Biology Ch 12

Front 1

central nervous system (CNS)

Back 1

consists of the brain and spinal cord
-cannot repair self

Front 2

peripheral nervous system (PNS)

Back 2

all the nervous system EXCEPT brain and spinal cord; composed of nerves and ganglia

Front 3

nerve

Back 3

bundle of nerve fibers (axons) wrapped in fibrous connective tissue

Front 4

ganglion

Back 4

a knotlike swelling in a nerve where the cell bodies of neurons are concentrated

Front 5

sensory (afferent) division of nervous system

Back 5

carries signals TO CNS from various receptors, is divided into somatic and visceral divisions

Front 6

somatic sensory division

Back 6

carries signals to CNS from muscles, skin, bones, and joints

Front 7

visceral sensory division

Back 7

carries signals to CNS from viscera (vital organs) of chest and abdominal cavities

Front 8

motor (efferent division)

Back 8

"Exit," carries signals FROM CNS to effector cells and organs, is divided into somatic and visceral as well

Front 9

somatic motor division

Back 9

carries signals from CNS to skeletal muscle

Front 10

visceral motor divisioin

Back 10

carries signals from CNS to glands, heart, and smooth muscle...is also called the AUTONOMIC NERVOUS SYSTEM...is divided into sympathetic and parasympathetic

sympathetic: arouses body for action
parasympathetic: calms body

Front 11

3 universal properties of neurons

Back 11

excitability, conductivity, secretion (of neurotransmitter)

Front 12

sensory (afferent) neurons

Back 12

neurons that detect stimuli (light, heat pressure, chemicals) and transmit this information to CNS

Front 13

interneurons

Back 13

lie entirely WITHIN CNS, receive signals from other neurons and integrate (process, store, info) and make decisions, most neurons are this

Front 14

motor (efferent)

Back 14

send signals to muscle and gland cells (the effectors)

Front 15

soma

Back 15

the cell body of a neuron, the "control center", mature ones do not have centrioles because they do not divide

Front 16

axon hillock

Back 16

a mound where axon originates, forms part of trigger zone

Front 17

axonal transport

Back 17

the two way passage of proteins, organelles and other materials along an axon

Front 18

anterograde transport

Back 18

down the axon

Front 19

retrograde transport

Back 19

up the axon

Front 20

oligodendrocytes

Back 20

CNS only, bulbous body with armlike processes that reach out and spiral around nerves to form a myelin sheath

Front 21

ependymal cells

Back 21

CNS only, produce cerebrospinal fluid

Front 22

microglia

Back 22

CNS only, microphages that probe CNS for foreign matter, "little doctors"

Front 23

astrocytes

Back 23

CNS only, wide variety, most abundant, form supportive framework, stimulate blood capillaries to form blood-brain barrier, secrete nerve growth factors, communicate electronically with nuerons, form scar tissue

Front 24

Schwann cells

Back 24

PNS only, envelope nerve fibers of PNS

Front 25

satellite cells

Back 25

PNS, surround neurosomas, provide electrical insulation, regulate chemical environment for neurons

Front 26

myelin sheath

Back 26

an insulating layer around a nerve fiber

-CNS: oligodendrocytes
-PNS: Schwann cells

Front 27

myelination

Back 27

process of producing myelin sheath
-begins in fetal development but proceeds rapidly in infancy, fat important in infant diet (Omega 3's)

Front 28

neurilemma

Back 28

the outermost coil of the myelin sheath - contains nucleus and cytoplasm - covered by endoneurium

Front 29

endoneurium

Back 29

thin layer of fibrous connective tissue that covers basil lamina, neurilemma, and rest of individual nerve fibers

Front 30

nodes of Ranvier

Back 30

the unmyelinated segments between segments of myelin

Front 31

internodes

Back 31

the myelinated covered segments of a nerve fiber

Front 32

initial segment

Back 32

short section of nerve fiber between axon hillock and first glial cell

Front 33

trigger zone

Back 33

formed by axon hillock and initial segment - area where action potentials are fired

Front 34

multiple sclerosis

Back 34

degenerative disease of myelin sheath, myelin is replaced by harden scar tissue which disrupts its ability to conduct an electric current (double vision, tremors, speech defects)

Front 35

Tay-Sachs disease

Back 35

a glycolipid called GM2 abnormally accumulates in the myelin sheath, disrupts conduction of signal as well, fatal before age 4

Front 36

mesaxon

Back 36

the neurilemma wrapping of unmyelinated nerve fibers

Front 37

2 factors that determine conduction speed of nerve fibers

Back 37

1. size (diameter)
2. presence of myelin

Bigger size, faster.
Myelin, faster.

