Nervous System

Question 1

While epinephrine infusion is indicated for treatment of symptomatic bradycardia, it is not the first choice for pharmaceutical intervention. Which of the following might also alleviate bradycardia?
Propanolol that inhibits beta adrenergic receptor binding
Atropine which inhibits parasympathetic activation
Acetylcholine
Adenosine which decreases conduction of the Av node

Answer 1

Although epinephrine mimics the actions of sympathetic stimulation, reduced heart rate (bradycardia) could also occur due to excessive parasympathetic activity, which could potentially be controlled by an inhibitor of the parasympathetic system.

Question 2

bradycardia

Answer 2

reduced heart rate

Question 3

True or false: Sympathetic ganglia generally reside close to their effector tissues.

Answer 3

This statement is false. Sympathetic postganglionic neurons tend to be particularly long because the target tissue resides far from the ganglion. In contrast, parasympathetic ganglia tend to reside proximal to target tissue; consequently, the parasympathetic system has longer preganglionic neurons.

Question 4

prosencephalon

Answer 4

prosencephalon (or forebrain)

Question 5

mesencephalon

Answer 5

midbrain

Question 6

rhombencephalon

Answer 6

hindbrain

Question 7

An action potential originates at the…

Answer 7

axon hillock

Question 8

Describe the process of an action potential when it reaches the axon terminal

Answer 8

When the action potential reaches the axon terminal, membrane depolarization triggers the opening of voltage-gated calcium channels. Calcium-sensitive docking proteins change conformation in response to the calcium influx, initiating vesicle docking and subsequent release of neurotransmitter into the synaptic space.

Question 9

True or False: the CNS is composed of brain, spinal cord, and cerebrospinal fluid

Answer 9

Cerebrospinal fluid is secreted by the ependymal cells in the CNS, they essentially bathe the brain and spinal cord.

Question 10

True or False: the thalamus is part of the cerebrum

Answer 10

While the thalamus, as an important neural processing center, interacts with several cerebral structures, it is itself located elsewhere in the forebrain, specifically in the diencephalon, while the cerebrum is the largest component of the telencephalon.

Question 11

Frontal Lobe

Answer 11

The frontal lobe is responsible for most higher order functions that we associate with humans, such as cognition. It also contains the primary motor cortex, where voluntary muscle impulses originate.

Question 12

Location of Primary Motor Cortex

Answer 12

Frontal Lobe

Question 13

Home to the somatosensory cortex

Answer 13

The parietal lobe contains the primary somatosensory cortex and processes most somatosensation (touch).

Question 14

Lobe responsible for language processing

Answer 14

The temporal lobe processes language, as well as most sound input in general, and plays some role in memory formation.

Question 15

Lobe associated with the visual pathway

Answer 15

The occipital lobe is most notable as the termination point of the visual pathway (which is why trauma to the back of the head can induce visual damage).

Question 16

Studying suggestion

Answer 16

watch nervous system parts of the brain brain sturcture video

Question 17

Ganglia

Answer 17

Ganglia serve as intermediates that translate the neural impulse of the central nervous system into actionable commands for the target organs. Each ganglion is flanked by pre and postganglionic neurons, whose specific properties vary between the sympathetic and parasympathetic nervous systems.

Question 18

Where in the thalamus does visual stimuli travel before going to the occipital lobe?

Answer 18

The visual pathway passes through the superior colliculus and the lateral geniculate body of the thalamus before arriving at the occipital lobe.

Question 19

Where is the primary somatosensory cortex located?

Answer 19

Somatosensation is processed at the primary somatosensory cortex, located on the postcentral gyrus in the parietal lobe.

Question 20

Where in the thalamus does auditory stimuli travel before going to the temporal lobe?

Answer 20

The auditory pathway passess through the similar named medial geniculate body and inferior colliculus, before being processed in the temporal lobe.

Question 21

The primary inhibitory neurotransmitter in the nervous system is…

Answer 21

GABA

Question 22

The primary excitory neurotransmitter in the nervous system is…

Answer 22

Glutamate is the nervous system’s primary excitatory neurotransmitter. It has the opposite effect of GABA, making it more likely that a neuron will generate an action potential.

