BHSC 1200 FINAL EXAM QUESTIONS & ANSWERS
organization of nervous system - Answers :1) central nervous system = brain and spinal
cord
-processes many different kinds of incoming sensory information
-source of thoughts, emotions and memories
-produces signals causing muscles to contracts and glands to secrete
2) peripheral nervous system = consists of all nervous tissue outside the CNS
-further divided into sensory (afferent) division [provides information about somatic
senses] and motor (efferent) division [conveys output from CNS to effectors]
-efferent division is further divided: somatic nervous system (conveys output from CNS
to skeletal muscle) and autonomic nervous system (conveys output from CNS to
smooth muscle, cardiac muscle, and glands)
-autonomic nervous system is further divided: sympathetic nervous system and
parasympathetic nervous system (usually have opposing actions)
functions of nervous system - Answers :-sensory function: sensory receptors detect
internal stimuli; sensory information is carried to brain and spinal cord
-integrative function: nervous system processes sensory information by analyzing it and
making decisions
-motor function: nervous system activates effectors causing muscles to contract and
glands to secrete
parts of a neuron - Answers :-cell body: contains a nucleus surrounded by cytoplasm
which includes organelles
-dendrite: receiving or input portions
-axon: long, thin, cylindrical projection; propagates nerve impulses toward another
neuron
-axon hillock: cone shaped elevation; joins axon to cell body
-trigger zone: junction of axon hillock and initial segment; generates nerve impulses
which travel along the axon to their destination
-axon terminal: numerous fine processes originating from the axon
-synaptic bulb: bulb-shaped swellings of the tips of axon terminals; contain synaptic
vesicles that store neurotransmitters
structural classification of neurons - Answers :-multipolar: have several dendrites and
one axon; brain and spinal cord
-bipolar: one main dendrite and one axon; retina of eye, inner ear, olfactory area of
brain
-unipolar: have dendrites and one axon that are fused together to form a continuous
process that emerges from the cell body; function as sensory receptors
functional classification of neurons - Answers :-sensory: afferent neurons; either contain
sensory receptors at their distal ends or are located just after sensory receptors that are
separate cells; forms action potentials; most are unipolar
,-motor: efferent neurons; convey action potentials away from CNS to effectors; most are
multipolar
-interneurons: association neurons; mainly located within CNS between sensory and
motor neurons; process incoming sensory information and elicit motor response by
activating motor neurons; most are multipolar
characteristics and function of astrocytes - Answers :-most abundant, versatile, and
highly branched glial cells
-cling to neurons, synaptic endings, and capillaries
-functions: support and brace neurons; play role in exchanges between capillaries and
neurons through BBB; guide migration of young neurons; respond to nerve impulses
and neurotransmitters; influence neuronal functioning
characteristics and function of microglia - Answers :-small, ovoid cells with thorny
processes that touch and monitor neurons
-migrate toward injured neurons
-can transform to phagocytize microorganisms and neuronal debris
characteristics and function of ependymal cells - Answers :-range in shape from
squamous to columnar
-may be ciliated (cilia beat to circulate CSF)
-line the central cavities of the brain and spinal column
characteristics and function of oligodendrocytes - Answers :-branched cells
-processes wrap CNS nerve fibres, forming insulating myelin sheaths thicker nerve
fibres
myelin sheath - Answers :lipid protein material that acts as an insulator of nerve cells
and speeds up nerve conduction
structure and function of satellite cells - Answers :-cover surface of nerve cell bodies
-regulation of extracellular environment of PNS neurons
characteristics and function of Schwann cells - Answers :-wrap around axon in jelly roll
fashion
-one cell forms one segment of myelin sheath
myelination of neurons in CNS vs myelination of neurons in PNS - Answers :CNS: an
oligodendrocyte puts forth about 15 broad, flat processes that spiral around CNS axons,
forming myelin sheath
PNS: a Schwann cell spirals around an axon many times, forming myelin sheath. The
