synapses and integration

Question 1

properties of chemical synapses

Answer 1

• uses neurotransmitters
• slower and less reliable
• specific postsynaptic receptors allows for neurons to have different effects
• allows for habituation

Question 2

action of chemical synapse

Answer 2

1. action potential reaches synaptic terminal, depolarisation opens Ca2+ channels
2. Ca2+ enters cell, triggering exocytosis of vesicles containing neurotransmitters into synaptic cleft
3. neurotransmitters diffuse across synaptic cleft, binding to receptors on the postsynaptic neuron
4. binding initiates a response

Question 3

receptor potential

Answer 3

graded potential propagated at receptor

Question 4

EPSPs

Answer 4

• excitatory post synaptic potentials
• cell is depolarised
• neurotransmitter binding typically causes Na+ or Ca2+ channels to open

Question 5

IPSPs

Answer 5

• inhibitory post synaptic potentials
• cell is hyperpolarised
• neurotransmitter binding typically triggers K+ or Cl- channels to open

Question 6

choligernic receptors

Answer 6

• receptors for acetylcholine (ACh) neurotransmitter
• heart has nicotinic receptors that trigger an inhibitory response, G-protein coupled pathway opens K+ ion channels
• muscles have muscarinic receptors that trigger an excitatory response

Question 7

Inactivation of neurotransmitters in synaptic cleft

Answer 7

• some taken into blood by glial cells
• some broken down by enzymes so they can be reabsorbed

Question 8

temporal summation

Answer 8

Frequent action potentials in the presynaptic cell cause graded potentials in the postsynaptic cell to overlap

Question 9

spatial summation

Answer 9

a single postsynaptic neuron has synapses with many presynaptic neurons along its dendrite, EPSPs can sum together as they propagate

Question 10

habituation

Answer 10

• decrease in behavioural response to a repeated stimulation
• presynaptic neuron less likely to release neurotransmitters when excited
• facilitates learning and flexibility

Question 11

electrical synapse

Answer 11

• direct contact between presynaptic and postsynaptic neuron via gap junctions (continuous cytoplasm)
• rapid and reliable
• does not allow for habituation
• does not allow for change in signal