Week 3- Blood brain Barrier Flashcards
what is the blood brain barrier?
network of vessels that form
a structural and chemical barrier
between the brain and systemic
circulation
what is required for the brain to work in a stable environment? function
-requires precise communication between nerve cells in the the brain
-Protects the brain against xenobiotics(foreign chemicals/material) but
also a barrier to neuroactive pharmaceuticals
what are the two main cells of the BBB?
- astrocytes, which attach to outside capillary endothelium cells
- brain capillaries
what is the big mian different between a brain capillary and other capillaries?
-they dont have foot processes which is a type of glial cell found in the brain
what is the astroctyte foot processes important for. and its function?
-Essential for formation and maintenance of the BBB
-Secreted factors maintain brain pH, uptake and metabolism of
neurotransmitters, antioxidant production
what are all the differences between brain and general capillaries?
- Systemic/general capillary Fenestrated or continuous small solutes can diffuse through intercellular clefts pinocytosis independent of molecular size (pass large molecules)
what are all the differences between brain and general capillaries?
-Brain capillary Continuous tight junctions reduced pinocytosis Efflux transporters no fenestrations Astrocyte foot processes for support and allowing secretion
what are some regions of the brain that are not enclosed by BBB?
known as the circumventricular organ (CVO) • Pineal gland • Subfornical organ • Organum vasculosum of the lamina terminalis (OVLT) • Area Postrema • Median eminence • Neurohypophysis (Posterior pituitary)
What is the transport mechanism for capillaries in the brain?
- liquid soluble substances can pass
- theres tight junctions as theres no pores
- theres carrier-mediated transport
what type of cells is the CVO surrounded by? function?
CVO’s surrounded by tanycytic membrane (specialisedependymal cells) possessing tight junctions (TJ) and limiting diffusion of proteins from CVO to deeper brain tissues
what are the 4 different types of ventricles in the brain?
theres 4 (two lateral, third and fourth)
• Membrane bound cavities lined with
ependymal cells.
• Filled with CSF (10 mm Hg pressure)
• CSF (cerebralspinal fluid) production: walls of lateral ventricle and
third ventricle, by choroid plexus
what is cerebrospinal fluid?
is a clear fluid present in the ventricles of the brain, the central canal of the spinal
cord, and the subarachnoid space. Normal: almost no blood cells, little protein
what is the function of Cerebrospinal fluid?
• Gives protection (mechanical and chemical). By circulating it exchanges nutrients and wastes. • Maintenance of a constant external environment for neurons and glia • Mechanical cushion to protect the brain, provides buoyancy • Serves as a conduit for neuropeptides • pH of CSF regulates pulmonary ventilation and CBF
where is the CSF secreted from?
-the chorid plexus
-made from epithelial cells stitched together by tight junctions
• Secretes CSF (lateral and 3rd), secretes proteins (e.g. prealbumin), removes waste products,
serves as a barrier blood-CSF, active transport
• Display tight junctions limiting passive protein transport from blood to intraventricular
space containing CSF
how does the CSF flow? then reabsorbed
• CSF flows from the lateral ventricle to the third ventricle• The third ventricle and fourth ventricle are connected to each other by the cerebral aqueduct. • CSF then flows through the central spinal cord canal into the subarachnoid space • Resorbed by arachnoid villi and granulations, either by classical lymphatics in sinonasal tissues or recently described meningeal–dural sinus lymphatics back into the systemic circulation or to regional and cervical lymph nodes
what way is a drug injected straight into the cerebrospibal fluid?
Intrathecal drug administration involves the direct injection
of the drug into the CSF within the intrathecal space of the spinal column
-done at the bottom of the back
