Podcast
Questions and Answers
Fenestrated capillaries allow small molecules to pass freely between blood and interstitial fluid.
Fenestrated capillaries allow small molecules to pass freely between blood and interstitial fluid.
True (A)
The only molecules that can pass freely through the blood-brain barrier are polar molecules.
The only molecules that can pass freely through the blood-brain barrier are polar molecules.
False (B)
Paul Ehrlich and Edwin Goldmann first discovered the blood-brain barrier by using trypan blue ink.
Paul Ehrlich and Edwin Goldmann first discovered the blood-brain barrier by using trypan blue ink.
True (A)
The blood-CSF barrier allows all types of molecules to pass freely into the cerebrospinal fluid.
The blood-CSF barrier allows all types of molecules to pass freely into the cerebrospinal fluid.
Endothelial cells in some capillaries are sealed to tightly control exchanges between blood and brain interstitial fluid.
Endothelial cells in some capillaries are sealed to tightly control exchanges between blood and brain interstitial fluid.
Big molecules can pass freely through the blood-brain barrier without any form of transport.
Big molecules can pass freely through the blood-brain barrier without any form of transport.
The concept of the blood-brain barrier implies that the CNS is completely excluded from blood circulation.
The concept of the blood-brain barrier implies that the CNS is completely excluded from blood circulation.
Capillary structure remains constant throughout the body with no variations.
Capillary structure remains constant throughout the body with no variations.
CSF is primarily produced in the lateral ventricle.
CSF is primarily produced in the lateral ventricle.
The arachnoid membrane contains loose connections between its cells, allowing free communication with CSF.
The arachnoid membrane contains loose connections between its cells, allowing free communication with CSF.
CSF-filled spaces serve only as a mechanical cushion for the central nervous system.
CSF-filled spaces serve only as a mechanical cushion for the central nervous system.
Homeostasis of the interstitial fluid is not dependent on the blood-brain barrier (BBB).
Homeostasis of the interstitial fluid is not dependent on the blood-brain barrier (BBB).
The blood-cerebrospinal fluid barrier (BCSFB) allows for free diffusion from blood to CSF.
The blood-cerebrospinal fluid barrier (BCSFB) allows for free diffusion from blood to CSF.
Exchanges between CSF and brain interstitial fluid occur freely at the level of the pia mater.
Exchanges between CSF and brain interstitial fluid occur freely at the level of the pia mater.
The communication between cerebral arterial blood and the brain’s interstitial fluid is facilitated by the BBB.
The communication between cerebral arterial blood and the brain’s interstitial fluid is facilitated by the BBB.
Trypan blue can pass from the ventricular system to the brain due to the ependyma alone.
Trypan blue can pass from the ventricular system to the brain due to the ependyma alone.
Lipid soluble substances can easily penetrate the blood-brain barrier due to passive diffusion.
Lipid soluble substances can easily penetrate the blood-brain barrier due to passive diffusion.
Facilitated transport proteins rely solely on ATP for transporting substances across the blood-brain barrier.
Facilitated transport proteins rely solely on ATP for transporting substances across the blood-brain barrier.
The uptake of D-glucose is low despite being a large water-soluble molecule.
The uptake of D-glucose is low despite being a large water-soluble molecule.
Transporters at the blood-brain barrier only work to move substances into the brain.
Transporters at the blood-brain barrier only work to move substances into the brain.
The oil/water partition coefficient helps determine the lipid solubility and uptake rate of solutes.
The oil/water partition coefficient helps determine the lipid solubility and uptake rate of solutes.
Energy-dependent transporters include Na+/K+ ATPase and are crucial for moving substrates against their concentration gradient.
Energy-dependent transporters include Na+/K+ ATPase and are crucial for moving substrates against their concentration gradient.
Morphine and penicillin are both physiological substrates that have high uptake rates at the blood-brain barrier.
Morphine and penicillin are both physiological substrates that have high uptake rates at the blood-brain barrier.
Enzymes like monoamine oxidase serve solely as transporters in the blood-brain barrier.
Enzymes like monoamine oxidase serve solely as transporters in the blood-brain barrier.
The MCT1 at the BBB assists in lactate removal to prevent its accumulation in the blood.
The MCT1 at the BBB assists in lactate removal to prevent its accumulation in the blood.
During starvation or a ketogenic diet, the plasma levels of lactate and ketone bodies increase.
During starvation or a ketogenic diet, the plasma levels of lactate and ketone bodies increase.
The L-system of amino acid transporters is independent of sodium (Na+).
The L-system of amino acid transporters is independent of sodium (Na+).
The A-system of amino acid transporters operates without the need for Na+.
The A-system of amino acid transporters operates without the need for Na+.
The ASC-system preferentially recognizes small neutral amino acids like valine and leucine.
The ASC-system preferentially recognizes small neutral amino acids like valine and leucine.
The excitatory amino acid transporters (EEAT) facilitate the net removal of glutamate from the brain.
The excitatory amino acid transporters (EEAT) facilitate the net removal of glutamate from the brain.
Alanine and serine are preferred amino acids in the A-system.
Alanine and serine are preferred amino acids in the A-system.
