Chapter 45: Nuerons and Nervous System

Question 1

dendrites

Answer 1

receive information from other neurons

Question 2

cell body

Answer 2

contains the nucleus and most of the cell organelles

Question 3

axon

Answer 3

conducts action potentials away from the cell body

Question 4

axon terminals

Answer 4

synapse with a target cell

Question 5

synapse

Answer 5

axon terminal comes extremely close to the membrane of the target cell

Question 6

neurotransmitter

Answer 6

chemical messengers

Question 7

oligodendrocytes

Answer 7

wrap around axons of neurons of brain and spinal cord, covering them with concentric layers of insulating plasma membrane

Question 8

schwann cells

Answer 8

outside brain and spinal cord, wrap axons

Question 9

myelin

Answer 9

covering produced by the oligodendrocytes and schwann cells. Give glistening white appearance

Question 10

Astrocytes

Answer 10

contribute to the blood-brain barrier

Question 11

blood-brain barrier

Answer 11

protects the brain from toxic chemicals in the blood

Question 12

tripartite synapse

Answer 12

idea that a synapse includes not only the pre- and postsynaptic neurons but also connections from astrocytes

Question 13

microglia

Answer 13

provide the nervous system with immune defenses

Question 14

membrane potential

Answer 14

is a charge difference across the membrane. with the inside of cell negative relevant to outside

Question 15

resting potential

Answer 15

steady state membrane potential

Question 16

voltage

Answer 16

force that causes electrically charged particles to move from one point to another

Question 17

sodium potassium pump

Answer 17

keeps the concentration of K+ greater on the outside. requires ATP to do work

Question 18

patch clamping

Answer 18

record in real time the tiny electric currents caused by the opening and closings of single ion channels

Question 19

depolarized

Answer 19

inside of neuron becomes less negative (or more positive) in comparison to its resting condition

Question 20

hyperpolarized

Answer 20

membrane potential become even more negative

Question 21

graded membrane potential

Answer 21

change from the resting potential

Question 22

axon hillock

Answer 22

region of the cell body at the base of the axon

Question 23

refractory period

Answer 23

about 1-2 milliseconds during which, voltage-gated sodium pumps cannot open again

Question 24

after-hyperpolarization

Answer 24

dip in the membrane potential following an action potential

Question 25

nodes of Ranvier

Answer 25

regularly spaced gaps, where axon is not covered with myelin

Question 26

saltatory conduction

Answer 26

action potentials "jump" from node to node in myelinated axons, allowing faster transmissions

Question 27

electrical synapses

Answer 27

action potential spreads directly from presynaptic cell to postsynaptic cell

Question 28

chemical synapses

Answer 28

neurotransmitters released from presynaptic cell induces change is postsynaptic cell

Question 29

neuromuscular junctions

Answer 29

synapses between neurons and skeletal muscle cells

Question 30

acetylcholine

Answer 30

neurotransmitter used by all vertebrate neuromuscular synapses

Question 31

motor end plate

Answer 31

postsynaptic membrane of the neuromuscular junction is modified part of the muscle cell plasma membrane

Question 32

synaptic cleft

Answer 32

space between the pre synaptic membrane and the postsynaptic membrane

Question 33

spatial summations

Answer 33

adds up the simultaneous influences of synapses at different sites on the postsynaptic cell

Question 34

temporal summation

Answer 34

adds up the postsynaptic potentials generated at the same site in a rapid sequence

Question 35

ionotropic receptors

Answer 35

ion channels or directly influence ion channels. generally fast

Question 36

metabotropic receptors

Answer 36

influence the postsynaptic cell through various signal transduction pathways an can result in the opening or closing of ions. slower than inotropic receptors

Question 37

agonist

Answer 37

drugs that mimic or potentiate the effect of a neurotransmitter

Question 38

antagonists

Answer 38

block the actions of neurotransmitter

Question 39

afferent neuron

Answer 39

carry sensory information into the nervous system.

Question 40

efferent neuron

Answer 40

carry commands to physiological and behavioral effectors such as muscles and glands

Question 41

interneuron

Answer 41

integrate and store information and communicate between afferent and efferent neuron

Question 42

gray matter

Answer 42

rich in neural cell bodies

Question 43

whiter matter

Answer 43

contains myelinated axons

Question 44

spinal reflex

Answer 44

conversion of afferent to efferent information in the spinal cord without the participation of the brain