CHAPTER3 Flashcards

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1
Q

Tetrodotoxin

A

an extremely powerful poison that puffer (fugu) fish contain with no known antidote

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2
Q

what make tetrodotoxin lethal?

A

like similar poisons, it prevents the transmission of action potentials

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3
Q

action potentials

A

the electrical signals by which neurons communicate quickly over long distances

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4
Q

what do motor neurons do?

A

command the muscles to contract or relax

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5
Q

what do your eyes and ears do?

A

carry signals about external events by responding to physical stimuli such as light patterns and sound waves

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6
Q

the brain has the consistency of ________

A

slightly hardened mashed potatoes

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7
Q

Santiago Ramon y cajal

A

used new techniques to stain and visualize brain tissue

- he realize that the brain is built of billions of discrete cells

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8
Q

what is the most important type of cell in your nervous system?

A

neuron

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9
Q

how many neurons does the human brain contain?

A

100 billion neurons

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10
Q

components of a neuron

A

they have a membrane, nucleus, and specials organelles

- they produce traffic and secrete chemicals

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11
Q

what does the membrane of a neuron do?

A

seperates the cell’s components from environment outside the cell

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12
Q

neurons have ____ that are inserted into the membranes, and these ____ allow the cells to interact with it’s outside environment

A

proteins

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13
Q

what property do neurons posses that distinguishes them?

A
  • because of the particular proteins on their surfaces,

they can transmit electrical signals quickly over long distances

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14
Q

neurons 4 zones of importance

A
  • dendrites
  • soma or cell body
  • axon / nerve fiber
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15
Q

dendrites

A

long, branching extensions from the cell body

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16
Q

soma

A

greek for body

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17
Q

a typical soma spans about _____ micrometers

A

10-25

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18
Q

the key feature of the soma is the cell’s _______, which is the control centre of the cell’s that regulates cell activity, including gene expression

A

nucleus

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19
Q

dendrites are specialized for ________________

A

collecting information from thousands of tiny chemical signals that they receive all along their extent

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20
Q

the soma plays a key role in ______ the signals coming in from the dendrites

A

integrating

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21
Q

axon

A

an extension that reaches long distances beyond the soma that is essentially capable to conduct signals rapidly across long distances

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22
Q

which three ways does the axon differ from dendrites?

A

1) there is only one axon coming from a neuron, whereas there can be many dendritic extensions
2) axons tend to remain constant in diameter all along their length
3) axons tend to be much longer than dendrites, dendritic trees rarely extend more than 3 millimeters, whereas azons carrying signals from your spinal chord to your big toe (sciatic nerve) run the entire length of your leg

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23
Q

in giraffes, ______ are several meterslong and run the entire span of the neck!

A

axons

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24
Q

a typical axon will branch robustly at its ends, typically splitting into about _______ axon terminals

A

10,000

25
Q

which 4 zones of importance do axon terminals consist of?

A

1)

26
Q

where are axon terminals typically found?

A

in close proximity to the dendrites and somas of other cells, and such junctions are called synapses

27
Q

what does the synapse do?

A

links axons to other neruons (in the central nervous system) or to a neuron, muscle or gland (in the peripheral nervous system)

28
Q

en passant synapses

A

synapses that exist along the axon itself

29
Q

the typical synapse connects an _______ to a _____ or ____

A

axon

dendrite or soma

30
Q

there are also synapses that can join axon to ____ or dendrite to _____, although these are more rare.

A

axon to axon

dendrite to dendrite

31
Q

in the three year old brain, the amount of synapses is estimated to be a ____

A

quadrillion

32
Q

an adult brain contains somewhere between ____ and ____ trillion synapses, in a total volume of about 1,200 cubic centimeters

A

100 and 500

33
Q

there are _____ of these tiny connections (synapses) in a cubic milimeter of cerebral cortex for a typical college student

A

several billion

34
Q

collecting: _____
integrating: _____
conducting: _____
outputting information: ______

A

dendrites
soma
axon
axon terminals

35
Q

what can you use to classify neurons?

A
function
shape
36
Q

sensory neurons

A

neurons that directly respond to signals from outside environment

37
Q

motor neurons

A

direct output to muscles or glands; final step for signals to exit the nervous system and effect change in the body or environment

38
Q

afferent neurons: _______

A

incoming sensory neurons

39
Q

efferent neurons: _______

A

outgoing motor neurons

40
Q

in mammals, the vast majority of neurons can not be classified as either afferent or efferent - instead they are _____ between the sensation of a ____ at one end and the _____ at another end

A

interneurons
signal
action

41
Q

primitive animals, such as _____, have neurons that contain both sensory and motor qualities in the same cell
- this combination is NOT found in more advanced species

A

jellyfish

42
Q

multipolar neurons (most common)

A

neurons with multiple dendrites

43
Q

bipolar neurons

A

composed of a single dendrite on one end and a single axon on the other end

44
Q

_____ neurons are often found in sensory neruons such as the retina and inner ear

A

bipolar

45
Q

monopolar neurons

A

neurons with only a single extension that leaves the soma and branches into two directions

46
Q

one end of monopolar neurons ________ while the other end _______

A

recieves the information

serves for output

47
Q

_______ neurons are typically found in sensory neruons that signal touch and pain

A

monopolar

48
Q

all neurons are _____, which means they do not divide like many other cells in the body

A

postmitotic

49
Q

greek word for glue

A

gila

50
Q

gila

A

cells that play several roles including providing ways to speed up the signalling from neurons, regulating concentrations of extracellular chemicals, and determining the extent to which networks of neurons can modify their connections

51
Q

ogliodendrocytes

A

1/4 of the forms of gila: large cells whose main fucntion is to wrap a layer of “insulation” around axons - known as myelination (similar to the way that a copper wire is wrapped in rubber)

52
Q

a single ogliodendrocyte wraps the axon of up to ___ different neurons and are found only in the _______; the function of myelination is accomplished in the _________, by a second type of glial cell, the ________ cells

A

50
central nervous system
peripheral nervous system
schwann cells

53
Q

schwann cells

A

similar in function to ogliodendrocytes, but they wrap myelin only around a single axon

54
Q

nodes of ranvier

A

the gaps between myelinated segments

short segments like stringed sausages

55
Q

myelination:

no myelination:

A

axons in cortex

subcortical and peripheral axons

56
Q

astro

cyte

A

greek for star

greek for cell

57
Q

astrocyte

A

3/4 of the glial cells, perform critical functions in maintaining the chemicals outside the neruons, the repair of injury in the central nervous system, the contribution of nutrients, the regulation of local blood flow to a region & the release of chemical signals

58
Q

microglia

A

4/4 type of glial cell, makes up 20% of glial cell population, these small cells are the front line of immune defense in the central nervous system: they are constantly on the move, searching for any infectious agents that might damage neural tissue. When they detect a foreign body they consume it and destroy it to prevent disease and inflamination