Lecture 2

Question 1

White vs grey matter

Answer 1

Spinal cord: white matter outside, grey matter inside
Cerebrum: grey matter outside, white matter inside
Division of CNS on macroscopic level

Question 2

White matter:

Answer 2

myelinated axons, very few cell bodies, pale due to myelin

Question 3

Bundles of axons within CNS:

Answer 3

tracts (=nerves in PNS)

Question 4

Grey matter:

Answer 4

pericaria of neurons (multipolar, interneurons, motorneurons), unmyelinated fibers, astrocytes, microglia cells

Question 5

Clusters of nerve cell bodies in CNS:

Answer 5

nuclei (=ganglion in PNS)

Question 6

CNS consistency:

Answer 6

jelly-like, minimal extracellular matrix

Question 7

CNS support

Answer 7

connective tissue layers and fluid

Question 8

4 protective mechanisms

Answer 8

1. Bone structure
2. Protective membranes (meninges)
3. Cerebrospinal fluid (CSF)
4. Blood-brain barrier

Question 9

Neurons: terminally differentiated, little extracellular matrix

Question 10

1. Bone structures

Answer 10

Enclosed by hard, bony structures
- Cranium (skull) encases brain
- Vertebral column surrounds spinal cord

Question 11

2. Meninges:

Answer 11

• protection and nourishment
• Dura mater (durus: hard)
  > Dense connective tissue, inelastic
• Arachnoid mater (arachnoideus: spiderweb-like)
• Pia mater (pius: gentle)

Question 12

Question 13

Question 14

Question 15

Damage in relation to the meninges

Answer 15

Question 16

3. Cerebrospinal Fluid (CSF)

Answer 16

Surrounds and cushions brain and spinal cord
Exchange of materials between neural cells and interstitial fluid surrounding brain

Question 17

CSF major function

Answer 17

Serves as a shock-absorbing fluid to prevent brain from bumping against hard skull

Question 18

Anchored by the meninges, floating in CSF

Answer 18

• Brain floats
  > Neurons and synaptic vessels in a special environment

Question 19

CSF generates by

Answer 19

Formed primarily by choroid plexuses

Question 20

choroid plexuses

Answer 20

Richly vascularized masses of pia matter tissue that dip into pockets formed by ependymal cells
- filtrates and modifies fluid

Question 21

CSF forms as a result of

Answer 21

selective transport mechanisms across membranes of choroid plexuses

Question 22

Choroid plexus located in

Answer 22

In roof of 3rd ventricle

Question 23

CSF constitutions

Answer 23

• Lower in K+, slightly higher in Na2+, almost no proteins, up to 3 leucocytes/ml
• CSF volume: 125-150 ml, replaced more than 3x/day (500-700 ml)
• If >6 leucocytes/ml = inflammation/meningitis

Question 24

Question 25

CSF generated and reabsorbed

Question 26

CSF circulation

Answer 26

from arachnoid villus into venous sinus Ciliary beating, 10 mm HG Choroid plexus (arteries) --> 4 ventricles and central canal -->entering subarachnoidal space at 4th ventricle --> flows between meninges --> entire surface of brain and spinal chord --> arachnoid villi --> venous sinus --> blood stream --> choroid plexus

Question 27

CSF dysfunction:

Answer 27

hydrocephalus (fluid on the brain) = Intracranial pressure - Damage of brain tissue Pressing on brain stem into foramen magnum>affecting breathing centre

Question 28

4. Blood Brain Barier (BBB)

Answer 28

- Highly selective interface between the blood and the CNS - Endothelium in CNS with tight junctions - Drug delivery sometimes difficult (dopamine as L-dopa) - Some things diffusable through phospholipid bilayer, or must be transorted = very controlled environment

Question 29

Blood-Brain Barrier (BBB) functions

Answer 29

- Protects brain from chemical fluctuations in blood Strictly limits exchange between blood and brain - Minimizes possibility that harmful blood-borne substances might reach central nervous tissue - Prevents certain circulating hormones that could also act as neurotransmitters from reaching brain - Limits use of drugs for treatment of brain and spinal cord disorders - Many drugs cannot penetrate BBB

Question 30

What can get through the BBB?

Answer 30

Lipid soluble substances: O2, CO2, alcohol, steroid hormones, small water molecules drug abuse

Question 31

Tight junctions

Answer 31

Sealing off intercellular diffusion (in BBB) ZO: zonula occludens = tight junction

Question 32

BBB

Question 33

Cancer

Answer 33

Neurons are terminally differentiated  do not form tumours

Question 34

Sources for brain tumours of neural origin:

Answer 34

- glia cells--> glioma - astrocytes--> astrocytoma - ependyma cells --> ependymoma

Question 35

Sources for brain tumours of non-neural origin:

Answer 35

1. meningiomas 2. metastasized cancers

Question 36

Astrocytoma (infiltrative homogeneous lesion)

Question 37

Glioblastoma multiforme (cystic change, necrosis, hemorrhage)

Question 38

Question 39

Answer 39

Meningioma - origin: meningothelial cells from dura - push rather than infiltrate