FUNDAMENTALS OF ANATOMY AND PHYSIOLOGY 11 BIOL
242 EXAM 1 QUESTIONS WITH ANSWERS
The reticular formation is a web of ___ scattered throughout the ____.
a. nerves; white matter in the cerebrum
b. white matter; cerebellum
c. gray matter; brainstem
d. gray matter; cerebrum
e. neuroglia; hypothalamus - answer-c. gray matter; brainstem
Loss of equilibrium and motor coordination would most likely be related
to a lesion in the
a. limbic system
b. pons
c. pituitary gland
d. midbrain
e. cerebellum - answer-e. cerebellum
Explain the functional divisions of the nervous system. Include the
subdivisions of each. - answer-Central Nervous System and Peripheral
Nervous System
- CNS includes the brain and spinal cord
- PNS includes autonomic and somatic nervous systems
,Are thermoreceptors part of the PNS or CNS? - answer-PNS
A child eats a whole bottle of salt (NaCl) tablets. What effect does this
have on the resting membrane potential? - answer-no effect - think of the
analogy of adding a handful of sand to the beach. The concentration of
Na+ outside the cell is already very high at the resting potential, so adding
a (relatively) small amount will not have an effect on resting potential
Why are potassium ions the major factors that determine the resting
membrane potential? - answer-cell membranes are more permeable to K+
than to other ions (via potassium leak channels)
Define leak and gated ion channels. How are they responsible for the
permeability characteristics of a resting versus a stimulated plasma
membrane? - answer-Leak channels - membrane channels with no gating
mechanism; due to the size/shape of the membrane protein, each is only
permeable to specific ions; form of passive transport, as they allow ions to
diffuse down their concentration gradients
Gated ion channels - membrane channels with a gating mechanism such
as voltage or ligands; opening of these channels stimulated by the binding
of a particular ligand or changes in cell voltage; once these channels are
open, ions can diffuse down their concentration gradient (passive
transport); ion specific
Leak channels always allow diffusion (both resting and stimulated
membranes); gated-channels are only permeable when the membrane is
stimulated in a specific way
,If you decrease the K+ concentration outside of the cell (hypokalemia),
would lead to hyper- or de- polarization? - answer-hyperpolarization
Decreasing the K+ concentration outside the cell would cause K+ to leak
out from inside the cell via the potassium leak channels. This would
further polarize the charge difference between the inside and outside of
the cell, making the inside more negative relative to the outside of the cell.
Define action potential. How do depolarizing and hyperpolarizing graded
potentials affect the likelihood of generating an action potential? - answer-
Action potential - change in electrical potential; generated at the axon
hillock when a stimulus passes a threshold
Depolarizing graded potentials (e.g. EPSPs) increases the likelihood of
generating an action potential because it brings the resting potential closer
to the level of the threshold;
Hyperpolarizing graded potentials (e.g. IPSPs) reduces the likelihood of
generating an action potential because it brings the resting potential farther
from the threshold.
Why is action potential considered to be an all-or-non phenomenon? -
answer-A certain threshold of depolarization must be crossed by the
neuron before an action potential is generated; if the charge reaches
halfway to the threshold, there will be no action potential, NOT half an
action potential
, An action potential does not get smaller as it propagates. Why? - answer-
voltage-gated ion channels along the membrane of the axon (or in the
nodes of Ranvier of myelinated axons) essentially allow for the
regeneration of local/graded potentials as the AP travels down the axon;
in myelinated cells, action potentials undergo saltatory conduction in
which the segments of myelin insulate the axon and prevent the charge
from dispersing, and the intermediate nodes of Ranvier are packed with
voltage-gated ion channels.
A stronger stimulus cannot generate a greater action potential, but it can
increase the frequency of action potentials generated in the trigger zone.
