BIO 253 EXAM 2 UPDATED ACTUAL QUESTIONS AND CORRECT ANSWERS
VERIFIED 2027 EDITION
1. Name two cell types in neural tissue.
neurons and glia
2. What are neurons?
"rapid communicators," excitable cells that transmit electrical signals
3. What are glia cells?
"caregivers," cells that provide support for neurons
4. Name two groups of nervous system organs.
Central Nervous System (CNS) and Peripheral Nervous System (PNS)
5. List the general functions of the nervous system.
sensory function: -nervous system receives information -sensory receptors gather information by
detecting changes -information is carried to the CNS integrative function: -nervous system coordinates
sensory information to create new sensations, memory, thoughts -nervous system makes decisions on
body's response to sensory information motor function: -decisions are acted upon -impulses are carried to
effectors (muscles or glands) -divisions of motor portion of PNS -somatic nervous system- transmits
voluntary instructions to skeletal muscles -autonomic nervous system- transmits involuntary instructions
from the CNS to smooth muscles, cardiac muscle, and glands
1
,6. Describe a neuron.
-dendrites: receive signals -cell body: manufactures cell components, integrates signals -axon: conducts
impulses -synaptic knob: site of contact with target cell -myelin sheath: formed by neuroglia cells to
insulate axons; interrupted in peripheral neurons by nodes
7. Explain how an axon in the PNS becomes myelinated.
myelinated axons in the PNS have a series of Schwann cells lined up along the axon, each having a
wrapped coating of myelin insulating the axon
8. Describe the types of neurons based on structural characteristics.
multipolar neurons: -99% of neurons -many processes -most neurons of CNS bipolar neurons: -two
processes -eyes, ears, nose unipolar neurons -one process -cell bodies are in ganglia -sensory
9. Indicate the function of sensory neurons.
-afferent neurons -carry impulse to CNS -most are unipolar -some are bipolar
10. Indicate the function of interneurons.
-association neurons -link neurons -multipolar -located in CNS
11. Indicate the function of motor neurons.
-multipolar, efferent -carry impulses away from CNS -carry impulses to effectors
12. Name the six types of neuroglia.
astrocytes, oligodendrocytes, microglia, ependyma or ependymal cells, Schwann cells, Satellite cells
13. What are some functions of neuroglia?
astrocytes: -connect neurons to blood vessels; exchange nutrients and growth factors -form scar tissue
-aid metabolism of certain substances -regulate ion concentrations, such as part of blood brain barrier
oligodendrocytes: -myelinate CNS axons -provide structural support microglia: -phagocytic cell -provides
structural support ependyma or ependymal cells: -line central canal of spinal cord and ventricles of brain,
cover choroid plexuses -help regulate composition and circulation of CSF Schwann cells: -produce myelin
sheath found on some peripheral axons -speed up nerve impulse transmission Satellite cells: -support
clusters of neuron cell bodies (ganglia)
2
, 14. Summarize how a resting membrane potential is achieved.
-inside of an axon is negative (-70mV) compared to outside -sodium-potassium pump actively transports
Na+ out and K+ into the axon -electrical and chemical potential maintained by ATP
15. Explain how a polarized axon responds to stimulation.
-when the neuron receives the stimulation, as a result of this stimulation, the local potentials within the
neuron add up to reach the threshold -when this happens, the sodium ions diffuse the membrane inwards
and trigger the axon part of the neuron, thereby depolarizing the membrane
16. List the major events of an action potential.
-axon hillock / initial segment / trigger zone at first part of axon contains many voltage gated sodium
channels -when threshold is reached (-55mV), voltage-gated Na+ channels open -Na+ ions diffuse into the
cell, and membrane depolarizes -Na+ channels close and K+ channels open -K+ diffuses out of the cells,
and membrane repolarizes -the voltage goes below -70mV, so the membrane is temporarily
hyperpolarized -K+ channels close -Na+/K+ pumps bring the membrane back to RMP (RMP = -70)
17. Define refractory period.
during an impulse, the portion of the axon actively conducting the action potential is not able to respond
to another threshold stimulus of normal strength absolute refractory period: -time when threshold
stimulus cannot generate another action potential -voltage gated channels are briefly unresponsive
relative refractory period: -time when only high-intensity stimulus can generate another action potential
-repolarization is not complete, and membrane is re-establishing resting potential
