BIOS 255 EXAM 3 CERTIFICATION
EVALUATION QUESTIONS AND SOLUTIONS
FULL REVIEW SHEET
●● Define autonomic and somatic nervous system
Answer: The somatic nervous system controls voluntary movements and
skeletal muscles; the autonomic nervous system regulates involuntary
functions (smooth muscle, cardiac muscle, glands) and includes
sympathetic and parasympathetic divisions.
●● What is the difference between motor and sensory neurons?
Answer: Sensory (afferent) neurons carry information from receptors to
the CNS; motor (efferent) neurons carry signals from the CNS to
effectors (muscles/glands).
●● What is the difference between sympathetic and parasympathetic
nervous system?
Answer: The sympathetic system prepares the body for "fight or flight"
(increases heart rate, dilates pupils); the parasympathetic system
promotes "rest and digest" (slows heart rate, stimulates digestion).
●● What happens during neurulation?
,Answer: The neural plate folds to form the neural tube (future CNS) and
neural crest cells migrate to form diverse structures (including parts of
PNS).
●● What are the different parts of a neuron?
Answer: Dendrites (receive signals), cell body/soma (integrates), axon
(conducts impulse), axon terminals (transmit signals).
●● What is gray and white matter? What part of the neuron is in gray
matter and in white matter?
Answer: Gray matter contains neuron cell bodies, dendrites, and
unmyelinated axons; white matter consists mainly of myelinated axons.
●● What is the neuron membrane resting potential?
Answer: The resting potential is about −70 mV, maintained by ion
gradients and the sodium-potassium pump.
●● What is depolarization, repolarization and hyperpolarization?
Answer: Depolarization: membrane becomes less negative (Na⁺ influx);
repolarization: return to negative (K⁺ efflux); hyperpolarization:
membrane becomes more negative than resting.
●● What is the threshold membrane potential to send an action potential
along the axon?
,Answer: Approximately −55 mV.
●● What channels/pumps are responsible for depolarization and
repolarization?
Answer: Voltage-gated Na⁺ channels cause depolarization; voltage-gated
K⁺ channels cause repolarization; Na⁺/K⁺ pump restores gradients.
●● What is an action potential?
Answer: A rapid, all-or-none electrical signal that travels along an axon
due to sequential depolarization and repolarization.
●● What are neurotransmitters?
Answer: Chemical messengers released at synapses that transmit signals
between neurons or to effector cells.
●● What is a synapse space?
Answer: The synaptic cleft, a small gap between neurons where
neurotransmitters diffuse.
●● Know where Purkinje and pyramidal neurons are located in the CNS
Answer: Purkinje neurons are in the cerebellar cortex; pyramidal
neurons are in the cerebral cortex.
, ●● What are the different cells of the central nervous system (neurons
and all glial cells) and peripheral nervous system? What are the
particularities and roles of each type of glial cell?
Answer: CNS glia: astrocytes (support, BBB, regulate ions),
oligodendrocytes (myelin in CNS), microglia (immune defense),
ependymal cells (line ventricles, produce CSF). PNS glia: Schwann cells
(myelin or ensheath axons), satellite cells (support ganglia neurons).
●● Recognize neurons that are myelinated and ensheathed, identify glial
cells (astrocytes, ependymal cells, Schwan and oligodendrocytes)
Answer: Myelinated neurons have segmented myelin sheaths (Schwann
in PNS, oligodendrocytes in CNS); ensheathed axons lack true myelin
but are wrapped by Schwann cells; astrocytes are star-shaped,
ependymal cells line cavities.
●● Be able to identify myelin, ensheathment, nodes of Ranvier and
connective tissue associated with nervous system. Know the role of
myelin and where it comes from
Answer: Myelin is a lipid-rich sheath from Schwann cells (PNS) or
oligodendrocytes (CNS) that increases conduction speed; nodes of
Ranvier are gaps enabling saltatory conduction; connective tissues
include endoneurium, perineurium, epineurium.