outer nucleated cytoplasmic layer of the Schwann cell is the neurolemma, found only in
PNS
,composition of white and gray matter - Answers :-white matter: regions of the brain and
spinal cord with dense collections of myelinated fibres
-gray matter: mostly neuron cell bodies and nonmyelinated fibers
organization of white and gray matter in brain and spinal cord - Answers :brain: white
matter = deep; gray matter = superficial
spinal cord: white matter = superficial; gray matter = deep
resting membrane potential - Answers :-charge of plasma membrane at rest; potential
difference across membrane of resting cell
-approximately -70mV in neurons (cytoplasmic side of membrane negatively charged
relative to outside)
-membrane termed polarized
-generated by: differences in ionic makeup of ICF and ECF; differential permeability of
the plasma membrane
discuss the role of ion channels in establishing the resting membrane potential -
Answers :-leak channels: gated channels that randomly open and close; found in nearly
all cells
-ligand-gated channels: gated channels that open in response to binding of ligand
(chemical) stimulus; found in dendrites of some sensory neurons and dendrites and cell
bodies of interneurons and motor neurons
-mechanically-gated channels: gated channels that open in response to mechanical
stimulus (i.e., touch, pressure, vibration, or tissue stretching); found in dendrites of
some sensory neurons
-voltage-gated channels: gated channels that open in response to voltage stimulus
(change in membrane potential); found in axons of all types of neurons
discuss the role of intracellular proteins in establishing the resting membrane potential -
Answers :-ECF is rich in Na+ and Cl-; ICF is rich in K+
-plasma membrane has more K+ leak channels than Na+ leak channels so the inside of
membrane becomes increasingly negative as more K+ leave the cell than Na+ enter
-this is why the resting membrane potential is negative
discuss the role of the Na/K pump in establishing the resting membrane potential -
Answers :-stabilizes resting membrane potential
-maintains concentration gradient for Na+ and K+
-3 Na+ pumped out of cell; 2 K+ pumped in
graded potential vs action potential - Answers :-graded potential: small deviation from
the resting membrane potential that makes the membrane either more polarized or less
, polarized; occurs when a stimulus causes mechanically-gated or ligand-gated channels
to open or close in an excitable cell's plasma membrane
-action potential (aka impulse): a sequence of rapidly occurring events that decrease
and reverse the membrane potential and then eventually restore it to the resting state;
occurs in the axon of a neuron when depolarization reaches a certain level termed the
threshold (-55mV)
define threshold, depolarization, repolarization, and hyperpolarization - Answers :-
threshold: -55mV in most neurons; action potential occurs when this level is reached
-depolarization: negative membrane potential becomes less negative, reaches zero,
and then becomes positive
-repolarization: membrane potential is restored to resting state of -70mV
-hyperpolarization: membrane potential temporarily becomes more negative than the
resting level
role of voltage-gated Na+ channels in the depolarization phase - Answers :Na+
channels open first, allowing Na+ to rush into the cell, causing the depolarizing phase
role of voltage-gated K+ channels in the repolarization phase - Answers :after
depolarization, K+ channels open, allowing K+ to flow out, causing the repolarizing
phase
define absolute and relative refractory periods and explain their significance - Answers
:-absolute refractory period = when voltage-gated Na+ channels open, neuron cannot
respond to another stimulus; time from opening of Na+ channels to resetting of the
channels; ensures that each AP is an all-or-none event; enforces one-way transmission
of nerve impulses
-relative refractory period = period of time during which a second AP can be initiated,
but only by a larger-than-normal stimulus; coincides with the period when the voltage-
gated K+ channels are still open after inactivated Na+ channels have returned to their
resting state
significance: act as a protective mechanism so we can't have multiple AP constantly
firing
discuss how an action potential is propagated - Answers :-depends on positive
feedback loop
-travel from where they arise at the trigger zone to the axon terminals
-action potential keeps its strength as it spreads along the membrane (propagation)
-sodium flows in, voltage gated ion channels open
