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Roles of Blood

Removal ofwaste products

ThermoregulationDelivery ofnutrients

and oxygen

Composition

Cellular Components

• Erythrocytes (RBC)• Leucocytes (WBC)• Platelets

Plasma

• Water• Electrolytes• Proteins

55%

45%

+ dissolved nutrients and waste materials

Plasma

AppearanceStraw coloured liquid

ContentsWaterElectrolyteso Na+ (Sodium ions)o K+ (Potassium ions)o Ca2+ (Calcium ions)o Mg2+ (Magnesium ions)o Cl- (Chloride ions)o HCO3

- (Bicarbonate ions)o PO4

3- (Phosphate ions)Proteinso Albumino Immunoglobulinso Others

Function1.Transport nutrients

• Glucose• Amino acids• Fatty acids• etc.

2.Transport waste products• CO2

• Urea• Lactic acid

3.Homeostasis• Temperature• Acid-base balance• etc.

Erythrocytes

StructureBiconcave discPacked with haemoglobinNo nucleus

FunctionTransport of oxygen (and carbon dioxide)

Leucocytes

LymphocyteStructure: Small, little cytoplasm,

no RER (i.e. inactive)Function: Adaptive immunity

to viruses

Natural Killer cellStructure: Large, lymphocyte-like,

but with distinct granulesFunction: Destroys virus infected

cells

NeutrophilStructure: Multi-lobular nucleus,

granulesFunction: 1st line defense against

bacteria (Phagocytosis)

EosinophilStructure: Normally transparent,

stain brick red, granules.Function: Defense against parasites

BasophilStructure: Many large granules which

when stained obscure abi-lobular nucleus

Function: Probably similar to mast cells

MonocyteStructure: Large kidney-shaped

nucleus, granulesFunction: Develop into macrophages

on entering tissues, thenact by phagocytosis

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Platelets

Only little… …fragments of huge megakaryocytes

Function: Secrete growth factors which promote repairand regeneration of connective tissue.

Blood clotting

Where is blood made?

Bone marrow

InfantsMost bones

AdultsFemurPelvis

Sternum

Haematopoiesis Anaemia

DefinitionLevel of haemoglobin in blood lower than normal

Classification

NormocyticMicrocytic Macrocytic

Low Hb

Low MCV

Low Hb

Normal MCV

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

Iron Deficiency Anaemia

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

Sources

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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• Commoner in the Mediterranean

• Inherited abnormality of haemoglobin production

• Imbalance of various Hb chains = instability and haemolysis

• Some forms not compatible with life...

Thalassaemia Megaloblastic Anaemia

Vitamin B12 Folate

A very complex pathway

DNA synthesis necessary

for the production of red

blood cells

Vitamin B12

Bonds with a protein called

‘Intrinsic Factor’ in the stomach

and is absorbed in the terminal

end of the small intestine.

Not synthesised by plants or animals. It must be sourced directly or indirectly

from bacteria.

Dietary (indirect) sources: fish, meat, poultry, eggs, milk

Sources

Absorption

Folate

Upper small intestine.

Only a small amount stored in the body.

Metabolism is interfered with by a number of drugs.

Green leafy vegetables

Fortified cereals

Sources

Absorption

• 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

Sickle Cell Anaemia