CHAPTER3

Question 1

Tetrodotoxin

Answer 1

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

Question 2

what make tetrodotoxin lethal?

Answer 2

like similar poisons, it prevents the transmission of action potentials

Question 3

action potentials

Answer 3

the electrical signals by which neurons communicate quickly over long distances

Question 4

what do motor neurons do?

Answer 4

command the muscles to contract or relax

Question 5

what do your eyes and ears do?

Answer 5

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

Question 6

the brain has the consistency of ________

Answer 6

slightly hardened mashed potatoes

Question 7

Santiago Ramon y cajal

Answer 7

used new techniques to stain and visualize brain tissue

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

Question 8

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

Answer 8

neuron

Question 9

how many neurons does the human brain contain?

Answer 9

100 billion neurons

Question 10

components of a neuron

Answer 10

they have a membrane, nucleus, and specials organelles

- they produce traffic and secrete chemicals

Question 11

what does the membrane of a neuron do?

Answer 11

seperates the cell’s components from environment outside the cell

Question 12

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

Answer 12

proteins

Question 13

what property do neurons posses that distinguishes them?

Answer 13

• because of the particular proteins on their surfaces,

they can transmit electrical signals quickly over long distances

Question 14

neurons 4 zones of importance

Answer 14

• dendrites
• soma or cell body
• axon / nerve fiber

Question 15

dendrites

Answer 15

long, branching extensions from the cell body

Question 16

soma

Answer 16

greek for body

Question 17

a typical soma spans about _____ micrometers

Answer 17

10-25

Question 18

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

Answer 18

nucleus

Question 19

dendrites are specialized for ________________

Answer 19

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

Question 20

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

Answer 20

integrating

Question 21

axon

Answer 21

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

Question 22

which three ways does the axon differ from dendrites?

Answer 22

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

Question 23

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

Answer 23

axons

Question 24

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

Answer 24

10,000

Question 25

which 4 zones of importance do axon terminals consist of?

Answer 25

1)

Question 26

where are axon terminals typically found?

Answer 26

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

Question 27

what does the synapse do?

Answer 27

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

Question 28

en passant synapses

Answer 28

synapses that exist along the axon itself

Question 29

the typical synapse connects an _______ to a _____ or ____

Answer 29

axon | dendrite or soma

Question 30

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

Answer 30

axon to axon | dendrite to dendrite

Question 31

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

Answer 31

quadrillion

Question 32

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

Answer 32

100 and 500

Question 33

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

Answer 33

several billion

Question 34

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

Answer 34

dendrites soma axon axon terminals

Question 35

what can you use to classify neurons?

Answer 35

``` function shape ```

Question 36

sensory neurons

Answer 36

neurons that directly respond to signals from outside environment

Question 37

motor neurons

Answer 37

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

Question 38

afferent neurons: _______

Answer 38

incoming sensory neurons

Question 39

efferent neurons: _______

Answer 39

outgoing motor neurons

Question 40

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

Answer 40

interneurons signal action

Question 41

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

Answer 41

jellyfish

Question 42

multipolar neurons (most common)

Answer 42

neurons with multiple dendrites

Question 43

bipolar neurons

Answer 43

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

Question 44

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

Answer 44

bipolar

Question 45

monopolar neurons

Answer 45

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

Question 46

one end of monopolar neurons ________ while the other end _______

Answer 46

recieves the information | serves for output

Question 47

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

Answer 47

monopolar

Question 48

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

Answer 48

postmitotic

Question 49

greek word for glue

Answer 49

gila

Question 50

gila

Answer 50

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

Question 51

ogliodendrocytes

Answer 51

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)

Question 52

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

Answer 52

50 central nervous system peripheral nervous system schwann cells

Question 53

schwann cells

Answer 53

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

Question 54

nodes of ranvier

Answer 54

the gaps between myelinated segments | short segments like stringed sausages

Question 55

myelination: | no myelination:

Answer 55

axons in cortex | subcortical and peripheral axons

Question 56

astro | cyte

Answer 56

greek for star | greek for cell

Question 57

astrocyte

Answer 57

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

Question 58

microglia

Answer 58

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