A & P Nervous System - Chapter 11

Which neurotransmitter is thought to be the most primitive?

ATP

Excites skeletal muscle?

Acetycholine

Which of the following electrical currents occurs when a certain threshold is reached?

Action potential

Comparing graded and action potentials - which is bigger?

Action potentials are bigger and travel farther. Graded potentials generally initiate action potentials.

What best describes the membrane situation in the resting state in a neuron?

All the voltage-gated Na+ and K+ channels are closed

The resting state of a neuron?

All voltage-gated Na+ and K+ channels are closed

Why does an action potential not get smaller as it propogates along an axon terminal?

An action potential is regenerated at each membrane patch.

Which glial cell is the most abundant and versatile, and aids in making exchanges between capillaries and neurons?

Astrocytes

Which neuroglia is most responsible for the blood-brain barrier?

Astrocytes

Which type of neuroglia controls extra-cellular fluid environment around neuron cells in the CNS? PNS?

Astrocytes in CNS, Satellite Cells in the PNS.

Conducts impulses from CNS to internal organ muscles?

Autonomic Nervous System

Which of the following divisions of the nervous system is also known as the involuntary nervous system?

Autonomic Nervous System

Which part of the nervous system regulates the activity of smooth muscles, cardiac muscles, and glands -those activities we generally can not control?

Autonomic Nervous System

Which system is involved in an increasing heart rate?

Autonomic Nervous System-Motor-Efferent. PNS Controls heart rate.

Why is conduction of action potentials faster in myelinated rather than unmyleinated?

Because myelin allows the axon membrane between nodes to change voltage rapidly and allows current to flow only at widely spaced nodes.

Which type of neuron is found in the retina of the eye?

Bipolar

What is the difference between nerves and tracts?

Bundles of neuron processes are called tracts in the CNS and nerves in the PNS

Consists of brain and spinal cord?

CNS

For an open channel, what factors determine in which direction ions will move through the channel?

Concentration and electrical gradient together called the electrochemical gradient.

Where are the main receptors or input regions found in neurons?

Dendrites

What type of circuit is exemplified by impulses that travel from a single neuron of the brain, activate a hundred or more motor neurons in the spinal cord and excite thousands of skeletal muscle fibers?

Diverging circuits

"Feel good" transmitter; deficient in Parkinson's disease?

Dopamine

Peptides with inhibitory, opiate-like actions?

Endorphins

Which of the following neurotransmitters acts as a natural opiate?

Endorphins

Which glial cell lines the cavities of the brain and spinal cord, where they help circulate the cerbrospinal fluid?

Ependymal Cells

What lines the central cavities of the brain and spinal cord and provides a barrier between the CSF and nervous tissue?

Ependymal cells

Where do the axon collaterals emerge on a myelinated nerve?

From the Nodes of Ranvier

Indirect synaptic responses which are complex, prolonged, and often diffuse, as a result of the production of intracellular second messenger molecules

G-protein-linked receptors

Generally inhibitory; found thoughout CNS?

GABA

What is a structure that joins two neurons in the electrical synapse?

Gap junctions.

A potential of -90 mV is considered______?

Hyperpolarized

What ions flow through chemically gated channels to produce IPSP? EPSP?

IPSP - K+ or Cl- EPSP - Na+ and K+

How is the nucleus within the brain different from a nucleus within a neuron?

In the brain it is a cluster of cell bodies, whereas the nucleus within each neuron is a larger organelle that as the control center of the cell.

What is the phase in an action potential known as the "after hyperpolization"

Increased potassium efflux as a result of the sluggish closure of the potassium gates

Where do most action potentials originate?

Initial segment

What is meant by integration and does it occur primarily in the CNS or PNS?

Integration involves processing and interpreting sensory information and making decisions about motor output. Occurs in CNS.

Which subdivision of the PNS would be involved in relaying a "feeling of a full stomach" after a meal?

It would be relayed by the sensory "afferent" division.

For which cation is there the greatest amount of leakage (through leakage channels) across the plasma membrane?

K+

Which of the following membrane ion channels in the neuron are always open?

Leakage channels

What disease is directly related to demyelination?

Multiple sclerosis

What is the most common neuron type in humans?

Multipolar

What structural and function type of neuron is activated to move your finger away from the source of heat?

Multipolar neurons that are motor "efferent" neurons.

What is the function of a myelin sheath?

Myelin sheaths protect, electrically insulate fibers and increase the speed of transmission of nerve impulses.

Binds to postsynaptic receptor/channel

Neurotransmitter

Main neurotransmitter of sympathetic nervous system?

Norepinephrine

What is the difference between the clusters of cell bodies called nuclei and those known as ganglia?

