Lesson 4 Vocabulary

Front 1

acetylchlorine

Back 1

a neurotransmitter found in both the central nervous system and the peripheral nervous system. It is the neurotransmitter released at neuromuscular junctions and cause muscle contraction

Front 2

action potential

Back 2

A nerve impulse. An electrochemical signal conducted along an axon. A wave of depolarization cause by the inward flow of sodium ions followed by re-polarization caused by the outward flow of potassium ions.

Front 3

axon

Back 3

A long extension from the cell body of a neuron that carries an electrochemical message away from the cell body toward another neuron or effector (muscle or gland). The tips of the axon release a chemical called a neurotransmitter that can affect the activity of the receiving cell. Typically, there is one long axon on a neuron.

Front 4

dendrite

Back 4

a process of a neuron specialized to pick up messages and transmit them toward the cell body. There a typically many short branching dendrites in a neuron.

Front 5

effector

Back 5

lymphocytes that are responsible for the attack on cells or substances not recognized as belonging in the body

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graded potential

Back 6

a temporary local change in the membrane potential that varies directly with the strength of the stimulus

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interneuron

Back 7

an association neuron. Neurons located within the central nervous system between sensory and motor neurons that serve to integrate information.

Front 8

ion channel

Back 8

a protein-lined pore or channel through a plasma membrane through which one type or a few types of ions can pass. Nerve cell ion channels are important in the generation and propagation of nerve impulses.

Front 9

motor neuron

Back 9

a neuron specialized to carry information away from the central nervous system to an effector, either a muscle or a gland.

Front 10

myelin sheath

Back 10

an insulating layer around axons that carry nerve impulses relatively long distances that is composed of multiple wrappings of the plasma membranes of certain glial cells.

Front 11

nerve

Back 11

a bundle of parallel axons, dendrites, or both from many neurons. Usually covered with tough connective tissue.

Front 12

neuroglial cell

Back 12

cells of the nervous system that support, insulate, and protect nerve cells; also called glial cells.

Front 13

neuron

Back 13

nerve cells involved in intercellular communication. Consists of a cell body, dendrites, and an axon. Excitable cels in the nervous system specialized to generate and transmit electrochemical signals called action potentials or nerve impulses.

Front 14

neurotransmitter

Back 14

a chemical released from the axon tip of the neuron that affects the activity of another cell (usually a nerve, muscle, or gland cell) by altering the electrical potential difference across the membrane of the receiving cell.

Front 15

refractory period

Back 15

the interval following an action potential during which a neuron cannot be stimulated to generate another action potential.

Front 16

resting potential

Back 16

the separation of charge across the plasma membrane of a neuron when the neuron is not transmitting an action potential.

Front 17

saltatory conduction

Back 17

the type of nerve transmission along a myelinated axon in which the nerve impulse jumps from one node of Ranvier to the next. Greatly increases the speed of conduction.

Front 18

Schwann cell

Back 18

a type of glial cell in the peripheral nervous system that forms the myelin sheath by wrapping around the axon many times. The myelin sheath insulates axons, increases the speed at which impulses are conducted, and assists in the repair of damaged neurons.

Front 19

sensory neuron

Back 19

a nerve cell specialized to conduct nerve impulses from the sensory receptors toward the central nervous system.

Front 20

sodium-potassium pump

Back 20

a molecular mechanism in a plasma membrane that uses cellular energy in the form of adenosine triphosphate (ATP) to pump ions against the concentration gradients. Typically, each ejects three sodium ions from the cell while bringing in two potassium ions.

Front 21

synapse

Back 21

the site of communication between a neuron and another cell cell, such as another neuron or a muscle cell.

Front 22

threshold

Back 22

the degree to which the voltage difference across the plasma membrane of a neuron or other excitable cell must change to trigger an action potential.

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autonomic nervous system

Back 23

the parts of the peripheral nervous system that governs the involuntary, unconscious activities that maintain a relatively stable internal environment. Has two branches; the sympathetic and the parasympathetic.

Front 24

blood-brain barrier

Back 24

a mechanism that protects the central nervous system by selecting the substances permitted to enter the cerebrospinal fluid from the blood. Results from the relative impermeability of the capillaries the brain and spinal cord.

Front 25

central nervous system (CNS)

Back 25

the brain and the spinal cord

Front 26

cerebellum

Back 26

a region of the brain important in sensory-motor coordination. It is largely responsible for posture and smooth body movements.

