Unit 1 Exam
Explain the difference between action potentials (all-or-none) and synaptic potentials (graded).
Action potentials have the same amplitude regardless of stimulus frequency and intensity. In contrast, the amplitude of a synaptic potential does depend on the stimulus: the number of synapses activated, strength of each synapse, and the amount of synaptic activity.
Which conclusion can be drawn from Hodgkin and Huxley's studies of K+ and Na+ conductances?
All of the above.
Which of Camillo Golgi's contributions enabled Santiago Ramón y Cajal to make observations that suggested that nerve cells are discrete entities?
Development of a staining method based on impregnation with silver salts.
The classic voltage clamp technique would be suitable for which application?
Direct measurement of current flowing through the cell membrane.
Which part of DNA is transcribed into messenger RNA?
Exons only
What was the substance of the disagreement between Golgi and Cajal that, nevertheless, earned them both the 1906 Nobel Prize in Medicine or Physiology?
Golgi was a proponent of the "reticular theory," which stated that all nerve cells are connected, whereas Cajal argued that nerve cells are discrete entities, which is now known as the neuron doctrine.
Which of the following is used to predict whether a certain disease will occur in a family?
Homozygosity mapping
The resting membrane potential typically ranges from _____ to _____ .
-40mV ; -90mV
Which current is produced in response to a hyperpolarizing stimulus in a giant axon of a squid?
Inward capacitive current.
Which statement best describes the function of a neuron with multiple, highly branched dendrites and one axon?
It integrates information from many neurons
Which statement about Na+ permeability during an action potential is most accurate?
It is responsible for the rising phase of the action potential.
Which statement best describes the Nernst equation?
It relates the equilibrium potential of an ion to its intra- and extracellular concentrations.
How will a neuron respond to an injection of negative current?
It will become more hyperpolarized
Which stimulus is most likely to evoke an action potential?
Large depolarizing current pulse
Which glial cell type serves as a resident immune cell in the central nervous system?
Microglia
There is an excess of _______ in the extracellular compartment, relative to the intracellular compartment.
Na+, Cl-, and Ca2+
In what ways are neurons specialized for communication? How do these specialized features distinguish neurons from other types of cells?
Neurons have axons and dendrites, structures for maintaining and transmitting electrical potential, and synapses, all of which allow neurons to establish connections and share information.
Which type(s) of electrical signals occur(s) within the neural circuit for a spinal reflex?
Receptor potential, synaptic potential, and action potential.
Practically speaking, how would you determine that Na+ influx into a cell underlies the early current?
Remove Na+ from the extracellular compartment and assess the early current under new conditions.
Which cell produces myelin in the nerves of the peripheral nervous system?
Schwann cell
Which of the following component does not represents part of the brain?
Spinal nerve
Explain the difference between hyperpolarization and depolarization.
The membrane potential becomes more negative during hyperpolarization, and it becomes more positive during depolarization.
Which current corresponds to a flow of Na+ in response to a depolarizing stimulus in a giant axon of a squid?
Transient inward current.
The amplitude of the action potential of a given neuron is _____
always the same
In the knee-jerk reflex, the afferent neurons (towards the CNS) _____
are sensory neurons
Compared with projection neurons, axons of local circuit neurons (interneurons) _____
are shorter
The resting potential of a cell is negative because
at rest there is an excess of K+ inside the cell, and the membrane is permeable chiefly to K+.
The voltage clamp method controls the _______ at any desired level.
membrane potential
In a two-compartment model of a cell with a K+-permeable membrane, at K+ equilibrium potential, there is _______ flux of K+ ions.
no net
What physical characteristic distinguishes neurons from other types of cells?
Axon
Which statement best describes most neurons?
They are polarized
Which of the following is true about synapses?
They are the tiny space into which neurotransmitter is released.
Which is the leading hypothesis about the proposed actions of inhalation anesthetics?
They hyperpolarize the resting membrane potential of neurons thus making it more difficult to fire action potentials.
Which statement about active ion transporters is true?
They move certain ions against the concentration gradient.
