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Biological Foundations > Chapter 2 - Neurons and Action Potentials > Flashcards

Chapter 2 - Neurons and Action Potentials Flashcards

1
Q

neurons

A

cells in nervous system that receive and transmit information

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2
Q

how many neuwons does the human brain contain? (estimate)

A

100 billion neurons

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3
Q

santiago ramon y cajal

A

developed staining techniques to show a small gap separates the tips of one neurons fibers from the surface of the next neuron.

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4
Q

membrane

A

the surface of a cell that separates the inside of the cell from the outside environment

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5
Q

what is the cell membrane composed of?

A

two layers of fat molecules.

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6
Q

what chemicals can cross the membrane with the aid of a pump?

A

water, oxygen, sodium, potassium, calcium, chloride, and others

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7
Q

nucleus

A

structure in the cell that contains the chromosomes

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8
Q

mitochondrion (pl: mitochondria)

A

structure that performs metabolic activities

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9
Q

ribosomes

A

sites at which the cell synthesizes new protein molecules

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10
Q

endoplasmic reticulum

A

transports newly synthesized proteins to other locations. sometimes have ribosomes attached.

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11
Q

motor neuron

A

soma in spinal cord. conducts impulses along its axon to a muscle

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12
Q

sensory neuron

A

specialized at one end to be highly sensitive to a particular stimuli (i.e. light, sound or touch)

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13
Q

dendrites

A

branching fibers that receive information from other neurons

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14
Q

dendritic spines

A

short outgrowths that increase the surface area available for synapses

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15
Q

soma / cell body

A

contains nucleus, ribosomes & mitochondria. most of metabolic work occurs here

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16
Q

axon

A

thin fiber, sends information to other neurons, organs, or muscles.

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17
Q

myelin sheath

A

insulation of axons in most vetebrates

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18
Q

nodes of ranvier

A

interruptions of myelin sheath which help transmit signals faster down the axon

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19
Q

presynaptic terminal / end bulb / bouton

A

point from which the axon releases chemicals that cross the junction to another neuron

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20
Q

afferent axon

A

brings information into the structure (approach)

every sensory neuron is afferent

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21
Q

efferent exon

A

carries information away from the structure (exit)

every nomtor neuron is efferent

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22
Q

interneuron / intrinsic neuron

A

neuron with dendrites and axon entirely contained in a single structure

23
Q

glia

A

more numerous than neurons

astrocytes
microglia
oligodendrocytes
schwann cells
radial glia
24
Q

astrocytes

A

star shaped. help synchronize activity of axons to ehable messages in waves. also remove waste material. dialate blood vessels to bring more nutrients into an area of hightened brain activity.

25
Q

glutamate

A

transmitter used by neurons to communicate

26
Q

microglia

A

very small cells. remove waste material, viruses, fungi and other microorganisims.

27
Q

oligodendrocytes

A

build myelin sheath in central nervous system

28
Q

schwann cells

A

build myelin sheath in the peripheral nervous system

29
Q

radial glia

A

guide migration of neurons and axons and dendrites during embroyonic development

30
Q

blood-brain barrier

A

mechanism that excludesmost chemicals from the vertebrate brain

31
Q

electrical gradient / polarization

A

difference in electrical charge between the inside (negative) and outside (positive) of the cell

32
Q

resting potential

A

difference in negative (inside) and positive (outside) voltage in a resting neuron

33
Q

typical electrical levels of a neuron

A

-70 millivolts (mV)

34
Q

selectively permeable

A

some chemicals pass through this membrane more freely than others. keeps membrane from depolarize

35
Q

sodium-potassium pump

A

protein complex, transports 3 sodium ions out of the cell while drawing two potassium ions into it. active transport. requires energy.

36
Q

concentration gradient

A

difference in distribution of ions across the membrane

37
Q

which ions are outside/ inside the cell?

A

sodium ions are concentrated outside, potassium is more concentrated inside

38
Q

when membrane is at rest, what drives potassium ions out of the cell? what draws them into the cell?

A

concentration gradeitn drives potassium out of the cell, electrical gradient drawsthem into the cell.

sodium-potassium pump also draws them in

39
Q

action potentials

A

messages sent by axons

40
Q

hyperpolarization

A

increased polarization, caused by stimulation by negative charge to an axon membrane

41
Q

depolarize

A

reduce polarization towards zero

42
Q

threshold of excitation

A

stimulation beyond this point produces a massive depolarization of the membrane. the membrane opens sodium channels and sodium ions flow into the cell. triggered by any stimulation beyond the threshold, regardless of how far.

43
Q

subthreshold stimulation

A

small response proportional to amount of current

44
Q

voltage-gated channels

A

changels with permeability dependant on the voltage difference across the membrane

45
Q

local anesthetics

A

attach to sodium channels of mjembrane, preventing sodium ions from entering and stopping action potentials. (i.e. novocain stop axons from transmitting pain messages to your brain)

46
Q

all-or-none-law

A

amplitude and veolicty of an action potential are independent of the stimulus that initiated it, provided that the stimulus reaches the threshold.

47
Q

refractory period

A

immediatly after action potential in shich a cell resists production of further action potentials

48
Q

absolute refractory period

A

membrane cannot produce an action potential, regardless of the stimulation

49
Q

relative refractory period

A

cell requires a stronger than usual stimulus to initiate an action potential.

50
Q

axon hillock

A

swelling where the axon exits the soma; where action potential begins

51
Q

propagation of the action potential

A

transmission of action potential down an axon

52
Q

saltatory conduction

A

the jumping of actio potentials from node to node to propogate the axon potential down the axon

53
Q

local neurons

A

neurons without an axon which exchange information only with closest neighbors

54
Q

graded potential

A

a membrane potential that varies in magnitude in proportion to the intensity of the stimulus.

Biological Foundations (2 decks)

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