Neurotransmission - Nerves Flashcards
1
Q
What is the nervous system divided into?
A
- peripheral nervous system
- Central nervous system
2
Q
What is the PNS?
A
- the interface between CNS and the environment
3
Q
What is the CNS?
A
- Brain and spinal cord
- responsible for integration and processing of information
4
Q
What forms the communication network?
A
- neurons
5
Q
What are neurons?
A
- the fundamental info processing unit
6
Q
What makes up the the support matrix?
A
- neuroglia
7
Q
What are the different types of neuroglia?
A
- astrocytes
- oligodendrocytes
- Schwan cells
- microglia
- ependymal cell
8
Q
What are neuroglia?
A
- cells around neurons
9
Q
What do astrocytes do?
A
- nourish and support the neurons
10
Q
What do oligodendrocytes do?
A
- increase speed of impulses and action potentials in the CNS
11
Q
What do Schwan cells do?
A
- increase the speed of impulses and action potentials in the PNS
12
Q
What do microglia do?
A
- they are phagocytes
- resident immune cells in the nervous system that act like macrophages as you don’t want macrophages in the nervous system
13
Q
What do ependymal cells do?
A
- epithelium lining CNS cavities and provide part of the BBB - regulating what goes in and out
14
Q
What are neurone doctrine?
A
- networks and connections formed by cells
15
Q
What are the different classifications of neurons?
A
- anaxonic neuron
- bipolar neuron
- unipolar neuron
- multipolar neuron
16
Q
What does the cell body (soma) contain?
A
- contains nucleus/other organelles
17
Q
What are dendrites?
A
- cellular extensions containing microtubules and neurofilaments
18
Q
Where do axons arise from?
A
- arise from the soma (or dendrite) in a specialised region called the axon hillock
19
Q
What does the Schwan cell comprise?
A
- comprise the myelin sheath (in the PNS)
20
Q
What comprises the myelin sheath in the CNS?
A
- oligodendrocytes
21
Q
Where is the axon terminal found?
A
- pre-synapse
22
Q
What neuroglia are found in the CNS?
A
- ependymal cells (BBB)
- astrocytes
- microglia
- oligodendrocytes (myelin sheath)
23
Q
What neuroglia are in the PNS?
A
- satellite cells
- Schwann cells
24
Q
What makes grey matter appear grey?
A
- the cell bodies
25
What makes white matter look white?
- myelinated axons due to fat and protein richness
26
What structures make up the nerve membrane?
- phospholipid bilayer
- protein molecules
- receptor proteins
- channel proteins
- transport proteins
27
What do receptor proteins bind in the nerve membrane?
- bind neurotransmitter
28
What do channel proteins do in the nerve membrane?
- from pore for ion movement
29
What do transport proteins do in the nerve membrane?
- bind and transfer ions (K+ and Na+)
30
What is a resting membrane like in terms of selective permeability?
- readily permeable to k+ ions
- slightly permeable to Na+ ions
- impermeable to large number of negatively charged proteins and anions
31
What means that k+ is continuously drawn into cell?
- due to the large number of anions in the cell
- electromotive force
32
Sodium concentration is highest where in terms of a cell?
- highest outside a cell
33
Where is potassium concentration and anions highest in terms of a cell?
- highest inside the cell
34
What leads to electrical potential across the membrane?
- the resulting difference in changed particles
34
What is the resting membrane potential (RMP) normally?
* - 75mV
35
What are the events that take place during an action potential?
1. depolarisation
2. threshold
3. repolarisation
4. sodium-potassium pump re-establish resting membrane ionic levels
36
What happens during depolarisation?
- stimulus cause membrane permeability to Na+ to increase causing reduction in membrane potential
37
What happens at threshold?
- critical voltage reached and voltage-sensitive Na+ and k+ channels undergo conformational change
- permeability to Na+ abruptly increase but k+ increase slowly
38
What happens at repolarisation?
- Na+ gates close at -35mV and k+ gates fully open removing k+ out and transmembrane potential becomes negative
next step: sodium-potassium pump re-establish resting membrane ionic levels
39
After an action potential generation the sodium-potassium pump uses energy to do what?
- move Na+ out of cell
- move k+ into the cell
- consequently restore the resting membrane potential
40
What is AP propagation dependent on?
- myelination
- node of Ranvier
- diameter of fibres
41
Why is myelination important in AP propagation?
- insulates the fibre reducing ion leaks
42
Why is the node of Ranvier important in AP propagation?
- produces saltatory effect
43
Why is the diameter of the fibre important in AP propagation?
- the higher the diameter the greater the velocity (giant squid axons)
44
What is pain awareness mediated by?
- mediated by nerve endings receptors in the peripheral tissues and transmitted to the CNS
45
The transmission of pain awareness can be disrupted by what?
- drugs acting on neurotransmitter receptors or by blocking the sodium channels
46
What do local anaesthetics do?
- they are a drugs that reversibly block generation and propagation of electrical impulses in the excitable tissues
47
What are local anaesthetics used for?
- have local analgesic affects
- are used to prevent or relive pain in specific regions of the body without loss of consciousness
48
What do local anaesthetics block and how is this achieved?
- block the initiation and propagation of APs by preventing the voltage-dependent increase in NA+ conductance
- achieved by physically pugging the pore of voltage gated sodium channels
49
How do local anaesthetics reach their site of action?
- by penetrating the nerve sheath and axonal membrane as un-ionised form
