AP Lecture - Neural Tissue
Describe a synapse.
A synapse is where one neuron communicates with another cell.
________ monitor the position of skeletal muscles and joints.
Proprioceptors
Extensive damage to oligodendrocytes in the CNS could result in
decreased production of cerebrospinal fluid. loss of the structural framework of the brain. x reduced speed of nerve impulses. inability to produce scar tissue at the site of an injury. a breakdown of the blood-brain barrier.
Which of the following is not associated with the cytoskeleton of the perikaryon?
dendrite x nucleus neurofilaments axon neurofibrils
Raising the potassium ion concentration in the extracellular fluid surrounding a nerve cell will have which effect?
depolarize it and decrease the magnitude of the potassium equilibrium potential
Which of the following is not a function of the nervous system
direct long-term functions, such as growth
Which division of the PNS brings information to the CNS?
efferent ---> afferent
In a(n) ________ synapse, current flows directly between cells.
electrical
The sum of the electrical and chemical forces acting on an ion is known as its ________ gradient.
electrochemical gradient
Name the neuroglia of the CNS.
ependymal cells, microglia, astrocytes, oligodendrocytes
EPSPs (excitatory postsynaptic potentials) occur when
extra sodium ions enter a cell.
In the peripheral nervous system, Schwann cells participate in the repair of damaged nerves by
forming a cellular cord that directs axonal regrowth.
Neuron cell bodies in the PNS are clustered together in masses called
ganglia
Regions of the CNS where neuron cell bodies dominate constitute the ________ matter.
grey
The ________ nervous system controls the skeletal muscles.
somatic
The buildup of depolarization when EPSPs arrive at several places on the neuron is called ________ summation.
spatial
the buildup of depolarization when EPSPs arrive at several places on the neuron is called ________ summation.
spatial
Summation that results from the cumulative effect of multiple synapses at multiple places on the neuron is designated
spatial summation.
The site of intercellular communication between neurons is the
synapse
When a second EPSP arrives at a single synapse before the effects of the first have disappeared, what occurs?
temporal summation
Compare presynaptic and postsynaptic cells.
(x) Presynaptic cells are usually found in the peripheral nervous system and postsynaptic cells are usually found in the central nervous system.
The Na-K ion exchange pump actively transports
1 intracellular sodium ion for 2 extracellular potassium ions. 2 intracellular sodium ions for 1 extracellular potassium ion. x 3 intracellular sodium ions for 2 extracellular potassium ions. 3 intracellular sodium ions for 1 extracellular potassium ion. 3 extracellular sodium ions for 2 intracellular potassium ions.
Which area of the graph occurs when there is a sudden inrush of sodium ions?
2 (1-4)
When is the neuron in the relative refractory period?
4
Which area of the graph shows when graded hyperpolarization is occurring?
4
Describe the components of a chemical synapse.
A presynaptic cell and a postsynaptic cell whose plasma membranes are separated by a narrow synaptic cleft
Describe a synapse
A synapse is where one neuron communicates with another cell.
Describe the all-or-none principle.
All stimuli that bring the membrane to threshold will generate identical action potentials.
Define action potential.
An action potential is the propagated change in membrane potential of an excitable cell.
Define excitatory postsynaptic potential (EPSP) and inhibitory postsynaptic potential (IPSP).
An excitatory postsynaptic potential is a graded repolarization by the postsynaptic cell and an inhibitory postsynaptic potential is a graded hyperpolarization by the postsynaptic cell. An excitatory postsynaptic potential is a graded hyperpolarization by the postsynaptic cell and an inhibitory postsynaptic potential is a graded depolarization by the postsynaptic cell. An excitatory postsynaptic potential is a graded depolarization by the postsynaptic cell and an inhibitory postsynaptic potential is a graded repolarization by the postsynaptic cell. x An excitatory postsynaptic potential is a graded depolarization by the postsynaptic cell and an inhibitory postsynaptic potential is a graded hyperpolarization by the postsynaptic cell. An excitatory postsynaptic potential is a graded hyperpolarization by the postsynaptic cell and an inhibitory postsynaptic potential is a graded repolarization by the postsynaptic cell.
Describe depolarization, repolarization, and hyperpolarization.
