neuron structure and function

Question 1

neurons function as?

Answer 1

specialized cells that transmits and process information (action potentials) from one part of the body to another

Question 2

action potentials are?

Answer 2

electrochemical impulses that information takes form in

Question 3

the soma of a neuron is the?

Answer 3

central cell body which contains the nucleus where most of the biosynthetic activity takes place

Question 4

axons and dendrites of a neuron are?

Answer 4

slender projections that extend from the cell body
bipolar = one dendrite
multipolar = many dendrites

Question 5

synaptic knobs are?

Answer 5

branches off the axon that form connections with target cells

Question 6

synaptic clefts are areas where?

Answer 6

chemical messengers from action potentials that are released from the synaptic knob and travel across to the target cell

Question 7

resting membrane potential across the plasma membrane is?

Answer 7

-70mV

the interior of the cell is more negatively charged than the exterior

Question 8

what are the primary membrane proteins that are required for establishing resting membrane potential?

Answer 8

Na+/K+ ATPase (pump three sodium ions out of the cell and two potassium ions into the cell with the hydrolysis of one ATP molecule)
K+ leak channels
because they cause for the loss of positively charged ions

Question 9

when the cell is negative on the inside and positive on the outside, it is referred to as?

Answer 9

polarized

Question 10

depolarization is when?

Answer 10

the resting membrane potential become less negative or even positive

Question 11

repolarization is when?

Answer 11

the cell returns to resting membrane potential (-70mV) after depolarization

Question 12

what are the primary membrane proteins that are required for depolarization?

Answer 12

voltage-gated sodium channels that respond to the change and allow for sodium ions to flow down their gradient into the cell and depolarize that section

Question 13

voltage-gated sodium channels are opened by depolarization of the membrane from the resting potential of -70mV to?

Answer 13

-50mV, which is the threshold potential

Question 14

once the threshold potential is reached, the voltage-gated sodium channels?

Answer 14

open completely (but below the threshold they are closed) for sodium ions to flow into cell and depolarizing the membrane to about +35mV

Question 15

what are the factors that contribute to repolarization?

Answer 15

voltage-gated sodium channels are inactivate
voltage-gated potassium channels open slowly in response to depolarization and overshoots resting potential to -90mV and closes channels
Na+/K+ ATPase and K+ leak channels continue to function to bring back resting membrane potential

Question 16

an insulating sheath wrapped around neurons’ axons are called?

Answer 16

myelin

Question 17

myelin is created by what cells?

Answer 17

schwann cells, which are a type of glial cell

Question 18

nodes of ranvier are gaps where?

Answer 18

no membrane polarization and no voltage-gated sodium channels occur in regions of the axonal plasma membrane that are wrapped in myelin

Question 19

saltatory conduction is the?

Answer 19

rapid jumping conduction in myelinated axons

Question 20

glial cells are classified by?

Answer 20

being specialized, non-neuronal cells that typically provide structural and metabolic support to neurons

Question 21

glia maintain a resting membrane potential but do not generate what?

Answer 21

action potentials

Question 22

schwann cells are glial cells located in PNS and the primary function is?

Answer 22

form myelin and increase speed of conduction of APs along axon

Question 23

oligodendrocytes are glial cells located in CNS and primary function is?

Answer 23

form myelin and increase speed of conduction of APs along axon

Question 24

astrocytes are glial cells located in CNS and primary function is?

Answer 24

guide neuronal development

regulate synaptic communication via regulation of neurotransmitter levels

Question 25

microglia are glial cells located in CNS and primary function is?

Answer 25

remove dead cells and debris

Question 26

ependymal cells are glial cells located in CNS and primary function is?

Answer 26

produce and circulate cerebrospinal fluid

Question 27

equilibrium potential is the membrane potential at which?

Answer 27

the gradient force does not exist thus there is no net movement of ions across the membrane

Question 28

the refractory period is when?

Answer 28

the passage of one action potential makes the neuron non responsive to membrane depolarization and unable to transmit another action potential for a short time
(two phases)

Question 29

during the absolute refractory period what happens and why?

Answer 29

a neuron will not fire another action potential no matter how strong a membrane depolarization is induced
voltage-gated sodium channels are inactivated after depolarization and will not be opened until the membrane potential reaches the resting potential and the Na+ have returned to their closed state

Question 30

during the relative refractory period what happens and why?

Answer 30

a neuron can be induced to transmit an action potential, but the depolarization required is greater than normal because the membrane is hyperpolarized