Ganong 24e chapter 33 - Circulation through Special Regions (1) Flashcards
What percentage of cardiac output goes to each of these: liver, kidneys, brain, skin, skeletal muscle, heart muscle?
Liver 28%, Kidneys 23%, Brain 14%, Skin 9%, Skeletal muscle 15%, Heart muscle 5%.
Which organ receives the highest blood flow per gram of tissue?
The kidneys, by far.
What envelopes capillaries in the brain?
Endfoot processes of glial cells, such as astrocytes.
What is the volume of CSF present in a normal healthy adult?
About 150mL
What is the normal rate of production of CSF in an adult?
About 20-25mL/hr
What is the name of the tissue that produces CSF?
Choroid plexus.
What is the difference in protein composition of CSF compared to plasma? And osmolality?
CSF contains only 0.3% the concentration of protein that plasma contains. Osmolality is 290mOsm/kg H2O for both plasma and CSF.
Why is headache common post lumbar puncture?
Because CSF has an important cushioning effect on the brain, and when there is reduced CSF volume, there is less cushioning.
In basic terms, explain what features make up the blood-brain barrier.
Tight junctions between the endothelial cells of the brain capillaries prevent the penetration of proteins, and slow the movement of some smaller molecules such as urea. There are numerous carrier-mediated and active transport mechanisms to move selected substance from the blood to the brain.
Name a few substances that easily cross the blood-brain barrier.
Water, CO2, O2, and non-protein-bound steroid hormones.
What is the major method of glucose uptake from blood into the brain?
The glucose transporter called GLUT 1.
True or false: The posterior pituitary is not covered by the blood-brain barrier.
True. The posterior pituitary, as well as several other small regions near the brainstem, are not subject to the blood-brain barrier, and are called “circumventricular organs”. Remember that the anterior pituitary and the pineal glands are also “outside” of the blood-brain barrier, but they are not actually part of the brain.
Blood flow to which parts of the myocardium is compromised during systole? Why are the other sections not compromised during systole?
Areas supplied by the Left Coronary Artery, in particular the subendocardial portion of the left ventricle. The Right Coronary Artery is maintained patent throughout the cardiac cycle, due to the high pressure differential between the aorta and the right ventricle during systole.
How much blood per minute goes to the liver?
1500mL/min
How much blood per minute goes to the kidney?
1250mL/min
