haematology 1 Flashcards
what are the functions of the blood
- deliver nutrients to tissue
- removal of waste products
- transports - oxygen, carbon dioxide, hormones, heat
- regulates body fluid, pH, temperature and cell water content
- protects against excess loss by clotting and infection
what are the bloods components
cells - RBC,WBC and platelets and soluble factors eg. proteins and gases
plasma - add anticoagulant, centrifuge immediately and forms Buffy coat
serum - allow clot to form, more efficiently remove RBC
that is the scientific name for red blood cells
erythrocytes
what is the scientific name for white blood cells
leukocytes
what is the scientific name for platlets
thrombocytes
what is a factor
protein
what is the key fact about lymphocytes
- long lived - years
what is the scientific name for blood cell production
haematopoiesis
what cells differentiate into blood cells
pluripotent stem cells
what is the scientific name for the production of red blood cells
erythropoiesis
where do red blood cells originate from
myeloid stem cells
how are red blood cells formed
1) proerthrocytes ejects the nucleus to form reticulocytes ( immature RBC)
2) biconcave discs
where does erythropoiesis occur
bone marrow red pulp
how long to red blood cells live and how are dead ones removed
120 days
removed by spleen and liver
what happens when low O2 concentration is low
1) sensed by the kidneys which releases erthripoietin
2) stimulates differentiation of HSC to be converted into reticulocytes
what are the two types of white blood cells
- granular contain vesicles
- agranular - do not contain granules
what are the facts about neutrophils
- 70% of white blood cells
- short lived - 0.5-3 days
- granular cytoplasm with multilobular nucleus
- accumulate rapidly at sites of infection - phagocytosis and secretes enzymes
what are the facts about eosinophils
- short lived - 5-12 days
- most abundant in small intestine
- prominent cytoplasmic granules for immune response to helminths and parasites
what are the facts about basophils
- low numbers
- roles in allergy and autoimmune disorders
- granules contain heparin (anticoagulant), cytokines and lipid mediators
what do plasma, memory B cells and cytotoxic T cells do
plasma B- secrete antibodies
memory B - speed up subsequent response to infection
cytotoxic T - induce cell death of infected/ cancer cells
what is degranulation
- release of granule contents into extracellular space
what are the key facts about monocytes
- agranular myeloid cell in the bloodstream
- mobilised to inflammatory sites after neutrophils
- differentiate into tissue-resident macrophages
what are the key facts about platelets
- produced by splintering of megakaryocytes in red bone marrow
- HSC differentiate into MK and platelets controlled by thrombopoietin
- contain many vesicles but no nucleus
- facilitate blood clotting
- survive 5-9 days
what are the volumes of RBC, WBC and platelets
RBC- 4.8x106/μL (females)
5.4x106/μL (males)
WBC - 5-10x103/μL
platelets - 1.5-4x105/μL
what are the 3 stages of haemostasis
- sequence of response that stops bleeding
1) vascular constriction
2) platelet plus formation
3) blood clotting - coagulation
what are the two pathways in coagulation
- extrinsic and intrinsic
what occurs in vascular constriction
1) rapture in the endothelial lining could lead to blood loss
2) smooth muscle surrounding the endothelium constrict to prevent this happening
3) damaged endothelium secretes endothelin which binds to receptors on the smooth muscle cell initiating constriction
what are the functions of platelets
- haemostasis
- inflammation
- antimicrobial activity
- angiogenesis
- tumour growth
what are the families of receptors on a platelet
- intergins
- immunoglobin superfamily receptors
- selectins
- tyrosine kinse receptors
- transmembrane receptors
- lipid receptors
- prostaglandin receptors
how are platelets activated
1) activation of surface receptors increase calcium concentration in platelets
2) platelet conformational shape changer to spiny spherical shape
3) activated platelets release granule contents
4) increased platelet (CA2+) also stimulates membrane phospholipase A2 activity
5) Phospholipase A2 liberates arachidonic acid from membrane phospholipids
6) arachidonic acid is converted to prostaglandin H2 by cycloxygenase 1 (COX-1)
7) PGH2 is further metabolised to thromboxane A2 by thromboxane synthase
what does won willebrand factor do
- multimeric glycoprotein
- promotes platelet adhesion to expose collagen - temporary plug formation
- contains binding sites for platelets, glycoprotein receptors and collagen
what does serotonin (5HT) and TXA2 do
- induces smooth muscle contraction and platelet aggregation
what supports von willebrand factor
high molecular weight multimers
what are the quick and slow caogulation cascades
extrinsic - quick
intrinsic - slow
how are components in circulation
inert
describe the extrinsic pathway
1) ruptured blood vessel exposes tissue factor
2) tissue factor binds to factor VII forming TF-VII
3) TF-VII activates factor X to factor Xa aswell as factor IX to IXa
4) IXa activates factor X to Xa
- amplifying mechanism
describe the intrinsic pathway
1) ruptured blood vessels expose prekallikrein and high molecular weight kininogen and activates XIIa
2) XIIa activates factor XI into XIa
3) XIa activates factor IX to IXa
4) IXa activates factor X to Xa
describe the common pathway
1) begging with factor X produced in liver and is activated to Xa
2) Xa forms a dimer with factor Va to form prothrombinase
3) prothrombinase converts prothrombin (II) to thrombin (IIa)
4) thrombin converts fibrinogen to fibrin - cross links and stabilises clot
what is amplification in the common pathway
positive feedback loop
what is polymerised fibrin held together by
non covalent and electrostatic forces
what is the fibrinolytic system
small, unwanted clots dissolved by plasmin
what is vitamin K refried for in coagulation
normal clot formation
synthesis of 4 clotting factors
what does tissue factor pathway inhibitor inhibit
tissue factor
produced in epithelial cells
what does thrombomodulin do
- released by endothelium
- converts thrombin to inactive form
what does prostacyclin I2 do
- released by endothelium
- inhibits platelet activation
what does protein c do
- activated by thrombin
- inhibits V an VIII
what does antithrombin do
- inhibits IIa, Xa, IXa, XIa, XIIa
what does warfarin do
- tablets
- blocks formation of vitamin dependent clotting factors
- II, VII, IX, X
what is heparin and what does it do
- occurs naturally in the blood but also a drug
- activates antithrombin III to inactive thrombin to prevent formation of fibrin/ clot
what is haemophilias inheritance
- X linked recessive
- no son affected
- daughter is carriers
what is disseminated intravascular coagulation
- overactive clotting obstructs small vessels, decreased platelets and factors, excessive bleeding
what happens with overdevelopment of circulating anticoagulants
decreased clotting, similar symptoms to haemophilia
what happens with liver disease
- impaired liver function causes impaired production of clotting factors by liver parenchymal cells
what happens with a vitamin K deficiency
- impaired activations of zymogens for factor II (thrombin), VII, IX and X causing impaired clotting
what causes haemophilia A and B
A- VIII mutation and deficiency
B- IX mutation and deficiency
- prolonged bleeding, internal bleeding
