Flashcard decks

Synaptic Transmission

81 flashcardsby Logan
Study these flashcardsFree · spaced repetition · iPhone, Android, Mac & web

All cards

1
What is a synapse?
A junction between neurons or effectors
2
What is the synaptic cleft?
The tiny gap between cells
3
What does the presynaptic neurone contain?
A swelling called a synaptic knob
4
What does the synaptic knob contain?
Synaptic vesicles filled with neurotransmitters
5
What happens when an action potential reaches the end of a neurone?
Neurotransmitters are released
6
Where do neurotransmitters diffuse to?
Across the synaptic cleft
7
Where do neurotransmitters bind?
To receptors on the postsynaptic membrane
8
What can neurotransmitter binding trigger?
Muscle contraction or hormone secretion
9
Where are receptors found?
On the postsynaptic membrane
10
In which direction do synapses transmit impulses?
One direction
11
Why are neurotransmitters removed from the cleft?
To stop the response
12
How are neurotransmitters removed?
By reuptake or enzyme breakdown
13
What happens to neurotransmitters after breakdown?
Products are reabsorbed by the presynaptic neurone
14
What are acetylcholine-releasing synapses called?
Cholinergic synapses
15
What is ACh short for?
Acetylcholine
16
What is the structure of cholinergic synapses like?
The same as the diagram
17
What causes ACh release?
A nerve impulse
18
Where does an action potential arrive?
At the presynaptic neurone’s knob
19
What does the action potential open?
Voltage-gated calcium channels
20
What diffuses into the synaptic knob?
Calcium ions
21
How are calcium ions pumped out?
By active transport
22
What does calcium influx cause?
Synaptic vesicles to move
23
What do synaptic vesicles fuse with?
The presynaptic membrane
24
What do vesicles release into the cleft?
Acetylcholine (ACh)
25
What is the release of ACh called?
Exocytosis
26
Where does ACh diffuse?
Across the synaptic cleft
27
Where does ACh bind?
Cholinergic receptors on postsynaptic membrane
28
What does ACh binding cause?
Sodium ion channels to open
29
What happens when sodium ions enter?
Postsynaptic membrane depolarizes
30
What is triggered if the threshold is reached?
An action potential
31
What happens to ACh in the cleft?
Broken down by an enzyme
32
What is ACh broken into?
Choline and acetate
33
What happens to breakdown products?
Reabsorbed by presynaptic neurone
34
What is reabsorbed choline used for?
To make more ACh
35
What do synapses connect to?
Another neurone, muscle, or gland cell
36
What is a postsynaptic membrane?
The membrane receiving neurotransmitters
37
What is the role of neurotransmitters?
To transmit signals across synapses
38
What is a neuromuscular junction?
A synapse between a motor neurone and a muscle cell
39
What is the postsynaptic membrane of a muscle fiber called?
The sarcolemma
40
What receptors do neuromuscular junctions use?
Nicotinic cholinergic receptors
41
How do neuromuscular junctions compare to cholinergic synapses?
They work similarly
42
What do neuromuscular junctions release?
Acetylcholine (ACh)
43
What happens when ACh binds to receptors at a neuromuscular junction?
It triggers muscle contraction
44
Where are neurotransmitter receptors located in neuromuscular junctions?
On the sarcolemma
45
What is summation in synapses?
The process of adding stimuli to trigger an action potential
46
What are the two types of summation?
Spatial summation and temporal summation
47
What is spatial summation?
Multiple presynaptic neurones release neurotransmitters to reach the threshold
48
When does spatial summation occur?
When multiple neurones connect to one neurone
49
What does spatial summation help with?
Combining weak signals to trigger an action potential
50
What is temporal summation?
One presynaptic neurone releases neurotransmitters repeatedly in a short time
51
When does temporal summation occur?
When a neurone fires quickly
52
What does temporal summation do?
Builds up neurotransmitter to trigger an action potential
53
What do excitatory neurotransmitters cause?
Depolarisation of the postsynaptic membrane
54
What can excitatory neurotransmitters trigger?
An action potential
55
What do inhibitory neurotransmitters cause?
Hyperpolarisation of the postsynaptic membrane
56
What does hyperpolarisation prevent?
An action potential
57
Give an example of an excitatory neurotransmitter.
Acetylcholine (ACh)
58
Give an example of an inhibitory neurotransmitter.
GABA
59
What do inhibitory synapses make more negative?
The postsynaptic membrane potential
60
What ions can inhibitory neurotransmitters open channels for?
Potassium (K+) or chloride (Cl⁻)
61
What happens if the threshold isn’t reached?
No action potential occurs
62
How do drugs affect synaptic transmission?
By altering neurotransmitter action
63
How do agonist drugs work?
They mimic neurotransmitters
64
What do agonist drugs do to receptors?
They bind and activate them
65
Give an example of an agonist drug.
Nicotine
66
What neurotransmitter does nicotine mimic?
Acetylcholine (ACh)
67
How do antagonist drugs work?
They block receptors
68
What is the result of receptor blockage?
No activation by neurotransmitters
69
Give an example of an antagonist drug.
Curare
70
What does curare block?
ACh receptors at neuromuscular junctions
71
What happens when ACh is blocked by curare?
Muscles become paralyzed
72
What does nerve gas inhibit?
Acetylcholinesterase (AChE)
73
What happens when AChE is inhibited?
ACh is not broken down
74
What does continuous ACh cause?
Loss of muscle control
75
What does botulinum toxin prevent?
ACh release
76
What effect does botulinum toxin have?
Causes paralysis
77
How can drugs affect receptor number?
By increasing or decreasing them
78
What happens when receptor numbers increase?
Cells are more sensitive
79
What happens when receptor numbers decrease?
Cells are less sensitive
80
What type of synapses do drugs affect?
Cholinergic synapses
81
What can drug interference lead to?
Paralysis or muscle control loss
Study all 81 cards for free