L12&13 - Blood & Body Fluids

Question 1

outline the phases of red cell production in the bone marrow

Answer 1

Haemocytoblast (stem cell)

→ proerythroblast

stimulated by erythropoietin

→ erythroblast

→ normoblast

nucleus expelled

→ reticulocyte

→ erythrocyte (released into blood)

Question 2

what happens when the kidneys detect low oxygen levels?

Answer 2

erythropoietin is secreted into the blood which increases mitotic rate and accelerates cell maturation
this means proerythroblasts mature into reticulocytes rapidly and enter the blood stream
larger number of RBCs in blood means increased oxygen delivery to tissues
return to homeostasis

Question 3

what do normal RBCs look like?

Answer 3

biconcave, non-nucleated, approx. same diameter as capillaries

Question 4

what nutrients are required for red cell production in the bone marrow?

Answer 4

• adequate nutrition
• protein
• vitamins e.g. folic acid
• hormone - erythropoietin

Question 5

what are reticulocytes?

Answer 5

fully matured RBCs that are released into the blood

Question 6

what is the function of RBCs?

Answer 6

transportation of oxygen and carbon dioxide
blood buffer - maintains pH 7.4

Question 7

what is the structure of a normal haemoglobin molecule?

Answer 7

4 polypeptide chains each linked to one Haem molecule, each haem contains one iron atom to which O2 associates

Question 8

what 2 factors contribute to the generation of the oxyhaemoglobin curve?

Answer 8

oxygen partial pressure and haemoglobin saturation

Question 9

what is the significance of the plateau on the oxyhaemoglobin curve?

Answer 9

the ‘plateau’ portion of the oxyhaemoglobin dissociation curve is the range that exists at the pulmonary capillaries (minimal reduction of oxygen transported until the PO2 falls below 60mmHg

Question 10

describe the breakdown of RBCs

Answer 10

• 120day lifespan (trapped in spleen)
• haem separates from globin, globin recycled as amino acids
• haem breakdown yields iron (recycled)
• other haem breakdown products yield biliverdin and bilirubin (taken to liver and secreted in bile)

Question 11

what is sickle cell disease?

Answer 11

genetic disorder, symptoms in children

Question 11

what is sickle cell disease?

Answer 11

genetic disorder, symptoms in children

Question 12

what is sickle cell haemolytic anaemia?

Answer 12

sickled cells are fragile - need for transfusions +++
cells become trapped in microcirculation - obstruct blood flow - ischaemia & severe pain, stroke, jaundice, resp symptoms

Question 13

what is the basis for major blood group classifications?

Answer 13

determined by the antigen present on red cell membrane

Question 14

why is group O negative the universal?

Answer 14

no antigens present - no reaction with patients plasma

Question 15

what might happen during a mismatched blood transfusion?

Answer 15

agglutination of patients RBC with haemolysis and release of Hb and K+ into circulation - kidney damage and liver damage

Question 16

what may happen during pregnancy if the woman is rhesus negative and the baby is rhesus postive?

Answer 16

• Rh- person will produce antibodies to antigen D if contact is made with Rh+ blood
  mother produces antibodies to the Rh antigen - if they remain in her circulation, she becomes sensitized