Synapses and Neurotransmitters

Question 1

What happens when you touch a hot pan

Answer 1

• Thermoreceptor cells are activated by heat and start action potential
• A.P at sensory neurons (of PNS)
• A.P. transferred to interneuron of spine (of CNS) through neurotransmitters released in synapse
• Signal is processed in CNS and decision is made
• signal is sent back to PNS to motor neurons to somatic nervous system for muscle contraction

Question 2

what are synapses and why are they needed?

Answer 2

• space between the end of an axon terminal and dendrite
• transfer action potentials to different neurons/sensory cells/muscles

Question 3

Pre synaptic cell

Answer 3

neuron axon, sensory cell

Question 4

Post synaptic cell

Answer 4

neuron dendrite, muscle cell, gland

Question 5

Arrival of action potential

Answer 5

• when A.P. reaches axon terminal, calcium voltage gated channels open
• Ca^2+ rush in

Question 6

Synaptic vesicles

Answer 6

• vesicles contain NRTM that will be released in synaptic cleft through ACTIVE TRANSPORT (exocytosis: vesicle fuses with pre-synaptic membrean and releases NRTM into cleft)

Question 7

What do NRTM do in synaptic cleft once released?

Answer 7

• diffusion
• Bind with receptors
• Degraded by enzymes
• Re-uptake

Question 8

NRTM + NRTM receptors

Answer 8

• NRTM receptors are specific to the shape of the NRTM

Question 9

How do NRTM allow Na+ or K+ to flood into cell and start action potential

Answer 9

• NRTM binds to its receptor on membrane of Post synaptic cell which can open ion channels - starts action potential

Question 10

EPSP

Answer 10

• excitatory post synaptic potentials
• neurotranmitters allow Na+ to enter post synaptic cell
• axon becomes more (+)
• closer to threshold

Question 11

IPSP

Answer 11

• inhibitory post synaptic potentials
• NRTM allow K+ to leave post synaptic cell
• axon becomes more (-)
• furter from threshold

Question 12

What are the effects of a NRTM determined by?

Answer 12

• time spent in cleft
• concentration
• type
• IPSP vs EPSP balance
• Neural pathway (NRTM can be inhibitory in some places and excitatory in others… adrenaline excites HR, but inhibits memory)

Question 13

How are NRTM reuptaken
(diagram)

Answer 13

• brought back into pre-synaptic cell by active transport

Question 14

how does reuptake benefit us

Answer 14

Saves energy

Question 15

what happens if reuptake does not happen in synapse

Answer 15

• if NRTM excitatory: A.P. constantly fires and overstims us
• if NRTM inhibitory: A.P. cant fire and no muscle contraction

Question 16

What happens if there is no degradation enzymes

Answer 16

• NRTM keep starting next action potential - overstimulation

Question 17

draw and label a diagram of neurotransmitters in synapse