Essentials of Clinical Medicine Introduction to physiology

1. Essentials of Clinical Medicine Introduction to physiology

2. Anatomy – how things are constructed Physiology – how things work Introduction to Physiology

3. Physiology The movement of water, ions and molecules throughout the body, and particularly across membranes. The movement of fluids and gases through the body, usually through tubes The movement of parts of the body relative to other parts The movement of the body relative to the surroundings

4. Introduction to physiology

6. Extra-cellular fluid 14 Plasma and Tran Interstitia Cell membrane ICF Capillary membrane 28 10 4 Total body water 42

7. TBW = 60% BODY WEIGHT = 42 litres Divided into ICF – 2/3 [66%] = 28 ECF – 1/3 [33%] = 14 Divided into Interstitial = 10 Intravascular/plasma = 3 Transcellular [Cell wall, CSF etc] = 1 Water compartmentsin health

8. Introduction to physiology liquid

9. Does this matter?Yes!

10. Diffusion

12. Dependent on Force – pressure difference Tube – diameter [fourth power] and length Fluid – viscosity and density Flow – laminar or turbulent Flow of fluids through a tube

13. Quiet Noisy

14. Length Pressure difference Diameter [ 4th power!] Viscosity Normal in blood vessel

15. Length Pressure difference Diameter Density Abnormal in blood vessel, usual in respiratory

16. Does this matter?Yes! Laminar flow is silent - so if you hear a noise [murmur or bruit] in the cardiovascular system it must mean there is turbulent flow and something is wrong! E.g. arteries in the neck or kidneys. In the heart, you will hear the NORMAL heart sounds, which are caused by the valves closing; if you hear any other noise, something is wrong!

17. Does this matter?Yes! Turbulent flow is noisy and in the respiratory system, flow is usually at least partially turbulent. So you can normally hear breath sounds. You can also hear abnormal sounds, such as a wheeze caused by asthma.

18. Atherosclerosis

19. Atheroma can occur in any artery and is a major cause of death and disability Brain – stroke Heart - heart attack Kidneys – renal failure Peripheral – lose limb Does this matter?Yes!

20. Length Pressure difference Diameter [d 4th] Viscosity

21. Length Pressure difference Diameter [d 4th] Viscosity

22. Equilibrium between plasma and interstitial fluid is established Governed by ‘Starling forces’ where loss of fluid from the plasma, owing to hydrostatic pressure is opposed by reabsorption of fluid into plasma, owing to colloid osmotic pressure or oncotic pressure EH Starling

23. Hydrostatic pressure forces fluid out of the plasma across capillary walls Arteriolar Venular Hydrostatic pressure hydrostatic pressure 35mm Hg hydrostatic pressure 15mm Hg filtration of plasma

24. Impermeance of plasma proteins generates a colloid osmotic pressure Colloid osmotic pressure draws fluid back into capillaries from interstitial space Arteriolar Venular Colloid osmotic pressure 25mm Hg

25. equilibrium between plasma and interstitial fluid Filtration pressure = hydrostatic pressure – colloid osmotic pressure Arteriolar Venular hydrostatic pressure 35mm Hg hydrostatic pressure 15mm Hg Colloid osmotic pressure 25mm Hg reabsorption at venular end

26. Things can go wrong! Fall in plasma protein Defect in capillary membrane Rise in venous pressure Does this matter?Yes!

27. Oedema Starvation [low input of nutrients] Liver failure [not enough made] Anaphylaxis Heart failure Does this matter?Yes!