CSF and BBB: Lecture 4
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Questions and Answers

What is the primary function of the Choroid epithelium?

  • To mix with CO2 to form H+ and HCO3-
  • To regulate the passage of ions and molecules (correct)
  • To filter blood plasma
  • To produce CSF

    • What is the main source of micronutrients for neurons and neuroglia cells?

  • Interstial capillaries
  • Capillaries in the choroid plexus (correct)
  • The bloodstream
  • The cerebrospinal fluid

    • What is the absorption of the CSF dependent on?

  • Pressure (correct)
  • To absorb CSF into the venous sinuses
  • To filter blood plasma
  • The passage of ions and molecules

    • Due to the high rate of formation, flow, and absorption of the CSF, how often is it replaced?

    <p>3x-5x/ day</p> Signup and view all the answers

    What is the main function of the Blood-Brain Barrier?

    <p>To restrict the passage of certain substances into the brain</p> Signup and view all the answers

    What is the term for the abnormal dilation of the ventricular system due to an increased volume of CSF?

    <p>Hydrocephalus</p> Signup and view all the answers

    What is the purpose of facilitated diffusion in the BBB?

    <p>To facilitate the transport of glucose and large neutral amino acids</p> Signup and view all the answers

    What is the term for the space between the arachnoid membrane and the dura mater?

    <p>Subarachnoid space</p> Signup and view all the answers

    Which of the following best describes the Dura Mater?

    <p>A layer of connective tissue with a periosteal layer</p> Signup and view all the answers

    What is the mechanism by which water diffuses into the ventricles to maintain osmotic balance?

    <p>Osmosis</p> Signup and view all the answers

    What is the term for the procedure of injecting radiopaque dyes into the CSF to assess the integrity of the spinal canal?

    <p>Myelography</p> Signup and view all the answers

    What is the main function of the Arachnoid Villi?

    <p>Absorbing cerebrospinal fluid into the bloodstream</p> Signup and view all the answers

    What is the primary function of the cerebrospinal fluid?

    <p>To protect the CNS from mechanical injuries</p> Signup and view all the answers

    Where is cerebrospinal fluid primarily formed?

    <p>In the choroid plexus</p> Signup and view all the answers

    What is the blood-brain barrier primarily composed of?

    <p>Tight junctions between endothelial cells</p> Signup and view all the answers

    What is the primary reason for the low permeability of the blood-brain barrier?

    <p>The presence of tight junctions</p> Signup and view all the answers

    What is the function of the subarachnoid space?

    <p>To store cerebrospinal fluid</p> Signup and view all the answers

    What is the purpose of the Arachnoid Trabeculae?

    <p>To facilitate cerebrospinal fluid circulation</p> Signup and view all the answers

    Which of the following is NOT a function of cerebrospinal fluid?

    <p>Regulation of blood pressure</p> Signup and view all the answers

    What is the primary mechanism of nutrient transport across the blood-brain barrier?

    <p>Facilitated diffusion</p> Signup and view all the answers

    What percentage of the body weight does the CNS account for?

    <p>2%</p> Signup and view all the answers

    Where is the Blood-CSF barrier and Blood Brain barrier located?

    <p>Choroid plexus and the tissue capillary membranes</p> Signup and view all the answers

    What is the BBB almost totally impermeable to?

    <p>Plasma Proteins</p> Signup and view all the answers

    What is the primary location of the blood-brain barrier?

    <p>Glial limiting membrane</p> Signup and view all the answers

    The interaction between ____________ and endothelial cells is important for the maintainance of the BBB.

    <p>Astrocytes</p> Signup and view all the answers

    The BBB has specific carrier molecules that facilitate the tranport of nutrients. Which of the following ions/substances is HIGHLY permeable to the BBB?

    <p>Water, CO2, O2, &amp; most lipid-soluble substances</p> Signup and view all the answers

    What is the path of CSF flow from the ventricles?

    <p>Lateral ventricles -&amp;gt, Interventricular foramen -&gt; third ventricle -&gt; fourth ventricle -&gt; subarachnoid space</p> Signup and view all the answers

    What is the primary function of the CNS?

    <p>To integrate and process sensory information</p> Signup and view all the answers

    What is the name of the space that contains the CSF and surrounds the CNS?

    <p>Subarachnoid space</p> Signup and view all the answers

    What type of epithelium lines the ventricular system?

    <p>Ependymal epithelium</p> Signup and view all the answers

    What is the function of the subarachnoid space?

    <p>To trap and absorb cerebrospinal fluid</p> Signup and view all the answers

    A spinal tap to collect CSF contains substances that veterinarians can sample. What are these, respectively?

