Neuroanatomy II Flashcards Preview

PY5030 CNS and Mental health > Neuroanatomy II > Flashcards

Flashcards in Neuroanatomy II Deck (26)
1

Dendrites are...

receiving area of a neuron

2

What happens at the axon hillock?

Action potentials received from dendrites are gathered and decided if there is going to be a response

3

Function of glia

Supports neuron

4

Sensory neuron adaptation

Have several dendrites but not too many in order to localise where stimulus is coming from

5

Motor neuron adaptation

Receive signals from many different dendrites telling it what its exact response will be and communicates this to a finite region

6

What do interneurons do?

- Receive and send out information
- Process information

7

Membrane potential

The voltage difference across the plasma membrane

8

Resting potential

Membrane potential of a neuron not sending signals
- Formed due to different ion concentrations intracellular and extracellular
- -70mV

9

Potassium concentration

Intra - 140
Extra - 5

10

Sodium concentration

Intra - 15
Extra -150

11

Chloride

Intra - 10
Extra - 120

12

Large anions e.g. Proteins

Intra - 100

13

How is resting potential maintained

- Na+/K+ pumps (ATPase)
- For every 3 Na + out, 2 K+ into cell
- Creates electrical gradient as well as chemical gradient

14

What happens at resting potential

K+ channels are open
- Net outflow due to chemical gradient (high to low conc. K+)
- Not all K+ flows out due to electric gradient ( positive charge of K+ attracted to negative charge inside the cell

15

Nernst equation

Eion = 62mV (log [inside]/[outside])

16

What does nernst equation tell you

There are more K+ channels than Na+ channels

17

How does an action potential occur?

1.) stimulus causes change in membrane potential
2.) Once threshold value (-55mV) is reached, voltage-gated Na+ channels open causing an influx
3.) Depolarisation occurs as all voltage-gated Na+ channels are open
4.) At +40mV Na+ channels deactivate. Voltage-gated K+ channels open causing an efflux
5.) Hyperpolarisation occurs
6.) There is an undershoot as membrane potential gpes below resting potential as K+ channels stay open for longer

18

What is the refractory period?

A second action potential cannot be initiated

19

Adaptations of an axon

- Greater the diameter, the faster the AP
- Myelinated neurons have a faster AP

20

Myelinated neurons

- Insulated by myelin sheath which is formed by oligodendrocytes in CNS and schwann cells in PNS
- Voltage-gated Na+ channels are located at nodes of Ranvier
- Action potentials jump from one node to the next
SALTATORY CONDUCTION

21

Synapses in the brain

- Chemical synapses

22

EPSP

Excitatory post synaptic potentials cause depolarisation and bring about an AP

23

IPSP

Inhibitory postsynaptic potentials cause hyperpolarisation

24

Temporal summation

Two EPSPs produced in rapid succession at the same synapse

25

Spatial summation

Two EPSPs produced nearly simultaneously by different synapses on the same neuron

26

Summation

AP at synapses and dendrites are summed together