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AP Biology Ch 48
Terms in this set (66)
Nerve cells are called:
They do not have a central and peripheral nervous system. Their nerves are arranged in fiberlike extensions called nerve nets.
Explain why organisms that exhibit radial symmetry have simpler nervous systems than organisms that exhibit bilateral symmetry.
Central nervous system
Brains and central nerve cords for the:
Peripheral nervous system
The nerves that connect to the central nervous system make up the:
Segmentally arranged clusters of nerves.
What are ganglia?
1. Sensory input: Sensory neurons trasmit information from external stimuli.
2. Integration: Interneurons analyze and interpret signals from the sensory neurons.
3. Motor output: motor neurons communicate with effector cells leading to a response
What are the three general stages of information processing in neurons?
The greatest amount of complexity exists between the connections of the:
The body's automatic responses to stimuli.
What are reflexes?
The cell body, dendrites, and the axon.
What are the three major parts of the nerve cell?
Most of a nerve cells organelles are found in the:
They receive signals from other cells.
What do dendrites do?
What is the part of the nerve cell that is a long extension that transmits signals to other cells?
The site of communication between a synaptic terminal and another cell.
What is a synapse?
The end of an axon where it usually divides into several branches.
What is a synaptic terminal?
A presynaptic cell is the cell transmitting the signal, a postsynaptic cell is the cell receiving the signal.
What is the difference between a presynaptic and postsynaptic cell?
Neurons communicate with one another using mainly ___________ signals.
The chemical messengers that are transmitted between nerve cells.
What are neurotransmitters?
Cells that support the nervous system.
What are glia?
Astrocytes, Schwann cells, radial glia, oligodendrocytes.
What are the four major types of glial cells?
-Provide structural support to neurons
-Regulate extracellular concentrations of ions
-Facilitate information transfer between neurons
-Cause dialation of blood vessels
-induce formation of blood brain barrier.
What are the functions of astrocytes?
Tight junctions that form between the cells that line the capillaries of the brain and spinal cord that restrict the passage of most substances from the blood into the CNS.
What is the blood-brain barrier?
What is a voltage difference across a plasma membrane called?
The interior of the cell has a negative charge relative to the outside.
What does a negative membrane potential indicate?
The membrane potential of a neuron that is not transmitting signals.
What is the resting potential?
If the concentration gradient for a polar molecule is greater on one side of a cell membrane and it is separated by ion channels; only one of the ions will flow through. This continues until the electrical gradient formed by the opposing charges on each side of the membrane equals the concentration gradient of the molecules.
Explain how ion channels and concentration gradients can lead to the formation of an ionic gradient.
The magnitude of membrane voltage at equilibrium.
What is equilibrium potential?
An equation that calculates the equilibrium potential for membranes that are permeable to a single type of ion. It is expressed: Eion = 62 mV (log ([ion]outside/[ion]inside)
What is the Nernst equation?
What is the equilibrium potential (Ex) at 37 C for an ion X+ if [X]outside = 10mM and [X]inside = 100mM?
Gated ion channels.
What type of ion channels are used to change a neuron from resting potential?
Stretch-gated, ligand-gated, voltage-gated.
What are the three types of gated ion channels?
Mechanical deformation of the membrane.
What causes stretch-gated ion channels to open?
When a specific chemical binds to a receptor on the channel.
What causes ligand-gated ion channels to open?
A change in the membrane potential.
What causes voltage-gated ion channels to open?
At resting potential; the interior of a neuron is ________ charged
An increase in the magnitude of the membrane potential is called:
A reduction in the magnitude of a membrane potential
What is a depolarization?
Partial changes in membrane potential are called:
A change in membrane voltage that leads to an action potential is called the:
An action potential
An all or nothing response that leads to a signal being passed along an axon is called:
Na+ and K+
The movement of which ions leads to the generation of action potentials?
Na+: Extracellular fluid
Where are the highest concentrations of Na+ and K+ ions located at resting potential?
An external signal causes some Na+ channels to open. This causes a depolarization that leads to even more Na+ channels to open, leading to a reversal in charge between the interior and exterior of the cell.
What begins an action potential?
Most of the gates of the sodium channels close and the gates of K+ channels open allowing K+ to move to the extracellular space and restoring the initial resting potential.
What causes the falling phase of the action potential?
More K+ flows into the extracellular space than Na+ in the cytoplasm, this causes the membrane potential to be lower than the original resting potential.
What is undershoot?
Active transport via Na+ K+ pumps.
What restores the gradients of Na+ and K+ to their states prior to an action potential?
The time it takes for the resting potential to be reestablished. A second action potential cannot occur until this occurs.
What is the refractory period?
The refractory period of the previous segment of axon will not let the signal travel in both directions.
What causes the unidirectional movement of action potentials along an axon?
Action potentials that "leap" from one node of Rainvier to the next.
What is saltatory conduction?
1. The diameter of the axon.
2. Insulation of the axon with myelin.
What are two ways that will increase the speed of conduction of a nerve impulse?
What produces the myelin sheath on neurons?
Gap junctions between neurons that do conduct electrical impulses from one neuron to another.
What is an electrical synapse?
The membrane that packages neurotransmitters in the presynaptic neuron.
What are synaptic vesicles?
An action potential depolarizes the synaptic terminal, causing voltage gated calcium channels on the membrane to open. The increase in calcium causes the synaptic vesicles to fuse with the presynaptic membrane and release the neurotransmitters.
What signal causes neurotransmitters to be released from a presynaptic cell?
The gap between the presynaptic and postsynaptic neurons.
What is the synaptic cleft?
Excitatory postsynaptic potentials and inhibitory postsynaptic potentials.
What are the two general types of direct synaptic transmission?
Excitatory potentials move a cell toward its action potential, inhibitory potentials move a cell away from its action potential.
What is the difference between an excitatory potential and an inhibitory potential?
No, they are graded.
Are postsynaptic potentials all-or-nothing responses like action potentials?
1. If several separate potentials occur in a short amount of time.
2. If two potentials signal a cell simultaneously at dentrites that are close to one another in the postsynaptic cell.
What increases the chances of an action potential being generated by excitatory potentials.
Direct transmission is when signals travel directly from the presynaptic neuron to ion channels in the postsynaptic neuron.
Indirect transmission is when neurotransmitters bind to a site on a receptor that is not part of an ion channel.
How are indirect and direct synaptic transmission different?
It is excitatory to vertebrate skeletal muscles and functions both excitatory and inhibitory at other sites.
What is the function of acetylcholine?
They are most commonly associated with indirect synaptic transmission.
What is the main function of the biogenic amines?
GABA, glycine, glutamate, aspartate
What are the four amino acids that function as neurotransmitters?
Which of the four amino acid neurotransmitters are excititory or inhibitory?
It mediates perception of pain.
What is the function of substance P?
What types of neurotransmitter decreases pain?
NO and CO
What gases function as neurotransmitters?
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