Physiology Lecture 1 PDF

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