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Physiology Organization of human body Lecture 1 DR. El-Sawy 1 Physiology Organizat...
Physiology Organization of human body Lecture 1 DR. El-Sawy 1 Physiology Organization of human body Organization of human body Human body Systems Organs Tissues Cells Cell Definition Basic unit of structure & function of body. Contain Nucleus and cell organelles e.g. mitochondria and ribosomes. Plasma membrane: allows communication between the Surrounded by intracellular and extracellular compartments DR. El-Sawy 2 Physiology Organization of human body Body Fluids 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. Note ICF is separated from ECF by the cell membrane DR. El-Sawy 3 Physiology Organization of human body Extracellular fluid (ECF) 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 & cells cerebrospinal fluid (CSF) Separated by the wall of the capillary. 3 - 3.5 liters 10-12 liters 1 liter of body fluids: ECF ICF Contains large amounts of sodium, Contains large amounts of potassium chloride, & bicarbonate ions. , magnesium, & phosphate ions. DR. El-Sawy 4 Physiology Organization of human body Measurement of Volumes of Body Fluids: 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: Volume of fluid = Characters of indicator or dye used: 1. Not toxic. 2. Rapidly and evenly distributed throughout the compartment. 3. Not metabolized. 4. Not rapidly excreted. 5. Easily measured. Measurement of total body water (TBW): Deuterium oxide (D2O, heavy water) (most frequently used). Indicators Tritium oxide and aminopyrine. Character Distributed evenly in all body fluid compartments i.e. ICF and ECF. Measurement of ECF volume: Indicators Inulin (polysaccharide), mannitol and sucrose. Character distributed only in ECF and not enter ICF. DR. El-Sawy 5 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. body water Def : Body water is kept constant by adjusting water input & water output. 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 6 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) Powerful solvent that Dissolve various substances. 4) Digestive function: shares in formation of digestive secretions & action of enzymes. 5) Moistens tissues such as mouth, eyes & nose & lubricate joints. 6) Water can pass easily through the cell membrane it helps in osmotic equilibrium between various body compartments. 7) Absorption: at the venous end of capillaries, GIT and kidney. 8) Filtration: at arterial end of capillaries and glomeruli. 9) Excretion: at GIT, kidney and skin. DR. El-Sawy 7 Physiology Organization of human body Water Balance 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 & liquid → 2200 ml/day. skin 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 the urine volume. This is caused by stimulation of thirst Volume of urine is controlled mainly center (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 8 Physiology Organization of human body Homeostasis 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 9 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 Heart 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. El-Sawy 10 Physiology Organization of human body DR. El-Sawy 11
