bone marrow produces red blood cells in adults.
bone marrow produces red blood cells in adults.
what bones produce red blood cells in adults?
bone marrow
jeff, a well-known cyclist, is cycling in a non-profit charity race, when he is unable to breathe and taken to the hospital. house finds it surprising that jeff admitted he is taking illegal enhancement drugs. he agreed to blood doping, which is common among cyclists, to better one's athletic performance. because red blood cells carry oxygen between the lungs and the muscles, a higher number of red blood cells can increase an athlete's endurance. while trying to figure out what cause of jeff's respiratory distress, they find an air embolus in his chest. while dr. chase works to remove the air bubble, jeff begins to feel numbness in his legs, but is told that it might be due to the sedation. while his manager talks to the press, jeff loses feeling in his legs. dr. cameron informs house that jeff's red blood count is continually dropping, revealing that his body is no longer able to produce red blood cells on its own. house becomes convinced that jeff lied about a specific drug that could be the cause of all of his symptoms, erythropoietin (epo), a hormone produced in the kidney that promotes the formation of red blood cells by the bone marrow. adding more red blood cells increases the oxygen level in the blood, thus presumably causing all of jeff's symptoms as he fails to produce red blood cells on his own. this explains him also having anemia, caused by chronic acquired pure red cell aplasia (prca), probably resulting from blood doping. after responding to prednisone, jeff begins losing more red blood cells, to the point of requiring a transfusion. house scans jeff's neck and a thymoma is discovered; an extremely rare tumor on the thymus, confirming that he wasn't taking epo, but did have chronic acquired pure red cell aplasia. due to the diagnosis he can legally blood dope or get a thymectomy, which could only bring a temporary remission, after which he would have to be on medical steroids.
spin (house)
the mechanism by which topical progesterone in cream and water-based gel produces very high salivary and capillary blood levels in spite of low circulating levels is not well-understood. however, at least two hypotheses have been proposed. steroid hormones including progesterone have been found to be transported by red blood cells in addition to serum carrier proteins like albumin, sex hormone-binding globulin, and corticosteroid-binding globulin, and as much as 15 to 35% of total steroid hormone content in whole blood may be confined to red blood cells. according to the hypothesis, very high local concentrations of progesterone occur in skin capillaries after topical application and are taken up by red blood cells. the transit time of red blood cells from capillaries and the release of steroid hormones from red blood cells are both very rapid, so it is suggested that progesterone is delivered through circulation to tissues via red blood cells without having time to equilibrate with systemic blood. this could potentially explain the low levels of progesterone in venous blood in spite of very high levels in capillary blood and saliva. however, one study assessed progesterone levels in red blood cells with topical progesterone and found that they were significantly increased but still very low. nonetheless, according to other authors, "[a]lthough the investigators of that study concluded that the progesterone levels in red blood cells were too low to be important in the delivery of progesterone to target tissues, it should be realized that even small amounts of progesterone taken up by red blood cells might be important because the transit time of red blood cells from capillaries is very rapid. [...] however, the role of red blood cells in steroid hormone transport has not been studied thoroughly, and such studies are warranted."
pharmacokinetics of progesterone