Ch 48

Question 1

Nervous processes info. in 3 stages

Answer 1

-sensory input, integration, motor output

Question 2

sensory neurons

Answer 2

-recieve signals from sensors that detect external stimuli and internal condition

Question 3

interneurons

Answer 3

-on CNS
-intergrate info sent to brain/ganglia

Question 4

motor neurons

Answer 4

-send motor output out of brain or ganglia
-trigger muscle or gland activity

Question 5

central nervous system

Answer 5

-brain and nerve cord
-intergration takes place

Question 6

peripheral nervous system

Answer 6

-carries info into and out of CNS
-neurons of PNS form nerves

Question 7

cell body

Answer 7

where most of neurons organelles are

Question 8

dendrites

Answer 8

-highly branchd extensions on neuron that receives signals from other neurons

Question 9

axon

Answer 9

-longerextension that transmits signals to other cells at synapses

Question 10

axon hillock

Answer 10

-cone shaped base of axon

Question 11

synaptic terminal/bulb

Answer 11

-bulb at end of axon terminal where neurotransmitter molecules are stored/released
-electrical signal (action potential) > chemcial signal (neurotransmitter)

Question 12

neurotransmitter

Answer 12

-chemical messengers
-signaling molecule secreted by neuron to affect another cell across a synapse
-over 100
-5 groups:
-acetylcholine
-Biogenic amines (norepinephrine, dopamine, serotonin),
-Amino acids (GABA, glutamate, glycine),
-Neuropeptides (substance p)
-Gases (nitric oxide)
-a single one may have more than a dozen diff. receptors

Question 13

synapse

Answer 13

junction between axon and another cell
-info. is transmitted from presynaptic (neuron) to postsynaptic cell (neuron, muscle, or gland cell)
-most are chemical synapses
-many neurons have this on dendrites and cell body

Question 14

membrane potential

Answer 14

-voltage
-difference in electrical charge across plasma membrane
-major source is resulting buildup of negative charge within neruon
-becomes more negative: at resting potential, hyperpolarized
-becomes more positive; at resting potential, depolarized

Question 15

resting potential

Answer 15

-membrane potential of neuron not sending signals
-neuron contains many open K+ channels and fewer open Na+ channels
-K+ diffuses out of cell

Question 16

ion channels

Answer 16

-in plasma membrane
-converts chemical potential to electrical potential

Question 16

ligand gated channels

Answer 16

-on dendrites
-triggered to open when bound to specefic molecule
-involved in direct synaptic transmission binding of neurotransmitters
-bind neurotransmitters and open in response
-control synaptic transmission between 2 neurons or neuron and muscle
-less selective than voltage gated and allow 2 or more ions through

Question 17

action potential

Answer 17

-series of stages
-travels in one direction (towards synaptic terminals)
-prevented from moving backwards are the inactivated Na+ channels behind the zone of depolarization
-formed only at nodes of Ranvier
-causes release of neurotransmitter
-all or nothing process

Question 18

refractory period

Answer 18

-after action potential, where second action potential can’t be initiated

Question 19

electrical synapses

Answer 19

-electrical current flows from one neuron to another

Question 20

chemical synapses

Answer 20

-chemical neurotransmitter carries info. across gap junction

Question 21

synaptic vesicles

Answer 21

-located in synaptic terminal
-where presynaptic neuron synthesizes and packages neurotransmitter

Question 22

synaptic cleft

Answer 22

-where neurotransmiter diffueses across
-between pre/post synaptic cell

Question 23

after release, the transmitter…

Answer 23

-may diffuse out of synaptic cleft
-may be taken out by surrounding cells
-may be degraded by enzymes

Question 24

excitatory post synaptic potentials

Answer 24

-depolarizations that bring the membrane potential toward threshold -single one is usually too small to trigger an action potential in post synaptic neuron -combination of EPSPs through spatial/temporal summation can trigger an action potential

Question 25

inhibitory postsynaptic potentials

Answer 25

hyperpolarizations that move the membrane potential farther from the threshold -through summation, can counter the effect of EPSPs -summed effect of EPSPs and IPSPs determines whether an axon hillock will reach the threshold and generate an action potential

Question 26

temporal summation

Answer 26

when 2 EPSPs are produced in rapid succession

Question 27

spatial summation

Answer 27

-when EPSPs produced nearly simultaneously by diff. synapses on same postsynaptic neuron add together

Question 28

gated ion channels

Answer 28

-in neurons that cause changes in membrane potential -open or close in response to stimuli

Question 29

myelin sheath

Answer 29

-cause an action potential speed to increase -insulates axons -made of glia (oligodendrocytes in CNS) and Schwann cells in PNS

Question 30

stages of action potential

Answer 30

1. most voltage-gated Na+ and K+ are closed 2. Voltage-gated Na+ open first 3. rising phase: the threshold is crossed, membrane potential increases 4. falling phase: voltage-gated K+ channels open and K+ flows out of 5. undershoot: membrane permeability to k+ is first higher than at rest, then voltage-gated K+ channels close and resting potential is restored

Question 31

nodes of Ranvier

Answer 31

-gaps in myelin sheath -where voltage gated Na+ channels are found

Question 32

saltatory conduction

Answer 32

-process in which action potentials in myelinated axons jump between nodes of Ranvier

Question 32

post synaptic potential/neuron

Answer 32

-receives neurotransmitter to facilitate nerve impulse transmission 2 categories -excitatory postsynaptic potentials (EPSPs) -inhibitory postsynaptic potentials (IPSPs)

Question 33

presynaptic potential/neuron

Answer 33

-releases neurotransmitter

Question 34

voltage gated channels

Answer 34

-needs signal to open or close -only open when membrane potential reaches certain value allow permeation of only one type of ion -integral membrane proteins -enable passage of selected inorganic ions across cell membranes