Haemopoiesis

Question 1

Where does haemopoiesis occur?

Answer 1

Bone marrow (also occurs in embryonic liver before birth)

Question 2

What are the main sites of haemopoiesis in adult marrow?

Answer 2

Sternum, skull, ribs and vertebrae

Question 3

What is haemopoiesis?

Answer 3

Production of blood cells - all types

Question 4

What are the 2 important hormones involved in haemopoiesis and where are they secreted?

Answer 4

• Erythropoietin secreted by kidney, stimulates RBC production.
• Thrombopoietin produced by liver and kidney, regulates production of platelets..

Question 5

What is the lifespan of a red blood cell?

Answer 5

Approximately 120 days

Question 6

what are some of the functions of RBC (5)?

Answer 6

• deliver O2 to tissues
• carry haemoglobin
• maintain haemoglobin in its reduced state
• maintain osmotic equilibrium
• generate energy

Question 7

What does an excess of unconjugated bilirubin (hyperbilirubinaemia) in the blood cause?

Answer 7

Jaundice - yellowing of the skin and eyes

Question 8

What gives faeces its brown colour?

Answer 8

Stercobilin

Question 9

What gives urine its yellow colour?

Answer 9

Urobilin

Question 10

What are the functions of neutrophils?

Answer 10

First-responder phagocytes

Question 11

What do the suffixes -philia and -penia mean?

Answer 11

—philia = increase
—penia = decrease

Question 12

What is the role of monocytes?

Answer 12

Phagocytose microorganism and breakdown/remove cellular debris

Question 13

What is there of eosinophils?

Answer 13

• Responsible for immune response against multicellular parasites
• mediator of allergic responses
• phagocytosis of antigen-antibody complexes
• inappropriate activation responsible for tissue damage and inflammation

Question 14

What is the function of basophils?

Answer 14

Active in allergic reactions and inflammatory conditions

Question 15

What are the roles of the spleen and liver in the reticuloendothelial system?

Answer 15

To remove dead or damaged cells and identify and destroy foreign antigens in blood and tissues

Question 16

What are the functions of the spleen in adults

Answer 16

• Sequestration and phagocytosis (removal and degradation)
• Blood pooling
• extramedullary haemopoiesis
• immunological function

Question 17

What are some potential causes of splenomegaly?

Answer 17

• Back pressure - portal hypertension in liver disease
• over work (red or white pulp)
• reverting to what it used to do - extramedullary haemopoiesis
• expanding as infiltrated by cells (cancer cells of blood origin or other cancer metastases)
• expanding as infiltrated by other material (sarcoidosis (granulomas))

Question 18

Can the spleen be felt in a normal patient?

Answer 18

No - spleen should be protected by ribs

Question 19

What are some causes of hyposplenism?

Answer 19

• Splenectomy (due to spleen injury)
• sickle cell disease (due to increased breakdown of blood cells)
• gastrointestinal diseases e.g. coeliac disease
• autoimmune disorders e.g. rheumatoid arthritis

Question 20

What advice should be given to patients with splenomegaly?

Answer 20

Avoid contact sports and vigorous activity (spleen is at risk of rupture as it isn’t protected by rib cage)

Question 21

Why may low blood counts be found in patients with splenomegaly?

Answer 21

Pooling of blood in enlarged spleen

Question 22

What are patients with hyposplenism at risk of? How is this guarded against?

Answer 22

Patients with hyposplenism are at risk of sepsis from encapsulated bacteria e.g. streptococcus pneumonia, haemophilus influenzae, meningococcus

Patients must be immunised and given life long antibiotic prophylaxis