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Questions and Answers
What is the main structural component of the blood-brain barrier?
What is the artifact created during dissection concerning the space between the pia and white matter of the spinal cord?
Which layer acts as a shock-absorbing pad between the Central Nervous System (CNS) and bone?
What structure separates the pia mater from the white matter of the spinal cord?
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What contributes to the blood-brain barrier by closely enveloping the basement membrane of continuous capillaries in most CNS regions?
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What is the main function of the BBB?
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Which layer is sometimes referred to as the pia-arachnoid or leptomeninges?
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Which component of the BBB is responsible for having tight junctions?
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What type of substances can diffuse rapidly across the BBB?
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Which structure is an exception to having a blood-brain barrier?
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What damage mechanism can lead to vasogenic edema by breaking tight junctions in endothelial cells?
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What effect do hyperosmolar solutions like mannitol have on the blood-brain barrier?
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Which molecules are transported slowly across the BBB through selective mechanisms?
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Where is the choroid plexus primarily located within the brain?
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What happens if there is a blockage of outflow from the ventricles during fetal or postnatal development?
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What is the function of the choroid plexus in relation to CSF?
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What is the composition of cerebrospinal fluid (CSF) in terms of proteins?
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What is one of the key roles of CSF in relation to the central nervous system?
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Study Notes
Meninges and Subdural Space
- The subdural space is located between the arachnoid mater and the dura mater.
- The arachnoid mater is a thicker, web-like layer containing the subarachnoid space and connective tissue trabeculae.
- The subarachnoid space is filled with cerebrospinal fluid (CSF) and the arachnoid acts as a shock-absorbing pad between the CNS and bone.
- Fairly large blood vessels course through the arachnoid.
- The pia mater is thin and closely applied to the surface of the CNS tissue.
Blood-Brain Barrier
- The blood-brain barrier (BBB) is a functional barrier that tightly controls the passage of substances from blood into CNS tissue.
- The main structural component of the BBB is the capillary endothelium with tight junctions and a basement membrane.
- The limiting layer of perivascular astrocytic feet also contributes to the BBB and regulates the passage of molecules and ions.
- The BBB protects neurons and glia from bacterial toxins, infectious agents, and other exogenous substances.
- The BBB is not present in certain regions, such as the hypothalamus, posterior pituitary, and choroid plexus.
Blood-Brain Barrier Components and Transport
- Components: capillary endothelial cells, basal lamina, astrocytes, and pericytes.
- Transport mechanisms: ion channels (e.g., sodium, potassium), selective transport (e.g., amino acids, glucose), and diffusion (e.g., nonpolar and lipid-soluble substances).
Structures with No Blood-Brain Barrier
- Area postrema: vomiting center with chemoreceptor trigger zone.
- Organum vasiculosum lamina terminalis (OVLT): osmoreceptors.
- Neurohypophysis: oxytocin and ADH release directly into the blood.
Choroid Plexus
- The choroid plexus consists of highly vascular tissue, elaborately folded and projecting into the large ventricles of the brain.
- It is found in the roofs of the third and fourth ventricles and parts of the two lateral ventricular walls.
- The function of the choroid plexus is to remove water from blood and release it as CSF.
- CSF is clear, contains Na+, K+, and Cl– ions but very little protein, and is produced continuously.
- CSF fills the ventricles, the central canal of the spinal cord, the subarachnoid and perivascular spaces.
- CSF provides ions required for CNS neuronal activity and helps absorb mechanical shocks in the arachnoid.
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Description
Learn about the blood-brain barrier (BBB) which protects neurons and glia from toxins and maintains the stable composition of interstitial fluid. Explore where BBB is absent and its functions in different regions of the brain.
