7.8.9. Haematology Flashcards
What type of tissue is the Blood
Blood is a fluid connective tissue.
What is the average blood volume
5 decimeters cubed/ 5L
What percentage of our body weight does the Blood comprise?
7 percent
What percentage composition of the blood is plasma
55 percent of the blood is made up of plasma
Describe the percentage compositions of the blood
55 percent plasma
45 percent red blood cells
less than 1 % is White blood cells and platelets
Describe the composition of the blood plasma and its function.
92 percent water
7% plasma proteins - albumin, Globulin, Fibrinogen, regulatory proteins,
1% other solutes including electrolytes, organic nutrients and waste.
f(x) is transport of organic and inorganic ions
State the functions of the blood
Transport of gases, nutrients, waste products, temperature control.
Defense, contains antibodies, white blood cells and clotting factors.
What is the role of platelets
Form a platelet plug, prevent blood loss, and involved in the clotting process.
What is Hematopoiesis
This is the process by which red blood cells are formed.
The Hemocytoblast is what type of cell
A stem cell, that differentiates to produce all blood cells.
What does the Hemocytoblast differentiate into
Common myeloid progenitor
Common lymphoid progenitor
Myeloid cell line produces which cells
Megakaryocytes
Erythrocytes
Mast cells
Myeloblast - which differentiates and produces basophils, neutrophils, Eosinophils and monocytes.
Describe the stages of the cells involved in red blood cell formation and in order of their formation
- Hemocytoblast
- Proerythroblast
- Early erythroblast - ribosome synthesis
- Late erythroblast - haemoglobin synthesis
- Normoblast - Haemoglobin accumulates
- Shape changes and the nucleus shrinks and degenerates.
- Nucleus and organelles are ejected.
- Reticulocyte keep some ribosomes (blue)
- Cell can collapse inward becoming biconcave.
- Erythrocyte
Requirements for Haemoglobin Synthesis
- Iron
- Vitamins B12 & folic acid (B9)
- Intrinsic factor
- Amino acids
Where does erythropoiesis occur?
- Foetus - early in yolk sac, then liver & spleen
○ later in bone marrow - Infant - all bone marrow
- Adult - only red bone marrow (ribs, vertebrae, skull, upper ends of long bones)
Describe RBC structure
- Specific Shape and Size ○ Biconcave - Very strong - Highly flexible and can deform readily. - Red blood cell contents ○ Organelles - lost its organelles as it matured. ○ Haemoglobin - O2 binds - Main function - Lifespan - 120 days
Describe the life cycle of a red blood cell - breakdown and recycling
- After RBC has aged or become damaged, Macrophages in the liver, spleen, lymph nodes break it down.
- Haemoglobin broken down into heme and globin.
- Some components are recycled and some are degraded.
- Heme converted to bilirubin. Which is converted to bilirubin and serum albumin. This is picked up by liver and bilirubin is secreted as bile.
- Bile absorbed by intestine where it is metabolised into urobilinogen. This is excreted as stercobilinogen in the faeces.
- Iron in heme complex is recycled. It is combined with transferrin (transport protein) in the blood. Carried to the spleen for storage, or stored in the liver as ferritin.
- Iron goes back into circulation.
Causes of hypoxia
- Increase in exercise
- High altitude
- Smoking
- Bleeding
Describe Erythrocyte homeostasis
- Low O2 blood level detected in kidneys (stimulus)
- Kidneys increase production of erythropoietin
- In bone marrow, stem cells increase Red Blood Cell Production
- O2 blood level returns to normal
- Stimulus is resolved
At which stage in the pathway does a redblood cell loose its nucleus
During the normoblast stage
What happens if the reticulocyte is released prematurely.
More haemoglobin can be carried.
Is it possible to see reticulocytes during circulation
Yes, it is normal to be able to see up to 2 percent of reticulocyte
Under which situation would you see a lot of reticulocytes in the blood
If a person is anaemic, then lots of reticulocytes are released early to compensate for the loss of haemoglobin. Remember that anaemia is defined as a total hb concentration that is lower than normal range.