Depolarization is a shift in membrane potential toward a more negative value; repolarization is the return of the membrane potential to resting; and hyperpolarization is a shift in membrane potential toward a more positive value. Depolarization is the return of the membrane potential to resting; repolarization is a shift of the membrane potential toward a more positive value; and hyperpolarization is a shift in membrane potential toward a more negative value. Depolarization is a shift in membrane potential toward a more negative value; repolarization is a shift of the membrane potential toward a more negative value; and hyperpolarization is the return of the membrane potential to resting. x Depolarization is a shift in membrane potential toward a more positive value; repolarization is the return of the membrane potential to resting; and hyperpolarization is a shift in membrane potential toward a more negative value. Depolarization is the return of the membrane potential to resting; repolarization is a shift of the membrane potential toward a more negative value; and hyperpolarization is a shift in membrane potential toward a more positive value.
Which of the following interactions between electrical and chemical gradients does not lead to the establishment of a neuron's resting potential?
Electrical forces push sodium ions out of the cell.
line the brain ventricles and spinal canal.
Ependymal cells
Define graded potential.
Graded potential is the minimum ability of a cell to generate electrical impulses. x Graded potential is the membrane potential of an unstimulated cell. Graded potential is the change in charge across the inner and outer membrane of a cell. Graded potential is the resting speed a cell can propagate electrical impulses. Graded potential is a temporary, localized change in the potential of a cell.
In which part of a neuron does Wallerian degeneration occur?
In which part of a neuron does Wallerian degeneration occur? (Module 11.5B) dendrites of the PNS neurons cell bodies of PNS neurons cell bodies of CNS neurons axons of CNS neurons x axons of PNS neurons
________ are the most numerous type of neuron in the CNS.
Interneurons
How would the absolute refractory period be affected if voltage-regulated sodium channels failed to inactivate?
It would last indefinitely.
channels open or close in response to physical distortion of the membrane surface.
Mechanically gated
Which of the following is not involved in creating the resting potential of a neuron?
Membrane permeability for potassium ions is greater than for sodium ions
Why is a CNS neuron not usually replaced after it is injured
Most CNS neurons are not replaced because they lack centrioles so they cannot divide
account for roughly half of the volume of the nervous system.
Neuroglia
Classify neurons based on their function.
Neurons are classified functionally as sensory, interneurons, or motor neurons.
clusters of RER and free ribosomes in neurons are called
Nissl bodies.
Define resting membrane potential.
Resting membrane potential is the membrane potential of an unstimulated cell.
Describe synaptic fatigue.
Synaptic fatigue occurs during oxygen deficiency and the synapse fails to bind neurotransmitters. Synaptic fatigue occurs when not enough ATP is present to cause the release of neurotransmitters out of the axon terminal. Synaptic fatigue occurs when the axon terminal can no longer receive action potentials from the axon hillock due to overstimulation. x Synaptic fatigue occurs in an axon terminal when neurotransmitters are released into the synaptic cleft faster than they can be reabsorbed or recycled. Synaptic fatigue occurs during starvation and not enough neurotransmitters are synthesized for normal synaptic function.
What determines the frequency of action potential generation?
The degree of sustained depolarization at the axon hillock determines the frequency of action potentials.
If the potassium permeability of a resting neuron increases above the resting permeability, what effect will this have on the transmembrane potential?
The inside of the membrane will become more negative.
What factors account for the local currents associated with graded potentials?
The movement of sodium ions parallel to the inner and outer surfaces of the cell.
Which of the following statements about the action potential is false?
The rapid depolarization phase is caused by the entry of potassium ions
What effect would decreasing the concentration of extracellular potassium ions have on the resting membrane potential of a neuron?
The resting membrane potential would become more negative because more potassium ions would leave the cell through potassium leak channels.
What happens at the sodium-potassium exchange pump?
The sodium-potassium exchange pump maintains the resting membrane potential of the cell by ejecting 3 sodium ions for every 2 potassium ions entering the cell.
Functions of astrocytes include all of the following except
X conducting action potentials. forming a three-dimensional framework for the CNS. maintaining the blood-brain barrier. responding to neural tissue damage. absorbing excess neurotransmitter.