●● Know the overall brain and spinal cord organization. Where is the
gray matter and where is the white matter in CNS parts? Know the role
of the cortex, cerebellum and brain stem
EVALUATION QUESTIONS AND SOLUTIONS
FULL REVIEW SHEET
●● Define autonomic and somatic nervous system
Answer: The somatic nervous system controls voluntary movements and
skeletal muscles; the autonomic nervous system regulates involuntary
functions (smooth muscle, cardiac muscle, glands) and includes
sympathetic and parasympathetic divisions.
●● What is the difference between motor and sensory neurons?
Answer: Sensory (afferent) neurons carry information from receptors to
the CNS; motor (efferent) neurons carry signals from the CNS to
effectors (muscles/glands).
●● What is the difference between sympathetic and parasympathetic
nervous system?
Answer: The sympathetic system prepares the body for "fight or flight"
(increases heart rate, dilates pupils); the parasympathetic system
promotes "rest and digest" (slows heart rate, stimulates digestion).
●● What happens during neurulation?
,Answer: The neural plate folds to form the neural tube (future CNS) and
neural crest cells migrate to form diverse structures (including parts of
PNS).
●● What are the different parts of a neuron?
Answer: Dendrites (receive signals), cell body/soma (integrates), axon
(conducts impulse), axon terminals (transmit signals).
●● What is gray and white matter? What part of the neuron is in gray
matter and in white matter?
Answer: Gray matter contains neuron cell bodies, dendrites, and
unmyelinated axons; white matter consists mainly of myelinated axons.
●● What is the neuron membrane resting potential?
Answer: The resting potential is about −70 mV, maintained by ion
gradients and the sodium-potassium pump.
●● What is depolarization, repolarization and hyperpolarization?
Answer: Depolarization: membrane becomes less negative (Na⁺ influx);
repolarization: return to negative (K⁺ efflux); hyperpolarization:
membrane becomes more negative than resting.
●● What is the threshold membrane potential to send an action potential
along the axon?
,Answer: Approximately −55 mV.
●● What channels/pumps are responsible for depolarization and
repolarization?
Answer: Voltage-gated Na⁺ channels cause depolarization; voltage-gated
K⁺ channels cause repolarization; Na⁺/K⁺ pump restores gradients.
●● What is an action potential?
Answer: A rapid, all-or-none electrical signal that travels along an axon
due to sequential depolarization and repolarization.
●● What are neurotransmitters?
Answer: Chemical messengers released at synapses that transmit signals
between neurons or to effector cells.
●● What is a synapse space?
Answer: The synaptic cleft, a small gap between neurons where
neurotransmitters diffuse.
●● Know where Purkinje and pyramidal neurons are located in the CNS
Answer: Purkinje neurons are in the cerebellar cortex; pyramidal
neurons are in the cerebral cortex.
, ●● What are the different cells of the central nervous system (neurons
and all glial cells) and peripheral nervous system? What are the
particularities and roles of each type of glial cell?
Answer: CNS glia: astrocytes (support, BBB, regulate ions),
oligodendrocytes (myelin in CNS), microglia (immune defense),
ependymal cells (line ventricles, produce CSF). PNS glia: Schwann cells
(myelin or ensheath axons), satellite cells (support ganglia neurons).
●● Recognize neurons that are myelinated and ensheathed, identify glial
cells (astrocytes, ependymal cells, Schwan and oligodendrocytes)
Answer: Myelinated neurons have segmented myelin sheaths (Schwann
in PNS, oligodendrocytes in CNS); ensheathed axons lack true myelin
but are wrapped by Schwann cells; astrocytes are star-shaped,
ependymal cells line cavities.
●● Be able to identify myelin, ensheathment, nodes of Ranvier and
connective tissue associated with nervous system. Know the role of
myelin and where it comes from
Answer: Myelin is a lipid-rich sheath from Schwann cells (PNS) or
oligodendrocytes (CNS) that increases conduction speed; nodes of
Ranvier are gaps enabling saltatory conduction; connective tissues
include endoneurium, perineurium, epineurium.
●● Know the overall brain and spinal cord organization. Where is the
gray matter and where is the white matter in CNS parts? Know the role
of the cortex, cerebellum and brain stem
