Chapter 12 Check Points
Identify the neuroglia of the central nervous system.
central nervous system neuroglia include ependymal cells, astrocytes, oligodendrocytes, and microglia.
Classify neurons according to their function.
According to function, neurons are classified as sensory neurons, motor neurons, and interneurons
Classify neurons according to their structure.
According to structure, neurons are classified as anaxonic, bipolar, unipolar, and multipolar
Are unipolar neurons in a tissue sample more likely to function as sensory neurons or motor neurons?
Because most sensory neurons of the PNS are unipolar, these neurons most likely function as sensory neurons.
What would be the effect of damage to the afferent division of the PNS?
Damage to the afferent division of the PNS, which is composed of nerves that carry sensory information to the brain and spinal cord, would interfere with a persons ability to experience a variety of sensory stimuli
If a synapse involves direct physical contact between cells, it is termed ____; if the synapse involves a neurotransmitter, it is termed ____.
If a synapse involves direct physical contact between cells, it is termed electrical; if the synapse involves a neurotransmitter, it is termed chemical.
Name the structural components of a typical neuron.
Structural components of a typical neuron include a cell body or SOMA (which contains the nucleus and perikaryon), dendrites, and axon, telodendria, nissl bodies, neurofilaments, Intermediate neurotubules, neurofibrils, axoplasm, axolemma, initial segment, axon hillock, and collaterals.
Define resting potential.
The resting potential is the transmembrane potential of a normal cell under homeostatic conditions.
Which of the following axons is myelinated: one that propagates action potentials at 50 meters per second, or one that carries them at 1 meter per second?
action potentials travel along myelinated axons at much higher speeds( by saltatory propagation); the axon with a propagation speed of 50 meters per second must be the myelinated axon
Define action potential.
an action potential is a propagated change in the transmembrane potential of excitable cells, initiated by a change in the membrane permeability to sodium ions.
One pathway in the central nervous system consists of three neurons, another of five neurons. If the neurons in the two pathways are identical, which pathway will transmit impulses more rapidly?
because of synaptic delay, the pathway with fewer neurons(in this case, three) will transmit impulses more rapidly.
Differentiate between a neurotransmitter and a neuromodulator.
both neurotransmitters and neuromodulators are compounds that are released by one neuron and that affect another neuron. a neurotransmitter alters the transmembrane potential of the other neuron whereas a neuromodulator alters the other neuron's response to specific neurotransmitters.
Identify the three functional groups into which neurotransmitters and neuromodulators fall. neurotransmitters and neuromodulators are either
compounds that have a direct effect on membrane potential compounds that have an indirect effect on membrane potential lipid-soluble gases that exert their effects inside the cell
List the steps involved in the generation and propagation of an action potential. the four steps involved in the generation of action potentials are
depolarization to threshold activation of sodium channels and rapid depolarization inactivation of sodium channels and activation of potassium channels return to normal permeability
What effect would decreasing the concentration of extracellular potassium ions have on the transmembrane potential of a neuron?
if the extracellular concentration of potassium ions decreased, more potassium would leave the cell, and the electrical gradient across the membrane( the transmembrane potential) would increase. this condition is called hyperpolarization.
What effect would blocking voltage-gated calcium channels at a cholinergic synapse have on synaptic communication?
if the voltage-gated calcium channels at a cholinergic synapse were blocked, Ca2+ could not enter the presynaptic terminal and trigger the release of ACh into the synapse, so no communication would take place across the synapse.
What effect would a chemical that blocks the voltage-gated sodium channels in neuron plasma membranes have on a neuron's ability to depolarize?
if the voltage-gated sodium channels in a neuron's plasma membrane could not open, sodium ions could not flood into the cell, and it would not be able to depolarize.
One EPSP depolarizes the initial segment from a resting potential of -70 mV to -65 mV, and threshold is at -60 mV. Will an action potential be generated?
no action potential will be generated
Identify the neuroglia of the peripheral nervous system.
peripheral nervous system neuroglia include satellite cells(amphicytes) and schwann cells(neurilemma cells)
If the two EPSPs in checkpoint 26 occurred simultaneously, what form of summation would occur?
spatial summation would occur if the two EPSPs happened simultaneously
Describe the general structure of a synapse.
the major structural components of a synapse, the site where a neuron communicates with another cell, are a presynaptic cell and a postsynaptic cell, whose plasma membranes are separated by a narrow synaptic cleft.
What is the relationship between myelin and the propagation speed of action potentials?
the presence of myelin greatly increases the propagation speed of action potentials.
Which type of neuroglia would increase in number in the brain tissue of a person with a CNS infection?
the small phagocytic cells called microglia occur in increased numbers in infected (and damaged) areas of the CNS
Identify the two anatomical divisions of the nervous system.
the two anatomical divisions of the nervous system are the central nervous system(CNS), consisting of the brain and spinal cord, and the peripheral nervous system(PNS), consisting of all neural tissue outside the CNS.
Identify the two components of the efferent division of the PNS.
the two components of the efferent division of the PNS are the somatic nervous system(SNS) and the autonomic nervous system(ANS)
Identify the two functional divisions of the peripheral nervous system, and cite their primary functions.
the two functional divisions of the peripheral nervous system are the afferent division, which brings sensory information to the CNS from receptors in peripheral tissues and organs, and the efferent division, which carries motor commands from the CNS to muscles, glands and adipose tissue.
Given the situation in checkpoint 25, if a second, identical EPSP occurs immediately after the first, will an action potential be generated?
yes, an action potential will be generated