Neurotransmission and neurotransmitters

Question 1

Name the types of glial cells and what do they do?

Answer 1

• glial cells - provide support for the neurons

    *     astrocytes-hold the neurons in place 
    *     oligodendrocytes - provide myelin
    *     microglia - clean up from dead tissue and important link with the immune system

Question 2

what is an ion?

Answer 2

an atom with different protons (+) and electrons (-). e.g. can be positive or negative

Question 3

What are some of the ion qualities?

Answer 3

electorstatic gradient - attraction/repulsion

osmotic balance of diffusion gradient - ions ten to spread around uniformly

Question 4

Why do the extracellular and intercellular environments have different charges?

Answer 4

difference in the charge is due to different concentration of sodium (Na+), potassium (K+), Chloride (Cl-) and organic aminos (A-)

Question 5

What are gated channels?

Answer 5

sodium-potassium pump, forcing our sodium (Na+)

Question 6

What are non-gated channels?

Answer 6

membrane permeability allowing ions to move more easily

Question 7

What does it mean that AP is all or none?

Answer 7

if stimulation is strong enough it produces an action potential - rapid depolarisation and repolarisation of membrane

Question 8

Describe the process of neurotransmission

Answer 8

the action potential opens calcium channels located at the presynaptic membrane, which binds with the protein embedded in the membrane of the synaptic vesicles. The pores widen and the neurotransmitter is released into the synaptic cleft. the neurotransmitter binds with the post synaptic receptor and then it is quickly deactivated

Question 9

How are neurotransmitters deactivated?

Answer 9

• reactivating pumps that send back the neurotransmitter into the presynaptic membrane
  
  • broken down or de-activation by enzymes
  • by diffusion of the neurotransmitter away from the region of synapse

Question 10

What does the type of neurotransmitter release, by a neuron depends on?

Answer 10

the rate of stimulation or sometimes on the postsynaptic neuron

Question 11

What are the major types of excitatory neurotransmitters

Answer 11

• acetylcholine
  
  • catecolamine (dopamine, norepinephrine, epinephrine, noradrenaline)
  • glutamate
  • histamine
  • serotonine, etc

Question 12

What are the major types of inhibitory neurotransmitters

Answer 12

GABA

Clycine

Question 13

what is an antagonist drug?

Answer 13

reduce the ability of neurotransmitter to bind to the receptor sites

Question 14

what is an agonist drug?

Answer 14

prevents there-uptake of the neurotransmitter

Question 15

What causes the neurotransmitter release?

Answer 15

In neurotransmission when the signal reaches the buttons, it is the action potential that causes a rush of calcium into the synaptic cleft, binding to the receptors inside. That leads to a change in little vesicles (containing neurotransmitters)

Question 16

What are the qualities of active conduction?

Answer 16

Active conduction (action potential) i.e.,

• no Inhibitory or Excitatory
• no graded
• no degradation
• grey and white matter

Question 17

What are the qualities of passive conduction?

Answer 17

Inhibitory or Excitatory

• Graded
• Degradation
• grey matter

Question 18

Describe electrical synapses

Answer 18

ions move from one neuron to the next via direct physical connection.
- passive current flow. - no delay, - bidirectional, synchronisation role of large population of neurons

Question 19

What does LTP stand for?

Answer 19

Long term potentiation o the lasting increase in synaptic strength

Question 20

What does LTD stand for?

Answer 20

Long term depression. Lasting decrease in synaptic strenght

Question 21

What is an ATP

Answer 21

adenosine triphosphate is an extracellular signaling molecule, which acts as a neurotransmitter in CNS and PNS.
It is energy storing

Question 22

What does ATO do?

Answer 22

Used for fuel to operate small transmembrane pumps that release the enzymes that move potassium and sodium. Each ATP has enough energy to move two potassium ions in the cell for every 3 sodium ions out of the cell

Question 23

What is LTP triggered by?

Answer 23

by the NMDA receptors

Question 24

What is LTP maintained by?

Answer 24

The AMPA receptors

Question 25

What is the NMDA receptor?

Answer 25

the NMDA is blocked by magnesium, which is only released when postsynaptic cells are sufficiently depolarised, it then becomes permeable to calcium, sodium and potassium

Question 26

What happens if a stimulus is strong enough to cause an LTP?

Answer 26

If the stimulus is strong enough, the post synaptic neuron is depolarised following sustained activation of AMPA. Once the threshold is reaches the magnesium in NMDA withdraws and lets calcium into the cell. The increase calcium contraiton makes the synapse ore efficient. Both glutamate and depolarisation are needed to occur at the same time, to activate NMDA and without it an LTP cannot occur

Question 27

What happens in AMPA when glutamate is released?

Answer 27

When glutamate binds to AMPA the channels open to let sodium in the post synaptic dendrite to start depolarisation. If it reaches the threshold an action potential is triggered and the impulse is transmitted to the next neuron. Then the NMDA receptor admits calcium into the post-synaptic cell. When it is at rest the calcium channel is blocked by magnesium, so even if glutamate binds the calcium cannot enter the cell. Only if depolarisation is reached the magnesium will withdraw to let calcium into the cell