L21- Structure and function of the nervous system

Question 1

NS can be divided into the

Answer 1

central and peripheral NS

Question 2

CNS

Answer 2

brain stem and spinal cord

• has relay neurones- reflex

Question 4

Peripheral NS

Answer 4

cranial and spinal nerves

• Somatic NS
• ANS

Question 5

peripheral nervouss sytem contains

Answer 5

sensory and motor neurones

Question 6

grey matter in the brain

Answer 6

found in the periphery in areas called nuclei

Question 7

grey matter in the spinal cord (butterfly shaped)

Answer 7

central

Question 8

grey matter consists of

Answer 8

Nerve cell bodies

Dendrites

Axon terminals

Non-myelinated axons

Neuroglia (support cells)

Question 9

white matter found where in the brain

Answer 9

central

Question 10

white matter found where in the spinal cord

Answer 10

the periphery

Question 11

white matter consits of

Answer 11

myelinated axons

Question 12

cross section of the human spinal cord (grey)

Answer 12

Grey matter- butterfly

• Anterior and posterior prongs are referred to as ventral horns (VH) and dorsal horns (DH_ respectively
• Connected by grey commissure (GC)

Question 14

white matter in the spinal cord

Question 15

white matter in the soinal cord contains

Answer 15

nerve fibres that form ascending and descending tracts

Question 16

normal structure of a neurone

Answer 16

Normal set of cell organnels

Cytoplasmic projections- dendrites and a single axon

Question 18

parts of neurone found within the CNS

Answer 18

• Cell body (soma)
• Dendrites
• Proximal part of the axons

Question 19

parts of the neurone found within the PNS

Answer 19

Distal axon

Sometime coated with insulation (myelin)

Question 20

Myelin in the CNS produced by

Answer 20

Oligodendrites

Question 21

Myelin in the PNS produced by

Answer 21

Schwann cells

Question 22

three types of neuroens

Answer 22

sensory

interneuron

motor neurone

Question 23

sensory neurones

Answer 23

• Location: periphery towards CNS
• Function: send environmental signals to integrative centre
• Structure:
• Body sits to one side
• Sometimes body in the middle of the axon

Question 24

integrative (interneurons)

Answer 24

• Location: CNS
• Function: collate all info
• Structure:
• Purkinje cells have a massive number of dendrites- allows a number of different inputs- just one or two signals out
• Pyramidal cells- body looks like pyramid- many dendrites- one axon

Question 25

Anaxonic neurone

Answer 25

Location: Retina Function: act as relays

Question 26

majority of neuroens in the CNS are

Answer 26

interneurones- collate all infor

Question 27

Unipolar, bipolar and postsynaptic autonomic neurone cell bodies are located

Answer 27

outside the CNS

Question 28

multipolar neurones

Answer 28

One axon and multiple dendrites Most common Most neurones in the brain and spinal cord

Question 29

biploar neurones

Answer 29

One axon and one dendrite Olfactory cells, retina and inner ear

Question 30

Unipolar neurones

Answer 30

* Single process leading away from the soma (body) * Sensory from skin and organs to spinal cord

Question 31

anaxonic neurone

Answer 31

Many dendrites but no axons Help in visual processes

Question 32

characteristics of neuroens int he CNS

Answer 32

Have lots of RER (protein synthesis) Golgi (vesicles e.g. for NT) Many free ribosome Mitochondria, peroxisome and lysosomes found in axon hillock NISSAL bodies- RER and ribosomes Majority of material go out through the zones

Question 33

axon hillock

Answer 33

neck of the neurone

Question 34

transport of vesicles from the soma to the axon terminals

Answer 34

Empty vesicles transported to the axons via intracellular neurofilaments (intermediate filaments) - antegrade - retrograde

Question 35

antegrade

Answer 35

Assembly of kinesin- transport empty vesicle and mitochondria from the axon hillock to the distal end of the neurone via microtubules

Question 36

retrograde

Answer 36

* Brings empty vesicles back * Does not bring the mitochondria back

Question 37

NT synthesis and vesicle transport

Answer 37

Immature vesicle contains only enzymes in its membrane. * As it travels down the axon it starts to synthesise the NT

Question 38

outlien movement of vesicles in neurones

Answer 38

1. Synthesis of NT and formation of vesicle in the cell body 2. Transport of NT down axon via microtubules using kinesin 3. AP travels down the axon 4. AP causes calcium to enter- evoking release of NT 5. NT attaches to receptor, exciting or inhibiting postsynaptic neurone 6. Separation of NT from receptor 7. Reuptake of NT to be recycled

Question 39

Vesicles have 2 fates:

Answer 39

1) recycled through clathrin-coated endocytosis 2) Lost to neuormolemma:

Question 40

different types of synapses (5)

Answer 40

1. axosomatic 2. axodendritic 3. axoaxonic 4. dendro 5. axo-axonal

Question 41

axosomatic

Answer 41

Directly to the plasma membrane of nerve or cell

Question 42

axodendritic

Answer 42

Axon terminal synapses with a dendritic spine

Question 43

axoaxonic

Answer 43

Synapse at the axonic bouton

Question 44

dendro-dendritic

Answer 44

dendritic dendron touching another dendron

Question 45

Axo-axonal

Answer 45

impinging dendritic/ atonal synapse usually inhibits other inputs

Question 46

the synapse and fusion of vesicles

Answer 46

SNARE complex and synaptotagmin (calcium dependent) • Fuse vesicle (membrane) and create pore for NT to leave (porocytosis)

Question 47

nerves bundle together to form

Answer 47

fibres- look like skeletal muscle

Question 48

all 3 types of nevre fibres (motor, sensory and integrative) can be

Answer 48

present in peripheral nerves - each are separated y connective tissue layers

Question 49

endonuerium

Answer 49

loos connectiev tissue- surrounds single nerve cells

Question 50

perineurium

Answer 50

* Specialised connective tissue- transport proteins * Maintain ionic composition * Surrounds clusters of axons (fascicles)

Question 51

epineurium

Answer 51

* Around all the fascicles * Dense irregular connective tissue * Separates different types of nerves and fills spaces between fascicles

Question 52

paraneurium

Answer 52

Fascia that separates nerves from surround structures

Question 53

what stain is used to visualise neuroens and myelin

Answer 53

toluidine blue- stains fat e.g. myelin

Question 54

myelination

Answer 54

Saltatory condcution faster in myelinated nerves Conduction faster in large diameter axons

Question 55

electrical conduction fastest in

Answer 55

A fibre- thickest

Question 56

electrical conduction is intermediate in

Answer 56

B fibres- medium thickness

Question 57

electrical conduction is slowest in

Answer 57

C fibres- thinnest