Brainscape's Knowledge GenomeTM


Top Flashcards (Certified)
All Flashcards

Medicine Year 1 Semester 1 - Part 2 > Synapse 1 & 2 > Flashcards

Synapse 1 & 2 Flashcards

1
Q

Features of neuronal cells

A

Dendrites
Cell body (SOMA)
Axon
Myelin sheath
Node of Ranvier

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Function of dendrites

A

Information arrives at the cell body via the dendrites where it is assimilated and processed.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Describe the movement of information through a neuron

A

Information arrives at the cell body via the dendrites where it is assimilated and processed.

Processed information isn then digitised and transmitted along the axon.

At the end of the axon, the information is passed to the target (muscle or neuron) via the nerve terminal.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What is a synapse ?

A

A junction between 2 cells, where electrical changes in one cell cause a signal to be passed to another usually via chemical neurotransmitter.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What is the most common type of synapse ?

A

The majority of synapses are chemical synapses, but some are electrical.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Location of synapses

A

Synapses primarily occur between neurones but also at the neuro-muscular junction (NMJ).

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Function of synapses

A

Chemical synapses transmit neuronal action potentials in one direction between cells.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Describe the synaptic cleft

A

The gap between 2 cells (the synaptic cleft) is approximately 20nm (20 x 10^-9)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Describe modulation of activity at synapses

A

Activity at synapses can be modulated (neuromodulation)

This is a slower timescale than normal transmission, and affects the excitability of the pre- and post-synaptic cell using modulation of endogenous system.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What is modulation of endogenous system ?

A

Receptor density
NT production
Re-uptake ability

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What is a bouton ?

A

The terminal of the presynaptic cell forms a swelling called a bouton or nerve terminal.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What do vesicles in the neuron contain ?

A

Molecules of neurotransmitter

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Size of the synaptic gap

A

20nm

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What have very careful electrophysiological experiments shown ?

A

That the release of neurotransmitters is quantal (meaning the amount of neurotransmitter found in each vesicle is the same).

And those quanta relate to the contents of single vesicles found at presynaptic membrane.

The more vesicles released, the stronger the signal at the post synaptic membrane.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

State the 3 categories that synaptic activity can be divided into

A

Presynaptic activity - signalling
Postsynaptic activity - listening
Neurotransmitter inactivation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Describe small molecule transmitters

A

Synthesis of enzymes in the cell body

Slow axonal transport of enzymes

Synthesis and packaging of neurotransmitter

Release and diffusion of neurotransmitter

Transport of precursors into terminal

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Describe larger peptide transmitters

A

Synthesis of neurotransmitter precursors and enzymes

Transport of enzymes and pre-peptide precursors down microtubule tracks.

Enzymes modify pre-peptides to produce peptide neurotransmitters.

Neurotransmitter diffuses away and is degraded by proteolytic enzymes.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Small molecule transmitters VS Peptide transmitters

A

SMT - Vesicles are recycled
PT - Diffusion ad Degradation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Describe vesicle recycling

A

Budding from a larger molecule

Storage of vesicles
Docking of vesicles
Priming of vesicles

Ca2+ entry
Fusion/Exocitosis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Where are peptide neurotransmitters made ?

A

In the RER and Golgi then transported.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What is packaged in the bouton ?

A

Amine / Amino Acid NT’s are made and packaged in the bouton

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

When is neurotransmitter released ?

A

NT release takes about 0.2ms from calcium entry

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

Describe the release of neurotransmitters

A

SNARE proteins in the vesicle and cell membrane bind.

These then form a helical structure which brings the 2 membranes close.

Entering Ca2+ binds to synaptotagmin.

Ca2+ bound synaptotagmin catalyses membrane fusion.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