Explain - answer-Because action potentials are "all-or-nothing," a stimulus
stronger than the threshold will not generate an action potential stronger
than the average;
instead, the frequency of action potentials is proportional to the strength
of the stimulus, because action potentials can occur more frequently if
there is a constant source of stimulus as long as the relative refractory
period is achieved
How do EPSPs and IPSPs affect the likelihood of generating an action
potential? - answer-EPSPs - increase the likelihood
- EPSPs are excitatory signals, and result in depolarizing, increasing the
likelihood of an action potential;
IPSPs - decrease the likelihood
- IPSPs are inhibitory signals, and result in hyperpolarization, decreasing
the likelihood of an action potential
242 EXAM 1 QUESTIONS WITH ANSWERS
The reticular formation is a web of ___ scattered throughout the ____.
a. nerves; white matter in the cerebrum
b. white matter; cerebellum
c. gray matter; brainstem
d. gray matter; cerebrum
e. neuroglia; hypothalamus - answer-c. gray matter; brainstem
Loss of equilibrium and motor coordination would most likely be related
to a lesion in the
a. limbic system
b. pons
c. pituitary gland
d. midbrain
e. cerebellum - answer-e. cerebellum
Explain the functional divisions of the nervous system. Include the
subdivisions of each. - answer-Central Nervous System and Peripheral
Nervous System
- CNS includes the brain and spinal cord
- PNS includes autonomic and somatic nervous systems
,Are thermoreceptors part of the PNS or CNS? - answer-PNS
A child eats a whole bottle of salt (NaCl) tablets. What effect does this
have on the resting membrane potential? - answer-no effect - think of the
analogy of adding a handful of sand to the beach. The concentration of
Na+ outside the cell is already very high at the resting potential, so adding
a (relatively) small amount will not have an effect on resting potential
Why are potassium ions the major factors that determine the resting
membrane potential? - answer-cell membranes are more permeable to K+
than to other ions (via potassium leak channels)
Define leak and gated ion channels. How are they responsible for the
permeability characteristics of a resting versus a stimulated plasma
membrane? - answer-Leak channels - membrane channels with no gating
mechanism; due to the size/shape of the membrane protein, each is only
permeable to specific ions; form of passive transport, as they allow ions to
diffuse down their concentration gradients
Gated ion channels - membrane channels with a gating mechanism such
as voltage or ligands; opening of these channels stimulated by the binding
of a particular ligand or changes in cell voltage; once these channels are
open, ions can diffuse down their concentration gradient (passive
transport); ion specific
Leak channels always allow diffusion (both resting and stimulated
membranes); gated-channels are only permeable when the membrane is
stimulated in a specific way
,If you decrease the K+ concentration outside of the cell (hypokalemia),
would lead to hyper- or de- polarization? - answer-hyperpolarization
Decreasing the K+ concentration outside the cell would cause K+ to leak
out from inside the cell via the potassium leak channels. This would
further polarize the charge difference between the inside and outside of
the cell, making the inside more negative relative to the outside of the cell.
Define action potential. How do depolarizing and hyperpolarizing graded
potentials affect the likelihood of generating an action potential? - answer-
Action potential - change in electrical potential; generated at the axon
hillock when a stimulus passes a threshold
Depolarizing graded potentials (e.g. EPSPs) increases the likelihood of
generating an action potential because it brings the resting potential closer
to the level of the threshold;
Hyperpolarizing graded potentials (e.g. IPSPs) reduces the likelihood of
generating an action potential because it brings the resting potential farther
from the threshold.
Why is action potential considered to be an all-or-non phenomenon? -
answer-A certain threshold of depolarization must be crossed by the
neuron before an action potential is generated; if the charge reaches
halfway to the threshold, there will be no action potential, NOT half an
action potential
, An action potential does not get smaller as it propagates. Why? - answer-
voltage-gated ion channels along the membrane of the axon (or in the
nodes of Ranvier of myelinated axons) essentially allow for the
regeneration of local/graded potentials as the AP travels down the axon;
in myelinated cells, action potentials undergo saltatory conduction in
which the segments of myelin insulate the axon and prevent the charge
from dispersing, and the intermediate nodes of Ranvier are packed with
voltage-gated ion channels.
A stronger stimulus cannot generate a greater action potential, but it can
increase the frequency of action potentials generated in the trigger zone.
Explain - answer-Because action potentials are "all-or-nothing," a stimulus
stronger than the threshold will not generate an action potential stronger
than the average;
instead, the frequency of action potentials is proportional to the strength
of the stimulus, because action potentials can occur more frequently if
there is a constant source of stimulus as long as the relative refractory
period is achieved
How do EPSPs and IPSPs affect the likelihood of generating an action
potential? - answer-EPSPs - increase the likelihood
- EPSPs are excitatory signals, and result in depolarizing, increasing the
likelihood of an action potential;
IPSPs - decrease the likelihood
- IPSPs are inhibitory signals, and result in hyperpolarization, decreasing
the likelihood of an action potential
