Blood - RBCs Flashcards
What is the shape of RBCs?
RBCs are biconcave discs with thin central regions and a thicker outer margin
Why are RBCs shaped like they are?
- The structure gives each RBC a large surface area to volume-ratio
- It also enables RBCs to form stacks called rouleaux
- Enables RBCs to bend and flex when entering small capillaries and branches
What organelles do RBCs have?
Only a cytoskeleton
What is the average lifespan of a RBC and why?
Less than 120 days because of their lack of organelles
Why do RBCs have so little organelles?
So they have low energy demands
What does hemoglobin do?
Transport oxygen and carbon dioxide
What are hemoglobin molecules comprised of?
Each hemoglobin has two alpha chains and two beta chains of polypeptides, each with a single molecule of heme
What is the difference between Deoxyhemoglobin, Oxyhemoglobin, and Carbominohemoglobin?
Deoxyhemoglobin has no oxygen bound to it, Oxyhemoglobin does, and Carbominohemoglobin has carbon dioxide bound to it because of the lack of oxygen in the plasma
What is the difference between fetal and non-fetal hemoglobin?
Fetal hemoglobin more readily binds to oxygen
Do Capillaries’ plasma have high or low carbon dioxide and oxygen levels?
They have high oxygen levels and low carbon dioxide levels
What is anemia?
Low hematocrit or low Hb content of the RBCs
What does hemolyzed mean?
Ruptured
What part of red blood cells are removed after the death of the cell?
Hemoglobin
How are the alpha and beta chains of hemoglobin eliminated after death of the cell?
They are filtered through the kidneys and eliminated by urine
What is hemoglobinuria?
When an abnormally large number of RBCs break down in the bloodstream; Brown or red urine
What is hematuria?
Intact RBCs in urine; occurs only after kidney damage or damage to vessels along the urinary tract
How are globular proteins used after RBC hemolyzation?
Globular proteins are broken apart into their component amino acids, which are metabolized by the cell or released into the bloodstream
How are heme units disposed of?
Heme units are stripped of their iron and converted to biliverdin which is then converted to bilirubin which is released into the bloodstream
What is jaundice?
When the bile ducts are blocked so bilirubin has to diffuse through peripheral tissues, giving the a yellow color, which is apparent in the skin and over the sclera of the eyes
How is bilirubin disposed of?
Bacteria convert bilirubin to related pigments in the large intestines which are then excreted through urine. These related pigments can be converted to urobilin and stercobilin when exposed to oxygen.
What is iron generally bound to?
Iron is generally bound to transport or storage proteins
What happens to Iron in heme molecules after hemolyzation?
Iron from heme molecules may be stored in a phagocytic cell or released into the bloodstream
What does iron bind to in the bloodstream?
Transferrin
What protein complexes is iron stored in?
Ferritin and hemosiderin
When do embryonic blood cells appear in the bloodstream?
During the third week of development
Where does erythropoiesis take place?
Red bone marrow or myeloid tissue is the only place for erythropoiesis
What does red bone marrow need for erythropoiesis?
Red bone marrow needs adequate supplies of amino acids, iron, and vitamins for erythropoiesis
What is erythropoiesis stimulated by?
Erythropoiesis is stimulated directly by erythropoietin and indirectly by several hormones, including thyroxine, androgens, and growth hormone
When is erythropoietin released?
- During anemia
- Blood flow to the kidney declines
- Oxygen content of air in the lungs declines
- When the respiratory surfaces of the lungs are damaged
What are the effects of erythropoietin?
- Stimulates cell division rates in erythroblasts and in stem cells
- Speeds up maturation of RBCs
What is blood doping?
Blood doping is increasing the hematocrit of the blood, therefore increasing the viscosity of the blood, increasing the workload on the heart
