INTS2 - The Haematopoietic System Flashcards
Define the haematopoietic system
System of organs and tissues involved in the production and maintenance of cellular blood components, including the bone marrow, spleen, thymus and lymph nodes.
Define embryonic development.
Beginning of cell and tissue development during embryonic life which covers conception to birth.
Define foetal development.
Organ formation within an embryo.
Define stem cells.
Undifferentiated cells that can differentiate into specialised cells but also main the ability to divide, through mitosis, to form more stem cells. Found in multicellular organisms.
Define bone marrow.
Tissue located in the cavity of some bones. Location of haematopoietic tissue and cell development. Commonly located in large bones e.g. femur and pelvic bones.
Define peripheral blood.
Fluid circling in veins and arteries which carries main cells allowing oxygen distribution by red cells, immunity provided by lymphocytes, antibacterial defence provided by granulocytes and fluid distribution.
Define what lymphocytes are.
Cells originating in bone marrow and are transferred to lymphoid tissues e.g. thymus, spleen and lymph nodes.
Define terminology for low and high levels of lymphocytes.
Low - lymphocytosis.
High - lymphocytopenia.
Define what granulocytes are.
Granule containing cells - include eosinophils, basophils and neutrophils. Involved in bacterial and parasite defence.
Define terminology for low and high levels of granulocytes.
Low - granulocytosis.
High - granulocytopenia.
What are the two main cell lineages from a HSC.
Myeloid and lymphoid.
Where does HSC proliferation occur in embryos.
Foetal liver.
What are the three layers of the yolk sac.
Ectoderm, mesoderm, endoderm.
Which layer of the yolk sac, results in the development of the haematopoietic system.
Mesoderm.
What cells are produced by the ectoderm.
Epidermis (skin)
Brain neurons
Pigment cells
What cells are produced by the mesoderm
Muscle - cardiac and skeletal (smooth in gut)
Tubule cells of kidney
Red blood cells
What cells are produced by the endoderm.
Lung cells.
Thyroid cells.
Pancreatic cells.
Define embryogenesis.
First 8 weeks of development following fertilisation .
What are osteoblasts
Bone forming cells.
What are Chondrocytes.
Cartilage cells.
Discuss the AGM system
Aorta-gonad-mesonephorns are a region of the mesoderm constituting the dorsal aorta and the gonad regions.
What are the first two sites of haematopoiesis in a developing foetus.
Yolk sac and dorsal aorta.
Discuss the process by which haematopoiesis occurs in different locations
First sites in embryo are dorsal aorta - part of AGM, and the yolk sac.
Develops to the foetal liver which then migrated to the bone marrow upon bone formation.
What are hemogenic endothelial cells.
Cells in dorsal aorta with ability to differentiate into haematopoietic cells.
What is the primary haematopoietic organ.
Foetal liver.
Discuss formation of embryonic stem cells from the endothelial cells of dorsal aorta.
Cells start to ‘bud’ off which is a type of asexual reproduction.
Can adult liver be a site of haematopoiesis.
Only under stress or leukaemia. Works with the spleen.
What are progenitors in cell differentiation.
More differentiation than a stem cell however not fully differentiated yet. Will always differentiate into its specific target.
What are the possible sites where HSCs (differentiated or not) from the foetal liver go to.
Spleen. Thymus. Bone marrow.
Discuss primitive or primary haematopoiesis.
HSCs originating in the yolk sac the dorsal aorta of embryos.
Discuss definitive/secondary haematopoiesis.
Liver is colonised as site of haematopoiesis by circulation of cells from dorsal aorta and yolk sac. Eventually, bone marrow is established as definitive site of haematopoiesis
What are immature early versions of cells called.
End in -blasts
What are mature versions of cells called.
End in -cytes or -phils
How can cells in bone marrow and peripheral blood be differentiated in a normal healthy human.
Bone marrow has homogeneity. Contains early immature versions of cells which are similar. Peripheral blood has heterogeneity. Contains fully differentiated haematopoietic cells. Will not contain immature cells.
Define common name for leukocytes. What are the two main type song leukocytes.
White blood cells. Granular and non-Granular.
What are the granular leukocytes.
White blood cells containing granules. Eosinophils. Basophils. Neutrophils. Mast cells.
What are the non granular leukocytes.
B and T lymphocytes. Natural killer cells. Monocytes.
Discuss appearance of red blood cells under a microscope. Provide explanation for appearance.
Light in the middle, dark on periphery. Haemoglobin, giving the red colour, is concentrated on periphery, therefore appears darker.
Discuss appearance of neutrophil.
Segmented nucleus. Neutral staining granules.
Discuss appearance of basophils.
Blue staining granules. Kidney bean shaped nucleus.
Discuss appearance of eosinophils.
Nucleus in two pieces. Red granules found in cytoplasm.
Discuss link between megakaryocytes and thrombocytes.
Megakaryocytes are large cells. Cytoplasms breaks off the form thrombocytes e.g. platelets.
Discuss nucleus in a monocyte.
One large kidney bean shaped nucleus.
What two types of growth factors stimulate HSC differentiation.
Cytokines and interleukins.
What types of cells are in the bone marrow.
HSCs. Adipose tissue. Stromal cells. Endothelial cells of blood vessels. Bone matrix.
Why is bone marrrow highly vascularised.
Contains many blood vessels to aid movement of differentiated HSCs into circulation.
What is the role of stromal cells in bone marrow,
Source of growth factors which aid HSC differentiation.
What is a bone marrow aspirate and when is it carried out.
Extraction of bone marrow sample for observation if abnormal blood cells are observed in blood sample.