organization of nervous system - Answers :1) central nervous system = brain and spinal
cord
-processes many different kinds of incoming sensory information
-source of thoughts, emotions and memories
-produces signals causing muscles to contracts and glands to secrete
2) peripheral nervous system = consists of all nervous tissue outside the CNS
-further divided into sensory (afferent) division [provides information about somatic
senses] and motor (efferent) division [conveys output from CNS to effectors]
-efferent division is further divided: somatic nervous system (conveys output from CNS
to skeletal muscle) and autonomic nervous system (conveys output from CNS to
smooth muscle, cardiac muscle, and glands)
-autonomic nervous system is further divided: sympathetic nervous system and
parasympathetic nervous system (usually have opposing actions)
functions of nervous system - Answers :-sensory function: sensory receptors detect
internal stimuli; sensory information is carried to brain and spinal cord
-integrative function: nervous system processes sensory information by analyzing it and
making decisions
-motor function: nervous system activates effectors causing muscles to contract and
glands to secrete
parts of a neuron - Answers :-cell body: contains a nucleus surrounded by cytoplasm
which includes organelles
-dendrite: receiving or input portions
-axon: long, thin, cylindrical projection; propagates nerve impulses toward another
neuron
-axon hillock: cone shaped elevation; joins axon to cell body
-trigger zone: junction of axon hillock and initial segment; generates nerve impulses
which travel along the axon to their destination
-axon terminal: numerous fine processes originating from the axon
-synaptic bulb: bulb-shaped swellings of the tips of axon terminals; contain synaptic
vesicles that store neurotransmitters
structural classification of neurons - Answers :-multipolar: have several dendrites and
one axon; brain and spinal cord
-bipolar: one main dendrite and one axon; retina of eye, inner ear, olfactory area of
brain
-unipolar: have dendrites and one axon that are fused together to form a continuous
process that emerges from the cell body; function as sensory receptors
functional classification of neurons - Answers :-sensory: afferent neurons; either contain
sensory receptors at their distal ends or are located just after sensory receptors that are
separate cells; forms action potentials; most are unipolar
,-motor: efferent neurons; convey action potentials away from CNS to effectors; most are
multipolar
-interneurons: association neurons; mainly located within CNS between sensory and
motor neurons; process incoming sensory information and elicit motor response by
activating motor neurons; most are multipolar
characteristics and function of astrocytes - Answers :-most abundant, versatile, and
highly branched glial cells
-cling to neurons, synaptic endings, and capillaries
-functions: support and brace neurons; play role in exchanges between capillaries and
neurons through BBB; guide migration of young neurons; respond to nerve impulses
and neurotransmitters; influence neuronal functioning
characteristics and function of microglia - Answers :-small, ovoid cells with thorny
processes that touch and monitor neurons
-migrate toward injured neurons
-can transform to phagocytize microorganisms and neuronal debris
characteristics and function of ependymal cells - Answers :-range in shape from
squamous to columnar
-may be ciliated (cilia beat to circulate CSF)
-line the central cavities of the brain and spinal column
characteristics and function of oligodendrocytes - Answers :-branched cells
-processes wrap CNS nerve fibres, forming insulating myelin sheaths thicker nerve
fibres
myelin sheath - Answers :lipid protein material that acts as an insulator of nerve cells
and speeds up nerve conduction
structure and function of satellite cells - Answers :-cover surface of nerve cell bodies
-regulation of extracellular environment of PNS neurons
characteristics and function of Schwann cells - Answers :-wrap around axon in jelly roll
fashion
-one cell forms one segment of myelin sheath
myelination of neurons in CNS vs myelination of neurons in PNS - Answers :CNS: an
oligodendrocyte puts forth about 15 broad, flat processes that spiral around CNS axons,
forming myelin sheath
PNS: a Schwann cell spirals around an axon many times, forming myelin sheath. The
outer nucleated cytoplasmic layer of the Schwann cell is the neurolemma, found only in
