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Physiology Organization of human body LECTURE (1) DR. El-Sawy 0  Physiology O...

Physiology Organization of human body LECTURE (1) DR. El-Sawy 0  Physiology Organization of human body Human Systems Organs Tissues Cells body Definition  Basic unit of structure & function of body. Contain  Nucleus and cell organelles e.g., mitochondria & ribosomes.  Plasma membrane: Surrounded Allows Selective communication between the intracellular by and extracellular compartments (Semipermeable) DR. El-Sawy 1  Physiology Organization of human body Definition:  Solutions of water containing:  Carbohydrates.  Proteins. Organic molecules  Lipids.  Nucleic acids. Inorganic molecules Ions Constitute: 65 % i.e., 40 - 42 liters in an adult weighing 70 Kg. Compartments: Intracellular fluid (ICF) Extracellular fluid (ECF)  Fluid Inside cell.  Fluid Outside cell.  2/3 of total body fluids.  1/3 of total body fluids.  25-28 liters.  14-15 liters. DR. El-Sawy 2  Physiology Organization of human body Definition:  Internal environment that supplies cells with nutrients & other substances. Consists of : Plasma Interstitial fluid Trans-cellular fluid  Inside blood vessels  In spaces between  In body cavities as GIT , Eye cells ,Joints & cerebrospinal fluid (CSF). Separated by the wall of the capillary.  3 - 3.5 liters  10-12 liters  1 liter Composition of body fluids: ECF ICF  Contains large amounts of:  Contains large amounts of: Sodium, chloride & bicarbonate Potassium, Protein, phosphate & ions. magnesium. DR. El-Sawy 3  Physiology Organization of human body Principle of measurement: Indicator or dye dilution technique  A known amount of a dye or indicator is injected into the body.  This dye stays in one compartment only.  Enough time is allowed for uniform distribution of the dye in that fluid compartment.  Then the dye concentration in that compartment is measured.  The compartment volume is calculated as follow: Amount of dye injected Volume of fluid = Concentration of dye Characters of indicator or dye used: 1. Not toxic. 2. Not metabolized. 3. Not rapidly excreted. 4. Rapidly & evenly distributed throughout the compartment. 5. Easily measured. Measurement of total body water (TBW):  Deuterium oxide (D2O, heavy water) (most frequently used). Indicators  Aminopyrine and Tritium oxide. Character  Distributed evenly in all body fluid compartments i.e. ICF and ECF. Measurement of ECF volume: Indicators  Mannitol, Inulin and sucrose. Character  Distributed only in ECF and not enter ICF. DR. El-Sawy 4  Physiology Organization of human body Measurement of intracellular fluid volume:  Intracellular fluid volume = TBW - ECF volume. Measurement of plasma volume: 1. Evans blue dye (bound to plasma protein) Indicators 2. Injecting serum albumin labeled with radioactive iodine. Percentages of total body water (TBW) : Female Male Children Old age 50% 60% 70% Decreased Note ↑ percentage of fat → ↓ percentage of water. ↑ Age → ↓ percentage of water. DR. El-Sawy 5  Physiology Organization of human body Functions of body water : 1) Regulation of all chemical reactions. 2) Regulation of body temperature: Each gram H2O needs 0.58 Co to evaporate  called latent heat of evaporation. 3) Dissolve various substances (solvent). 4) Digestive function: shares in formation of digestive secretions & action of enzymes. 5) Filtration: in kidney 6) Osmotic function. 7) Moistens tissues such as mouth, eyes & nose & lubricate joints. 8) Absorption: GIT and kidney. 9) Excretion: GIT, kidney and skin. DR. El-Sawy 6  Physiology Organization of human body Definition :  Body water is kept constant by adjusting water input and water output. Include : Water input or intake Water output or loss Amount  2400 ml/day.  2400 ml/day.  Urine → 1500 ml.  Exogenous water :  Insensible → 700ml. Ingested in form of water or Lung (water vapor & skin liquid → 2200 ml/day. perspiration) Source  Endogenous water:  Sweating →100 ml. Synthesized as a result of but ↑ in exercise. metabolism → 200 ml/day.  Feces → 100ml. but ↑ in diarrhea. Control of water balance : Control of water input Control of water loss  By thirst sensation.  By adjusting urine volume.  Caused by stimulation of thirst center  Volume of urine is controlled mainly (in anterior hypothalamus) by: by antidiuretic hormone (ADH) 1. ↑ plasma osmolarity which is secreted from the posterior (hypertonicity) pituitary gland. 2. ↓ blood volume (hypovolemia).  Its secretion is stimulated by 3. Angiotensin II. hypertonicity and hypovolemia.  It allows the person to drink much water. DR. El-Sawy 7  Physiology Organization of human body Definition  Mechanisms keeping the internal environment constant.  Maintenance of normal: 1. Body water 2. Ions Importance 3. Body temperature 4. Blood glucose 5. pH 6. Arterial blood pressure  All body systems work to maintain homeostasis as : Body 1. Nervous system → Rapid. systems 2. Endocrine system → Slow. Mechanisms (Feedback mechanisms)  Response inhibits the stimulus e.g. a) ↑ CO2 → hyperventilation → washout of excess CO2 →↓ CO2 to normal. b) ↑ blood glucose → ↑ insulin secretion →↑ glucose utilization →↓ glucose level to normal. c) ↑ arterial blood pressure (ABP) →reflex vasodilatation & ↓heart rate →↓ABP back to normal. A) Negative feedback mechanisms DR. El-Sawy 8  Physiology Organization of human body  The response increases the stimulus e.g. 1) Usually +ve feedback disturb homeostasis e.g. death cycles: Heart failure → decreased cardiac output (stimulus) → decreased arterial blood pressure → decreased coronary blood flow (response) → more heart failure. B) Positive feedback Heat stroke → ↑ metabolic rate → ↑ heat production. mechanisms 2) Some positive feedback cycles are useful e.g. Cervical dilatation (stimulus) → ↑ uterine contractions→ descent of baby → more cervical dilatation → more uterine contractions (response) → more descent of baby, till complete labor. DR. 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