CATH Flashcards
Haematopoiesis
Haematopoiesis?
blood cell production
Blood volume of adults?
7%, 8% including bone marrow
Blood cells include…
erythrocytes, leucocytes, and platelets
Plasma contains…
proteins, electrolytes, substances absorbed from GI tract, hormones, and products of metabolism
Sites of haematopoiesis in foetus?
0-2 months = yolk sac
2-7 months = liver and spleen
5-9 months = bone marrow
Sites of haematopoiesis in infants?
bone marrow of all bones
Sites of haematopoiesis in adults?
vertebrae, ribs, sternum, skull, sacrum and pelvis, proximal end of femur
What is bone marrow?
soft, plumpy tissue that fills bone cavities
What does bone marrow contain?
network of blood vessels and fibres
What is bone marrow surrounded by?
fat and blood producing cells / haematopoietic cells
What do haematopoietic cells cluster around?
vascular sinuses that allow mature cells into blood
Blood precursor cells…
lie in close proximity to stromal cells
What does bone marrow stroma consist of?
a heterogenous population of cells that provide the structural and physiological support of haematopoietic cells
tissue that is not directly involved in the primary function of blood cells production
What is bone marrow stroma composed of?
stromal cells and microvascular network
What does bone marrow stroma form?
a suitable environment for stem cell growth and development
Stromal cells…
do NOT mature
Examples of stromal cells
adipocytes, fibroblasts, endothelial cells and macrophages
What do stromal cells secrete?
extracellular molecules such as collagen, glycoproteins (fibronectin and thrombospondin), glycosaminoglycans to form extracellular matrix
Constitutive haematopoiesis…
the normal generation of cells in the immune system in the bone marrow
inducible haematopoiesis…
extra production of cells in times of stress
Pluripotent cells…
appear as medium sized lymphocytes
capability of self-renewal
one stem cell is capable of producing 10^6 mature blood cells
Regulation of haematopoiesis requires…
growth factors = glycoproteins produced by the stroma
What actions do the growth factors have?
promotion of proliferation, differentiation, and maturation
changing functional activity
alter behaviour of cells by interacting with specific cell surface receptors
How are cells released from the bone marrow?
only mature blood cells contain the membrane proteins required for attachment and pass through the blood vessel epithelium