Where is intrinsic factor produced and what does it do.
in the stomach. IF attaches to the b12 vitamin
Where does red blood cell prodction occur in the infant
in ALL bone marrow
Where does red blood cell production take place in the Adult
Only in Red bone marrow.
Ribs, Vertebrae, Skull, upper ends of long bones.
Why can’t the red blood cells repair any damage that it may encounter over the course of its lifespan
no nucleus
What is the transport protein for Iron
Transferrin
What happens to damaged aged RBCs
They are broken down by macrophages in the liver spleen or lymph nodes.
When is Haemoglobin produced
Synthesis begins in the pro erythroblast stage
65% at the erythroblast stage
35% at the reticulocyte stage
Where is Iron and Transferrin Stored
spleen
Upon ingestion from a macrophage, what happens to the Haemoglobin in the RBC
- Hb is broken down into Heme and Globin
- Heme breaks down into bilirubin and iron
- Bilirubin is transported to the liver and secreted into the bile
- Iron is transported by transferrin back to the spleen for storage.
Describe the Structure of Haemoglobin
4 globin subunits
2 alpha subunits
2 beta subunits
Globin is a single polypeptide chain
Each blown subunit has a Haem group.
Haem Group has an Fe2+ ion that binds to oxygen reversibly
How much oxygen can one Hb molecule transport
4 Oxygen molecules
Megaloblastic anaemia can be detected due to which physical signs
abnormal enlarged red blood cells
macryocytic cells give rise to an increased mean cell volume
What are the causes of Iron deficiency anaemia
pregnancy
malnutrition
bleeding from GI tract
signs and symptoms of Iron deficiency anaemia.
Hypochromic RBCs due to loss of colour from Hb loss
microcytic cells
decreased mean cell volume
State the causes of sickle cell anaemia
genetic
recessive disease
State some signs of sickle cell anaemia
Malformed RBC shape, sickle shaped.
Abnormal Hb structure.
Thalasaemia causes and signs
genetic
abnormal Hb production
During which stage of Eryhtocyte formation is the cell commited to its fate
during pro erythroblast stage
During which stage of Erythrocyte formation is ribosome synthesis
ribosome synthesis
Describe the structure of a platelet.
- Small, oval, no nucleus
- 2-3µm diameter
- contain granules Megakaryocyte cytoplasm
Platelet production is controlled by what?
- no. of circulating platelets (negative feedback),
- thrombopoietin (TPO) release (increase platelet numbers).
○ When low level of platelets increased production TPO
Define Platelet aggregation
Platelet aggregation - platelets clump together and form primary platelet plug, where the stable fibrin clot will form.
Describe the Extrinsic Pathway of Coagulation of platelets.
- Initiated by exposure of tissue factor on the surface of damaged blood vessel. TF exposed to circulation.
- TF comes into contact with inactive clotting factors.
- Binds to Factor VII=
Tissue Factor-FVIIa complex - This complex binds to FX and activates it become FXa
Describe the Intrinsic Pathway of Coagulation of platelets.
- Negatively charged collagen surface activates clotting factors that it comes into contact with.
- Factor XII is activated = Factor XIIa
- Factor III (PF-3) release by aggregated platelets that form on surface of damaged blood vessel.
- Activation of Factor IX and co-factor VIII
- Activates FX = Fxa
Describe the Common Pathway of Coagulation of platelets.
- Both pathways join
- Factor V and it co-factor (FV) forms the prothrombinase complex.
PROTHROMBINASE:
- Consists of FXa and FVa as a co-factor
- Activates prothrombin to form THROMBIN
- THROMBIN converts FIBRINOGEN to FIBRIN
Role of Calcium and Potassium in the clotting process
- Affect almost every aspect of clotting process
- Any disorder that decreases Ca2+ concentration will impair blood clotting
- Adequate vitamin K necessary for production of certain clotting factors in the liver including prothrombin
How is clotting controlled?
Plasma has natural anticoagulants.
