BIO 253 EXAM 2 NEWEST ACTUAL EXAM 200 QUESTIONS
AND CORRECT DETAILED ANSWERS WITH RATIONALES
|A+ GRADE
Name two cell types in neural tissue. - (correct answer) neurons and glia
What are neurons? - (correct answer) "rapid communicators," excitable cells that
transmit electrical signals
What are glia cells? - (correct answer) "caregivers," cells that provide support for
neurons
Name two groups of nervous system organs. - (correct answer) Central Nervous
System (CNS) and Peripheral Nervous System (PNS)
List the general functions of the nervous system. - (correct answer)
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
Describe a neuron. - (correct answer)
-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
Explain how an axon in the PNS becomes myelinated. - (correct answer) 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
Describe the types of neurons based on structural characteristics. - (correct answer)
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
Indicate the function of sensory neurons. - (correct answer)
-afferent neurons
-carry impulse to CNS
-most are unipolar
-some are bipolar
Indicate the function of interneurons. - (correct answer)
-association neurons
-link neurons
-multipolar
-located in CNS
Indicate the function of motor neurons. - (correct answer)
-multipolar, efferent
-carry impulses away from CNS
-carry impulses to effectors
Name the six types of neuroglia. - (correct answer) astrocytes, oligodendrocytes,
microglia, ependyma or ependymal cells, Schwann cells, Satellite cells
What are some functions of neuroglia? - (correct answer)
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)
Summarize how a resting membrane potential is achieved. - (correct answer)
-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
Explain how a polarized axon responds to stimulation. - (correct answer)
-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
List the major events of an action potential. - (correct answer)
-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)
Define refractory period. - (correct answer) 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
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