated sodium channels are inactivated

What surrounds muscle and connects it to adjacent tissue?

Epimysium

70% of the bodies receptors are in the ______________?

Eye

What does the special senses include? What sense does it exclude?

Includes: Vision, hearing & equilibrium, Taste, Smell Excludes: Touch b/c it is a general sense

What surrounds fascicles (muscle fiber bundles)?

Perimysium

What are the functional units of a muscle fiber?

Sarcomeres