Blood Cells Flashcards
(19 cards)
What is haematopoiesis?
Where do all blood cells originate from?
Haematopoiesis is the production of all blood cells.
All blood cells originate from pluripotent stem cells in the red bone marrow
In babies haematopoiesis is performed by the embryonic yolk sac. 2-9 months it is carried out by spleen and liver.
In adults haematopoiesis occurs in vertebrae, ribs, sternum, skull, sacrum, pelvis and proximal long bones (mostly femur)
Name blood cells.
Erythrocytes (red blood cells)
Leukocytes (white blood cells)
Thrombocytes (platelets)
What is haematocrit?
The percentage of total blood volume occupied by erythrocytes.
Female = 42%. Lower because of menstruation Males = 47%
What is haemoglobin?
Hemoglobin is the protein molecule in red blood cells which carries mostly o2 & co2
Hemoglobin is made up of four protein molecules (globulin chains) that are connected together.
Define the structure of erythrocytes?
Each erythrocyte has 280 million haemoglobin molecules
A haemoglobin molecule is made up of 4 polypeptide chains. (Globin). Each chain is bound to a pigment called harm which contains iron
Each haemoglobin can carry up to 4 oxygen molecules.
How is adult and foetal haemoglobin different?
Adult haemoglobin (HbA) is composed of two alpha and two beta subunits
Foetal haemoglobin (HBF) is composed of two alpha and two gamma subunits
Explain the meaning of erythropoiesis.
It is the formation of erythrocytes which occurs in the red bone marrow
B12, folic acid and iron all required for RBC formation
Why is blood red?
Blood appears red due to the interaction of iron and oxygen within haem units.
What is haemolysis?
The destruction/breakdown of RBCs.
RBCs normally survive 90-120 days
Which tissues carry out Haemolysis and how does it occur in the body?
Haemolysis is carried out by macrophages (phagocytic cells) in spleen, bone marrow and liver.
When haemoglobin splits globin amino acids and iron are recycled by the body.
What is the yellow coloured pigment formed from haem catabolism called which is excreted in bike and urine?
Bilirubin
Bilirubin is made in the body when old red blood cells are broken down. The breakdown of old cells is a normal, healthy process. After circulating in your blood, bilirubin then travels to your liver. In the liver, bilirubin is excreted into the bile duct and stored in your gallbladder.
What stimulates erythropoiesis?
Hypoxia (lack of oxygen) stimulates the secretion of hormone erythropoietin (EPO) which stimulates erythropoiesis in bone marrow.
After birth, where does erythropoiesis take place?
The liver produces EPO.
Liver less sensitive to hypoxia so smaller response to anaemia.
What is the function of leukocytes?
Defend the body from microbes and foreign particles
Granulocytes (no granules in their cytoplasm)
Describe the three types of granulocytes and their primary function
Basophils/mast cells (1%)
Function: Contain heparin & histamine which cause inflammation Not chemotaxic (won't move down concentration gradient)
Neutrophils (60%)
Function: phagocytosis (ingest and destroy bacteria and fungi). First on scene of infection
Eosinophils (2-4%)
Function: eliminate parasites. Predominant inflammatory cells in allergic reactions. Migrate to allergic site. Phagocytosis
Agranulocytes (no granules in cytoplasm)
Describe the two types of agranulocytes and their function
Monocytes/macrophages
Function: inflammation & repair through phagocytosis & chemotaxis. Secretes cytokines
Lymphocytes
Function: manufacture certain anti-bodies
B-lymphocytes, T-lymphocytes, natural killer cells.
B-lymphocytes activate immune response via antibody formation
T-lymphocytes & NK cells kill abnormal/invading pathogens
What is the function of thrombocytes and what hormone produces it?
Thrombocytes are involved in. Looks clotting and preventing blood loss.
Produced under influence of thrombopoietin from liver. Life span 10 days.
Explain the 4 stages of blood clotting.
- Vasoconstriction: when collagen exposed in vascular endothelium, thromboxane release causing vascular spasm and attracting platelets
- Platelet plug formation: platelets stick to damaged wall, activated and release binding proteins. Lead to platelet aggregation (becomes sticky)
- Coagulation: clotting factors form clot. Thrombin produced which converts fibrinogen into fibrin. Fibrin produce mesh in clot and erythrocytes become caught and clot formed.
- Firbinolysis: breakdown of clot. Plasmid dissolves clot by digesting fibrin threads and inactivating fibrinogen and thrombin.
Which vitamin is an important anti-coagulant?
Vitamin K - fat soluble and responsible for making 4 clotting factors. Produced by gut bacteria.