The period during which an excitable membrane cannot respond to further stimulation is the
absolute refractory period
Cholinergic synapses release the neurotransmitter
acetylcholine
The all-or-none principle states that
all stimuli great enough to bring the membrane to threshold will produce identical action potentials
The ________ principle states that the size and speed of an action potential are independent of the stimulus strength.
all-or-none
Graded potentials
always cause repolarization. x may be either a depolarization or a hyperpolarization. ---> x produce an effect that increases with distance from the point of stimulation. *x produce an effect that spreads actively across the membrane surface without diminishing. ---> are often all-or-none.
neurons are small and have no anatomical features that distinguish dendrites from axons.
anaxonic
The glial cells in the central nervous system that form scar tissue after central nervous system injury are the
astrocytes.
The ________ nervous system provides involuntary regulation of smooth muscle, cardiac muscle, and glandular activity.
autonomic
The plasma membrane of an axon is called the
axolemma
The axon is connected to the cell body at the
axon hillock
Neurons that have one axon and one dendrite, with the soma in between, are called
bipolar
If the permeability of sodium ions increases in an axon
both the inward movement of sodium ions will increase and the membrane potential will depolarize.
The ion that triggers the release of acetylcholine into the synaptic cleft is
calcium
Which of the following activities or sensations is not monitored by interoceptors?
cardiovascular activities activities of the digestive system x sight joint movement urinary activities
Name the structural components of a typical neuron.
cell body, axon, and dendrites
At a(n) ________ synapse, a neurotransmitter is released to stimulate the postsynaptic membrane.
chemical
Which type of synapse is most common in the nervous system?
chemical
Branches that may occur along an axon are called
collateral branches.
An action potential traveling along the entire length of an axon demonstrates ________ propagation.
continuous
The greater the degree of sustained depolarization at the axon hillock, the ________ (higher or lower) the frequency of action potentials generated.
higher
Voltage-gated channels are present
in the membrane that covers axons
Opening of each of the following types of channels will contribute toward a graded potential except
inactivated voltage-gated sodium channel. (x) sodium leak channel. ---> mechanically gated sodium channel. chemically gated acetylcholine receptor. closed voltage-gated sodium channel.
monitor the digestive, respiratory, cardiovascular, urinary, and reproductive systems.
interoreceptors
Ion channels that are always open are called ________ channels.
leak
Identify the neuroglia of the PNS.
mast cells, microglia, satellite cells ependymal cells, microglia, astrocytes, oligodendrocytes Kuppfer cells, dendritic cells, astrocytes x Schwann cells and satellite cells dendritic cells, axonal cells, oligodendrocytes
Small, wandering cells that engulf cell debris and pathogens in the CNS are called
microglia
Which neuroglia appear in increased numbers in a person with a brain infection?
microglia
after a stroke, what type of glial cell accumulates within the affected brain region?
microglia
The smallest neuroglia of the CNS that act as phagocytes are the
microglia.
The sodium-potassium ion exchange pump
moves sodium and potassium opposite to the direction of their electrochemical gradients.
The most abundant class of neuron in the central nervous system is
multipolar
neurons are the most common class in the CNS.
multipolar
Which of the following is not contained in the axoplasm of the axon?
neurofibrils- Nissl bodies- vesicles- neurotubules- x mitochondria
The basic functional unit of the nervous system is the
neuron
The tiny gaps between adjacent Schwann cells are called
nodes
The myelin sheath that covers many CNS axons is formed by
oligodendrocytes
Which glial cell protects the CNS from chemicals and hormones circulating in the blood?
oligodendrocytes satellite cells microglia x astrocytes ependymal cells
The cytoplasm that surrounds the nucleus of a neuron is called the
perikaryon.
The separation of plus and negative charges across the membrane creates a ________ difference, or voltage.
potential
Which of the following would not have an effect on synaptic function?
preventing neurotransmitter inactivation - interfering with neurotransmitter reuptake - interfering with neurotransmitter synthesis - interfering with chemically gated sodium channels x interfering with voltage-gated sodium channels
Which of the following is not a recognized structural classification for neurons?
pseudopolar
The period from when an action potential begins until another action potential could be initiated is known as the ________ period.
relative refractory period
Opening of sodium channels in the axon membrane causes
repolarization and increased positive charge inside the membrane. hyperpolarization and increased negative charge inside the membrane. hyperpolarization and decreased positive charge inside the membrane. depolarization and increased negative change inside the membrane. x depolarization and increased positive charge inside the membrane.
