Physiopatho - neuro

Question 1

Which part of a neuron is primarily characterized as the information-receiving component?
a. Axon
b. Presynaptic terminal
c. Cell body
d. Dendrite
e. Myelin

Answer 1

D - dendrite

Almost all neurons have an information-receiving area of the cell membrane, usually composed of radiating dendrites; a cell body, or soma, containing the organelles for most cell metabolic activity; an information-carrying extension of the cell membrane, called an axon; and a presynaptic terminal at the end of the axon to transmit information to other cells. The axon is often covered with a punctuated fatty coating called the myelin sheath that enhances the speed of information (saltatory conduction)

Question 2

Which of the following is not characteristic of glial cells?
a. Production of action potentials
b. Immune responses of the nervous system
c. Production of the myelin sheaths of axons
d. Modulating the growth of developing or damaged neurons
e. Buffering extracellular concentrations of some ions and neurotransmitters

Answer 2

a - production of action potentials

Question 3

What’s the value of the resting membrane potential? And what does make it so?

Answer 3

-70 mV
Is the result of the differential separation of charged ions, especially sodium (Na+) and potassium (K+), across the membrane and the resting membrane’s differential permeability to these ions as they attempt to move back down their concentration and electrical gradients. Even though the net concentration of positive and negative charges is similar in both the intracellular and extracellular fluids, an excess of positive charges accumulates immediately outside the cell membrane, and an excess of negative charges accumulates immediately inside the cell membrane, making the resting potential negative.

Question 4

If the number of IPSPs on the dendritic membrane decreases while the number of EPSPs remains the same, what will happen to the action potentials on that neuron?
a. Probability of triggering action potentials increases.
b. Probability of triggering action potentials decreases.
c. Probability of triggering action potentials remains unchanged. d. Action potentials would be eliminated.
e. Action potentials would be conducted with increased
velocity.

Answer 4

a - Probability of triggering action potentials increases.

Question 5

During an excitatory postsynaptic potential in a neural mem- brane, which of the following is the most important ion flow?
a. Sodium ions diffuse out of the cell.
b. Sodium ions diffuse into the cell.
c. Potassium ions diffuse out of the cell.+ +
d. Potassium ions pumped in by the Na , K pump. e. None of the above.

Answer 5

b - sodium diffuse into the cell

Question 6

Describe how the Resting Membrane Potential Can Be Changed by Synaptic Signals From a Presynaptic Cell:

Answer 6

By summation of postsynaptic potentials - either excitatory (EPSP) or inhibitory (IPSP). Summation of several postsynaptic potentials slowly opens voltage-gated Na+ channels and the consequent influx of Na ions (in case of EPSP) - which would eventually lead to depolarisation if continued.
Summation of IPSP instead open chemically gated K+ channels, then K+ ions diffuse out, moving the membrane potential even closer to the equilibrium potential for K+ (−90 mV). This change from the resting potential to a more negative membrane potential is called hyperpolarization.

Question 7

At the neuromuscular junction, Ca2+ ions are necessary for:
a - Binding the transmitter with the postsynaptic receptor. b - Facilitating diffusion of the transmitter to the postsynaptic membrane.
c - Splitting the transmitter in the cleft, thus deactivating the transmitter.
d - Fusing the presynaptic vesicle with the presynaptic mem- brane, thus releasing the transmitter.
e - Metabolizing the transmitter within the presynaptic vesicle.

Answer 7

d - Fusing the presynaptic vesicle with the presynaptic mem- brane, thus releasing the transmitter.

Question 8

Which one of the following is true with regard to the termination of synaptic action at the neuromuscular junction?
a. - The reuptake of intact acetylcholine molecules into the
motor neuron terminal is responsible.
b. - Diffusion of acetylcholine away from the synapse is solely
responsible.
c. - Acetylcholinesterase rapidly breaks down acetylcholine into
choline and acetate.
d. - Dissociation of acetylcholine from the muscarinic receptor,
after binding for several seconds, is solely responsible.

