Blood

Blood

1. FUNCTIONS OF THE BLOOD

   • Transport
     • Transport gases CO2 and O2
     • Transports metabolic waste
     • Transports hormones
     • Transports nutrients
   • Regulation of pH and electrolyte concentration in the interstiual fluid
   • Limit fluid losses
   • Defence against toxins
   • Stabilizes body temperature

2. COMPOSITION OF BLOOD

   • Blood is madeup of two parts: the plasma and the cellllular elecments
     • Plasma
       • Water
       • Ions
       • Organic Molecules
         • These include amino acids, proteins, lipids, and nitrogenous waste
       • Gases such as O2 and CO2
     • Cellular Elements
       • White blood cells
       • Red blood cells
       • Platelets

3. RED BLOOD CELLS

   • Shape
     • Biconcave which gives it a good overall surface area allowing for maximum carrying of oxygen
   • Pigment
     • Contains haemoglobin protein which binds to oxygen. Haemoglobin is made up of two alpha and two beta chains. It is associated with a haem group
   • Role
     • The transport of Oxygen to cellls and removal of CO2 from cells
   • Formation (through haematopoiesis)
     • Pluripotent Heamatopoietic stem cell - Uncommited stem cell- Commited progenitor cells- Erythroblast- Recticulocyte- Erythrocyte
     • Low levels of O2 result in the production of EPO from the kidney, which stiumlates the bone marrow to produce RBC
   • Conditions
     • Anaemia
       • This is where not enough O2 is transported in the blood due to a lack of RBC or haemoglobin
     • Malaria
       • This is an infection spread by female mosquitos

4. WHITE BLOOD CELS (aka leukocytes)

   • Types
     • Main Tyoes
       • NEUTROPHIL- Phagocytic (engulf bacteria). First line of bacteria
       • LYMPHOCYTES- B and T cells which secrete antibodies
     • Other Tyoes
       • Monocytes, Eosinophil and basophil

5. HAEMATOPOIESIS (blood cell formation)

   • What is it?
     • This is the process by which stem cells in the bone marrow produce most white, all red blood cells and platellets
   • What is the process
     • Pluripotent hematopoietic stem cells form uncommitted stem cells.
       • These uncommited stem cells then form commited progenitor cells
         • After a series of further stages blood cells (erythrocyte) will be formed
           • These red blood cells will them slip through the endothelium into the bloodstream
     • This process occurs within the bone marrow

6. HAEMATOCRIT

   • What is it?
     • This is the measure the percentage of the blood which consists of red blood cells
   • How is it measured?
     • Centrifuging
       • 1) A sample of blood is collected in a capillary tube
       • 2) It is then centrifuged for 5 min at 10,000 RPM
       • 3.) The proportion of RBC is calculated against the total blood volume

7. HAEMOSTASIS

   • What is it?
     • Tries to prevent blood being lost from the body and forms clots aswell as repairing tissues
   • How does it work?
     • Check out haemostasis 1 by handwritten tutorials on youtube
     • Platlet formation
       • Exposed colllagen attracts plaetlets, these then release platelet factors attracting more platelet untila platelet plug forms
     • Fibrin Deposition
       • INTRINSIC PATHWAY- This is where there is a coagulition cascade in which activation of one factor leads to the activation of another factor until thrombin is produced. Thrombin then produces fibrin from fibrinogen. The fibrin stabilises the platelts
       • EXTRINSIC PATHWAY- The damaged tissue releases tissue factor which triggers a factor lower down in the coagulation cascade. The rest of the process is similar to the intrinsic pathway
   • Clonditons where haemostasis goes wrong includes haemophilia and thrombosis