18. Explain how impulse conduction differs in myelinated and unmyelinated axons.
-myelin is rich in lipids, and prevents water and water-soluble substances (such as ions) from crossing
membrane; acts as electrical insulator -ions can cross membrane only through gaps in myelin sheath, the
Nodes of Ranvier -myelinated axons transmit impulses through saltatory conduction, in which action
potentials "jump" from node to node down the axon -saltatory conduction is much faster than impulse
conduction in unmyelinated axons -axon diameter also affects conduction speed; thick axons transmit
faster than thin axons -thick myelinated axons: 120 m/sec -thin unmyelinated axons: 0.5 m/sec
19. Explain the function of a neurotransmitter.
when impulse reaches synaptic knob of an axon, neurotransmitters are released by exocytosis -chemical
messengers that transport messages between neurons
20. Explain how a neurotransmitter is removed from the synaptic cleft to prevent continuous
stimulation.
receptors on post-synaptic neuron bind to neurotransmitters and once their "job is done" they go back
into presynaptic neuron (reuptake)
21. How does the gray matter and white matter arrangement differ in the brain and spinal cord?
brain -gray matter outside, white matter inside spinal cord -white matter outside, gray matter inside
22. What part of the brain is connected inferiorly to the spinal cord?
brainstem
23. Describe the meninges.
layered membranes that lie between bony coverings in the CNS and protect the brain or spinal cord
24. Name the layers of the meninges.
-dura mater: outermost layer made of tough, dense connective tissue -arachnoid mater: middle layer, web
like membrane -pia mater: inner layer, attached to surface of brain and spinal cord, nourishes CNS, has
blood vessels and nerves
3
VERIFIED 2027 EDITION
1. Name two cell types in neural tissue.
neurons and glia
2. What are neurons?
"rapid communicators," excitable cells that transmit electrical signals
3. What are glia cells?
"caregivers," cells that provide support for neurons
4. Name two groups of nervous system organs.
Central Nervous System (CNS) and Peripheral Nervous System (PNS)
5. List the general functions of the nervous system.
sensory function: -nervous system receives information -sensory receptors gather information by
detecting changes -information is carried to the CNS integrative function: -nervous system coordinates
sensory information to create new sensations, memory, thoughts -nervous system makes decisions on
body's response to sensory information motor function: -decisions are acted upon -impulses are carried to
effectors (muscles or glands) -divisions of motor portion of PNS -somatic nervous system- transmits
voluntary instructions to skeletal muscles -autonomic nervous system- transmits involuntary instructions
from the CNS to smooth muscles, cardiac muscle, and glands
1
,6. Describe a neuron.
-dendrites: receive signals -cell body: manufactures cell components, integrates signals -axon: conducts
impulses -synaptic knob: site of contact with target cell -myelin sheath: formed by neuroglia cells to
insulate axons; interrupted in peripheral neurons by nodes
7. Explain how an axon in the PNS becomes myelinated.
myelinated axons in the PNS have a series of Schwann cells lined up along the axon, each having a
wrapped coating of myelin insulating the axon
8. Describe the types of neurons based on structural characteristics.
multipolar neurons: -99% of neurons -many processes -most neurons of CNS bipolar neurons: -two
processes -eyes, ears, nose unipolar neurons -one process -cell bodies are in ganglia -sensory