Answer 8

c. - Acetylcholinesterase rapidly breaks down acetylcholine into
choline and acetate.

Question 9

Troponin and tropomyosin are components of which one of the following structures?
a. Myosin thick filament
b. Sarcolemma
c. T tubule
d. Actin thin filament
e. Sarcoplasmic reticulum

Answer 9

a - myosin filament

Question 10

Action potentials in skeletal muscle cells trigger the release from the sarcoplasmic reticulum of what ion critical to the muscle’s contractile process?
a. Ca2+
b. Na+
c. K+
d. Cl–
e. HCO3–

Answer 10

a - Ca2+

Question 11

Which one of the following is not found in smooth muscle?
a. Actin filaments
b. Myosin filaments
c. T tubules
d. Voltage-gated calcium channels e. Sarcoplasmic reticulum

Answer 11

c - T tubules

Question 12

A gross skeletal muscle belly can be instructed (by the central nervous system) to contract more forcefully by:
a. Causing more of its motor units to contract simultaneously.
b. Increasing the amount of acetylcholine released during each
neuromuscular synaptic transmission.
c. Increasing the frequency of action potentials in the α motor
neuron’s axon.
d. Both a and c.
e. Both b and c.

Answer 12

d - both a and c

Question 13

Which one of the following is an example of a segmental reflex? a. Quadriceps stretch reflex
b. Cutaneous trunci reflex
c. Vestibulospinal postural reflexes

Answer 13

a

Question 14

An intersegmental reflex arc is one in which:
a. The course of the arc is restricted to one or a small number
of segments of the CNS.
b. No target organ is present.
c. No receptor is present.
d. The course of the arc traverses several segments of the CNS.
e. Both b and c.

Answer 14

d

Question 15

Activation of the Golgi tendon organ of a given muscle:
a. Monosynaptically produces EPSPs on the α motor neuron
that returns to that muscle.
b. Is most effectively produced by lengthening of the extrafusal
fibers of that muscle.
c. Polysynaptically produces IPSPs on the α motor neuron
that returns to that muscle.
d. Polysynaptically produces EPSPs on the α motor neuron
that returns to that muscle.
e. Activates motor neurons that return to the Golgi tendon
organ itself.

Answer 15

c

Question 16

Gamma (γ) motor neurons:
a. Innervate and produce contraction of the equatorial
(middle) region of an intrafusal fiber.
b. Have their cell bodies in the dorsal horn of the spinal cord. c. Are never activated at the same time as α motor neurons. d. Can regulate the sensitivity of the muscle spindle sensory
organ.
e. Innervate and regulate the sensitivity of the Golgi tendon
organ.

Answer 16

d

Question 17

You examine a dog that is bright, alert, and responsive. She can stand and bear weight on both front legs, but she cannot stand or bear any weight on the back legs. Her knee jerk and toe-pinch withdrawal reflexes are normal in all four legs. There is no atrophy. The proprioceptive positioning response is normal in the front legs but absent in both rear legs. Injecting acetylcholinesterase-inhibiting drugs causes no change in the clinical signs. Where is this dog’s pathological lesion most likely located?
a. Neuromuscular junction
b. Cervical spinal cord (spinal cord of the neck)
c. Spinal cord between the front and rear legs (thoracolumbar
spinal cord)
d. Lower motor neurons to the rear legs e. Brainstem

Answer 17

c

Question 18

You examine a dog that is bright, alert, and responsive but unable to stand on any of the four legs. Toe-pinch and knee jerk local (segmental) reflexes are normal in all four legs. There is no atrophy. The proprioceptive positioning response is absent in all four legs. Injecting an acetylcholinesterase-inhibiting drug does not change the clinical signs. Where is this dog’s pathological lesion most likely located?
a. Cervical spinal cord (spinal cord in the neck)
b. Spinal cord between the front and rear legs (thoracolumbar
spinal cord)
c. Lower motor neurons to all four legs
d. Neuromuscular junction

