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. ---->