9. Indicate the function of sensory neurons.
-afferent neurons -carry impulse to CNS -most are unipolar -some are bipolar
10. Indicate the function of interneurons.
-association neurons -link neurons -multipolar -located in CNS
11. Indicate the function of motor neurons.
-multipolar, efferent -carry impulses away from CNS -carry impulses to effectors
12. Name the six types of neuroglia.
astrocytes, oligodendrocytes, microglia, ependyma or ependymal cells, Schwann cells, Satellite cells
13. What are some functions of neuroglia?
astrocytes: -connect neurons to blood vessels; exchange nutrients and growth factors -form scar tissue
-aid metabolism of certain substances -regulate ion concentrations, such as part of blood brain barrier
oligodendrocytes: -myelinate CNS axons -provide structural support microglia: -phagocytic cell -provides
structural support ependyma or ependymal cells: -line central canal of spinal cord and ventricles of brain,
cover choroid plexuses -help regulate composition and circulation of CSF Schwann cells: -produce myelin
sheath found on some peripheral axons -speed up nerve impulse transmission Satellite cells: -support
clusters of neuron cell bodies (ganglia)
2
, 14. Summarize how a resting membrane potential is achieved.
-inside of an axon is negative (-70mV) compared to outside -sodium-potassium pump actively transports
Na+ out and K+ into the axon -electrical and chemical potential maintained by ATP
15. Explain how a polarized axon responds to stimulation.
-when the neuron receives the stimulation, as a result of this stimulation, the local potentials within the
neuron add up to reach the threshold -when this happens, the sodium ions diffuse the membrane inwards
and trigger the axon part of the neuron, thereby depolarizing the membrane
16. List the major events of an action potential.
-axon hillock / initial segment / trigger zone at first part of axon contains many voltage gated sodium
channels -when threshold is reached (-55mV), voltage-gated Na+ channels open -Na+ ions diffuse into the
cell, and membrane depolarizes -Na+ channels close and K+ channels open -K+ diffuses out of the cells,
and membrane repolarizes -the voltage goes below -70mV, so the membrane is temporarily
hyperpolarized -K+ channels close -Na+/K+ pumps bring the membrane back to RMP (RMP = -70)
17. Define refractory period.
during an impulse, the portion of the axon actively conducting the action potential is not able to respond
to another threshold stimulus of normal strength absolute refractory period: -time when threshold
stimulus cannot generate another action potential -voltage gated channels are briefly unresponsive
relative refractory period: -time when only high-intensity stimulus can generate another action potential
-repolarization is not complete, and membrane is re-establishing resting potential
18. Explain how impulse conduction differs in myelinated and unmyelinated axons.
-myelin is rich in lipids, and prevents water and water-soluble substances (such as ions) from crossing
membrane; acts as electrical insulator -ions can cross membrane only through gaps in myelin sheath, the
Nodes of Ranvier -myelinated axons transmit impulses through saltatory conduction, in which action
potentials "jump" from node to node down the axon -saltatory conduction is much faster than impulse
conduction in unmyelinated axons -axon diameter also affects conduction speed; thick axons transmit
faster than thin axons -thick myelinated axons: 120 m/sec -thin unmyelinated axons: 0.5 m/sec
19. Explain the function of a neurotransmitter.
when impulse reaches synaptic knob of an axon, neurotransmitters are released by exocytosis -chemical
messengers that transport messages between neurons
20. Explain how a neurotransmitter is removed from the synaptic cleft to prevent continuous
stimulation.
receptors on post-synaptic neuron bind to neurotransmitters and once their "job is done" they go back
into presynaptic neuron (reuptake)
21. How does the gray matter and white matter arrangement differ in the brain and spinal cord?
brain -gray matter outside, white matter inside spinal cord -white matter outside, gray matter inside
22. What part of the brain is connected inferiorly to the spinal cord?
brainstem
23. Describe the meninges.
layered membranes that lie between bony coverings in the CNS and protect the brain or spinal cord
24. Name the layers of the meninges.
-dura mater: outermost layer made of tough, dense connective tissue -arachnoid mater: middle layer, web
like membrane -pia mater: inner layer, attached to surface of brain and spinal cord, nourishes CNS, has
blood vessels and nerves
3