Answer 18

a

Question 19

You are presented with a horse that is unable to stand or support any weight on the hind legs. You electrically stimulate both the sciatic and the femoral nerves with a sufficient stimulus, but neither stimulation results in muscular contraction. However, direct stimulation of both the gastrocnemius and the quadriceps femoris muscles of the rear leg results in muscular contraction. From these observations, what do you logically conclude to be the location of this horse’s pathological lesion?
a. Upper motor neurons controlling the rear legs b. Lower motor neurons to the rear legs
c. Neuromuscular synapses of the rear legs
d. Muscles of the rear legs
e. Either b or c

Answer 19

e

Question 20

You examine a cat that cannot bear weight on the hind legs. The cat is bright, alert, and responsive. Atrophy is present in the back legs. Cranial nerve reflexes are within normal limits, as are segmental reflexes and the proprioceptive positioning responses of the front legs. Knee jerk and toe-pinch withdrawal reflexes are absent in the hind legs. What is the most likely location for this cat’s pathological lesion?
a. Brainstem
b. Cervical spinal cord (spinal cord in the neck)
c. Thoracolumbar spinal cord (spinal cord between the front
and rear legs)
d. Lower motor neurons to the front legs
e. Lower motor neurons to the hind legs

Answer 20

e

Question 21

A motor neuron pool located most laterally in the ventral horn of the spinal cord is most likely to operate a muscle controlling movement of the:
a. Proximal limb
b. Neck
c. Distal limb
d. Abdomen

Answer 21

c

Question 22

Which of the following is true regarding decerebrate rigidity? a. It can result from severe forebrain disease.
b. Disruption of the cortical control of medullary reticulospi-
nal neurons is a major contributor to the condition.
c. It can result in a fixed, rigid, hobbyhorse-like posture in the
quadruped.
d. Removal of normal inhibition to some of the antigravity
muscles contributes to the condition.
e. All of the above are true.

Answer 22

e

Question 23

Which of the following descending brainstem motor pathways controls distal limb musculature associated with skilled movement?
a. Medial vestibulospinal tract
b. Rubrospinal tract
c. Pontine reticulospinal tract
d. Tectospinal tract
e. All of the above play a major role in such control

Answer 23

b

Question 24

The corticospinal (pyramidal) tract, in general, initiates what form of movement?
a. Antigravity movement
b. Postural adjustment
c. Skilled, voluntary, mostly flexor movement
d. Tremulous, jerky movement
e. None of the above

Answer 24

c

Question 25

You are presented with a dog with a weakness, and proprioceptive placing reaction deficit, of his left front and left back legs. A single pathological site could cause these signs if it were located in the: a. Left side of the cervical spinal cord b. Left cerebral cortex c. Right cerebral cortex d. Either a or b e. Either a or c

Answer 25

e

Question 26

The Reticulospinal and Vestibulospinal Tracts Are Medial Brainstem Motor Pathways Important for Keeping the Body Upright Against the Pull of Gravity: true or false?

Answer 26

True

Question 27

Medial and Lateral Descending Brainstem Motor Pathways Respectively Control Proximal Muscles of Posture and More Distal Muscles of Skilled Movement: true or false?

Answer 27

True

Question 28

The Rubrospinal Tract Is a Lateral Brainstem Motor Pathway That Can Control Distal Limb Musculature Associated With Skilled Movement: true or false?

Answer 28

true

Question 29

The Corticospinal (Pyramidal) Tract Is a Direct Projection From Cerebral Cortex to Spinal Cord Responsible for the Most Skilled Voluntary Movements of Mammals. True or false?