Question 23

transport nutrients, such as glucose, and contribute to forming the blood brain barrier.

Answer 23

Astrocytes transport nutrients, such as glucose, and contribute to forming the blood brain barrier.

Question 24

create myelin, the primary insulation material that wraps around axons.

Answer 24

Oligodendrocytes create myelin, the primary insulation material that wraps around axons.

Question 25

work similarly to macrophages, defending neuronal cells from foreign pathogens.

Answer 25

Microglia work similarly to macrophages, defending neuronal cells from foreign pathogens.

Question 26

that cells secrete and circulate cerebrospinal fluid, which lubricates and protects the central nervous system.

Answer 26

Ependymal cells secrete and circulate cerebrospinal fluid, which lubricates and protects the central nervous system.

Question 27

True or false: A greater number of graded potentials will increase the likelihood of an action potential occurring.

Answer 27

This statement is false. The question stem asks about “graded potentials,” which can refer to both excitatory postsynaptic potentials (EPSPs) and inhibitory postsynaptic potentials (IPSPs). Enough graded potentials must accumulate to push the membrane potential past a certain depolarization threshold in order to generate an action potential. However, not all graded potentials cause depolarization. EPSPs cause depolarization and will help push the membrane potential towards the threshold, but IPSPs cause hyperpolarization and will push the membrane potential farther away from the threshold.

Question 28

True or false: The components of the peripheral nervous system are bathed in cerebrospinal fluid.

Answer 28

This statement is false. The central nervous system (the brain and spinal cord) are protected by cerebrospinal fluid, not the components of the PNS.

Question 29

How would a signal from the PNS proceed?

Answer 29

Parasympathetic preganglionic axons tend to be relatively long, while postganglionic axons are relatively short. The parasympathetic nervous system uses acetylcholine as its postganglionic neurotransmitter. Therefore, the signal will begin in the spinal cord, travel down a long axon, reach the ganglion, travel down a short axon, before finally releasing acetylcholine.

Question 30

True or Flase: a signal from the PNS would originate from the cervical or sacral region of the CNS

Answer 30

TRUE

Question 31

True or False: Bronchiolar smooth muscle relaxation enables increased ventilation

Answer 31

true

Question 32

True or false: In order for a postsynaptic cell to fire an action potential, multiple excitatory post-synaptic potentials (EPSPs) must be generated in spatial proximity on the postsynaptic membrane.

Answer 32

This statement is false. This statement describes spatial summation of EPSPs, which can certainly elicit a postsynaptic action potential. However, temporal summation, in which a number of consecutive EPSPs are generated before the postsynaptic membrane is able to return to a resting state, may also lead to the generation of an action potential.

Question 33

During depolarization, which channels are open?

Answer 33

Depolarization is the direct result of sodium influx, which occurs due to increased membrane permeability to sodium. This is only possible if voltage-gated sodium channels are open and in an activated state. Potassium channels do not fully open until the repolarization phase of the action potential.

Question 34

Pheochromocytes, which reside in the adrenal medulla, release epinephrine into systemic circulation in response to increased sympathetic activation. Structurally, these cells resemble modified postganglionic sympathetic neurons. Epinephrine release from pheochromocytes most likely occurs in response to:

Answer 34

Binding of acetylcholine to the pheochromocyte surface. If pheochromocytes are analogous to post-ganglionic sympathetic neurons, they are likely to respond to acetylcholine released by the preganglionic cells.

Question 35

At rest, the electrical potential difference across the plasma membrane is…

Answer 35

negative because the cytoplasm is relatively negative to the extracellular fluid

Question 36

True or false: Na+/K+ ATPase must constantly be active to counteract the effects of sodium leaving the cell via leak channels.

Answer 36

This statement is false. It is potassium that gradually “leaks” out of the cell via leak channels, not sodium. Additionally, the constant activity of Na+/K+ ATPase is not due exclusively or even primarily due to the effects of potassium leak channels.

