Neurobiology Exam 1

During the overshoot phase of an action potential, membrane potential briefly reaches a value near ______ mV.

-80

If the distribution of EPP amplitudes has peaks at 0.4 mV, 0.8 mV, 1.2 mV, 1.6 mV, and 2.0 mV, what is the most likely amplitude of the MEPP?

0.4 mV

What is the structure of serotonin?

A benzene ring, a hydroxyl group, another ring with a nitrogen, an amine group.

Which conclusion can be drawn from Hodgkin and Huxley's studies of K+ and Na+ conductances?

Both conductances exhibit the property of time-dependent activation. Both conductances depend on voltage. K+ conductance reaches its maximum with a pronounced delay. Unlike K+ conductance, Na+ conductance reaches its maximum and inactivates rapidly.

Which of the following parts of a neuron would be labeled by a Nissl Stain

Cell Body

Which structure can be found exclusively at an electrical synapse?

Connexon

In which order are catecholamine neurotransmitters synthesized?

Dopamine, norepinephrine, epinephrine

What is the likely source of the quanta that make up the EPP?

Fusion of individual synaptic vesicles with the plasma membrane

Which experimental model did Hodgkin and Katz use in their studies of the resting membrane potential?

Giant squid neuron

The cerebrospinal fluid is found where?

In ventricles and the subarachnoid space.

In the sequence of events in neurotransmission, which event occurs just after the action potential arrives and spreads and depolarization at the presynaptic terminal?

Influx of Ca2+ into the presynaptic terminal

What is the mechanism of organophosphate toxicity?

Inhibition of acetlycholinesterase

Which characteristic is an accepted criterion for classifying a molecule as a neurotransmitter?

It must be present in the presynaptic terminal. It must be released in response to presynaptic electrical activity. It must exert an effect on the postsynaptic cell via specific receptors.

Which statement best describes the Nernst equation?

It relates equilibrium potential of an ion to its intra- and extracellular concentration.

How will a neuron respond to an injection of a negative current?

It will become hyperpolarized

How would application of a Ca2+ channel blocker affect the function of a synapse?

It would eliminate the postsynaptic potential and the presynaptic Ca2+ current.

Concentrations of which ion, inside and outside of a neuron, have the greatest effect on the resting membrane potential?

K+

Hodgkin and colleagues found which of the following ratios for relative permeability to ions during resting vs. action potentials?

Resting potential, Pk+:PNa+:PCl- = 1:0.04:0.45. Action potential, Pk+:PNa+:PCl- = 1:20:0.45

Which cell produces myelin in the nerves of the peripheral nervous system?

Schwann cell

Where will voltage-gated Na+ channels be most abundant?

Structure D: the nodes of ranvier

What is the function of microtubules in a neuron?

Supports the characteristic shape of a neuron, primarily within the axon. Provides the structure for a molecular motors to transport vesicles and other cargos from the soma to the terminal. Provides the structure for molecular motors to transport vesicles and other cargos from the axon terminal toward the soma.

Which evidence supports the assertion that the macroscopic Na+ current is the sum of many microscopic Na+ currents?

The averaged collective response of single channels resembles the time course of the macroscopic current.

Which of the following best describes the "Neuron Doctrine"

The nervous system is made up of a discreet individual cells (neurons).

Which of the following statements regarding refractory periods is true?

The refractory period sets an upper limit on the frequency of action potentials.

Which process(es) underlie(s) the refractory period?

The slow time course of turning off K+ conductance activation and the persistence of Na+ conductance inactivation.

Which of the following is true regarding graded potentials?

Their amplitude is proportional to the magnitude of the triggering stimulus.

Which statement about the astrocytes is true?

They play a role in the formation of the blood-brain barrier.

Which function is a characteristic primarily of neurons only, and not glia?

Transmits action potentials

Interneurons are found only in the CNS?

True

What is a common precursor of all catecholamines?

Tyrosine

What are the causes of membrane potential?

Unequal distribution of ions across the membrane, and a plasma membrane selectively permeable to some ions more than others.

Under which circumstances is the Goldman equation equivalent to the Nernst equation?

When a membrane is permeable to only one ion.

The pia mater is:

a basement membrane (lamina) generated by astrocytes

The amplitude of the action potential of a given neuron is

always the same

In the knee-jerk reflex, the afferent neurons

are sensory neurons

Amphetamines cause release of:

catecholamines and serotonin

Ion channels that are involved in generation of action potentials open or close in response to

changes in voltage

Studies of the ionic basis of the action potential in a squid giant axon found that

decreasing sodium outside the cell decreases the size of the action potential

An action potential occurs if current injected into a neuron ____ the neuron to reach _____ potential.

depolarizes; threshold

The voltage clamp method controls the ______ at any desired level.

membrane potential

Sub-threshold current injected into an axon flows _____ along the axon and ______ with distance from the site of injection.

passively; decays

Which vesicles, loaded with neuropeptides, arrive in the presynaptic terminal via axonal transport?

Large, dense-core vesicles

The cell bodies of neurons that release norepinephrine project from which structure?

Locus coeruleus

Which glial cell type serves as a resident immune cell in the central nervous system?

Microglia

Which statement accurately describes the expression of genes in the nervous system?

Most of the genes in the human genome are expressed in the CNS.

In general, the CNS of vertebrates has what type of organization?

Motor functions are predominantly ventral while sensory functions are predominantly dorsal.

You are performing a patch clamping experiment in which you measure a reversal potential for the channels in your patch of +60mV. To which ion(s) are your channels most likely permeable to?

Na+

EPSPs are most often triggered by changes in conductance for _______, while IPSPs are most often triggered by changes in conductance for _______.

Na+ and Ca++; K+ and Cl-

Which transporter plays a key role in maintaining the concentration gradients of ions in the brains that are critical for generating electrical signals?

Na+/K+ ATPase pump

Which component represents the peripheral nervous system?

Nerve

In the spinal cord, white matter is found on the ______ while gray matter is found on the _______.

Outside, inside

Which of the following best describes the thalamus?

Part of the forebrain, a central relay station for motor and sensory information.