How nerves work

Question 1

What is the somatic nervous system?

Answer 1

Part of PNS

Voluntary control of body movement

Question 2

What is the autonomic nervous system?

Answer 2

Part of nervous system controlling functions not directed consciously

Breathing, heartbeat etc

Question 3

What is the enteric nervous system?

Answer 3

Part of ANS

Governs function of Gastrointestinal tract

Question 4

What is the function of the Meninges?

Answer 4

Protect the central nervous system

Question 5

True or false

Sulcus are the tops of the folds, and the gyrus are the part within the fold

Answer 5

False

Gyrus = Tops

Sulcus = Bottom

Question 6

The Cerebrum is composed of what lobes? (4)

Answer 6

Frontal
Temporal
Parietal
Occipital

Question 7

What part of the brain contains the thalamus and hypothalamus?

Answer 7

Diencephalon

Question 8

What is the function of the thalamus?

Answer 8

Relay motor and sensory nerve signals

Question 9

What does the Hypothalamus do?

Answer 9

Hormone control/release

Body temperature

Question 10

The midbrain, pons and medulla oblongata are in what part of the brain?

Answer 10

Brainstem

Question 11

How many sets of cranial nerves are there?

Answer 11

12

Question 12

How many pairs of spinal nerves are there?

Answer 12

31

Question 13

“Catch the large snake carefully”

What does this refer to?

Answer 13

Cervical - 8 
Thoracic - 12
Lumbar - 5 
Sacral - 5 
Coccygeal - 1

Spinal nerve pairs

Question 14

What type of matter makes up the Ventral and dorsal horn?

Answer 14

Grey matter

Question 15

What horn is associated with Afferent signals?

Answer 15

Dorsal horn

Question 16

Where are the cell bodies of sensory fibres contained?

Answer 16

Ganglions

Question 17

Where are nerve tracts found?

Answer 17

Up spinal chord

In the white matter

Question 18

Describe the simple purpose of the axon hillock.

Answer 18

Decides and triggers action potentials

Question 19

What is the simple purpose of the presynaptic terminal?

Answer 19

Transmitter release

Question 20

What is the name of the support cells of the CNS?

Answer 20

Glia

Question 21

What 3 types of Glia is there?

Answer 21

Astrocytes
Oligodendrocytes
Microglia

Question 22

What is the function of astrocytes?

Answer 22

Maintains external environment for neurones:

• surrounds blood vessels and transports nutrients from the blood to neurones
• produces blood-brain barrier

Question 23

Describe the purpose of Oligodendrocytes.

Answer 23

Form myelin sheaths in CNS

Question 24

What do Microglia do?

Answer 24

Phagocytic hoovers

Question 25

Why do neurones need a resting membrane potential?

Answer 25

Allows depolarisation etc So signals can be transmitted

Question 26

In terms of K+ and Na+, why is there a RMP?

Answer 26

K+ moved into cell, Na+ moved out by pump K+ leaks out More +ve outside

Question 27

What equation predcits the RMP for a single ion species?

Answer 27

Nernst equation

Question 28

Why is the RMP not -90mV but is -70mV? | 3

Answer 28

Other leaky channels Electrogenic Na/K pump Large -ve intracellular molecules

Question 29

What is the purpose of a Graded potential?

Answer 29

Move the RMP to/away from threshold to trigger/inhibit an action potential

Question 30

What are the 4 types of Graded potential?

Answer 30

Generator Post-synaptic Endplate Pacemaker

Question 31

Why are graded potentials decremental?

Answer 31

Axons are poor conductors Current leaks out

Question 32

Why are graded potentials graded?

Answer 32

Strength of stimulus is encoded in change of membrane potential

Question 33

What are the 2 IPSP's?

Answer 33

Ionotropic chloride - fast Metabotropic potassium (opener) - slow

Question 34

What are the 2 EPSP's?

Answer 34

Ionotropic sodium/potassium - fast Metabotropic potassium (closer) - slow

Question 35

What is the significance of GABA and Glycine in graded potentials?

Answer 35

Neurotransmitters

Question 36

Simply describe how post-synaptic potentials are made.

Answer 36

Neurotransmitters open/close ligand-gated ion channels Causing MP to be de/hyperpolarised

Question 37

Voltage-gated ion channels are used to produce what?

Answer 37

Action potential

Question 38

What does summation of graded potentials mean?

Answer 38

They can add to each other

Question 39

What is the difference between spatial and temporal summation?

