Chapter 21: Transport Within Cells

Front 1

Spaces of CSF

Back 1

Ventricles, Spinal Canal and Subarachnoid Space (between the arachnoid and pia)

Front 2

CSF Functions

Back 2

Maintains the extracellular environment

Offers a route for the removal of metabolites from the brain

Throhgh changes in pH, it influences rates of pulmonary ventilation and cerebral blood flow

Acts as a mechanical cushion to reduce contact with the skull during movements.

Front 3

Spinal Tap/Lumbar Puncture

Back 3

L3-L4

Front 4

BBB Structure- Tight Juntions, Lipid Solubility and a Transcellular Route

Back 4

The capillaries of the BBB do not allow passage of all non-protein substances via a paracellular route. It is blocked by tight junctions.

Most of the cell membrane is occupied by the phospholipid bilayer component, so transport is also dependant on lipid solubility.

Here the capillary endothelial cells act as a selective barrier to solute transport, allowing passage of gas and uptake of glucose.

Front 5

GLUT 1 Transporters

Back 5

Allow glucose to easily cross the BBB via facilitated diffusion.

Front 6

L-Dopa

Back 6

Passes the BBB easily via facilitated transport.

Front 7

Glycine

Back 7

Crosses the BBB from brain to blood, operating on an Na dependant cotransport. (Secondary active transport.)

Front 8

What are the Circumventricular Organs

Back 8

Parts of the brain that lack tight junctions in their capillaries and thus, lack a BBB.

Front 9

Choroid Plexus Structure

Back 9

Joined by tight junctions that exclude paracellular transport, making a blood-CSF barrier akin to the BBB. All solutes and water must cross the cell membranes of the choroid plexus to enter the CSF

Front 10

Final Destination of CSF

Back 10

Absorbed by the arachnoid villus, (arachnoid granulations) into the lumen of the superior sagittal sinus.

Front 11

Monroe-Kellie Doctrine

Back 11

If there is a tendency for a fluid compartment of the brain to increase, there must be a corresponding decrease in another compartment or ICP will rise.

Front 12

Solute and Water transport between the blood and brain is regulated

Back 12

The ependymal cells lining the ventricles allow ready transfer of solutes and water via the paracellular route.

Nutrients secreted into the CSF by the choroid plexuses can then pass waily across the ependymal luning into the interstitial fliud of the brain.

Front 13

Post-trauma edema cause:

Back 13

Disturbances of blood supply interfere with normal well regulated exchange of solutes and water between the blood and brain.

Front 14

Vasogenic Edema

Back 14

Disruption of the BBB, rendering brain capillaries more permeable than normal.

Front 15

Cytotoxic Edema

Back 15

May be caused by direct tissue damage or by an inadewuate blood supply to neirons and glia, thus failing to deliver enough oxygen and glucose to the cells.

The Na-K pump in these cells is starves of ATP, thus dissipating the ionic gradients and the cell swells.