Chapter 28 Nervous System Vocabulary
1) Neuron – Nerve cells that transmit signals from one location in the body to another.
2) CNS – Abbreviation for the central nervous system, which consists of the brain and spinal cord.
3) PNS – Abbreviation for peripheral nervous system, which is predominately made f of nerves which carry signal into and out of the CNS.
4) Nerve – A nerve is a connection line that consists of neurons tightly wrapped in connective tissue.
5) Ganglia – Ganglia are clusters of neuron cell bodies.
6) Sensory neuron — Sensory neurons convey signals from sensory receptors to the CNS.
7) Motor neuron — Motor neurons convey signals from the CNS to effector cells.
8) Cell body – The cell body houses the majority of a neuron’s organelles, including the nucleus.
9) Dendrites – Dendrites are highly branched extensions that receive signals from other neurons and convey this information to the cell body.
10) Axon – An axon is a much longer extension that sends signals to neurons or other effector cells.
11) Glia – Glia are supporting cells of the nervous system. Depending on the type they may nourish neurons, insulate the axons of neurons, or help maintain the homeostasis of the extracellular fluid surrounding the neuron.
12) Myelin sheath – This is a type of insulating material found in Schwann cells.
13) Nodes of Ranvier – The Nodes of Ranvier are the gaps between Schwann cells.
14) Synapse – A synapse is a structure that permits a neuron to pass an electrical or chemical signal to another cell.
15) Sodium/potassium pump – These pumps help maintain resting potential.
16) Resting potential – The voltage across a plasma membrane of a resting neuron.
17) Membrane potential – The potential energy in a resting neuron.
18) Stimulus – A signal that elicits some type of response.
19) Response – A response is a response elicited by a stimulus.
20) Action potential – Action potential is a change in membrane voltage that transmits a nerve signal along an axon.
21) Threshold – The critical level at which the membrane potential must be depolarized in order to initiate an action potential.
22) Cephalization – An evolutionary trend toward the concentration of the nervous system at the head end.
23) Centralization – The presence of a central nervous system distinct from the peripheral nervous system.
24) Spinal cord – The spinal cord is a jellylike bundle of nerve fibers that runs lengthwise inside the spine, conveys information to and from the brain and integrates simple responses to certain stimuli (such as the knee-jerk reflex).
25) Brain – The brain is the master control center of the nervous system. It includes homeostatic center that keep the body running smoothly, sensory centers that integrate data from sense organs, center of emotion and intellect. The brain also sends motor commands to muscles.
26) White Matter – White matter is mainly composed of axons.
27) Gray Matter – Gray matter is composed mainly of nerve cell bodies and dendrites.
28) Somatic nervous system – A part of the PNS, it is associated with voluntary control of the body, via the skeletal muscles.
29) Autonomic nervous system – The autonomic nervous system regulates the internal environment by controlling smooth and cardiac muscles and the organs and glands of the digestive, cardiovascular, excretory, and endocrine systems. This control is generally involuntary.
30) Parasympathetic – Primes the body for activities that gain and conserve energy for the body.
31) Sympathetic – Prepares the body for energy consuming activities.
32) Cerebrum – The cerebrum is an outgrowth of the forebrain that is the most sophisticated center of homeostatic control and integration
33) Cerebellum – Another part