college biology chapter 34

nervous system

the body's communication lines for detecting stimuli and responding in suitable ways

stimulus

a signal to which an organism responds/change in environmental conditions

neuroglia

cells that metabolically support and protect neurons /framework that holds neurons in place

ganglion

collection of nerve cell bodies in the peripheral nervous system

cephalization

formation of the head

central nervous system

brain and spinal cord

peripheral nervous system

all the nerves carrying signals to and from the brain and spinal cord

afferent fibers

deliver signals INTO the brain and spinal cord

efferent fibers

carrying signals AWAY from brain and spinal cord

sensory neurons

detect a stimulus ate one or more receptor endings and relay information about it to other neurons

motor neurons

deliver excitatory or inhibitory commands from other neurons to muscles or glands

Interneurons

(in the brain and spinal cord) receive, process, and sometimes store sensory information, and integrate most of the responses to it

dendrites

numerous, usually short extensions that receive stimuli (input zones)

axon

usually a single, rather long extension that transmits impulses to other cells at its branched endings

input zones

cell body and dendrites

trigger zone

where action potential is generated

output zones

axon endings

resting membrane potential

the electrical charge of a neuron when it is not active; -70mv; inside is more negatively charged than the outside

action potential

a neural impulse; a brief electrical charge that travels down an axon

sodium-potassium pump

A transport protein in the plasma membrane of animal cells that actively transports sodium out of the cell and potassium into the cell

all-or-nothing event

a nerve impulse occurs completely or not at all

chemical synapse

junction between a neuron and an adjacent cell, separated by a synaptic cleft into which a neurotransmitter substance is released

presynaptic cell

the neuron that releases the neurotransmitter molecules into the cleft

Neurotransmitters

Chemicals that transmit information from one neuron to another

postsynaptic cell

The neuron, muscle, or gland cell that receives the signal from a neuron.

ACh

acetylcholine; transmitter releases at neuromusclular junctions

neuromuscular junction

point of contact between a motor neuron and a skeletal muscle cell

Norepnephrine; epineprhine

adrenaline

dopamine

affects fine motor control and pleasure-seeking behaviors

serotonin

affects mood and memory; low levels related to depression

endorphins

released by laughing, during orgasm, or during calming situations; reported to improve mood and enhance the function of certain immune cells

Oligodendrocytes

produce myelin in CNS

myelin

a fatty substance that helps insulate neurons and speeds the transmission of nerve impulses

astrocytes

form blood brain barrier; most abundant of all cells in the brain

microglia

move around the brain engulfing dead or dying tissue

nerves

bundle of axons held together by connective tissue

schwann cells

produce myelin in PNS

myelin sheath

covers the axon of some neurons and helps speed neural impulses

node

gap in the myelin sheath along the length of an axon; nerve impulses move from node to node

multiple sclerosis

A chronic disease of the central nervous system marked by damage to the myelin sheath

reflex

simple, stereotyped movements made in response to sensory stimuli

somatic nerves

relay sensory information fro receptors in the skin and muscles and motor commands to skeletal muscles (voluntary control)

autonomic nerves

send signals to and from smooth muscles, cardiac muscles, and glands (involuntary control)

viscera

internal organs

sympathetic neurons

increase overall body activity during times of stress, excitement, or danger; they also call on the hormone epinephrine to increase the "fight-flight" response

parasympathetic neurons

tend to slow down body activity when the body is not under stress

fight-flight response

an involuntary reaction resulting in a state of physiological readiness to deal with a sudden and immediate threat by either confronting it (fight) or running away to safety (flight)

spinal cord

pathway for signal travel between the peripheral nervous system and the brain

meninges

three layers of connective tissue in which the brain and spinal cord are wrapped

meningitis

inflammation of the meninges

brain stem

Connects the brain and spinal cord; contains simple, basic reflex centers

medulla oblongata

respiration and circulation

cerebellum

balance, smooths skeletal movements, maintains posture

cerebrum

integrates sensory and motor info, memory, emotions, consciousness, intelligence; limbic system/reticular formation

cerebrospinal fluid

the fluid in and around the brain and spinal cord

blood-brain barrier

controls which solutes enter the cerebrospinal fluid

left

the side of the brain that is more analytical

right

the side of the brain that deals with judgment and creativity, spacial reasoning

limbic system

cerebrum; governs out emotions and memory

reticular formation

cerebrum; consciousness, sleep and wake cycles