Cells and Tissue of the nervous system

Question 1

what comprises the central nervous system

Answer 1

brain and spinal cord

Question 2

what comprises the peripheral nervous system

Answer 2

cranial and spinal nerves

Question 3

what two divisions can the peripheral nervous system be further split into

Answer 3

sensory (afferent) and motor (efferent) divisions

Question 4

what are the two types of nervous cells

Answer 4

neurons and glial cells

Question 5

what are neurons

Answer 5

excitable cells - made up of a structural and functional unit - carry impulses as action potentials

Question 6

what are glial cells

Answer 6

non-excitable supporting cells - much smaller than neurons

Question 7

what is the structure of a typical neuron

Answer 7

multiple dendrites, one axon

Question 8

what describes the travel of impulse transmission by action potential in a neuron

Answer 8

impulse travles in only one direction from cell body to synaptic terminal

Question 9

what is the neuron nucleus made from

Answer 9

loose chromatin, prominent nucleolus

Question 10

what cell organelles are contained within the cell body of a neuron

Answer 10

mitochondria, rEr, diffuse golgi apparatus

Question 11

what are the different cytoplasms in the cell body and axon respectively

Answer 11

cell body - perikaryon

axon - axoplasm

Question 12

what are the long term consequences of injury to the neuron

Answer 12

if the axon is damaged - can grow back

if cell body is damaged - damage is irreversible

Question 13

what is the role of the myelin sheath

Answer 13

to increase conduction speed in axons

Question 14

what 2 classes are axons divided into

Answer 14

myelinated or non-myelinated - depends on presence of the myelin sheath

Question 15

what forms the myelin sheath in the CNS

Answer 15

oligodendrocytes

Question 16

what forms the myelin sheath in the PNS

Answer 16

schwann cells

Question 17

what are the gaps between myelin sheath called

Answer 17

nodes of ranvier

Question 18

what is the result of patch loss/scarring of the myelin sheath

Answer 18

DEMYELINATION - nerve conduction across affected axons is abnormal

Question 19

what are the causes of demyelination

Answer 19

causes unknown - ?viral, ?autoimmune

Question 20

what are the three types of neurons

Answer 20

multipolar, bipolar, pseudopolar

Question 21

what determines how axons are bundled together

Answer 21

determined by what information they carry

Question 22

(in the CNS) what forms grey matter

Answer 22

DIFFUSE collection of cell bodies and NON-MYELINATED axons

Question 23

(in the CNS) what forms nucleii

Answer 23

LOCALISED collection of cell bodies and NON-MYELINATED axons

Question 24

(in the CNS) what forms white matter

Answer 24

DIFFUSE collection of MYELINATED axons

Question 25

(in the CNS) what are tracts

Answer 25

bundles of MYELINATED axons carrying specific information within the white matter

Question 26

(in the PNS) what forms nerves

Answer 26

MYELINATED axons

Question 27

(in the PNS) what forms ganglia

Answer 27

cell bodies

Question 28

what are the 2 types of glial cells found in the PNS

Answer 28

1. satellite cells | 2. schwann cells

Question 29

what do satellite cells do

Answer 29

surround neuronal cells bodies

Question 30

what do schwann cells do

Answer 30

PNS myelination

Question 31

what are the 4 types of glial cells found in the CNS

Answer 31

1. ependymal cells 2. astrocytes 3. oligoendrocytes 4. microglia

Question 32

what do ependymal cells do

Answer 32

line ventricles

Question 33

what do astrocytes do

Answer 33

have endfeet, surround synapses and capillaries, help in K+ buffering

Question 34

what do oligodendrocytes do

Answer 34

CNS myelination

Question 35

what do microglial cells do

Answer 35

phagocytosis and scar tissue formation

Question 36

what are the 4 basic topographic areas of the brain

Answer 36

1. cerebrum - seat of consciousness 2. cerebellum - balance and coordination 3. diencephalon 4. brainstem - vital centres eg cardioresp, pathway for fibre tracts

