DAT Biology Nervous System

neuroglia

cells that support and protect neurons

neurons

functional units of the nervous system

dendrites

cytoplasmic extensions that receive information and transmit it toward the cell body

soma

the cell body

axon

a long cellular process that transmits impulses away from the cell body

action potentials

The form of electrical signals that the axon transmits

myelin

material of the sheath around the axon of a nerve; prevents leakage of signal and allows for faster conduction of impulses

nodes of Ranvier

the gaps between segments of myelin where saltatory conduction occurs

oligodendrocytes

glial cells in central nervous system that produce myelin sheath

Schwann cells

glial cells in the peripheral nervous system that produce myelin sheath

synaptic terminals

Ends of axon branches where signals pass to next cell.

neurotransmitters

chemical messengers that cross the synaptic gaps between neurons

synapse

A junction where information is transmitted from one neuron to the next.

astrocytes

glial cells in the central nervous system; maintain the integrity of the blood-brain barrier; regulate nutrient and dissolved gas concentrations; absorb and recycle neurotransmitters

oligodendrocytes

glial cells in the central nervous system that myelinate axons and provide structural framework

microglia

glial cells in the central nervous system that remove cellular debris and pathogens

ependymal cells

glial cells in the central nervous system that line the brain ventricles and aid in the production, circulation, and monitoring of cerebral spinal fluid

satellite cells

glial cells in the peripheral nervous system that surround the neuron cell bodies in the ganglia

Schwann cells

glial cells in the peripheral nervous system that enclose the axons and aid in the myelination of some peripheral axons

resting potential

electrical charge across the cell membrane of a resting neuron

-70 mV

typical resting potential of neuron (#)

3, 2

the sodium-potassium pump releases _____ sodium ions to the outside of the cell for every _____ potassium ions that enter

action potential

Reversal of charges across the cell membrane of a neuron; also called a nerve impulse

-55 mV

average threshold potential needed to begin an action potential (#)

threshold potential

membrane potential above which an excitable cell fires an action potential

Ca2+

the ion that rushes in at the end of an axon to trigger the exocytosis of synaptic vesicles containing neurotransmitters

repolarization

The reestablishment of a polarized state in a cell after depolarization

refractory period

following an activation potential, a period of hyperpolarization in which the neutron is especially difficult to activate, allowing neurotransmitters to be replenished and maintaining a one-way direction of action potential

frequency, magnitude

stimulus intensity is coded by the _____ of action potentials, not the _____

larger

impulses will travel faster on an axon with (larger/smaller) diameters

myelinated

impulses will travel faster on an (myelinated, unmyelinated) axon

effector cells

the muscle cells or gland cells that actually carry out the body's responses to stimuli.

curare

drug that blocks postsynaptic nicotinic acetylcholine receptors, such as those on muscles, so that acetylcholine is unable to interact with them; this leads to muscle relaxation and paralysis by blocking the ability to constrict muscles

botulinum toxin

drug that prevents the release of acetylcholine from the presynaptic membrane and results in paralysis

anticholinesterases

drugs used as nerve gases and insecticide; inhibit the activity of the acetylcholinesterase enzyme responsible for degrading acetylcholine released into the synapse; as a result, acetylcholine is not degraded and continues to affect the postsynaptic membrane; therefore, no coordinated muscular contractions can take place

afferent neurons

neurons that carry sensory information about the external or internal environment to the brain or spinal cord

efferent neurons

neurons that carry motor commands from the brain or spinal cord to various parts of the body

interneurons

connect sensory and motor neurons and carry impulses between them

brain, spinal cord

the central nervous system is comprised of _____

somatic nervous system

the division of the peripheral nervous system that controls the body's skeletal muscles and voluntary movement; also responsible for reflex arcs

autonomic nervous system

the division of the peripheral nervous system that regulates the body's internal environment without the aid of conscious control

white matter

tissue of the brain that contains dense collections of myelinated fibers

gray matter

tissue of the brain that contains mostly neuron cell bodies and nonmyelinated fibers

prosencephalon

What is another name for the forebrain?

telencephalon

part of the forebrain; its major component is the cerebral cortex

cerebral cortex

outer region of the cerebrum, containing sheets of nerve cells; gray matter of the brain

cerebral cortex

part of the brain that processes and integrates sensory input and motor responses and is important for memory and creative thought

diencephalon

part of the forebrain;

contains thalamus and hypothalamus

olfactory bulbs

center for reception and integration of smell-related input

thalamus

a relay and integration center for the spinal cord and cerebral cortex

hypothalamus

controls visceral functions such as hunger, thirst, sex drive, water balance, blood pressure, and temperature regulation; plays an important role in the control of the endocrine system (controls pituitary gland); maintains homeostasis

mesencephalon

fancy name for midbrain

midbrain

relay center for visual and auditory impulses; plays an important role in motor control

rhombencephalon

fancy name for hindbrain

cerebellum, pons, medulla

the hindbrain consists of which three things?

cerebellum

helps to modulate motor impulses initiated by the cerebral cortex and is important in the maintenance of balance, hand-eye coordination, and the timing of rapid movements

pons

acts as a relay center to allow the cortex to communicate with the cerebellum

medulla

part of brain that controls many vital functions such as breathing, heart rate, and gastrointestinal ativity

midbrain, pons, medulla

what three parts constitute the brain stem?

corpus callosum

a broad band of nerve fibers joining the two hemispheres of the brain.

dorsal horn

where sensory information enters the spinal cord

ventral horn

all motor information exits the spinal cord through the _____

somatic, autonomic

the two primary divisions of the PNS

sympathetic

the _____ nervous system is activated in an emergency (fight or flight)

norepinephrine

the primary neurotransmitter of the sympathetic nervous system

parasympathetic

the _____ nervous system acts to conserve energy and restore the body to resting activity levels after exertion: (rest and digest)

vagus nerve

one very important parasympathetic nerve that innervates many of the thoracic and abdominal viscera

acetylcholine

primary neurotransmitter of the parasympathetic nervous system