Name some SNARE proteins

A

Synaptotagmin
Syntaxin
SNAP-25
Synaptobrevin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
What happens at the post-synaptic membrane ?
26
Describe membrane spanning proteins
Embedded in the postsynaptic membrane are membrane spanning proteins called receptors. They all belong to either the G protein coupled receptor group, or to the ligand gated ion channel group.
27
Metabotropic receptors
G protein coupled receptor group
28
Ionotropic receptors
Ligand gated ion channel group
29
Describe ionotropic receptors
When the ligand binds to its binding site, it induces a conformational change in the receptor such that a pore from the inside to the outside of the cell is formed. The pore is characteristic of the receptor type in both size and charge, which means each receptor can be specific to a single or varied number of ions. The passage of ions into and out of the cell changes the voltage of the cell, either to depolarise (net positive charge) the cell or hyperpolarise (net negative charge) the cell.
30
PSP
Post-synaptic potentials
31
What causes PSP's ?
Post synaptic potentials or PSPs are caused by the passage of ions through ion channels which have been opened following receptor/neurotransmitter interactions
32
What are excitatory PSP's ?
A net flow of positive ions (Na+ or Ca2+) into the cell depolarises the membrane (brings it closer to the threshold) and is thus termed EXCITATORY (EPSP). Single EPSPs rarely result in an action potential.
33
What happens after inhibitory and excitatory PSP's ?
The amplitude of signals decreases with distance from the synapse and time. An influx of negative ions or efflux of positive ions hyper polarise the cell.
34
Name the 3 types of summation
Single EPSP Spatial Summation Temporal Summation
35
Single EPSP
One action potential
36
Spatial Summation
Multiple action potentials from different neurons
37
Temporal Summation
Multiple action potentials from the same neuron
38
Steps leading to an action potential
Neurotransmitter release Receptor binding Ion channels open Conductance change causes current flow Postsynaptic potential changes Postsynaptic cells excited or inhibited Summation determines whether or not an action potential occurs.
39
Differences between EPSP's and action potentials
EPSPs do not actively propagate along the axon. No voltage gated current in EPSPs, they are caused by direct (ionotropic) or indirect (metabotropic) ligand gating. EPSPs have no refractory period thus a series of EPSPs can summate
40
What does generation of an action potential depend on ?
The inherent excitability of the neurone. The frequency or amount of incoming excitatory impulses (from one or many synaptic connections) The frequency or amount of incoming inhibitory impulses (from one or many synaptic connections)
41
Inhibitory post synaptic potential function
Prevents the cell from firing an action potential
42
What causes excitation in our spinal cord ?
Glutamate (via AMPA channels mainly)
43
What causes inhibition in our spinal cord ?
Glycine (via Cl-channels mainly)
44
Function of chemical synapses
Computation Rectification Plasticity
45
Computation
As summation of multiple PSPs is required to achieve threshold, integration acts as a decision making process based on EPSP and IPSP input.
46
Rectification
As chemical synapses transmit impulses in one direction only, this rectification serves to channel information.
47
Plasticity
Controlled changes in the amount of transmitter released, the number of receptors present and the efficiency of the inactivation process provide a mechanism for adaptive plasticity (LTP and LTD) Also involved in learning and memory.
48
Function of small peptide molecules
Modulate the transmission of pain at the level of the spinal cord.
49
LTP
Long Term Plasticity
50
LTP in memory and learning
Stronger synaptic connections means easier/better synaptic transmission. Stronger synaptic connections come from more vesicles, greater excitability, more receptors, more parallel synapses.
51
What is LTP achieved through ?
Increased neurotransmitter release through increased vesicle numbers. Formation of new synapses or synaptic zones and dendritic spines. Increased post-synaptic receptor density and mitochondria.
52
LTD in a model of addiction
Overstimulation of a pleasure pathway (eg uncontrolled opiate use) Body responds by turning down transmission (reduced vesicles) or by turning down reception (reduced receptors) Normal dose insufficient so more taken to overcome reduced transmission Body further attenuates transmission New increased dose insufficient so more taken to compensate
53
Function of the synaptic cleft
At chemical synapses the gap or cleft between the two neurones is sufficiently large (20nm) that a neurotransmitter is required, but small enough for rapid diffusion across the gap.
54
Where are neurotransmitter molecules stored in vesicles ?
Molecules of the neurotransmitter are stored presynaptically in vesicles. These fuse with the membrane to release neurotransmitter by exocytosis. The vesicle membrane is then recycled.
55
What does an increase in dendrites result in ?
The more dendrites a neuron has, the higher the degree of convergence.
56
Neuronal divergence in a circuit
Information from a single neuron is passed to a number of other neurons simultaneously and without a loss of signal strength.
57
Forms of divergent neurons
Spatially focused Widely divergent
58
Examples of neuronal divergence
Knee jerk reflex Golgi tendon organ reflex
59
Describe knee jerk reflex
The reflex stimulates in the spinal cord, the motor neurons to the extensor muscle and inhibits the motor neurons to the flexor muscle.
60
Describe Golgi tendon organ reflex
The reflex inhibits in the spinal cord, the motor neurons to the extensor muscle and stimulates the motor neurons to the flexor muscle.
61
Local neuron feedback
As N1 is excited more, this information is passed to N2 If N2 crosses threshold it fires and so inhibits its target, but also feeds back inhibition to N1 Therefore N1 is moderated by negative feedback from N2.
62
Truncal ataxia
Cerebellar hypoplasia (predominantly of the vermis)

Medicine Year 1 Semester 1 - Part 2 (37 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions