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04/05/2011

Roles of Blood

Delivery of nutrients and oxygen

Composition Cellular Components

• Water • Electrolytes • Proteins

• Erythrocytes (RBC) • Leucocytes (WBC) • Platelets 55% 45%

+ dissolved nutrients and waste materials

Structure Biconcave disc Packed with haemoglobin No nucleus

Function Transport of oxygen (and carbon dioxide)

Thermoregulation

Plasma

Plasma

Erythrocytes

Removal of waste products

Appearance

Function

Straw coloured liquid

1.Transport nutrients • Glucose • Amino acids • Fatty acids • etc. 2.Transport waste products • CO2 • Urea • Lactic acid 3.Homeostasis • Temperature • Acid-base balance • etc.

Contents Water Electrolytes o Na+ (Sodium ions) o K+ (Potassium ions) o Ca2+ (Calcium ions) o Mg2+ (Magnesium ions) o Cl- (Chloride ions) o HCO3- (Bicarbonate ions) o PO43- (Phosphate ions) Proteins o Albumin o Immunoglobulins o Others

Leucocytes Lymphocyte Structure: Small, little cytoplasm, no RER (i.e. inactive) Function: Adaptive immunity to viruses

Neutrophil Structure: Multi-lobular nucleus, granules Function: 1st line defense against bacteria (Phagocytosis)

Natural Killer cell Structure: Large, lymphocyte-like, but with distinct granules Function: Destroys virus infected cells

Eosinophil Structure: Normally transparent, stain brick red, granules. Function: Defense against parasites

Monocyte Structure: Large kidney-shaped nucleus, granules Function: Develop into macrophages on entering tissues, then act by phagocytosis

Basophil Structure: Many large granules which when stained obscure a bi-lobular nucleus Function: Probably similar to mast cells

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04/05/2011

Platelets

Where is blood made? Bone marrow

Only little…

…fragments of huge megakaryocytes

Infants

Adults

Most bones

Femur Pelvis Sternum

Function: Secrete growth factors which promote repair and regeneration of connective tissue. Blood clotting

Haematopoiesis

Anaemia Definition Level of haemoglobin in blood lower than normal

Classification

Iron Deficiency Anaemia Sources

Microcytic Low Hb Low MCV

Normocytic Low Hb Normal MCV

Macrocytic Low Hb High MCV

MCV = Mean Corpuscular Volume – just a way of saying how big it is Possible Causes Iron-deficiency Thalassaemia

Possible Causes Acute blood loss Malignancy Infection Inflammation

Possible Causes Vit B12 deficiency Folate deficiency Alcohol abuse Hypothyroidism Bone marrow dysfunction

Meat, liver, green vegetables, flour, eggs… lots!

Causes Chronic blood loss • Gastrointestinal bleeding • Heavy periods Dietary inadequacy • Uncommon, can be at lower limit then exacerbated by increased demand Failure of iron absorption • Drug interaction • Malabsorption diseases, e.g. Coeliac disease Excessive requirements • Growth spurts • Pregnancy

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04/05/2011

Thalassaemia

Megaloblastic Anaemia

• Commoner in the Mediterranean • Inherited abnormality of haemoglobin production • Imbalance of various Hb chains = instability and haemolysis • Some forms not compatible with life...

Vitamin B12

Folate

A very complex pathway

DNA synthesis necessary for the production of red blood cells

Vitamin B12

Folate

Sources Not synthesised by plants or animals. It must be sourced directly or indirectly from bacteria. Dietary (indirect) sources: fish, meat, poultry, eggs, milk

Sources Green leafy vegetables Fortified cereals

Absorption Bonds with a protein called ‘Intrinsic Factor’ in the stomach and is absorbed in the terminal end of the small intestine.

Absorption Upper small intestine. Only a small amount stored in the body. Metabolism is interfered with by a number of drugs.

Sickle Cell Anaemia • Autosomal recessive mutation • Forming sickle cell haemoglobin (HbS) • Easily destoryed = haemolytic anaemia • Common in West Africans and Afro Caribbeans as being a carrier, protects against malaria

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Stage 1 Haematology