- Antithrombin – inhibits thrombin (among other factors)
- Heparin – released by basophils and mast cells – co-factor that accelerates actions of Antithrombin
Describe Fibrinolysis
- Fibrinolysis- fibrin clot is broken down
- Main enzyme – plasmin
- Produces fibrin degradation products
How are RBCs broken down?
- If blood cell with surface antigens come into contact with opposing antibodies the antibodies will bind to the surface antigen.
- The RBC will clump together (agglutination)
- Hemolysis will occur - broken down.
How are blood groups inherited?
- A and B genes are dominant
- O gene is recessive
Describe haemolytic disease of the newborn - Rhesus (D)
- Haemorrhaging at delivery causes blood to mix.
- Presence of Rh+ blood in mothers blood causes mothers body to produce antibodies, against the babies blood cells.
- In first pregnancy this is okay as the antibodies take 72hrs to accumulate. Baby is delivered before antibodies get into its system.
- In second pregnancy it’s more difficult, as the antibodies stay in the mothers system. If antibodies cross the placenta at delivery then they attack the baby’s RBCs and destroy them (haemolysis).
- This causes significant anaemia.
What is the Buffy coat?
Layer that exists between RCB at the bottom and the plasma at the top. Where you find WBC and platelets.
Where are lymphocytes produced?
Lymphocytes are produces by common lymphoid progenitor.
Name WBC granulocytes
Neutrophils (50-70%)
Eosinophils (2-4%)
Basophils (<1%)
Name the WBC agranulocytes
Lymphocytes (20-30%)
Monocytes (2-8%)
What are roles of Leukocytes (WBCs)
- defence vs pathogens
- remove toxin & waste
- remove damaged cells
- Act mainly outside in tissues (in transit between sites of activity)
Describe the structure and function of Neutrophils.
Structure:
- 9-15µm diameter (12 rim)
- distinctive nucleus, 2-5 lobes (multilobed), granular cytoplasm
Function:
- first line of defence against bacterial infection
- Phagocytic
- Mobile
- Circulate in blood for approx. 10 hours
- Major constituent of pus
Describe the structure of Eosinophils.
Structure:
- 10-12µm diameter
- Bilobular nucleus
- Distinct granules (granulocytes)
They have large acidophilic cytoplasmic granules. - appear red when stained with eosin
Describe the function of Eosinophils.
Function:
- Circulate in blood approx. 8-12 hours migrate to tissues - Protection
- Survive approx. 1-3 days in tissues
- Release toxic compounds, e.g. NO and cytotoxic enzymes
- Allergies, asthma
- Combat parasitic infections
- Also attack bacteria, protozoa, debris
- Increase in number when having allergic reaction, or has asthma.
- Eosinophilia - large number of eosinophils.
Describe the structure of Basophils.
Structure:
- 8-10µm diameter
- Bibbed “S” shaped nucleus, large cytoplasmic granules
- Granules - histamine, heparin
Describe the function of Basophils.
Function:
- Inflammatory response
- Lifespan unknown
- Maybe precursors to mast cells-share a common bone marrow precursor
Describe the structure of Monocytes.
Structure:
- Largest white cell,
- Up to 20µm diameter
- Large kidney/horse shoe shaped nucleus,
- Extensive cytoplasm
Describe the function of monocytes
Function:
- Little function in blood
- migrate out of circulation after 3-4 days
- Reside in the tissues as macrophages (several months-years)
- phagocytic
Describe Structure of Lymphocytes.
- Smallest white blood cell,
- 6-15µm diameter
- Lifespan: weeks to several years (variety depending on type of cell)
Describe the function of Lymphocytes.
- Central role in all immunological defence mechanisms
- Circulate between various lymphoid tissues and all other tissues of body via blood and lymphatic vessels
Name the 3 types of lymphocytes.
- T cells — mediates cell-mediated immunity (e.g. transplant rejection)
- B cells — differentiate into plasma cells; secrete antibodies (humoral immunity)
- NK cells - “immune surveillance” - important in preventing cancer
What is Lymphocytosis?
where there is an increased number of lymphocytes. Could be due to a viral infection as they are the first to respond.
