Synapse/ synaptic function

Question 1

synapse

Answer 1

site of communication between neurons

Question 2

components of synapse

Answer 2

• presynaptic neuron
• post synaptic neuron
• synaptic cleft

Question 3

presynaptic neuron (structure, function)

Answer 3

Structure

• axon terminal
• contains synaptic vesicles (holt NT)
• contain voltage gated calcium channels

Function
-transmits signal

Question 4

post synaptic neuron (structure, function)

Answer 4

Structure

• usually dendrites or soma
• contain receptors for NT

Function
-receives signal

Question 5

synaptic cleft (structure, function)

Answer 5

Structure
-narrow extracellular space between neurons

Function
-allow diffusion of NT

Question 6

Communication across membrane steps (6)

Answer 6

1. AP arrives at axon terminal
2. voltage gated calcium channels open
3. Ca2+ flows in –> exocytosis of synaptic vesicles
4. NT diffuse across cleft –> bind to receptors
5. postsynaptic cell responds
6. response is stopped when NT is removed from cleft
   - degradation, reuptake, diffusion

Question 7

Effects of NT

Answer 7

-change membrane potential in post-synaptic cell

1. excitatory
2. inhibitory

Question 8

excitatory

Answer 8

• excitatory postsynaptic potential (EPSP_
• depolarizing
  
  • NT bind to receptors triggering Na+ channels to open having Na+ move into cell –> depolarizing
• moves membrane closer to threshold

Question 9

Inhibitory

Answer 9

• inhibitory postsynaptic potential (IPSP)
• hyperpolarizing
  
  • NT binds to receptors triggering:
    
    • K+ channels to open. K+ moves out of the cell –> hyperpolarizing
  • Cl- channels to open. Cl- moves into cell –> hyperpolarizing
• moves membrane potential further from threshold
• membrane stabilizing

Question 10

divergence

Answer 10

one presynaptic neuron –> several post-synaptic neurons

Question 11

convergence

Answer 11

several presynaptic neurons –> one post synaptic neuron

Question 12

graded potentials (what they are and properties)

Answer 12

-small changes in membrane potential due to ion channels opening/ closing in response to stimuli

• properties
  1. graded
  2. decremental
  3. depolarizing or hyperpolarizing
  4. summation

Question 13

graded

Answer 13

-change in membrane potential reflects the strength of the stimulus

• weak stimuli –> small change
• strong stimuli –> large change

Question 14

decremental

Answer 14

-change dissipates with distance from the stimulus

Question 15

summation (what it is and types)

Answer 15

• can combine effects of stimuli
  
  • add, cancel

Types

• temporal
  
  • same stimulus
  • repeated close together in time
• spatial
  
  • different stimuli
  • overlap in time

Question 16

purpose of graded potentials and how

Answer 16

graded potentials determine if an action potential will occur or not.

How? if the membrane potential at the axon hillock is depolarized about threshold –> AP