Unit 2A Human Form & Function

1. Unit 2AHuman Form & Function Body systems Blood

2. Study Guide Read: • Text Chapter 9 Complete: • RQ 1-12 • AYK 5&6

3. The circulatory system Blood

4. Functions of blood • Transport • Transports nutrients, oxygen and hormones to the tissues. • Removes wastes such as carbon dioxide and urea.

5. Regulation • Helps to keep the body’s pH within its homeostatic range. • Helps in regulating the body's temperature.

6. Protection • Prevents blood loss if blood vessels are damaged. • Protects the body against pathogens and toxins.

7. Features of blood • Temperature 380C • pH 7.35-7.45 • Salinity 0.9% • Total body weight 8% • Volume Men 5-6 L, Women 4-5 L

8. Composition ~1% ~4% ~40% ~55%

9. Blood plasma • Plasma is a clear, pale yellow liquid which comprises 46-63% of the whole blood • Plasma consists of:water (92%) dissolved organic and inorganic solutes (e.g. sodium & chloride ions, nutrients & wastes) (1%)dissolved plasma proteins (7%)

11. Formed elements Red blood cells White blood cells Blood platelets

12. Red blood cells EM unit / Royal Free Medical School, Wellcome Images

13. White blood cells Neutrophil Basophil Eosinophil Monocyte

14. Clotting of blood David Gregory& Debbie Marshall, Wellcome Images

15. Clotting of blood • A blood clot is a jelly-like mass that forms at the site of a wound to stop bleeding. • A clot consists of a mesh of long, stretchy protein fibres, and trapped blood cells.

16. When the clot solidifies it forms a scab. • If a clot forms inside a blood vessel it forms a thrombus.If a thrombus breaks loose it can lodge in a vital blood vessel in the heart or brain causing a heart attack or stroke.

17. The thrombin system • Following damage to a blood vessel, blood platelets and the injured cells release thromboplastin. • Thromboplastin interacts with Ca ++ and prothrombin (an inactive plasma protein) to form thrombin. • Thrombin converts finbrinogen (another inactive plasma protein) to long, stretchy fibres of fibrin.

18. The thrombin system 4. The fibrin fibres form a mesh at the site of the wound, which traps platelets and blood cells. 5. Within a few minutes the clot starts to contract, which pulls the edges of the broken blood vessel together.

19. Serum is the clear yellow fluid that oozes out of the clot – this is plasma minus the fibrinogen. After a couple of days an enzyme in the clot activates fibrinolysis - this starts the break-down of the clot

20. The thrombin system - summary • Thromboplastin + prothrombin + Ca++ = thrombin • Thrombin + fibrinogen = fibrin • Fibrin + blood cells = clot

21. The inflammatory response

22. The inflammatory response • Inflammation is the body’s response to harmful substances, injury, or irritants. • Typically the affected area becomes red, tender and swollen.

23. Stages in the inflammatory response • When the body is injured, infected or exposed to irritants, radiation, or extreme temperatures, a complex chemical response is initiated.

24. This response involves several compounds being released in the affected area. These substances both interact and have specific outcomes (i.e. the inflammatory response) e.g. histamine is released by mast cells, which causes local dilation of the blood vessels and increases mucus secretion – anti-histamine drugs reverse this effect.

25. The inflammatory response The inflammatory response includes: • Dilation of the blood vesselsin the affected area. • Increased permeability of the capillaries, allowing plasma to leak into surrounding tissue. • Chemotaxis – phagocytes are attracted to the affected area. Resulting in redness, swelling, heat & pain

26. The inflammatory response Site of injury • Chemical response to injury • A variety of chemicals released in the affected area • 2. Inflammatory response • Vasodilation of blood vessels • Increased permeability of blood vessels • Chemotaxis