Question 37

embryologically what forms the nervous system

Answer 37

the neural tube

Question 38

what happens to the neural tube once it is formed

Answer 38

week 4 - divides into 3 primary vesicles week 5 - divides into 5 secondary vesicles = these develop into the adult brain

Question 39

what are the three primary vesicles formed

Answer 39

1. prosencephalon (FOREBRAIN) 2. mesencephalon (MIDBRAIN) 3. rhombencephalon (HINDBRAIN)

Question 40

what 2 secondary vesicles does the forebrain form

Answer 40

telencephalon and diencephalon

Question 41

what secondary vesicle does the midbrain form

Answer 41

doesnt change - still the mesencephalon

Question 42

what 2 secondary vesicles does the hindbrain form

Answer 42

metencephalon and myelencephalon | ultimately lead to the pons and medulla at the front - cerebellum at the back

Question 43

what does the cavity within the neural tube form in the adult brain

Answer 43

spaces called ventricles

Question 44

name the different ventricles

Answer 44

2 lateral ventricles (cavity in telencephalon), III ventricle (cavity in diencephalon), IV ventricle (cavity in hindbrain)

Question 45

what is contained within the ventricles

Answer 45

CSF

Question 46

what connects the III ventricle to the IV ventricle

Answer 46

cerebral aqueduct (cavity in the midbrain)

Question 47

what connects the lateral ventricles and the III ventricle

Answer 47

interventricular foramen

Question 48

what are the meninges

Answer 48

the coverings of the CNS

Question 49

what are the three layers of the meninges

Answer 49

dura mater, arachnoid mater, pia mater

Question 50

what is the structure of the dura mater

Answer 50

tough, fibrous and has dural folds

Question 51

what is the structure of the pia mater

Answer 51

vascularised and dips into the folds of the brain

Question 52

what is the subdural space

Answer 52

potential space which is traversed by blood vessels penetrating the CNS

Question 53

what is the subarachnoid space

Answer 53

space filled with CSF

Question 54

what is CSF

Answer 54

cerebrospinal fluid - fluid inside the cavity the brain and central canal of spinal cord - between the pia and arachnoid

Question 55

what does the CSF help maintain

Answer 55

intracranial pressure

Question 56

where is the CSF formed

Answer 56

the choroid plexus in each ventricle

Question 57

where is CSF absorbed

Answer 57

by arachnoid villi into saggital sinus (venous channel in the brain)

Question 58

what are the 5 layers of the scalp

Answer 58

1. skin 2. subcutaneous tissue 3. epicranial aponeurosis 4. loose areolar tissue 5. pericranium

Question 59

what is the blood brain barrier

Answer 59

a protective mechanism that helps maintain a stable environment for the brain - prevents harmful amino acids and ions present in the blood stream from entering - maintains HOMEOSTASIS in brain parenchyma

Question 60

where is the blood brain barrier not present

Answer 60

absent in a few "circumventricular" organs - parts of the hypothalamus and posterior pituitary plays a major role in drug delivery to CNS (drugs have to be lipid soluble or use suitable vectors)

Question 61

SUMMARY: what two parts is the nervous system divided into

Answer 61

CNS | PNS

Question 62

SUMMARY: what are the cell types in the nervous system

Answer 62

neruons | glial cells

Question 63

SUMMARY: what are the components of neurones

Answer 63

``` grey matter white matter nucleii fibre tracts ganglia peripheral nerves ```

Question 64

SUMMARY: briefly what is the embryologically order or development

Answer 64

surface ectoderm neural tube vesicles

Question 65

SUMMARY: what are the ventricles

Answer 65

spaces in the brain containing CSF

Question 66

SUMMARY: where is the CSP secreted and where does it go

Answer 66

secreted by choroid plexus enters subarachnoid space absorbed by arachnoid villa

Question 67

SUMMARY: what is the role of the blood brain barrier

Answer 67

maintains homestasis in the brain parenchyma