Lecture 6- Blood Flashcards
Transport functions of blood
delivery of oxygen and nutrients, transport of metabolic wastes for elimination, and transport of hormones.
Regulatory functions of blood
maintaining body temperature, maintaining pH and maintaining fluid balance.
Protective functions of blood
preventing blood loss and fighting infections.
What are the three layers of blood?
Blood plasma and dissolved elements
Buffy coat (white blood cells and platelets)
Erythrocytes (red blood cells)
What does blood hematocrit represent?
Percentage of erythrocytes in whole blood
Low hematocrit - lack of RBCs (anemia)
High hematocrit- elevated number of RBCs (polycythemia)
What does blood plasma consist of?
mostly water (90%) and solutes including nutrients, gases, hormones, wastes, products of cell activity, ions, and proteins.
What are the Formed elements of blood?
erythrocytes (red blood cells)
leukocytes (white blood cells)
platelets
leukocytes are complete cells: erythrocytes have no nucleus, and platelets are cell fragments.
Erythrocytes
small cells that are biconcave in shape, lack nuclei and most organelles, and contain mostly hemoglobin
size and shape of erythrocytes provide a larger surface area for gas exchange
Hemoglobin
protein consisting of four polypeptide chains, globin proteins, each with a ring-like heme
Each heme contains an iron atom that oxygen binds to
Oxyhemoglobin
Oxygen diffuses into the blood in the lungs and binds to hemoglobin, forming bright red blood
Deoxyhemoglobim
At body tissues, oxygen detaches from iron, forming dark red blood
Carbaminohemoglobin
When carbon dioxide carried in the blood is bound to amino acids on the globins
Arterial blood gas analysis
Only done for critical illnesses or respiratory disease
mostly used to determine how well gas exchange is functioning in the lungs
Pulse oximetry
estimates percentage of hemoglobin that is oxygen-saturated based on the absorption of light at two different wavelengths
Hematopoiesis
Blood cell formation
Occurs in red bone marrow
Myeloid stem cells
able to make platelets, erythrocytes and some kinds of leukocytes
Lymphoid stem cells
Able to make lymphocytes
Erythropoietin
formation of erythrocytes, begins when a hematopoietic stem cell is transformed to a proerythroblast.
Reticulocyte
Immature erythrocyte
ejects most organelles, the nucleus degenerates, and the cell assumes its biconcave shape.
What controls erythrocyte production?
Hormone erythropoietin ( produced in kidneys)
What triggers erythropoietin production?
loss of red blood cells
insufficient hemoglobin
reduced availability of oxygen
Dietary requirements for erythrocyte formation
iron
vitamin B12
and folic acid
proteins
lipids
carbohydrates.
Anemia
Deficiency in red blood cells
What can cause anemia?
Blood loss (hemorrhagic anemia)
Not enough red blood cells produced (iron deficiency)
Too many red blood cells destroyed (sickle cell anemia)
Polycythemia
excess of red blood cells due to oxygen deficiency or disease
What happens when erythrocytes die or are destroyed?
Heme is split from globin
globin is broken down to amino acids
iron from heme is salvaged.
What remains of the heme is degraded to bilirubin, which isultimately secretes in bile to the intestine for removal from the body.
Blood doping
artificially inducing polycythemia to try to get an advantage in athletic competitions, typically by injecting synthetic erythropoietin.
High altitude training can also cause temporary polycythemia.
