15,16-Basic Haemotology Flashcards
standard blood smear ?
WBC-pink coloured cytoplasm adn purple coloured nuceli
RBC-no nuclei
Platelets-purple coloured cell fragments
Function of blood ?
Transport (/communication):
o Nutrients from (GI) tract, or hormones, to the tissues; (respiratory) gas transport between lungs &
tissues; removal of metabolic waste products
* Regulation:
o Homeostasis of the internal environment: maintaining body
temperature blood/fluid volume in the circulatory system.
* Protection:
o Preventing blood loss (→ clot formation → stop bloodloss); preventing infection : defends
the body against foreign organisms
Blood plasma and formed elements ?
o Include erythrocytes, i.e. red blood cells (RBCs), leukocytes, i.e. white
blood cells (WBCs) and thrombocytes, i.e. platelets.
* One can show the nature of the suspension via centrifugation → heavier RBCs are ‘packed’ at bottom; plasma seen as clear, pale-yellow fluid at top.
Plasma proteins in plasma ?
lbumins (~60% of total plasma protein):
o Synthesised by liver; aid lipid, and steroid hormone transport.
o Body fluid balance: provide most of the colloid osmotic pressure
o Many drugs bind to albumins: affects their ‘free’ concentration.
* Globulins (~40%):
o Further subdivided into α, β and γ-globulins: α & β are made in
liver, help transport lipids & fat-soluble vitamins in blood; γ are
antibodies (by lymphocytes) → defend body against infection.
* Clotting factors (<5%; involved in coagulation):
o Fibrinogen (factor I; accounts for 2-4%) produced by the liver.
What are RBC ?
most abundant cell type in blood:
o Small, circular, biconcave discs (7-8 μm diameter); have no nucleus.
* Chief function is to carry the respiratory gases around body; haemoglobin protein binds O2
Haematocrit ratio: proportion of total blood volume occupied by RBCs/erythrocytes:
* Blood viscosity (i.e. its resistance to flow)
What are 5 classes of WBC ?
- Neutrophils
- Eosinophil
- Basophil
- Lymphocytes
- Monocyte
2 main categories of WBC ?
Granulocytes: lobed nuclei; large cytoplasmic granules:
1. Neutrophils: granules stain with both acidic & basic dyes.
2. Eosinophils: granules stain red with acidic dyes (e.g. Eosin).
3. Basophils: granules stain dark purple with basic dyes.
Agranulocytes: nuclei that are not lobed; no granules
1. Lymphocytes (B- & T-lymphocytes).
2. Monocytes; largest WBC; long-lived (months).
What are the prinicples of diapedis ?
When infection triggers a mast cell or
macrophage to secrete chemicals,
translocate P-selectin to cell surface.
* Circulating neutrophil (or other WBC)
meets P-selectin (adhesion molecule),
it slows & meets the cytokine (red) →
activation of integrins (blue) →
neutrophil then attaches to the cell.
* Via amoeboid movement, neutrophil
migrates (in)to site of infection.
What are platelets ?
minute fragments of cells; consist of very little cytoplasm, surrounded by a plasma membrane:
o Formed in bone marrow; ‘bud’ off cytoplasm of megakaryocytes.
o Normal blood smear: appear as densely staining small particles.
o Normally do not contain a nucleus
important role in control of bleeding
Platlets aggregation and clot retraction
What is Haematopoiesis ?
formation of blood cells
continuously renewed by haematopoiesis:
o All blood cell types are generated from a common population of
multipotent stem cells in red bone marrow (adult):
o Erythropoiesis→ new erythrocytes (RBCs).
o Leucopoiesis → new leucocytes (WBCs).
o Thrombopoiesis → new thrombocytes (platelets).
RBC lifespan ?
120 days
Type II diabetes screening tests include: random or fasting blood glucose
levels and checking glycated haemoglobin, i.e. HbA1c levels
Major disorders of RBC ?
Anaemia: variety of blood disorders characterised by a reduced
number of RBCs (reduced haematocrit), reduced [haemoglobin], or
both → reduction in O2-carrying capacity of blood.
Sickle cell anaemia: defect in 1 of the haemoglobin chains; sickle haemoglobin (HbS) is transmitted by
recessive inheritance:
o Homozygotes: HbS becomes ‘sickled’ when deoxygenated → deformation of RBCs.
* Deformed RBCs clump together; obstruct blood flow → tissue hypoxia (lack of O2); pain.
* The ↑ risk of blood clot formation primarily will affect the liver, spleen, heart and kidneys.
What is Haemostasis ?
prevents blood loss
Platelets are essential for the clotting process: they ‘stick’ to the damaged site (in/on plasma side) → ‘sticking’ action helps forms a temporary plug
What are the 3 steps involved in Haemostasis ?
- Vascular spasm / vasoconstriction: when vascular endothelium is damaged, causes blood vessel to narrow; short duration.
- Platelet aggregation & plug formation: Within seconds of injury, platelets begin to accumulate & adhere to the damaged site: platelets become attached to extracellular matrix via integrin receptors (activated by e.g. collagen) → platelets get activated → change their morphology: become more elongated, filopodia present → stick to each other & to damaged site: this requires
- Blood coagulation :fibrinin stands ceate a mesh–>blood components form a clot
What are clotting factors ?
are normally
present in plasma, in their
inactivated form.
* In general, have many names
and/or roman numerals..!
1 activated clotting factor goes on
to activate another, as shown:
Activated factor
↓
Inactive factor → Active factor