Glutamate is classified as a neutral amino acid and is transported by the ASC system.
Glutamate is classified as a neutral amino acid and is transported by the ASC system.
Glutamate concentration in the brain ISF is normally kept above 2 mM.
Glutamate concentration in the brain ISF is normally kept above 2 mM.
Circumventricular organs in the nervous system are free from the blood-brain barrier.
Circumventricular organs in the nervous system are free from the blood-brain barrier.
The two lateral ventricles are the primary producers of cerebrospinal fluid (CSF).
The two lateral ventricles are the primary producers of cerebrospinal fluid (CSF).
The blood-cerebrospinal fluid barrier (BCSFB) contains fenestrated capillaries.
The blood-cerebrospinal fluid barrier (BCSFB) contains fenestrated capillaries.
Glutamate can cause neurotoxicity if it accumulates in the blood plasma.
Glutamate can cause neurotoxicity if it accumulates in the blood plasma.
The foramen of Luschka allows cerebrospinal fluid to enter the subarachnoid space.
The foramen of Luschka allows cerebrospinal fluid to enter the subarachnoid space.
The choroid plexus membrane is similar in structure to that of the blood-brain barrier (BBB).
The choroid plexus membrane is similar in structure to that of the blood-brain barrier (BBB).
Arachnoid granulations are located in the venous sinus where CSF is reabsorbed.
Arachnoid granulations are located in the venous sinus where CSF is reabsorbed.
The production rate of cerebrospinal fluid (CSF) is 500mL per day.
The production rate of cerebrospinal fluid (CSF) is 500mL per day.
The total cerebrospinal fluid volume is approximately 200mL.
The total cerebrospinal fluid volume is approximately 200mL.
CSF flows from the choroid plexus directly to the 3rd ventricle.
CSF flows from the choroid plexus directly to the 3rd ventricle.
CSF is renewed four times a day in its entirety.
CSF is renewed four times a day in its entirety.
The hydrostatic pressure is higher at the reabsorption sites compared to the production sites.
The hydrostatic pressure is higher at the reabsorption sites compared to the production sites.
Arachnoidal villi facilitate the drainage of CSF into blood and lymph.
Arachnoidal villi facilitate the drainage of CSF into blood and lymph.
The pressure at the level of arachnoidal villi is approximately 10 mmHg.
The pressure at the level of arachnoidal villi is approximately 10 mmHg.
Ion exchange and channels in the choroid cells are similar to those found in the blood-brain barrier.
Ion exchange and channels in the choroid cells are similar to those found in the blood-brain barrier.
Flashcards
Blood Brain Barrier (BBB)
Blood Brain Barrier (BBB)
A specialized structure that regulates the passage of substances between blood and the brain's interstitial fluid.
Tight Junctions in BBB
Tight Junctions in BBB
Capillaries in the brain with tightly joined endothelial cells, preventing free passage of most substances.
Lipophilic Molecules
Lipophilic Molecules
Molecules that can readily pass through the plasma membrane of BBB endothelial cells, bypassing the tight junctions.
Brain Interstitial Fluid
Brain Interstitial Fluid
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Transcytosis
Transcytosis
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Blood-CSF Barrier (BCSFB)
Blood-CSF Barrier (BCSFB)
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Pharmacokinetics of BBB
Pharmacokinetics of BBB
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Neurophysiology
Neurophysiology
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What is cerebrospinal fluid (CSF)?
What is cerebrospinal fluid (CSF)?
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What is the choroid plexus?
What is the choroid plexus?
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Describe the circulation of CSF.
Describe the circulation of CSF.
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What is the meningeal barrier?
What is the meningeal barrier?
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What is the arachnoid membrane's role in CSF circulation?
What is the arachnoid membrane's role in CSF circulation?
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What is the ventricular ependyma?
What is the ventricular ependyma?
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What are the blood-brain barrier (BBB) and the blood-cerebrospinal fluid barrier (BCSFB)?
What are the blood-brain barrier (BBB) and the blood-cerebrospinal fluid barrier (BCSFB)?
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How do the BBB and BCSFB maintain the brain's internal environment?
How do the BBB and BCSFB maintain the brain's internal environment?
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Passive Transport across the BBB
Passive Transport across the BBB
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Passive Diffusion across the BBB
Passive Diffusion across the BBB
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Transporters in the BBB
Transporters in the BBB
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Facilitative Transporters in the BBB
Facilitative Transporters in the BBB
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Energy-Dependent Transporters in the BBB
Energy-Dependent Transporters in the BBB
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Transcytosis across the BBB
Transcytosis across the BBB
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Efflux Transporters in the BBB
Efflux Transporters in the BBB
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Glutamate Excitotoxicity
Glutamate Excitotoxicity
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Astrocyte Role in Glutamate Removal
Astrocyte Role in Glutamate Removal
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Circumventricular Organs (CVOs)
Circumventricular Organs (CVOs)
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Choroid Plexus and CSF Production
Choroid Plexus and CSF Production
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Cerebrospinal Fluid (CSF)
Cerebrospinal Fluid (CSF)
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Brain Interstitial Fluid (ISF)
Brain Interstitial Fluid (ISF)
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What is the Blood-CSF Barrier (BCSFB)?
