Topic 20: Synapses and Sensory Receptors Flashcards Preview

Biology 116 > Topic 20: Synapses and Sensory Receptors > Flashcards

Flashcards in Topic 20: Synapses and Sensory Receptors Deck (40):
1

What is a synapse?

a junction between synaptic terminal and another cell

2

What are the 2 types of synapses?

electrical and chemical

3

What are the steps in chemical synapses?

1. AP reaches terminal of presynaptic cell
2. presynaptic cells release neurotransmitters into synaptic cleft
3. response in polysynaptic cell

4

How does signaling across a chemical synapse work?

- presynaptic cell synthesizes neurotransmitters, stores them in synaptic vesicles
-When AP reaches synaptic terminal:
- voltage gated Ca2+ channels open
-> Ca2+ enters
-> some synaptic vesicles fuse with PM
-> neurotransmitters released into synaptic cleft

5

What do neurotransmitters do?

diffuse across synaptic cleft
bind and activate specific postsynaptic receptors

6

What are the 4 examples of neurotransmitters?

acetylcholine
glutamate
dopamine
endorphins

7

What is acetylcholine responsible for?

muscle stimulation, memory learning

8

What is glutamate responsible for?

AA, important in brain

9

What is dopamine responsible for?

level in brain affects mood

10

What is endorphins responsible for?

pain regulation

11

What is postsynaptic potentials?

change in membrane potential of postsynaptic cells

12

What are postsynaptic potentials triggered by?

ligand gated ion channels

13

What are the 2 types of postsynaptic potentials and what do they do?

excitatory postsynaptic potential: depolarizes
inhibitory postsynaptic potential: hyperpolarizes

14

What happens during summation of postsynaptic potentials?

addition of all excitatory and inhibitory cells

15

What happens during temporal summation?

2+ signals arrive at the SAME synapse

16

What happens during spatial summation?

2+ signals arrive at the same time at DIFFERENT synapses on the same postsynaptic neuron

17

What is neural plasticity?

capacity for the nervous system to be remodeled

18

What do neurons do during development?

form more synapses than needed

19

Where does STM take place and what happens during it?

hippocampus
forms temporary links with LTM which is essential for acquiring memories

20

Where does LTM take place and what happens during it?

cerebral cortex
temporary links replaced with permanent connections

21

What is LTP?

lasting increase in strength of synaptic transmission

22

What 2 conditions must be met to establish LTP?

1 high frequency series of APs
2. Those APs arrive at terminal when postsynaptic nerve is already depolarized from another stimulus

23

What are the 2 types of receptors in a postsynaptic neuron?

NMDA receptors
AMPA receptors

24

What are NMDA and AMPA receptors? When do they open?

ligand gated ion channels
open when something specific binds to it

25

What happens before LTP?

NMDA are already embedded in membrane
AP in presynaptic neuron -> glutamate released into synapse
Glutamate (ligand) opens NMDA receptors
BUT it's BLOCKED by Mg2+
-> no membrane depolarization

26

How do we establish LTP?

All happen simultaneously:
- depolarization from one synapse
-> Mg2+ released from NMDA receptor
- glutamate released into a different synapse
-> glutamate (ligand) opens NMDA receptors
-> Na+, Ca2+ flow in (only some)

27

What does the influx of Ca2+ cause?

it causes stored AMPA receptors to be embedded in the membrane

28

What are the 2 types of sensory receptors and what do they do?

chemoreceptors: stimulus = specific molecules
mechanoreceptors: stimulus = physical change

29

What are the 4 basic steps of sensory processing?

1. sensory reception
2. sensory transduction
3. transmission
4. perception

30

What is gustation?

sense of taste

31

What are the sensory receptor cells for taste called?

taste cells

32

What are the 5 tastant types?

sweet
salty
bitter
umami
sour

33

What kind of receptors do taste cells have? Which tastants do they open?

g protein-coupled receptors
sweet, umami, bitter

34

Which tastants open directly with ion channels?

sour
salty

35

What happens if tastant is sweet, bitter, or umami?

GPCR activates G protein
G protein activated adenylyl cyclase
adenylyl cyclase converts ATP to cAMP
cAMP opens Na+/Ca2+ channels

36

What happens if tastant is sour or sweet?

binding opens channels directly

37

Does everyone taste the same?

No, perception is unique to individuals

38

What is olfaction?

sense of smell

39

What is the biggest difference about olfaction and gustation?

sensory cells in the nose are ALSO the afferent neurons

40

What are olfactory receptor cells? Where are they? What do they do?

sensory cells/neurons
they line the upper nasal cavity
odorants bind to cilia in nasal cavity
send APs along axon to olfactory bulb in the brain