Nervous System Flashcards Preview

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Flashcards in Nervous System Deck (110)
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1

Cell Body

location of nucleus, ER, ribosomes

2

Dendrites

appendages from soma that received incoming signals from other cells

3

Axon Hillock

-integrates incoming signals from dendrites
-plays key role in initiation of APs by summing inhibitory and excitatory signals from dendrites

4

Myelin

-insulate axons to prevent signal loss/crossing of signals
-maintains electric signal in neuron
-increases speed of conduction
-nonpolar
-made of lipids (poor conductor of electricity)

5

Oligodendrocytes

-produce myelin in the CNS
-can myelinate multiple neurons at once

6

Schwann Cells

-produce myelin in the PNS
-can only myelinate one neuron at once

7

Synapse

space between neurons containing the synpatic cleft, nerve terminal, and postsynaptic membrane

8

Nerve

multiple neurons bundled together in the PNS

9

Ganglia

-structures containing cell bodies of neurons and glial cells
-function like relay stations - one nerve enters and the other exits

10

Tracts

-bundles of axons in the CNS
-only carry one type of information

11

Nuclei

group of cell bodies in the same tract

12

Glial Cells

-non-neuronal cells in both the CNS and PNS
-function in myelin formation, supporting neurons, and providing nutrients to neurons

13

Astrocytes

-nourish neurons
-form blood-brain barrier -- controls the transmission of solutes from bloodstream into nervous tissue

14

Ependymal Cells

-line ventricles of the brain
-produce cerebrospinal fluid which physically supports the brain and acts as shock absorber

15

Microglia

phagocytic cells that ingest and break down waste products and pathogens in CNS

16

Resting Potential

-net electric potential difference that exists across cell membrane
- -70 mV
-more negative inside the cell than the outside

17

What is the concentration of K+ inside the cell?

140mM

18

What is the concentration of K+ outside the cell?

4mM

19

What is the equilibrium potential of K+?

-90mV

20

Potassium Leak Channels

allow slow leak of K+ outside the cell

21

Is the cell more permeable to K+ or Na+?

K+

22

What is the concentration of Na+ inside the cell?

12mM

23

What is the concentration of Na+ outside the cell?

145mM

24

Sodium Leak Channels

slow leak of Na+ into the cell

25

What is the equilibrium potential of Na+?

60mV

26

Na+/K+ ATPase

pumps 3 Na+ out of cell and 2 K+ into cell

27

Threshold Potential

-ranges from -55mV to -40mV
-reached when the axon hillock receives enough excitatory input and an AP is triggered

28

Temporal Summation

-multiple signals integrated during short period of time
-number of small excitatory signals firing at nearly the same moment

29

Spatial Summation

-additive effects are based on the number and location of the incoming signals
-large number of inhibitory signals firing directly on soma cause more hyperpolarization of axon hillock than depolarization caused by few excitatory signals on dendrites

30

Steps of Action Potential (6)

(1) cell brought to threshold (-50mV)
(2) opening of voltage-gated Na+ channels (triggered by depolarization)
(3) Na+ channels inactivated at +35mV (inactive until resting potential is reached)
(4) K+ voltage-gated channels open to repolarize the cell
(5) efflux of K+ causes overshoot of resting potential (hyperpolarization)
(6) Na+/K+ ATPase restores resting potential