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.