Answer 29

True

Question 30

You are presented with a dog with a head tilt, compulsive circling, and spontaneous nystagmus. The most likely site of this dog’s pathological lesion is the: a. Oculomotor nucleus b. Cerebral cortex c. Vestibular system d. Cervical spinal cord e. Spinal accessory (eleventh cranial) nerve

Answer 30

c

Question 31

Which one of the following statements is false? a. In a given utricle, the cilia of all of the hair cells are oriented in the same horizontal direction. b. In a single vestibular hair cell, displacement of the cilia toward the largest cilium increases the firing rate of the hair cell’s associated sensory neuron. c. The axons of sensory neurons synaptically associated with vestibular hair cells form the eighth cranial nerve. d. A gelatinous layer is associated with the vestibular macula. e. The vestibular nuclear complex is located in the brainstem.

Answer 31

a - Utricular macula (horizontally oriented but different directions), and saccular macula (vertically orientated in different directions)

Question 32

If a normal dog is sitting on a piano stool and I start to spin (accelerate) the stool to the right, which two of the following will be false regarding the observed nystagmus? a. The pattern of nystagmus observed at the start of rotation will be seen in reverse briefly after the spinning is abruptly stopped. b. An intact medial longitudinal fasciculus (MLF) is important for producing the nystagmus. c. The nystagmus will continue long after constant velocity is achieved. d. The eyes will drift slowly to the left, as far as they can go, and then flip rapidly back to the right. e. Nystagmus will often be observed long after the spinning has stopped, while the dog is stationary.

Answer 32

c and e C - nystagmus stops after constant velocity is achieved. Answer "A" explains the transient postrotatory nystagmus, with the converse eye movement pattern to that just noted, can be seen if a spinning animal or person is suddenly stopped. Inertia of the endolymph causes it to continue rotating in the semicircular duct, pushing on the crista ampullaris, even though the head and duct have stopped moving. It is very brief/transient

Question 33

Which of the following is principally involved in planning ahead for the next appropriate movement? a. Vestibulocerebellum b. Spinocerebellum c. Cerebrocerebellum d. Archicerebellum e. Both a and b

Answer 33

c - Cerebrocerebellum Helps With Planning Coordinated, Properly Timed Movement Sequences - (located in the lateral hemispheres) Vestibulocerebellum coordinate Balance and Eye Movements - (located in ventral position) Spinocerebellum Coordinate Muscle Tone as Well as Limb Movement (located in a central position)

Question 34

With regard to symptoms of cerebellar dysfunction, movements that continue either too long, or not long enough, are most correctly referred to as which one of the following? a. Ataxia b. Asynergia c. Hypoplasia d. Dysmetria

Answer 34

d - dysmetria - too long or not long enough movements. Often manifested as difficulty in bringing the muzzle to a fixed point in space, such as a food dish, and as exaggerated “goose stepping” walking movements Ataxia is when animals often place their paws far apart (wide-based gait) and walk in an uncoordinated manner Asynergia failure of the components of a complex, multiple-joint movement to occur in a coordinated fashion, may also be seen. It is particularly characteristic of damage to the cerebrocerebellum.

Question 35

Which of the following is true regarding cerebellar Purkinje cells? a. They are located in the cerebellar cortex. b. They have large cell bodies. c. They have an extensive dendritic tree. d. When active, they inhibit the activity of cells in deep cer- ebellar nuclei, whose axons leave the cerebellum. e. All the above.

Answer 35

e - all the above

Question 36

Choose the incorrect statement below: a. A ganglion is a collection of nerve cell bodies outside the CNS. b. Acetylcholine is a chemical transmitter at the parasympa- thetic postganglionic–to–target organ synapse. c. Sympathetic postganglionic neurons are usually longer than those of the parasympathetic system. d. The adrenal medulla secretes mostly norepinephrine and relatively little epinephrine. e. Muscarinic acetylcholine receptors are found on peripheral targets of parasympathetic postganglionic neurons.