    <p>All the above</p> Signup and view all the answers

    The BBB has specific carrier molecules that facilitate transport. What is the BBB slightly permeable to?

    <p>More than one</p> Signup and view all the answers

    What is the function of the blood-brain barrier?

    <p>To regulate the entry of substances into the CNS</p> Signup and view all the answers

    Which layer of meninges is fused with the inner surface of the skull?

    <p>Dura mater</p> Signup and view all the answers

    What is the characteristic appearance of the arachnoid?

    <p>Spiderweb-like</p> Signup and view all the answers

    Where does the cerebrospinal fluid circulate?

    <p>Between the arachnoid and pia mater</p> Signup and view all the answers

    What is the function of the pia mater?

    <p>To join the arachnoid and dura mater</p> Signup and view all the answers

    The brain needs certain water-soluble nutrients, but they are restricted from passing through the BBB. Which of the following water-soluble substances falls under these restrictions?

    <p>Glucose</p> Signup and view all the answers

    What is the main component of the subarachnoid space?

    <p>Cerebrospinal fluid</p> Signup and view all the answers

    Study Notes

    The Choroid Epithelium and CSF Formation

    • The choroid epithelium forms a selective tight-junction barrier that regulates the passage of ions and molecules across the epithelial cell barrier.
    • The choroid epithelium controls the composition of CSF that enters the ventricles.
    • CSF is created from blood plasma, consisting of 99% water, different ions, and almost no proteins.
    • Micronutrients such as Vit B6, folates, and Vit C are present in CSF.

    CSF Formation and Circulation

    • Water in choroid epithelial cells combines with intracellular CO2 to form H+ and HCO3-.
    • H+ is exchanged for extracellular Na+ from the blood at the basal surface.
    • Na+ is pumped out through the apical surface into the ventricles.
    • Cl- and HCO3- move into the ventricles to neutralize the excess positive charge.
    • Water diffuses into the ventricles to maintain osmotic balance.

    Functions of CSF

    • CSF protects the brain and spinal cord against impact upon their surrounding bony walls.
    • CSF acts as an effective waste control system, removing potentially harmful cellular metabolites.
    • CSF acts as a distribution system for some peptide hormones and growth factors.
    • CSF maintains a consistent extracellular microenvironment for neurons and glia.

    Ventricular System and CSF Circulation

    • The ventricular system consists of four expanded regions forming ventricles, interconnecting foramina, and tubes.
    • Lateral ventricles are oriented longitudinally in each hemisphere and connected with the third ventricle.
    • The third ventricle is connected with the fourth ventricle through the mesencephalic aqueduct.
    • The fourth ventricle is connected with the subarachnoid space and central canal of the spinal cord.
    • CSF flows from the ventricles, through the interventricular foramina, into the subarachnoid space, and is absorbed into the venous sinuses through arachnoid villi.

    Barriers and Transport

    • Barriers exist between the blood and CSF, and the brain fluid, with different concentrations of constituents.
    • Many larger molecules hardly pass from the blood into the CSF or interstitial fluids of the brain.
    • Astrocytes form perivascular end feet around the capillary endothelium, interacting with endothelial cells to maintain the blood-brain barrier (BBB).
    • The BBB has specific carrier molecules for transport, and is highly permeable to water, CO2, O2, and lipid-soluble substances.
    • Glucose and large neutral amino acids use facilitated diffusion to cross the BBB.

    Meninges and Ventricular System

    • The brain and spinal cord are surrounded by three layers of connective tissue called meninges: dura mater, arachnoid, and pia mater.
    • The dura mater is the outermost meningeal layer, fused with the inner surface of the skull.
    • The arachnoid is a thin, loose connective tissue layer with a spiderweb appearance.
    • The pia mater is the innermost meningeal layer, adhering to the surface of the CNS.
    • The ventricular system is lined by ependymal cells, which create CSF flow through coordinated cilia beating.

    Hydrocephalus and CSF Circulation

    • Hydrocephalus is an abnormal dilation of the ventricular system from an increased volume of CSF.
    • CSF can flow from the subarachnoid space to the venous outflow system, but not in the reverse direction.
    • The rate of CSF formation, flow, and absorption are sufficiently high to cause its replacement several times daily.

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    Neurophysiology Part 4 - CSF and BBB Summer 2024 PDF

    Description

    Learn about the formation and composition of cerebrospinal fluid, including the role of the choroid epithelium and the regulation of ions and molecules across the epithelial cell barrier.

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