PNS
,composition of white and gray matter - Answers :-white matter: regions of the brain and
spinal cord with dense collections of myelinated fibres
-gray matter: mostly neuron cell bodies and nonmyelinated fibers
organization of white and gray matter in brain and spinal cord - Answers :brain: white
matter = deep; gray matter = superficial
spinal cord: white matter = superficial; gray matter = deep
resting membrane potential - Answers :-charge of plasma membrane at rest; potential
difference across membrane of resting cell
-approximately -70mV in neurons (cytoplasmic side of membrane negatively charged
relative to outside)
-membrane termed polarized
-generated by: differences in ionic makeup of ICF and ECF; differential permeability of
the plasma membrane
discuss the role of ion channels in establishing the resting membrane potential -
Answers :-leak channels: gated channels that randomly open and close; found in nearly
all cells
-ligand-gated channels: gated channels that open in response to binding of ligand
(chemical) stimulus; found in dendrites of some sensory neurons and dendrites and cell
bodies of interneurons and motor neurons
-mechanically-gated channels: gated channels that open in response to mechanical
stimulus (i.e., touch, pressure, vibration, or tissue stretching); found in dendrites of
some sensory neurons
-voltage-gated channels: gated channels that open in response to voltage stimulus
(change in membrane potential); found in axons of all types of neurons
discuss the role of intracellular proteins in establishing the resting membrane potential -
Answers :-ECF is rich in Na+ and Cl-; ICF is rich in K+
-plasma membrane has more K+ leak channels than Na+ leak channels so the inside of
membrane becomes increasingly negative as more K+ leave the cell than Na+ enter
-this is why the resting membrane potential is negative
discuss the role of the Na/K pump in establishing the resting membrane potential -
Answers :-stabilizes resting membrane potential
-maintains concentration gradient for Na+ and K+
-3 Na+ pumped out of cell; 2 K+ pumped in
graded potential vs action potential - Answers :-graded potential: small deviation from
the resting membrane potential that makes the membrane either more polarized or less
, polarized; occurs when a stimulus causes mechanically-gated or ligand-gated channels
to open or close in an excitable cell's plasma membrane
-action potential (aka impulse): a sequence of rapidly occurring events that decrease
and reverse the membrane potential and then eventually restore it to the resting state;
occurs in the axon of a neuron when depolarization reaches a certain level termed the
threshold (-55mV)
define threshold, depolarization, repolarization, and hyperpolarization - Answers :-
threshold: -55mV in most neurons; action potential occurs when this level is reached
-depolarization: negative membrane potential becomes less negative, reaches zero,
and then becomes positive
-repolarization: membrane potential is restored to resting state of -70mV
-hyperpolarization: membrane potential temporarily becomes more negative than the
resting level
role of voltage-gated Na+ channels in the depolarization phase - Answers :Na+
channels open first, allowing Na+ to rush into the cell, causing the depolarizing phase
role of voltage-gated K+ channels in the repolarization phase - Answers :after
depolarization, K+ channels open, allowing K+ to flow out, causing the repolarizing
phase
define absolute and relative refractory periods and explain their significance - Answers
:-absolute refractory period = when voltage-gated Na+ channels open, neuron cannot
respond to another stimulus; time from opening of Na+ channels to resetting of the
channels; ensures that each AP is an all-or-none event; enforces one-way transmission
of nerve impulses
-relative refractory period = period of time during which a second AP can be initiated,
but only by a larger-than-normal stimulus; coincides with the period when the voltage-
gated K+ channels are still open after inactivated Na+ channels have returned to their
resting state
significance: act as a protective mechanism so we can't have multiple AP constantly
firing
discuss how an action potential is propagated - Answers :-depends on positive
feedback loop
-travel from where they arise at the trigger zone to the axon terminals
-action potential keeps its strength as it spreads along the membrane (propagation)
-sodium flows in, voltage gated ion channels open