Answer 36

d - secretes both in equal manner

Question 37

A chemical neurotransmitter between preganglionic and postganglionic neurons of the parasympathetic component of the autonomic nervous system is: a. Norepinephrine b. Acetylcholine c. Epinephrine d. Serotonin e. γ-Aminobutyric acid

Answer 37

b - ACH mostly released in parasympathetic stimulation

Question 38

A neurotransmitter most often found at the synapse between sympathetic postganglionic neurons and their targets is: a. Norepinephrine b. Epinephrine c. Acetylcholine d. Dopamine e. γ-Aminobutyric acid

Answer 38

a - noradrenaline mostly released in sympathetic stem from the POSTganglionic neuron. Between pre- and post ganglion, the neurotrasmit is ACH

Question 39

Which of the following is true regarding sympathetic pregan- glionic neurons? a. Their cell bodies are located in thoracic and lumbar regions of the spinal cord. b. Their axons synapse within the sympathetic ganglion chain. c. Their axons form splanchnic nerves. d. Their axons travel in the ventral root. e. All the above are true.

Answer 39

e

Question 40

Horner’s syndrome is caused by the loss of: a. Sympathetic innervation to the eye. b. Parasympathetic postganglionic innervation to the eye. c. Peripheral muscarinic receptors. d. Vagus nerve fibers. e. Smooth muscle of the iris.

Answer 40

a

Question 41

Which of the following is true regarding interactions between the autonomic nervous system and the immune system? a. Lymphocytes can possess β-adrenergic receptors. b. The hypothalamus can indirectly modulate neuroinflam- mation. c. Postganglionic sympathetic neurons innervate lymph nodes. d. Activating parasympathetic axons of the vagus nerve can modulate cytokine release from immune cells. e. All the above are true.

Answer 41

e

Question 42

You examine a patient’s pupillary light reflexes. Shining a light into the left eye produces both a positive direct and a positive consensual pupillary response. However, shining the light into the right eye produces neither a direct nor an indirect pupillary response. This patient’s pathological lesion is located in which one of the following structures? a. Left optic nerve b. Left oculomotor nerve c. Right optic nerve d. Right oculomotor nerve e. Left primary visual cortex

Answer 42

C - must be pre-chiasma, and located in optic nerve

Question 43

A patient whose left pupil diameter is smaller than normal, whose left upper eyelid droops, and whose left “third eyelid” is abnormally displaced likely has a lesion of which of the following structures? a. Left oculomotor nerve b. Left vagosympathetic nerve trunk c. Right oculomotor nerve d. Right vagosympathetic nerve trunk e. Left optic tract

Answer 43

B - sympathetic stimulation (Horner) issue due affect same side

Question 44

In the veterinarian’s waiting room, your friend, a member of the soccer team, is trying without much success to explain the cause for the team’s recent losing trend. A variety of implausible explanations are proposed until she mentions that she is progres- sively losing vision, but only in her left visual field, and has frequent headaches. You recommend that she see a neurologist because she likely has a lesion in her: a. Left optic tract b. Right optic nerve c. Right optic tract d. Optic chiasm e. Left optic radiations

Answer 44

c - because lack is from left visual field, the right optic tract (after chiasma) must be affected (see picture that explains)

Question 45

# Which two of the following are false regarding the blood-brain barrier ( Which two of the following are false regarding the blood-brain barrier (BBB)? a. The BBB is very effective at the circumventricular organs of the brain. b. Astrocytic end-feet are part of the neurovascular unit. c. Brain capillaries generally have a high number of endothe- lial tight junctions. d. Many dyes injected into the blood can typically penetrate most tissues of the body but usually not the brain. e. Small, uncharged, lipid-soluble molecules do not generally pass through the BBB.

Answer 45

a and e As a general rule, molecules that are small, uncharged, lipid-soluble, and unbound to plasma proteins (e.g., O2, CO2, ethanol, nicotine) can easily pass across the capillary endothelium of the BBB. Some molecules that do not fit this profile (e.g., glucose, some amino acids) are able to pass through the BBB by specific, carrier-mediated transport mechanisms

Question 46

CSF is principally formed at the: a. Arachnoid villi b. Aqueduct of Sylvius c. Choroid plexuses d. Subarachnoid space e. Dorsal sagittal sinus

Answer 46

c