cardiovascular lecture 4 Flashcards
Hematocrit is the percent of blood volume that is composed of what
red blood cells
what percentage of blood is hematocrit
45%
the biconcave disk shape of erythrocytes leads to what
a high surface area-to-volume ratio –> contain large amounts of hemoglobin –> binds O2 via Fe atoms
how can you get more O2 to an organ if you can’t increase blood flow to that organ
extract more hemoglobin from the blood
T/F: the availability of dietary iron can be a limiting factor in erythropoiesis
TRUE thus there are well developed storage and recycling mechanisms
what is the storage buffer for iron
Ferritin
life span of RBCs
120 days
what is the major breakdown product of hemoglobin
bilirubin
_______ binds iron released from destroyed RBCs and delivers it to the _______
transferrin; bone marrow
what is folic acid needed for
needed for thymine –> if deficient, impaired cell division
what vitamin is required for action of folic acid
B12 –> absorption of B12 requires an intrinsic factor found only in meat thus vegans must take supplements (stupid vegans) –> if no intrinsic factor, pernicious anemia
erythropoiesis is _______ regulated
hormonally
what process leads to an increase in the rate of erythropoiesis
decreased O2 delivery to the kidney –> secretion of erythropoietin –> activates receptors in bone marrow –> increase in rate of erythropoiesis
major causes of anemia (5)
- dietary deficiencies of iron, vitamin B12, or folic acid
- bone marrow failure due to toxic drugs or cancer
- hemorrhage leading to iron deficiency
- inadequate secretion of erythropoietin in kidney disease
- excessive destruction of erythrocytes (eg. sickle cell anemia)
anemia
decrease in ability of blood to carry oxygen due to 1) decrease in total number of erythrocytes, 2) diminished concentration of hemoglobin, 3) combination