slow: pupil and stomach
fast: vision and muscle

Front 38

Requirements for regeneration of a peripheral nerve regeneration

Back 38

1. soma intact
2. at least SOME nuerolemma remains

Front 39

regeneration tube

Back 39

after trauma causes a peripheral nerve to sever, this tube is formed by Schwan cells, basal lamina and neurilemma near the injury and guides the growing sprout back to the original target cells and reestablishes synaptic contact

Front 40

denervation atrophy

Back 40

occurs when muscles deteriorate due to a lack of synaptic contact by a damaged nerve, and thus, use

Front 41

regeneration tube

Back 41

in the PNS, a "tube" formed by Schwann cells and basal lamina that allows a neuron to regrow to its original destination

Front 42

refractory period

Back 42

period in which a region of a nueron cannot be restimulated

Front 43

absolute refractory period

Back 43

nueron cannot be restimulated no matter what because the Na+ inactivation gates have not yet reset

Front 44

relative refractory period

Back 44

neuron can be restimulated with an extremely strong stimulus

Front 45

types of neurotransmitters

Back 45

1. Acetylcholine
2. Amino acid neurotransmitters (GABA)
3. Monoamines
4. Neuropeptides

Front 46

enzyme amplification

Back 46

an advantage of adrenergic synapes (norepinephrine), uses second messenger system so one NE molecule can induce formation of many cAMPs and make a lot of metabolic products

Front 47

3 methods of cessation of signal by neurotransmitter

Back 47

1. diffusion
2. reuptake
3. degradation in synaptic cleft

Front 48

neuromodulators

Back 48

hormones, neuropeptides, and other messengers that modify synaptic transmission

ex: laughing gas - "give me more" nuerotransmitter

Front 49

terminal arborizations

Back 49

branches off of singular axon

Front 50

types of nuerons

Back 50

1. Multipolar - multiple dendrites, common in brain and spinal cord
2. Bipolar - one axon and one dendrite, common in olfactory cells and inner ear and retina
3. unipolar - sensory nuerons from skin and organs to spinal cord, one process leading away from soma
4. anaxonic neuron - many dendrites but no axon, visual processes

Front 51

nerve growth factor

Back 51

a protein secreted by a gland, muscle, and glial cells and picked up by the axon terminals of the neurons, enables growing neurons to make contact with their target cells

Front 52

threshold for a neuron

Back 52

-55 mV

Front 53

Resting membrane potential for a neuron

Back 53

-70 mV

Front 54

postsynaptic neuron

Back 54

has receptors which determine the nuerotransmitter's effect, multiple receptor types exist for a particular neurotransitter

Front 55

excitatory cholinergic synapse

Back 55

uses acetylecholine as nuerotransmitter, uses calcium from voltage-gated channels to release Ach, diffuses across synaptic cleft and binds to post synaptic ligand gated channels that open sodium channels, hopefully causing postsynaptic neuron to fire

Front 56

inhibitory GABA-ergic synapse

Back 56

GABA released in synaptic cleft--receptors open chloride channels (Cl) which further polarizes the cell making it less likely to fire

Front 57

excitatory adrenergic synapse

Back 57

use norepinephrine, which acts through a second messenger system
-NE binds to receptor, receptor releases G protein, G protein activates adenylate cyclase which converts ATP to cAMP, which causes an effect

-advantage - enzyme aplification, "cascade" of results

Front 58

enkephalins

Back 58

a nueromodulator family that inhibits pain transimttion signals to brain in spinal nuerons

Front 59

excitatory postsynaptic potentials

Back 59

any voltage change in the direction of threshold that makes a nueron more likely to fire

Front 60

inhibitory postsynaptic potentials

Back 60

voltage change away from threwshold that make a neuron less likely to fire

Front 61

summation

Back 61

the process of adding postsynaptic potentials to decide whether or not you get an action potential - the NET effect of all the neurons acting on the postsynaptic nueron, this enables the nervous system to make decisions

Front 62

temporal summation

Back 62

occurs when a single synapes generates EPSP so quickly that each is generated before the pervious one fades away, produces an action potential by these added local potentials

Front 63

spatial summation

Back 63

occurs when EPSP from DIFFERENT synapses add up to threshold at an axon hillock

Front 64

facilitation

Back 64

when one neuron enhances the effect of another one

Front 65

presynaptic inhibition

Back 65

process in which one presynaptic neuron suppresses another one

Front 66

synaptic plasticity

Back 66

the ability of synapses to change (memory)

Front 67

synaptic potentiation

Back 67

the process of making transmission easier