Chapter 17: Nervous System
schwann cells
Supporting cells of the peripheral nervous system responsible for the formation of myelin.
parasympathetic division
The branch of the autonomic nervous system that generally conserves bodily resources.
resting potential
The difference in electric charge between the inside and outside of a neuron's cell membrane
somatic system
The division of the peripheral nervous system that controls the body's skeletal muscles. Also called the skeletal nervous system.
axon terminal
The endpoint of a neuron where neurotransmitters are stored
threshold
The level of stimulation required to trigger a neural impulse
meninges
The organs of the central nervous system (brain and spinal cord) are covered by 3 connective tissue layers collectively called the meninges
white matter
The portions of the central nervous system that are abundant in axons rather than cell bodies of neurons. The colour derives from the presence of the axon's myelin sheaths
potassium gates open
What happens when the action potential peaks
sodium gates open
When the membrane of a neuron becomes depolarized to threshold.
sodium-potassium pump
a carrier protein that uses ATP to actively transport sodium ions out of a cell and potassium ions into the cell
electroencephalogram
a graphical record of electrical activity of the brain
verterbra
a single spinal column bone; plural is vertebrae
repolarization
after Na+ ions have rushed into the cell, K+ ions rush out of the cell to restore the balance and the original polarity
postganglionic fibres
fibres from the ganglion to the effector organ
preganglionic fibres
ganglionic fibres of sympathetic nervous system from the central nervous system. It enters the sympathetic trunk and synapses with the axons of postganglionic neurons
post-synaptic membrane
membrane of dendrite or cell body beneath synaptic terminal
nerve impulse
the electrical discharge that travels along a nerve fiber
neuromuscular junction
the junction between a nerve fiber and the muscle it supplies
pre-synaptic membrane
the membrane on the cell receiving the original action potential from a stimulus. Transmits the chemical signal to the Post synaptic membrane (membrane on the cell receiving the signal)
corpus callosun
thick band of neurons that connects the right and left cerebral hemispheres
refractory period
(neurology) the time after a neuron fires or a muscle fiber contracts during which a stimulus will not evoke a response
spinal nerves
31 pairs of nerves arising from the spinal cord
thalamus
A Subcortical structure that relays and filters information from the senses and transmits the information to the cerebral cortex.
pons
A brain structure that relays information from the cerebellum to the rest of the brain
sympathetic division
A branch of the autonomic nervous system and prepares the body for quick action in emergencies; fight or flight; busiest when frightened, angry, or aroused; increases heart rate, increases breathing rate, enlarges pupils, stops digestion; connects to all internal organs; sudden reaction
peripheral nervous system
A division of the nervous system consisting of all nerves that are not part of the brain or spinal cord.
dorsal root ganglion
A group of sensory neuron cell bodies found just posterior to the spinal cord on either side. A pair of root ganglia exists for each spinal nerve that expands from the spinal cord. The ganglia are part of the peripheral nervous system (PNS).
synapse
A junction where information is transmitted from one neuron to the next.
cerebellum
A large structure of the hindbrain that controls fine motor skills.
myelin sheath
A layer of fatty tissue segmentally encasing the fibers of many neurons; enables vastly greater transmission speed of neural impulses as the impulse hops from one node to the next.
axon
A long projection off the cell body of a neruon down which an action potential can be propagated.
neurons
A nerve cell; the basic building block of the nervous system.
action potential
A neural impulse; a brief electrical charge that travels down an axon.
hypothalamus
A neural structure lying below the thalamus; it directs several maintenance activities (eating, drinking, body temperature), helps govern the endocrine system via the pituitary gland, and is linked to emotion and reward.
norepinephrine
A neurotransmitter involved in arousal, as well as in learning and mood regulation
acetylcholine
A neurotransmitter that enables learning and memory and also triggers muscle contraction
adrenal glands
A pair of endocrine glands that sit just above the kidneys and secrete hormones that help arouse the body in times of stress.
oscilloscope
A piece of test equipment used to view and measure a variety of different waveforms.
negative feedback
A primary mechanism of homeostasis, whereby a change in a physiological variable that is being monitored triggers a response that counteracts the initial fluctuation.
learning
A relatively permanent change in an organism's behavior due to experience.
reflexes
A simple, automatic, inborn response to a sensory stimulus, such as the knee-jerk response.
midbrain
A small part of the brain above the pons that integrates sensory information and relays it upward.
effector
A structure in the body that can change the value of a variable
homeostasis
A tendency to maintain a balanced or constant internal state; the regulation of any aspect of body chemistry, such as blood glucose, around a particular level
central canal
A tiny channel found within the spinal cord and inferior medulla oblongata
memory
Ability to hold content, style, and arrangement in ones own mind.
anterior pituitary
Adrenocorticotropic Hormone
ganglion
An anatomically isolated mass of nerve cell bodies
acetylcholinesterase
An enzyme that breaks down the neurotransmitter acetylcholine.
posterior pituitary
Antidiuretic Hormone
cerebrum
Area of the brain responsible for all voluntary activities of the body
ventricles
Bottom portion of the heart, thicker walled and larger
central nervous system
Brain and spinal cord
gray matter
Brain and spinal cord tissue that appears gray with the naked eye; consists mainly of neuronal cell bodies (nuclei) and lacks myelinated axons.
dendrites
Branchlike parts of a neuron that are specialized to receive information.
interneuron
Central nervous system neurons that internally communicate and intervene between the sensory inputs and motor outputs
brain
Cerebro
neurotransmitters
Chemical messengers manufactured by a neuron.
brain stem
Connection to spinal cord. Filters information flow between peripheral nervous system and the rest of the brain.
cerebral hemispheres
Divided into right and left by the cerebrum.
pituitary gland
Endocrine gland attached to the base of the brain that secretes hormones that affect the function of other glands as well as hormones that act directly on physical processes.
cerebrospinal fluid
Fluid in the space between the meninges that acts as a shock absorber that protects the central nervous system.
prefrontal area
Forethought, motivation and emotional regulation occurs in the
nodes of ranvier
Gaps in the myelin sheath of the axons of peripheral neruons. Action potentials can 'hump' from node to node, thus increasing the speed of conduction (saltatory conduction).
endocrine system
Glands secrete hormones that regulate processes such as growth, reproduction, and nutrient use (metabolism) by body cells.
cerebral cortex
Is the cerebrum's outer layer of nerve cell bodies which look like "gray matter" because it lacks myelin
cell body
Largest part of a typical neuron; contains the nucleus and much of the cytoplasm
central white matter
Lies deep to the gray matter of the cerebral cortex and is composed primarily of myelinated axons.
depolarization
Loss of a state of polarity; loss or reduction of negative membrane potential
spinal cord
Nerves that run up and down the length of the back and transmit most messages between the body and brain
sensory neuron
Neurons that carry incoming information from the sensory receptors to the brain and spinal cord.
motor neuron
Neurons that carry outgoing information from the brain and spinal cord to the muscles and glands.
autonomic system
Part of the PNS. Controls electric signals to motor neurons controlling involuntary muscle groups. 2 groups, the Sympathetic and the Parasympathetic systems. Controlled by different regions of the Medulla, Pons, and Diencephalon control it.
medulla oblongata
Part of the brainstem that controls vital life-sustaining functions such as heartbeat, breathing, blood pressure, and digestion.
primary motor area
Responsible for voluntary movement of skeletal muscles
synaptic vesicles
Saclike structures found inside the synaptic knob containing chemicals
synaptic cleft
Small gap between the presynaptic and postsynaptic membranes of a synapse.