What is the Blood-CSF Barrier (BCSFB)?
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How does the BCSFB differ from BBB in transport?
How does the BCSFB differ from BBB in transport?
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What is the CSF volume and turnover rate?
What is the CSF volume and turnover rate?
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Explain the CSF flow pattern.
Explain the CSF flow pattern.
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What are some key elements involved in CSF clearance?
What are some key elements involved in CSF clearance?
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How does pressure affect CSF flow?
How does pressure affect CSF flow?
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What is the pressure difference between CSF production and reabsorption?
What is the pressure difference between CSF production and reabsorption?
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What is the composition of CSF?
What is the composition of CSF?
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MCT1 at the BBB
MCT1 at the BBB
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Transcytosis across BBB
Transcytosis across BBB
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Amino acid transporter systems in BBB
Amino acid transporter systems in BBB
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L-system in BBB
L-system in BBB
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A-system in BBB
A-system in BBB
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ASC-system in BBB
ASC-system in BBB
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Excitatory Amino Acid Transporters (EEAT)
Excitatory Amino Acid Transporters (EEAT)
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Glutamate
Glutamate
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Study Notes
Blood-Brain Barrier (BBB)
- The BBB separates blood from the interstitial fluid of the brain
- Capillary structures vary throughout the body; endothelial cell junctions can change
- Fenestrated capillaries allow passage of small molecules and ions but larger molecules require other transport methods
- In the brain, capillaries have tight junctions, limiting molecule passage without control
- Only lipophilic (fat-soluble) molecules pass freely
- Ions, large molecules, proteins, and polar molecules cannot pass freely
Evidence of a BBB
- Paul Ehrlich and Edwin Goldmann (1885) were pioneers in observing brain interstitial fluid differences
- They injected trypan blue into the bloodstream, expecting it to diffuse everywhere. However, the CNS remained uncolored, indicating a barrier
- Injecting the dye into the ventricular system (containing CSF) colored the CNS, showing barrier between blood and interstitial fluid but not between CSF and CNS interstitial fluid
- The choroid plexus, which produces CSF, acts as another barrier, the blood-CSF barrier (BCSFB)
Brain Vascularization
- Blood is filtered in choroid plexuses (in ventricles), circulated throughout the ventricular system and subarachnoid space, and reabsorbed into the venous system through arachnoid granulations.
- Blood-brain barrier (BBB): exists between plasma and interstitial fluid in brain parenchyma capillaries.
- Blood-cerebrospinal fluid barrier (BCSFB): made of choroid plexus epithelium
- Meninges barrier: between CSF in subarachnoid space and overlying structures
- Ventricular ependyma: between CSF and interstitial fluid; allows for some exchange
Blood-Brain Barrier Components
- Endothelial cells: connected with tight junctions
- Basement membrane: surrounds endothelial cells
- Pericytes: surround and cover endothelial cells
- Astrocyte foot processes: surround capillary endothelial cells
Neurovascular Unit
- Microglia, astrocytes, and neurons form a functional unit. This affects blood-brain barrier (BBB) permeability
- BBB permeability may be altered by components of this unit
Solute Carriers
- Facilitative transport proteins (GLUT1, LAT1, MCT1) help move glucose, amino acids, and other substances
- Active transporters (e.g., Na+/K+ ATPase) actively move molecules against concentration gradients
- Lipid-soluble molecules move through passive diffusion
- Transcytosis and ion channels are limited in role in transportation
Glucose Transport
- GLUT1 transporters facilitate glucose uptake and are insulin independent and are expressed on both capillary sides
- Their expression is regulated by glucose levels
- The brain relies almost entirely on the supply of glucose from the circulation
Monocarboxylate Transporters (MCTs)
- MCTs transport monocarboxylic acids (e.g., lactate, B-hydroxybutyrate)
- MCT1 is a lactate transporter. It is important for glucose metabolism in the brain, transferring lactate
Amino Acid Transport
- Three systems (L-system, A-system, and ASC-system are involved in amino acid transport
- They transport different types of amino acids, and there is competition for the transporters
Blood-CSF Barrier
- The blood-CSF barrier is made of choroid plexus epithelial cells, and not fenestrated capillaries
- Tight junctions prevent free communication between blood and interstitial fluid
CSF Clearance
- CSF is drained through the arachnoid villi and into the venous sinuses
- The pressure at the level of these arachnoidal villi is about 5 mmHg
CSF Functions
- Mechanical support for brain and spinal cord
- Regulation of ambient pressure
Circumventricular Organs (CVOs)
- CVOs are areas of the brain that lack a fully functional blood-brain barrier, allowing direct access to the blood
BBB Dysfunction
- Damage can result from infections, tumors, or other pathologies.
- This can impact the homeostasis of the brain and has consequences to the function and signal processing of the CNS
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Description
Explore the fascinating biology of the blood-brain barrier and its functions in the central nervous system. This quiz covers key concepts such as capillary structures, molecular exchange, and the role of cerebrospinal fluid. Test your understanding and learn important facts about the barriers that protect the brain.
