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Insert additional logo here if necessary, otherwise delete this box by going to View Slide Master Essentials of Clinical Medicine Introduction to physiology

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

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

Physiology • The movement of water, ions and molecules throughout the body, and particularly

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

Introduction to physiology

Introduction to physiology

28 Plasma and Tran ICF Interstitia Extra-cellular fluid 14 10 4 Total body water

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

Water compartments in health TBW = 60% BODY WEIGHT = 42 litres Divided into

Water compartments in health 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

Introduction to physiology liquid

Introduction to physiology liquid

Does this matter? Yes!

Does this matter? Yes!

Diffusion

Diffusion

Flow of fluids through a tube Dependent on • • Force – pressure difference

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

Quiet Noisy

Quiet Noisy

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

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

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

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

Does this matter? Yes! Laminar flow is silent - so if you hear a

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!

Does this matter? Yes! Turbulent flow is noisy and in the respiratory system, flow

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.

Atherosclerosis

Atherosclerosis

Does this matter? Yes! Atheroma can occur in any artery and is a major

Does this matter? Yes! 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

Length Pressure difference Diameter [d 4 th] Viscosity

Length Pressure difference Diameter [d 4 th] Viscosity

Length Pressure difference Diameter [d 4 th] Viscosity

Length Pressure difference Diameter [d 4 th] Viscosity

Equilibrium between plasma and interstitial fluid is established Governed by ‘Starling forces’ where loss

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 EH Starling colloid osmotic pressure or oncotic pressure

Hydrostatic pressure forces fluid out of the plasma across capillary walls Arteriolar Venular Hydrostatic

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

Impermeance of plasma proteins generates a colloid osmotic pressure Colloid osmotic pressure draws fluid

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 25 mm Hg

equilibrium between plasma and interstitial fluid Filtration pressure = hydrostatic pressure – colloid osmotic

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

Does this matter? Yes! Things can go wrong! • Fall in plasma protein •

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

Does this matter? Yes! Oedema • • Starvation [low input of nutrients] Liver failure

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