neurons: cellular and network properties-chp 8

Question 1

pseudo unipolar neurons

Answer 1

they have a single process called the axon. During development the dendrites fuse with the axon

Question 2

bipolar neuron

Answer 2

bipolar neurons have two relatively equal fibers extending off the central cell body.

Question 3

Anaxonic

Answer 3

CNS interneurons that have no apparent axon

look like a star :)

Question 4

multipolar

Answer 4

these CNS interneurons are highly branched but lack long extensions

Question 5

slow axonal transport

Answer 5

moves material by axoplasmic (cytoplasmic) flow at 0.2-2.5 mm/day

Question 6

fast axonal transport

Answer 6

moves organelles at rates up to 400 mm/day

forwards and backward transport

Question 7

forward (or anterograde) transport:

Answer 7

from cell body to axonal terminal

Question 8

backward (or retrograde) transport:

Answer 8

from axon terminal to cell body

Question 9

where are peptides in neurons synthesized and packaged?

Answer 9

they are synthesized on rough ER and are packages by the golgi apparatus

Question 10

explain the steps of fast axonal transport

Answer 10

1-peptides are synthesized on rough ER and packages by the golgi apparatus
2-fast axonal transport walks vesicles and mitochondria along microtubule network
3-vesicle contents are released by exocytosis
4-synaptic vesicle recycling
5-retrograde fast axonal transport
6- old membrane components digested in lysosome.

Question 11

where do neurons receive input?

Answer 11

the spines/dendrites

Question 12

____% or cells in the brain are neurons and _____% of them are Glial Cells

Answer 12

10% neuron

90% glial cells

Question 13

Which Glial Cells are found in the PNS?

Answer 13

schwann cells

satellite cells

Question 14

schwann cells

Answer 14

form myelin sheaths and secrete neurotropic factors

Question 15

satellite cells

Answer 15

support cell bodies

Question 16

which glial cells are found in the CNS?

Answer 16

ependymal cells
astrocytes
microglia
oligodendrocytes

Question 17

oligodendrocytes

Answer 17

form myelin sheaths in the CNS

Question 18

Microglia

Answer 18

modified immune cells-monocytes

act as scavengers

Question 19

astrocytes

Answer 19

are a source of neural stem cells 
take up water , K+, neurotransmitters 
secrete neurotrophic factors 
help form blood brain barrier
provide substrates for ATP production

Question 20

membrane potential is influenced by:

Answer 20

concentration gradient of ions

membrane permeability to those ions

Question 21

which channels control ion permeability?

Answer 21

gated channels

mechanically, chemically and voltage

Question 22

action potentials change resting membrane potential to send signal so they use….

Answer 22

voltage-gated channels

Question 23

depolarization is a response to membrane potential being more____

Answer 23

positive

Question 24

How does a cell depolarize?

Answer 24

by opening Na+ gated channels

Question 25

how does a cell repolarize?

Answer 25

by opening + gated channels but this also causes the cell to hyperpolarize

Question 26

What causes graded potentials to lose strength as they move through the cell?

Answer 26

current leak and cytoplasmic resistance

Question 27

the goals of graded potentials is to….

Answer 27

stimulate/open Na+ voltage gated channels to send the signal.

Question 28

when do voltage gated Na channels open?

Answer 28

at -55 mV

Question 29

when do voltage gated K+ channels open?

Answer 29

+30mV

Question 30

why do K+ gated Na channels open?

Answer 30

to repolarize the cell

Question 31

why does it go to -80 when it is hyperpolarized?

Answer 31

because the reversal potential for K+ is -90 so it can technically go to -90 but it stops at -80

Question 32

Why cant you get another AP during the absolute refractory period?

Answer 32

because the inactivation gate is closed and incapable of opening until you repolarize to -55 and open the inactivation gate and close the Na+ voltage gated channel. plus you are hyperpolarized so you would need a lot of Na

Question 33

if you wanted to block pain, how would you do it?

Answer 33

by blocking voltage gated Na channels because they are the initiator

Question 34

what happens if too much K+ builds up outside our cells?

Answer 34

Constant firing because the blood K+ would be closer to threshold so a stimulus that would have probably been subthreshold would trigger an action potential .

Question 35

true or false: the more action potentials (higher frequency) the more pain.

Answer 35

true

Question 36

What influences speed of an action potential?

Answer 36

diameter (the bigger the faster)

resistance of axon membrane to ion leakage out of the cell (myelinated axons are faster)

Question 37

____ cells in the peripheral nervous system guide the regeneration of cut axons.

Answer 37

Schwann

Question 38

Schwann cells for a _________ that the axon grows back through

Answer 38

regeneration tube

Question 39

which cells inhibit regeneration of cut axons in the central nervous system?

Answer 39

oligodendrocytes

Question 40

which mediate faster responses? ionotropic or metabotropic recepors

Answer 40

ionotropic

Question 41

Divergent Pathway

Answer 41

one presynaptic neuron branches to affect a larger number of postsynaptic neurons

Question 42

convergent pathway

Answer 42

many presynaptic neurons provide input to influence a smaller number of postsynaptic neurons.

Question 43

what is an example of a divergent pathway?

Answer 43

reflex

Question 44

what is an example of convergent pathways?

Answer 44

reticular activating

Question 45

what ion(s) can make a synapse excitatory?

Answer 45

Ca2+

Question 46

an excitatory synapse mainly signals the ____of ____ ions into the postsynaptic neuron

Answer 46

influx of Na+ ions

Question 47

in inhibitory synapse signals the _____ of____ ions from the postsynaptic neuron or ______

Answer 47

outflow of K+ ions or the influx of chloride ions.