Question 37

Consider the classic depiction of a multipolar neuron. Ligand-gated ion channels are likely to be most abundantly expressed on the…

Answer 37

Dendrites, Presynaptic signals, usually in the form of neurotransmitter molecules, arrive at the dendrites or the cell body. Since many neurotransmitters act to open ligand-gated ion channels, it follows that the dendrites are likely to express such channels.

Question 38

At rest, what does the balance of Na look like?

Answer 38

At rest, the concentration of extracellular sodium greatly exceeds that of intracellular sodium.

Question 39

At rest, what does the balance of Na look like?

Answer 39

Conversely, intracellular potassium is higher than extracellular potassium. At rest, the presence of potassium leak channels confers upon the membrane some degree of potassium permeability.

Question 40

At rest, what does the balance of calcium look like?

Answer 40

The extracellular concentration of calcium is several orders of magnitude higher than the intracellular concentration, which allows calcium to elicit potent signaling responses when its intracellular concentration rises.

Question 41

What channels are found at the nodes of Ranvier?

Answer 41

Na voltage gated ion channel, K voltage gated ion channel, Na/K Atpase

Question 42

How is resting membrane potential established?

Answer 42

The sodium-potassium pump (Na+/K+ ATPase) transports three sodium out of the cell and two potassium into the cell with each use of an ATP. This results in a net negative charge, as more positive ions (three) are leaving the cell than entering (two). The action of these enzymes, along with the gradual diffusion of K+ out of the cell, results in a resting potential of about -70 mV.

Question 43

Membrane depolarization involves making it more negative

Answer 43

False, more positive, threshold is -55, resting is -70 mV

Question 44

True or false: the relative refractory period occurs after sodium channels have closed.

Answer 44

This statement is true. During the relative refractory period, sodium channels have closed, but can still potentially be opened again by a strong enough voltage, generating a second action potential. This contrasts with the absolute refractory period, during which the sodium channels cannot reopen.

Question 45

What happens to norepinephrine after it has bound to a receptor?

Answer 45

After binding to the target receptor, monoamines such as norepinephrine and dopamine are then typically reuptaken by presynaptic neurons or astrocytes, after which they may or may not be broken down.

Question 46

Compared to smaller neurons, larger neurons are…

Answer 46

Larger neurons have more area to store charge along their membranes and, therefore, they have a higher membrane capacitance, making them harder to depolarize. At the same time, larger neurons have lower cytoplasmic resistance than smaller ones, making them faster at conducting signals

Question 47

How does mylenation impact capacitance?

Answer 47

Myelin layers tend to be fairly thick, introducing a large separation between the cytoplasm and the extracellular fluid. This significantly decreases capacitance, since which capacitance is inversely proportional to the distance of charge separation.

Question 48

How does membrane permeability for Na during the upslope of an action potential compare to at rest

Answer 48

During the upslope of a typical action potential, membrane permeability to sodium is:

Question 49

Voltage-gated sodium channels open and sodium influx occurs

Answer 49

Depolarization

Question 50

Voltage-gated potassium channels open and potassium efflux occurs

Answer 50

Repolarization

Question 51

Potassium efflux causes membrane hyperpolarization

Answer 51

Relative Refractory Period

Question 52

Voltage-gated sodium channels are inactivated

Answer 52

Absolute Refractory Period

Question 53

A neurobiologist uses an electrode to induce a local depolarization at a point in the middle of the non-myelinated axon of a resting neuron. The neurobiologist has already confirmed that this voltage, when applied to a point on the cell body, is sufficient to induce the generation of an action potential. Which of the following is the most likely result of the researcher inducing a local depolarization along the axon?

Answer 53

2 AP’s will propograte in opposite directions. Retrograde (backwards) conduction is typically prevented by the inactivation of sodium channels. However, we are told that this neuron exists in a resting state. Therefore, its channels are not inactivated, and there is no reason why bidirectional conduction would not be possible, generating two separate action potentials (one propagating forward, the other propagating backwards)

Question 54

Put in the correct order: 
Potassium channels close
Sodium channels open
Cell becomes hyperpolarized
Sodium channels inactivate
Potassium channels finish opening

Answer 54

Sodium channels open

Potassium channels finish opening

Sodium channels inactivate

Cell becomes hyperpolarized

Potassium channels close