The neurilemma of axons in the peripheral nervous system is formed by
schwann cells
Are unipolar neurons in a tissue sample of the PNS more likely to have a sensory or a motor function?
sensory
Name the effectors of the ANS.
skeletal muscle, cardiac muscle, and smooth muscle skeletal muscle only x cardiac muscle and smooth muscle (smooth, cardiac, and glands) glands and adipose tissue cardiac muscle, smooth muscle, glands, and adipose tissue
If the sodium-potassium pumps in the plasma membrane fail to function, all of the following occur except that the
the intercellular concentration of potassium ions will increase
If the axon terminal of a motor neuron suddenly became permeable to calcium ions,
the motor end plate will be depolarized.
Sensory neurons of the PNS are
unipolar
n a(n) ________ neuron, the dendrites and axon are continuous or fused.
unipolar
Neurotransmitter for release is stored in synaptic
vesicles
Which of the following does not influence the time necessary for a nerve impulse to be transmitted?
whether or not the impulse begins in the CNS
Most CNS neurons lack centrioles. This observation explains
why CNS neurons cannot divide.
Compare the absolute refractory period with the relative refractory period.
x During the absolute refractory period the membrane can respond only to a larger-than-normal stimulus. During the relative refractory period the membrane cannot respond to further stimulation. ---> During the absolute refractory period the membrane is highly responsive to stimuli. During the relative refractory period the membrane is unresponsive to stimuli. During the absolute refractory period the membrane cannot respond to further stimulation. During the relative refractory period the membrane can respond to any stimulus. During the absolute refractory period the membrane is highly responsive to stimuli. During the relative refractory period the membrane can respond only to a larger-than-normal stimulus. (x*) During the absolute refractory period the membrane cannot respond to further stimulation. During the relative refractory period the membrane can respond only to a larger-than-normal stimulus.
Define information processing
x Information processing is transfer of neurotransmitters from the presynaptic cell to an effector cell. ---> (x*)Information processing is the integration of stimuli by an individual cell. ---> Information processing is the change in charge across the inner and outer membrane of a cell. Information processing involves the release of neurotransmitters by the presynaptic cell. Information processing is a temporary, localized change in the resting membrane potential of a cell.
Which of the following statement is false when comparing neurons and muscle tissue?
x Muscle tissue and neurons both have refractory periods. ----> Action potentials last longer in muscle tissues compared to neurons. (x*) Muscle tissue and nerves are both excitable. Muscle tissue and neurons both have a resting membrane potential. Resting membrane potentials are greater (more positive) in muscle compare to neurons.
Compare the central and peripheral nervous system.
x The central nervous system consists of the brain and spinal cord and it integrates, processes, and coordinates sensory data and motor commands. The peripheral nervous system consists of all the nervous tissue outside the central and enteric nervous systems. The central nervous system consists of the sensory and motor division in the axial region of the body. The peripheral nervous system consists of the sensory and motor division in the appendicular region of the body. The central nervous system consists of the spinal cord and all the nervous tissue outside the enteric nervous system. The peripheral nervous system consists of the brain and it integrates, processes, and coordinates sensory data and motor commands. The central nervous system consists of the brain and it integrates, processes, and coordinates sensory data and motor commands. The peripheral nervous system consists of the spinal cord, and sensory and motor divisions. The central nervous system consists of all the nervous tissue outside the enteric nervous system. The peripheral nervous system consists of the brain and spinal cord and it integrates, processes, and coordinates sensory data and motor commands.
Ions can move across the plasma membrane in all of the following ways except
x diffusion directly through the plasma membrane. through passive or leak channels. through voltage-gated channels along the axolemma. by ATP-dependent ion pumps like the sodium-potassium exchange pump. through chemically-gated channels as in neuromuscular transmission.
When cholinergic receptors are stimulated with acetylcholine,
x sodium ions enter the postsynaptic neuron. chloride ions leave the postsynaptic neuron. sodium ions leave the postsynaptic neuron. potassium ions leave the postsynaptic neuron. chloride ions enter the postsynaptic neuron.
The effect that a neurotransmitter has on the postsynaptic membrane does not depend on the
x the strength of the action potential.
Classify neurons based on their structure.
xNeurons are classified structurally as sensory, interneurons, or motor neurons. ---->