nonexcitable cells that provide structural support or that serve important physiological and immunological functions in the nervous system. also called Glial cells.
peripheral nervous sytem
portion of the nervous system that lies outside the brain and spinal cord; includes nerves and ganglia
refers to a cell that responds to stimuli by generating an electrical signal at the cell membrane.
a neuron with a central cell body that gives rise to multiple dendrites and a single axon. The most common type of neuron in humans.
cytoplasmic process that extends from a neurons cell body; usually shorter and thicker than axons and highly branched
long, thin cytoplasmic process that extends from a neurons cell body; may be insulated with myelin
main nutrional and metabolic region of neuron; receives signals from other cells and sends them towards the axon
long-distance regenerative electrical signal transmitted along an axon; an all-or-none event; also called a nerve impulse, spike, or discharge
formed by support cells that wrap repeatedly around an axon, forming a thick layer of insulation
type of support cell in peripheral nervous sytem that forms myelin sheath around axons
the distribution of ions across the cell membrane causes the inside of a cell to be slighlty _______ compared to the outside
integral proteins containing watery pores through which ions pass to cross the cell membrane
ion channels with gates that are opened or closed by changes in membrane voltage
the electrical potential, or voltage, across a cell membrane that results from the separation of charged particles across the membrane
ion channels with gates that open or close when a neurotransmitter binds to them
channels located on axon hillock, along unmyelinated axons, and at nodes of ranvier of myelinated axons
responsible for the generation and propagation of the action potential, the outgoing signal of the neuron
the difference in charge between the inside of the nerve cell membrane and the outside
a small tube or channel between adjacent cells formed by transmembrane proteins. Found at electrical synapses.
somatic nervous system
that portion of the peripheral nervous system whichy innervates skeletal muscle
autonomic nervous system
the efferent portion of the peripheral nervous system which innervates smooth muscle, cardiac muscle and glands.
synapse between an axon terminal and a dendrite; carry input signals to neurons
synapse between an axon terminal and the cell body of a neuron; carry input signals to neurons
synapse between two axon terminals; do not provide input signals to neurons; can regulate the amount of chemical transmitter released by another axon terminal thus inhibiting or facilitating the signal from another neuron
synapse formed by an axon terminal and neuronal cell membrane; a neurotransmitter conveys the signal from the axon terminal to the neuronal cell membrane; either excitatory or inhibitory; slow
most common type of synapse; associated with complex human behaviours such as learning and memory
incoming signal to neuron; short distance electrical signal which can vary in amplitude
combined electrical and chemical forces on an ion. this force determines the net movement of charged particles.
a molecule, usually a protein, that binds specifically to other molecules such as neurotransmitters and hormones
to change the membrane potential of a cell to a value that is more positive than its resting membrane potential
to change the membrane potential of a cell to a value that is more negative than its resting membrane potential
a critical level of membrane potential at which the depolarization process becomes regenerative and the cell generates an action potential
a chemical that is released at synapses and acts at a receptor on the postsynaptic cell
somatic motor system
the efferent portion of the peripheral nervous system which innervates skeletal muscle
nonexcitable cells that provide structural support or that serve important physiological and immunological functions in the nervous sytem. also called support cells.
when the postsynaptic potential is enhanced following repeated or continous activity at that synapse
the integration of synaptic potentials occuring at the same location but sequentially in time
the integration of synaptic potentials occuring at the same time at multiple locations
Depolarization phase in the generation of an action potential
Opening of potassium gates and the rushing out of K+
The autoimmune disease that leads to destruction of the myelin sheaths in the CNS
The all-or-none phenomenon
A. The situation where an action potential either happens completely or NOT at all
B. Indirect synaptic responses which are complex, prolonged, and often diffuse, as a result of the production of intracellular second messenger molecules
E. Rapid automatic responses to a stimulus in which the particular stimulus always produces the same motor response
A. Temporal summation
Numerous nerve impulses arriving at a synapse at closely timed intervals exert a cumulative effect
C. Spatial summation
Simultaneous stimulation of many terminals, distributed widely over the surface of a postsynaptic neuron
D. Threshold stimulus
Any stimulus above this intensity will result in an action potential in a neuron
The sensory, or afferent, division of the peripheral nervous system transmits information from the _____ to the CNS
potassium diffuses out of the cell
The interior of a nerve cell has a slight excess of negative charge because:
Rough endoplasmic reticulum
The Nissl bodies seen in the neuron cell body represents which cellular organelle?
lines the central cavities of the brain and spinal cord and provide a barrier between the CSF and nervous tissue
act as naturally occurring opiates and reduce the perception of pain under certain stressful conditions.
pump three sodium ions out of the cell for every two ions of potassium it brings into the cell.
The sodium-potassium ion pump will:
absolute refractory period
When the neuron is in the______________________ and all its voltage-gated sodium channels are open, it cannot respond to another stimulus, no matter how strong, until the channels are reset.
line the central cavities of the brain and spinal cord, where they form a fairly permeable barrier between the cerebrospinal fluid that fills those cavities and the tissue fluid bathing the cells of the CNS. The beating of their cilia helps to circulate the cerebrospinal fluid that cushions the brain and spinal cord.
are the most abundant and most versatile glial cells. Their numerous radiating processes cling to neurons and their synaptic endings, and cover nearby capillaries, supporting and bracing the neurons and anchoring them to their nutrient supply lines, the blood capillaries; have a role in making exchanges between capillaries and neurons, in helping to determine capillary permeability, in guiding the migration of young neurons, and in synapse formation.