2.0 Cerebral Blood Flow and Homeostasis Flashcards
What tissue makes the majority of CSF?
Choroid plexus
What two kinds of pressure are responsible for moving fluid from the blood vessels into the ventricles.
Hydrostatic pressure and oncotic pressure. At the choroid plexus, oncotic pressure is equal and opposite.
What are the concentrations of Na+, HCO3, Mg++, Cl-, CO2, K+, Ca++, Protein, and Glucose in the CSF relative to plasma?
Na+, HCO3 concentrations are about the same
CSF contains more Mg++, Cl-, and CO2
CSF contains less K+, Ca++, Protein, and Glucose
What components of capillaries in the brain limit exchange?
Tight junction between endothelial cells
Glial endfeet in close contact with blood vessel
What substances can cross the BBB via passive diffusion?
H2O via AQP-4
CO2
O2
free steroid hormones
What is the difference between Glut1 45K and Glut1 55K transporters?
Glut1 45K is found on astroglia
Glut1 55K is found on capillaries
What is the role of P-glycoprotein?
It pumps glycoprotein across the BBB.
It is also responsible for binding and transporting a wide variety of drugs that happen to cross the BBB.
What is the electrolyte composition of the CSF particularly related to?
The concentration of K+
What are the four circumventricular organs? (exceptions to BBB)
Posterior pituitary
Area postrema
Organum vasculosum of the lamina terminalis (OVLT)
Subfornical organ
What neurotransmitters/receptors are used for sympathetic innervation of cerebral circulation? What does it lead to?
Neurotransmitters: norepinephrine and neuropeptide Y (NPY)
Receptors: alpha-adrenergics
Leads to vasoconstriction, especially when systemic BP increases in order to prevent damage to capillaries and BBB.
What neurotransmitters are used for parasympathetic innervation of cerebral circulation? What does it lead to?
Ach
Vasoactive intestinal polypeptide (VIP)
PHM-27 (dereived from pre-pro-VIP)
Leads to vasodilation.
What neurotransmitters are responsible for causing vasodilation in response to increased torsion of blood vessels?
Substance P
Neurokinin A
CGRP
What is the body’s response when blood flow to the brian is compromised? What is a potential consequence of this?
The brain will drive systemic blood pressure up to force blood to the brain. Consequently, systemic blood pressure can be driven to very high levels in order to perfuse the brain.
