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Flashcards in 6. Nerve Deck (41)
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1
Q

Name the 4 lobes of the brain

A

Frontal
Parietal
Temporal
Occipital

2
Q

What are the ridges and valleys of the brain called?

A
Ridges= Gyri
Valleys= Sulci
3
Q

What are the 3 parts of the brainstem?

A

Midbrain
Pons
Medulla

4
Q

Why is the brainstem important?

A

Its the target or source of all cranial nerves

5
Q

What is the cerebellum responsible for?

A

Motor coordination
Balance
Posture

6
Q

Where does the spinal cord descend from?

A

Medulla

7
Q

Role of spinal cord

A

Conduit for neural transmission

Co-ordinates some reflex actions

8
Q

What are the 4 broad types of cells in the nervous system?

Named based on their appearance

A

Unipolar: 1 axonal projection
Pseudo-unipolar: single axonal projection that divides into 2
Bipolar: 1 axon, 1 dendrite projection
Multipolar: 1 axon, many dendrites

9
Q

What are the 3 types of multipolar cells?

A

Pyramidal
Golgi
Purkinje

10
Q

Neurones

A

Excitable cells of CNS
Heterogeneous morphology
Non-dividing cells

11
Q

What are the 3 main parts of a neurone?

A

Soma (cell body)
Axon (only 1)
Dendrites (numerous)

12
Q

Describe the soma

A

Contains nucleus and ribosomes

Has neurofilaments for structure and transport

13
Q

Although neurones can differ by morphology, all only have 1

A

Axon

14
Q

Describe the axon

A

Long process (aka nerve fibre)
Originates from soma at axon hillock
Can branch off into ‘collaterals’
Usually myelinated

15
Q

Describe dendrites

A

Highly branched
NOT myelinated
Receive signals from other neurons

16
Q

What are neuroglia?

A

All cell types in CNS that aren’t neurones

17
Q

What is the difference between axons and dendrites?

A

Axons are myelinated and dendrites are not

There is only 1 axon but there are many dendrites

18
Q

Name 5 neuroglia

A
Astrocytes
Ogliodendrocytes
Schwann cells
Microglial cells
Ependymal cells
19
Q

What is the most abundant cell type in the CNS?

A

Astrocytes

20
Q

Functions of astrocytes

A

Structural cells
Cell repair
Immune cells and are considered ‘facultative macrophages’
Neurotransmitter release and re-uptake – help maintain homeostasis

21
Q

Name 2 myelin producing cells

A

Ogliodendrocytes

Schwann cells

22
Q

Describe ogliodendrocytes

A
Provide myelin for other axons
Variable morphology and function
Numerous projections that form internodes of myelin
In CNS 
1 oligodendrocyte myelinates many axons
23
Q

Describe Schwann cells

A

Produce myelin for peripheral nerves

1 Schwann cell myelinates 1 axon segment

24
Q

Describe Microglial cells

A

Specialised cells - similar to macrophages

Perform immune functions in CNS

25
Q

Describe Ependymal cells

A

Epithelial cells - line fluid filled ventricles

Regulate production and movement of cerebrospinal fluid (CSF)

26
Q

What is the usual resting membrane potential?

A

Between -40 and -90mV

27
Q

What are the intracellular and extracellular concentrations of the 4 main ions involved in action potentials?

A

Na+ - inside: 10 outside: 140
K+ - inside: 150 outside: 4
Cl- - inside: 5 outside: 120
Ca2+ - inside: 0.1 outside: 2

28
Q

Why is transport of the main ions regulated by channels and pumps?

A

Cell membranes are impermeable to these ions

29
Q

Describe the uneven ion distribution which creates a potential difference across the cell membrane

A

High extracellular: Na+ & Cl-
Low extracellular: K+
High concentration gradient for Ca2+ (into cell)

30
Q

What is the charge inside neuronal cells compared to outside?

A

Negative charge inside compared to outside

31
Q

At resting membrane potential, what state are the voltage gated sodium and potassium channels in?

A

VGSCs: Closed
VGKCs: Closed

32
Q

Membrane depolarisation

A

Opening of VGSCs
Sodium influx
Further depolarisation

33
Q

What happens to VGKCs in an action potential?

A

VGKCs open at a slower rate

Potassium efflux out of cell

34
Q

Hyperpolarisation

A

Getting more and more negative

35
Q

What does an action potential leave?

A

Sodium and Potassium imbalance

Needs to be restored

36
Q

What restores the ion gradients after an action potential?

A

Na+-K+-ATPase (pump) restores the ion gradients

transporter, not channel

37
Q

Describe the process of depolarisation

A

Na+/K+-ATPase uses ATP hydrolysis to move 3 Na+ out (vestibule phosphorylated), changing shape
Then 2 K+ bind and are moved into cell as pump returns to resting configuration

38
Q

What is saltatory conduction?

A

Action potentials jump between adjacent nodes of ranvier

This increases the speed of transmission

39
Q

How does myelin prevent action potentials spreading?

A

Myelin has high resistance and low capacitance (doesn’t store charge)

40
Q

When is an action potential unable to ‘jump’?

A

Across the gap at the axon terminal (synapse)

41
Q

Describe what occurs when an action potential reaches a synapse

A

AP activates VGCCs at synaptic terminal: Ca2+ influx
Ca2+ influx causes vesicle exocytosis and NT release
NT binds to postsynaptic receptors transmitting the signal
NT is either metabolised within the synaptic cleft or recycled by transporter proteins