Physio 9/13 Synaptic Transmission

Front 1

Synaptic vesicles

Back 1

Located at chemical synapse

Front 2

Active Zones

Back 2

On the presynaptic membrane where vesicles are clustered.

Front 3

How is signal transmitted at chemical synapse?

Back 3

Via NTs

Front 4

In electrical synapse, how are pre and post synaptic membrane joined?

Back 4

Via gap junctions

Front 5

What are the required steps for releasing NTs at chemical synapse?

Back 5

1. AP arrives at membrane and depolarizes it.
2. Depolarization causes voltage gated Ca channels to open.
3. Ca enters cell and cause fusion of synaptic vesicles with the presynaptic membrane.
4. NTs released and some bind to receptors in postsynaptic membrane.
5. Receptors activated, open pores, causing depolarization or hyperpolerization of postsynaptic membrance.
6. NTs get degraded.

Front 6

Synaptotagmin

Back 6

It's a protein in synaptic vesicles that binds to Ca.

Helps to associate SNARE protein.

Front 7

Postsynaptic receptors are made of what?

Back 7

Ion channels.

Front 8

EPSP

Back 8

Excitatory PostSynaptic Potential.

Receptors that make the membrane potential to be slightly positive.

Front 9

EPSP is due predominantly to what influx?

Back 9

Na

Front 10

Name two examples of excitatory NTs?

Back 10

ACh and Glutamate

Front 11

IPSP

Back 11

Receptors for inhibitory NTs that make the membrane potential more negative.

Front 12

IPSP is due to what iion influx?

Back 12

Cl

Front 13

Name two examples of inhibitory NTs.

Back 13

GABA and Glycine

Front 14

NOTE: a single EPSP is about .5mV.

What is the threshold for action potential using EPSP?

Back 14

-55mV.
Therefore, you need a lot of EPSP to generate an AP.

Front 15

How is an AP generated under the EPSP influence?

Back 15

Through summation.

Front 16

Temporal summation

Back 16

When one EPSP is added upon another from A SINGLE NEURON, and you get a bigger EPSP.

Front 17

Spatial summation

Back 17

A way of achieving an AP in a neuron from multiple cells.

Front 18

Why is a synapse near the initial segment has greater effects on AP than a synapse in the outer most branch of a dendrite?

Back 18

The initial segment has a higher density of voltage gated Na channels and this makes the threshold at the initial segment lower than the threshold in cell body and dendrites.

Therefore, the location of individual synapses in the postsyn. cell affects the degree of a postsyn potential.

Front 19

Motor end plate

Back 19

The synapse that is located at the neuromuscular junction. Consisted of the axon terminal of motor neurons projected to muscles.

Front 20

What makes up Ach?

Back 20

Choline and acetate.

Front 21

Name two types of Ach receptors.

Back 21

Nicotinic and Muscarinic

Front 22

Nicotinic receptor

Back 22

An ion channel that moves na in and K out.

This type of receptor is called ionotropic receptor.

Front 23

Muscarinic receptor

Back 23

A G protein coupled receptor.

This type is called metabotropic receptor.

Front 24

Glutamate

Back 24

The most common NT in the CNS.

Have ionotropic receptors and metabotropic receptors.

Front 25

GABA and Glycine

Back 25

Inhibitory NTs.

Both move Cl ion into neurons.

Front 26

What are two types of GABA?

Back 26

GABA-a (ionotropic) and GABA-b (metabotropic)

Front 27

Biogenic amines

Back 27

Synthesized from amino acids and contain an amino group.

Front 28

What's a common example of biogenic amines?

Back 28

Catecholamines

Front 29

Catecholamines are derived from where?

Back 29

Tyrosine

Front 30

How is epinephrine formed from tyrosine?

Back 30

Tyrosine--> L-Dopa--> NE---> Epi

Front 31

What compound destroys the catecholamine?

Back 31

Monoamine oxidase.

Front 32

What organ secretes epi?

Back 32

Adrenal medulla

Front 33

What are adrenergic neurons?

Back 33

Neurons that release epi or NE.

Front 34

Serotonin

Back 34

Another biogenic amine. Synthesized from tryptophan.

Level is lowest during sleep and highest during state of alert.

Front 35

What are the five classes of receptors?

Back 35

Mechano
Thermo
Chemo
Photo
Noci

Front 36

Sensory receptor

Back 36

Are Either Specialized endings of afferent neurons or separate cells that can signal afferent neurons by releasing chemical messengers.

Can receive stimuli from external or internal environment.

Front 37

How does a sensory receptor work?

Back 37

At the receptor ending, an stimulus is transformed into an electrical signal which leads to opening or closing of particular ion channels.

This can lead to a production of membrane potential.

Front 38

Receptor potential

Back 38

A graded potential. A transmembrane potential difference in a sensory receptor.

Front 39

Sensory Coding

Back 39

Converting a stimulus energy into a signal that convey sensory info to CNS. Has to be precisely coded and delivered to CNS before our body can precisely respond to the stimulus.

Front 40

Modality

Back 40

A stimulus type.

Front 41

Stimulus intensity

Back 41

Coded as frequency of AP.

Ex. Increased stimulus strength means a larger receptor potential and a more frequent action potential firing.

Front 42

Stimulus location

Back 42

Spatial distribution of activated receptors.

Neuron with small receptive field can locate a stimulus more precisely.

Front 43

Lateral inhibition

Back 43

Information at edge of stimulus is strongly inhibited than info at center of stimulus.

Enhances the contrast btw periphery and center of a stimulated region, thereby increasing the brain's ability to localize a sensory input.