Nuclei exist in the CNS, Ganglia in the PNS

Which two types of neuroglia form insulating coverages called myelin sheaths.

Oligodendryocytes in CNS and Schwann Cells in PNS

What characterizes repolarization, the second phase of the action potential?

Once the membrane depolarizes to a peak value of 30 mV, it repolarizes to its negative value of -70 mV

What is the depolarization phase in the generation of an action potential?

Opening and then closing of the Na+ channels

Which of the following conditions would cause synaptic potentiation?

Opening of NMDA (N-methyl-D-asparate) receptors

What is the reploarization phase in an action potential?

Opening of potassium gates and the rushing out of K+

Consists of nerves carrying impulses to and from brain and spinal cord?

PNS

What pattern of neural processing occurs when we smell freshly baked pie at Thanksgiving and also the odor of cooked turkey?

Parallel processing

Which of the following is a chemical class for neurotransmitters?

Peptides, Amino Acids, Gases and lipids.

What is true regarding IPSP's?

Postsynaptic membrane becomes more permeable to potassium and chloride

Which of the following substances plays the major role in generating the membrane potential of a neuron?

Potassium

Why does the interior of a nerve cell have a slight excess of a negative charge?

Potassium diffuses out of the cell.

Triggers neurotransmitter release

Presynaptic calcium influx

Triggers voltage change in postsynaptic neuron

Receptor/channel

Rapid automatic responses to a stimulus in which the particular stimulus always produces the same motor response.

Reflexes

During which phase of an action potential are voltage-gated K+ channels open while voltage-gated Na+ channels are closed?

Repolarizing phase

Organelles for degradation in the axon are moved by_____?

Retrograde movement

What types of neural circuits would give a prolonged output after a single input?

Reverberating circuits and parallel after discharge circuits both result in prolonged output.

The Nissl bodies seen in the neuron cell body represents which cellular organelle?

Rough ER

The node to node "jumping" of a action potential along a myelinated sheath is called ___________?

Salatory conduction

What is the unique propogation process which occurs in myelinated axons?

Saltatory conduction

What pattern of neural processing occurs when we blink as an object comes toward the eye?

Serial processing and the response is reflex arc.

"Mood" transmitter; target of Prozac to relieve depression?

Serotonin

The sensory or afferent division of the peripheral nervous system transmits information from the ________ to the CNS?

Skin

What part of the nervous system allows us to consciously control our skeletal muscles?

Somatic Nervous System

Which system is involved with contracting muscles to lift your arm?

Somatic Nervous System-Motor-Efferent. This system controls movement of the skeletal muscles.

Skin, skeletal muscles and joints to CNS?

Somatic afferent fibers

CNS to skeletal muscles

Somatic motor fibers

Conducts impulses from CNS to skeletal muscles?

Somatic nervous system

Simultaneous stimulation of many terminals, distributed widely over the surface of a postsynaptic neuron?

Spatial summation

An insufficient stimulus

Subthreshold stimulus

Separates presynaptic terminal from postsynaptic membrane?

Synaptic cleft

Numerous nerve impulses arriving at a synapse at closely timed intervals exert a cumulative effect?

Temporal summation

The situation where an action potential either happens completely or NOT AT ALL

The all-or-none phenomenon

What characterizes depolarization, the first phase of an action potential?

The membrane potential changes from a negative value to a positive value.

What event triggers the generation of an action potential?

The membrane potential must depolarize from the resting voltage of -70mV to a threshold of -55mV

What criterion is used to structurally classify neurons?

The number of processes extending from their cell body.

What is the absolute refractory period?

The sodium channels remain open

What type of stimulus is required for an action potential to be generated?

Threshold Level Stimulus

Any stimulus above this intensity will result in an action potential in a neuron

Threshold stimulus

What structural and functional type of neuron is activated first when you burn your finger?

Unipolar (psuedounipolar) neurons that are sensory (afferent) neurons.

Organs in the ventral body cavity to the CNS?

Viseral afferent fibers

CNS to smooth muscles, cardiac muscles and glands?

Viseral motor fibers

What is the first change to occur in response to a threshold stimulus?

Voltage-gated Na+ channels change shape, and activation gates open.

What membrane ion channels open and close in response to changes in the membrane potential?

Voltage-gated channels

Spatial summation occurs when_________

multiple local potentials occur at different places on the same cell at the same time

The sodium-potassium pump will________?

pump three sodium ions out of the cell for every two ions of potassium it brings into the cell

Which voltage-gated channels are open during the absolute refractory period?

sodium channels

A neuron will not respond to a second stimulus of equal strength to the first stimulus to which it has already responded because ___________?

the neuron is in the absolute refractory period