Answer 39

Temporal = same synapse input repeated quickly Spatial = different synapse inputs integrating

Question 40

What is pre-synaptic inhibition?

Answer 40

Synapse with inhibitory input attached to excitatory synapse Reduces transmitter release - inhibits that one input

Question 41

What is post-synaptic inhibition?

Answer 41

Inhibitory input synapsed actually onto the neurone Inhibits all inputs

Question 42

What must happen for an action potential to fire?

Answer 42

MP must reach threshold -55mV

Question 43

What happens when membrane potential reaches threshold?

Answer 43

VG Sodium channels open Sudden massive depolarisation

Question 44

What causes a cell to re/hyperpolarise when an action potential fires?

Answer 44

Sodium channels close More potassium channels open - K+ goes out

Question 45

What does the frequency of an action potential encode?

Answer 45

Stimulus intensity

Question 46

Describe self propagation of action potentials.

Answer 46

Threshold reached, VGSC open, depolarisation Depolarises next VGSC along which opens - depolarises more Repeated

Question 47

What is the significance of the refractory period, in self propagation of action potentials?

Answer 47

Prevents AP from going backwards

Question 48

What 2 ways can conduction velocity be improved in axons?

Answer 48

Enlarged axons Myelination

Question 49

Why is conduction velocity higher in large axons?

Answer 49

Lower axial resistance Depolarisation spreads further Less VGSC needed

Question 50

Why does myelination increase conduction velocity?

Answer 50

Less leakage of current Depolarisation spreads further Less VGSC needed

Question 51

What cells produce myelin for the PNS?

Answer 51

Schwann cells

Question 52

What cells produce myelin for the CNS?

Answer 52

Oligodendrocytes

Question 53

What are the purpose of Nodes of Ranvier?

Answer 53

Gaps for VGSCs

Question 54

What is saltatory conduction?

Answer 54

Propagation of AP along myelinated axon Depolarisation at each NOR

Question 55

What is the effect of Multiple sclerosis and Guillain-Barre syndrome?

Answer 55

De-myelination

Question 56

What causes the compound action potential to have different spikes on an electrode graph?

Answer 56

Different sizes and myelinations of different axons in nerve trunk

Question 57

What are the 6 different axon types?

Answer 57

``` A(alpha) A(beta) A(gamma) A(delta) B C ```

Question 58

What axon *basic* type is responsible for proprioception, motoneurones, touch, pain etc?

Answer 58

A

Question 59

Whip or nae nae In terms of sensitivity to local anaesthetics; A is most sensitive, C is least sensitive.

Answer 59

Nae nae A is most sensitive to anoxia C is most sensitive to LA

Question 60

Yeet or skeet Action potentials have a refractory period whereas graded potentials have no refractory period.

Answer 60

Yeet

Question 61

What are the 2 types of synapses?

Answer 61

Chemical | Electrical

Question 62

What does the action potential do at the end of motor neurone?

Answer 62

Opens voltage gated Calcium channels in presynaptic terminal

Question 63

What effect does opening Ca2+ channels have in presynaptic terminal?

Answer 63

Change in [Ca2+] causes fusion of vesicles with membrane

Question 64

What happens after the vesicles in presynaptic terminal?

Answer 64

Acetylcholine released via exocytosis into synaptic cleft

Question 65

What does ACh bind to after diffusing across the synaptic cleft?

Answer 65

Binds to Ach (nicotinic) receptors

Question 66

What effect does ACh have when it binds to the ACh receptors? (3)

Answer 66

Opens ligand gates Na+/K+ channels Evokes end-plate potential Depolarises to threshold

Question 67

Describe what happens after the end plate potential is triggered.

Answer 67

Opens VGSC Evokes new AP

Question 68

What enzyme breaks down ACh?

Answer 68

Acetylcholinesterase

Question 69

In the CNS, synapses can be found on 3 different parts of the cell. What names are used for these synapses?

Answer 69

Axo-somatic Axo-dendritic Axo-axonal

Question 70

True or false Polysynaptic pathways are harder to predict because they are much more open to modulation at each synapse

Answer 70

True

Question 71

On a scale of 1 to 10 How fucking boring is nerves

Answer 71

11

Question 72

True or false Feedback inhibition (synaptic) is found only at neuromuscular junction to stop muscles repeatedly twitching.

Answer 72

False Only in CNS Means neurone fires once then stops