Question 1

At myelinated areas of the axon (i.e.between nodes of Ranvier), which of the following statements is true?

Accepted Answer

A) There is an increased number of voltage-gated sodium channels. 
B) There is increased resistance across the membrane. 
C) There is increased capacitance across the membrane. 
D) There is increased transport of potassium across the membrane.

Question 2

A patient of yours is injured in a car accident.The surgeon reports that while there is damage to the dorsal roots, the spinal cord and nerves otherwise appear intact.What functions would you expect to be affected in the patient?

Accepted Answer

A) The patient may lose somatic function, but should retain autonomic function. 
B) The patient may lose motor function, but should retain sensory perception. 
C) The patient may lose some sensory perception, but should retain motor function.However, lack of proprioceptive input may make muscle control difficult. 
D) The patient may lose parasympathetic function, but should retain sympathetic function.They should avoid stressful situations.

Question 3

How do somatic neurons and autonomic neurons differ? (Check all that apply.)
_____ Somatic neurons innervate the body surface, while autonomic neurons innervate internal structures.__X__ Somatic neurons control skeletal muscle, while autonomic neurons control smooth and cardiac muscle._____ Somatic neurons control exocrine glands, while autonomic neurons do not.__X__

Accepted Answer

The answer of How do somatic neurons and autonomic neurons...

Question 4

Sodium ions are single atoms.Why can't they simply diffuse through the cell membrane's lipid bilayer?

Accepted Answer

A) Since they are charged, ions can't cross the hydrophobic center of the membrane without a channel or pump. 
B) Sodium ions are covalently attached in groups of three, which are too large to diffuse easily. 
C) Ions do traverse the membrane easily, but the sodium-potassium pump moves them back across. 
D) Chelator proteins capture any ions that start to cross the bilayer.

Question 5

What diffuses across the narrow synaptic cleft between the presynaptic axon and the postsynaptic cell to transmit a nerve impulse?

Accepted Answer

A) neurotransmitter 
B) electrical impulse 
C) Na+ ion 
D) vesicle

Question 6

A region of the brain receives both sensory information from ascending nerve tracts and motor commands from the cortex and cerebellum.This region plays an important role in motor control.Which region is it?

Accepted Answer

A) basal ganglia 
B) pituitary gland 
C) parietal lobe 
D) thalamus

Question 7

Where do correlation, association, and learning occur in the brain?

Accepted Answer

A) cerebellum 
B) corpus callosum 
C) medulla 
D) cerebrum

Question 8

A patient suffers from a disease that slows fatty acid synthesis.What is a likely impact of this disease on nervous system function?

Accepted Answer

A) improved functioning due to a healthier weight 
B) insufficient myelination and slow axon conduction rate 
C) improved functioning due to better blood flow 
D) weaker action potentials with smaller depolarization

Question 9

A cheetah is chasing a gazelle.What division of the vertebrate nervous system is regulating the stress response in both animals?

Accepted Answer

A) somatic nervous system 
B) parasympathetic nervous system 
C) sympathetic nervous system 
D) parasymbiotic nervous system

Question 10

Which animal phylum lacks a network of nerve cells for gathering information from the environment?

Accepted Answer

A) Porifera - sponges 
B) Cnidaria - jellyfish, sea anenomes 
C) Platyhelminthes -- flatworms 
D) Nematoda - roundworms

Question 11

Which ion channel is primarily responsible for the action potential?

Accepted Answer

A) the voltage-gated sodium channel 
B) the voltage-gated potassium channel 
C) the ligand-gated sodium channel 
D) the ligand-gated potassium channel

Question 12

The outside of a neuron is positively charged at resting potential.Why do K+ ions leave the cell when K+ channels open during an action potential?

Accepted Answer

A) The diffusion gradient is the only factor that affects ion movement. 
B) K+ ions are actively pumped out by the sodium-potassium pump acting in reverse. 
C) Voltage-gated K+ channels open when membrane potential reaches +50 mV during the depolarization phase.The diffusion gradient and electrical force cooperate to drive K+ ions out of the cell. 
D) Negatively charged proteins leave the cell at the onset of the action potential.

Question 13

Another toxin that also blocks neurotransmitter release is tetanus toxin; however, it primarily affects inhibitory interneurons of the spinal cord that negatively regulate motor neurons.Which would be symptoms of tetanus toxin poisoning?

Accepted Answer

A) flaccid paralysis 
B) spastic paralysis 
C) slowed action potential conduction 
D) pupil dilation

Question 14

True or false: neurons are the only electrically-active cells.

Accepted Answer

A) True 
 B)False

Question 15

Botulinum toxin, or "botox", has become popular for cosmetic surgery.The toxin prevents neurosecretory vesicles from docking at the plasma membrane and releasing neurotransmitter.How would this toxin affect the neuromuscular junction?

Accepted Answer

A) Since ACh is not released, the muscles stay in a state of repeated contraction. 
B) Since ACh is not released, the muscles are not activated to contract and remain relaxed. 
C) Buildup of ACh causes promiscuous activation of all nearby sensory neurons. 
D) Buildup of ACh leaks back into the brain, creating a calming effect.

Question 16

K+ channels in the heart do not have binding sites for ACh, yet parasympathetic release of ACh causes outward flux of K+ from heart cells.How does this occur?

Accepted Answer

A) ACh triggers release of epinephrine from the adrenal glands, which in turn causes K+ flux out of heart cells. 
B) ACh binds to a G-protein coupled receptor on heart cells, and the G protein alpha subunit binds to a separate K+ channel and causes it to open. 
C) Parasympathetic neurons activate sympathetic neurons, which directly cause K+ flux from heart cells. 
D) ACh binds and activates a K+ pump on heart cells.

Question 17

What is the elongated extension of a neuron that nerve impulses travel along?

Accepted Answer

A) axon 
B) cell body 
C) dendrite 
D) oligodendrocyte

Question 18

The doctor informs you that your grandmother's stroke has caused damage to Wernicke's area.Which activity is likely to become more difficult for her?

Accepted Answer

A) walking 
B) doing laundry 
C) having a conversation 
D) sleeping

Exam 43: The Nervous System

At myelinated areas of the axon (i.e.between nodes of Ranvier) , which of the following statements is true?