Exam 2 – Cardio Ch 61 Flashcards
What does the blood tissue barrier depend on?
Structure of endothelial wall
What is the blood tissue barrier for the liver like?
Highly fenestrated (many compounds will pass into tissue)
What is the blood tissue barrier for the kidney glomerulus like?
Specific filtration
What is the blood tissue barrier for the brain like?
Very tight junctions
Very limited passage of molecules except small molecules (O2, CO2, Na, etc)
What cannot pass the blood-brain barrier? How can they pass?
Proteins and drugs, but some lipid soluble drugs can
Pinocytotic vesicles
What are the different types of barriers?
Blood-air barrier Blood-gas barrier Blood-aqueous barrier Blood-brain barrier Blood-CSF barrier Blood-retina barrier Blood-synovial barrier Blood-milk barrier Blood-testis barrier Blood-placental barrier
Where are the blood-air barrier and blood-gas barrier?
Alveolovapillary membrane
What is the blood-aqueous barrier?
The physiological mechanism that prevents exchange of materials between the chamber of the eye and the blood
What is the blood-brain barrier?
The barrier separating the blood from the brain parenchyma
How does the blood-CSF barrier compare to the blood-brain barrier?
It differs in that in consist of the epithelium of the choroid plexuses, but it has similar permeabilities
What is the blood-retina barrier?
Endothelium of the retinal capillaries and cells of the retinal pigment epithelium form a nonfenestrated barrier between choral tissue fluid and retinal tissue fluid
What is the blood-synovial barrier suggested by?
The presence of plasma proteins of small molecular size and catabolic products of articular cartilage in synovial fluid
What is the blood-milk barrier?
Specialized secretory tissue
What is the blood-testis barrier?
A barrier separating the blood from the seminiferous tubules
Provides an extravascular environment
What does the blood-placenta barrier depend on?
The type of placenta
What does the blood-brain barrier do?
Seals off every vessel in the brain to keep things from getting to it
How much of the resting cardiac output goes to the brain?
15%
What are the 3 metabolic factors that have potent effects on blood flow?
CO2
H+
O2
What does an increase in CO2 do to the blood flow?
Increases it
What is the CO2 increasing the blood flow thought to work through?
An increase in the H+ ion concentration
What can an increase in H+ concentration do?
Depresses neuronal activity
What is a normal PO2?
35-40 mmHg
At what PO2 level do you see an increase in flow?
Below 30 mmHg
What PO2 level causes a coma?
Below 20 mmHg
What is the regulation of cerebral blood flow like?
Autoregulated
At what pressure range is cerebral blood flow constant?
60 to 140 mmHg
At what pressure of cerebral blood flow does blood flow begin to fall?
60 mmHg
At what pressure of cerebral blood flow does the blood flow increase?
Above 140 mmHg
At a pressure of 140 mmHg, what happens to the blood vessels?
The begin to stretch, which can lead to damage and eventual rupture
What function does cerebrospinal fluid perform?
Cushioning
What is the total volume of cerebrospinal fluid?
About 150 ml
How much cerebrospinal fluid is produced each day by the choroid plexus of the ventricles of the brain?
500 ml
What does the reabsorption of CSF occur through?
The arachnoid villi
What is the normal CSF pressure?
10 mmHg
Where is CSF formed?
In the 3rd ventricle of the brain
Wha is the CSF flow?
Choroid plexus on lateral ventricles
Foramen of Monro to third ventricle
Aqueduct of Sylvius
Fourth ventricle
Foramina of Magendie and Luschka
Subarachnoid space offer brain and spinal cord
Reabsorption into venous sinus blood via arachnoid villi
Describe the brain
Highly metabolic organ
Limited anaerobic metabolism
What percentage of the total metabolism of the body is the brain?
15%