Front 27

cerebral cortex

Back 27

the extensive area of gray matter covering the surfaces of the cerebrum. It is often referred to as the conscious part of the brain. Has sensory, motor, and association areas.

Front 28

cerebrospinal fluid

Back 28

the fluid bathing the internal and external surfaces of the central nervous system. It serves as a shock absorber, supports the brain, nourishes the brain, delivers chemical messengers and removes waste products.

Front 29

cerebrum

Back 29

the largest and most prominent part of the brain, composed of the cerebral hemispheres. It is responsible for thinking, sensory perception, originating most conscious motor activity, personality, and memory.

Front 30

cranial nerves

Back 30

twelve pairs of nerves that arise from the brain and service the structures of the head and certain body parts such as the heart and diaphragm. Can be sensory, motor or mixed.

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ganglion

Back 31

a collection of nerve cell bodies outside the central nervous system

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gray matter

Back 32

regions of the central nervous system that contain neuron cell bodies and unmyelinated axons. Lack myelin. Important in neural integration.

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hippocampus

Back 33

the part of the limbic system of the brain that plays a role converting short-term memory into long-term memory.

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hypothalamus

Back 34

a small brain region located below the thalamus that is essential to maintaining a stable environment within the body. Influences blood pressure, heart rate, digestive activity, breathing rate, and many other vital physiological processes. Acts as the body's thermostat; regulates food intake, hunger, and thirst; coordinates the activities of the nervous system and the endocrine system; is part of the circuitry for emotions; and functions as a master biological clock.

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limbic system

Back 35

a collective term for several structures involved in emotions and memory.

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long-term memory

Back 36

memory that stores a large amount of information for hours, days, and years.

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medulla oblongata

Back 37

the part of the brain stem containing reflex centers for some of life's most vital physiological functions: the pace of the basic breathing rhythm, the force and rate of heart contraction, and blood pressure. Connects the spinal cord to the rest of the brain.

Front 38

meninges

Back 38

three protective connective tissue membranes that surround the central nervous system: the dura mater, the pia mater, and the arachnoid.

Front 39

parasympathetic nervous system

Back 39

the branch of the autonomic nervous system that is active during restful conditions. Its effects generally oppose those of the sympathetic nervous system. Adjusts bodily functions so that energy is conserved during non-stressful times.

Front 40

peripheral nervous system (PNS)

Back 40

the part of the nervous system outside the brain and spinal cord. Keeps the CNS in continuous contact with almost every part of the body. Composed of nerves and ganglia. Two branches are the somatic and the autonomic nervous systems.

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pons

Back 41

a part of the brain that connects upper and lower level of the brain

Front 42

prefrontal cortex

Back 42

an association area of the cerebral cortex that is important in decision making

Front 43

primary motor area

Back 43

a band of the frontal lobe of the cerebral cortex that initiates messages that direct voluntary movements

Front 44

primary somatosensory area

Back 44

a band of the parietal lobe of the the cerebral cortex to which information is sent from receptors in the skin regarding touch, temperature, and pain and from receptors in the joints and skeletal muscles

Front 45

reflex arc

Back 45

a neural pathway consisting of a sensory receptor, a sensory neuron, usually at least one interferon, a motor neuron and an effector

Front 46

reticular activating system (RAS)

Back 46

interconnected strands of collagen in certain connective tissues that branch extensively. Networks of reticular fibers support soft tissues, including the liver and spleen.

Front 47

short-term memory

Back 47

memory of new information that lasts for a few seconds or minutes

Front 48

somatic nervous system

Back 48

the part of the peripheral nervous system that carries information to and from the central nervous system, resulting in voluntary movement and sensations

Front 49

spinal cord

Back 49

a tube of neural tissue that is continuous with the medulla at the base of the brain and extends about 45 cm (17 in) to just below the last rib. It conducts messages between the brain and the rest of the body and serves as a reflex center

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spinal nerve

Back 50

thirty-one pairs of nerves that arise from the spinal cord. Each services a specific region of the body. Carry both sensory and motor information.

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sympathetic nervous system

Back 51

the branch of the autonomic nervous system responsible for the "fight-or-flight" responses that occur during stressful or emergency situations. Its effects are generally opposite to those of the parasympathetic nervous system.

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thalamus

Back 52

a brain structure located below the cerebral hemispheres that is important in sensory experience, motor activity, stimulation of the cerebral cortex, and memory.

Front 53

white matter

Back 53

regions of the CNS that are white owing to the presence of myelinated nerve fibers. Important in neural communication over distances.