L3) Homeostasis 1,2.pdf

Physiology Team 445 3 Homeostasis 1,2 EDITING FILE:...

Physiology Team 445 3 Homeostasis 1,2 EDITING FILE: OBJECTIVE - Main Text Understand the concept and importance of - Important Homeostasis. - Dr’s notes Discuss the physiological control mechanisms - Girls' Slides that enable maintenance of the normal steady state of the body. - Boys' Slides Differentiate between positive and negative - Extra feedback mechanisms and give examples for each in the body. [email protected] File editing  Homeostasis Homeostasis is the ability to maintain a relatively stable internal environment (Extracellular fluid) in an ever-changing outside world The internal environment of the body (ECF) is in a dynamic state of equilibrium All different body systems operate in harmony to provide homeostasis  Homeostasis Control Mechanism The variable produces a change in the body Components of control mechanisms 1- Receptor: monitors 2- Control center : 3- Effector : provides the environment and determines the set point the means to respond responds to changes at which the variable is to the stimulus (stimuli) maintained Regulation of body functions 1-Nervous system Sensory input. Central nervous system. Motor out put. 2-Hormonal system of regulation Endocrine gland. Pancreas, thyroid e.g: insulin control glucose level 444 Note : Nervous system is faster than hormonal system  Feedback Mechanisms Extra Information Type Positive Negative increases the effect oppose the effect Definition (secretion) (secretion) and maintain it Controls oxytocin controls Blood Example secretion pressure & blood (increase it) glucose & water drink only few systems Most systems work Note work with positive with negative feedback feedback Negative feedback Positive feedback ‫الهرمون المانع إل درار البول‪ADH:‬‬ Homeostatic Imbalance Disturbance of homeostasis or the body’s normal equilibrium. As a result of imbalance, it will lead to either: 1- Successful compensation: Homeostasis is reestablished 2- Failure to compensate: Pathophysiology which lead to Illness and Death Osmotic Equilibrium and Mechanisms for Movement Osmotic equilibrium is maintained between intracellular and extracellular fluids. Small changes in concentration of solutes in the extracellular fluid can cause tremendous change in cell volume. Intracellular osmolarity = extracellular osmolarity ≈ 285 mosm/L -300 mosm/L Note: Dr. Nervana says that osmolarity numbers can be different from reference to another and that is okay. 3 General mechanisms for movement Simple diffusion (passive) Facilitated transport (passive) Active transport Serum Values of Electrolytes Cations mEq/L Concentration Sodium 135 - 145 Potassium 3.5 - 4.5 Calcium 4.0 - 5.5 Magnesium 1.5 - 2.5 Anions Concentration Chloride 95 - 105 Phosphate 2.5 - 4.5 Osomsis Definition net diffusion of water from a region of high water concentration to region of low water concentration.  Tonicity means effective osmolality in relation to plasma (=285 milliosmol/L). Therefore isotonic solutions [e.g. 0.9% saline solution] have almost equal tonicity of the plasma. hypotonic solutions [e.g. 0.45% saline solution] have < tonicity than plasma. hypertonic [e.g. 3% saline solution] solutions have > tonicity than plasma. boys slides Osomsis and Tonicity Type of environment Hypertonic Isotonic Hypotonic less solutes More solutes same solutes outside cell outside cell less water in cell, More water in cell no change in cell volume more solutes in (no swells or shrink) cell. over time, cell loses water over time, cell gains water 0.9% solution of sodium (shrink) chloride stays the same (swelling) solution of sodium same in and out solution of sodium chloride 0.9% chloride 0.9% out is higher than in in is higher than out. Net movement of Equal movement of water Net movement of water out of cells into and out of cells water into cells Composition of common parenteral fluids (Electrolytes Content mEq/L) Effects of adding saline solution to the EFC Glucose and other solutions administered for nutritive purposes Who needs it? People who can not take adequate amount of food. How to give it for them? Slowly In order to maintain volume Where to prepare it ? Prepared in isotonic solution Water is excreted Volumes and Osmolarities of ECF and ICF in Abnormal states Some factors can Cause the change : Dehydration Intravenous infusion (IV) Abnormal sweating  Changes in volume Volume contraction Volume expansion removing Adding 1. isotonic solution. 1. isotonic solution. 2. hypertonic solution 2. hypertonic solution 3. hypotonic solution 3. hypotonic solution remember that Osmolarity is equal in ECF and ICF. As a result, we have 6 states depending on the type of fluid All the fluids we lost were from the ECF and based on it the ICF will change to achieve balance in concentration, whether by a decrease or an increase. Volume contraction (decrease in the ECF volume) 1. Loss of iso-osmotic fluid Diarrhea osmolarity of fluid lost = osmolarity of ECF volume in ECF e.g.Diarrhea arterial pressure Water deprivation 2.Loss of hypotonic solution Osmolarity and volume will change Osmolarity in both ECF and ICF e.g.Water deprivation, Excessive sweating (sweat is hypotonic) Volume in both ECF and ICF 3.Loss of hypertonic solution Adrenal insufficiency Na+ in the ECF. 444 Note osmolarity in both ‫ المكان اللي یكون‬-:‫مالحظه بتساعدكم عىل الفھم‬ ‫فيه تركیز الصودیوم اكثر یسحب المويه عنده عشان‬ ‫ الن یحتوي عىل تركیز صودیوم اكثر‬ICF ‫كذا كبر حجم‬ ‫ اللي فقدت الصودیوم الطبیعي انه تركیز‬ECF ‫مقارنه‬ ICF ‫ اكثر من‬ECF ‫الصودیوم في‬ in ECF volume e.g. Adrenal insufficiency i.e. Aldosterone deficiency aldosterone balances sodium and potassium in your blood. in ICF volume Volume Expansion (increase in the ECF volume) 1. Adding of isotonic NaCl Infusion of isotonic NaCl) osmolarity in ECF volume No change in osmolarity Liters Infusion of isotonic NaCl (0,9) Isomotic expansion 2.High NaCl intake High NaCl intake eating salt osmolarity in both Liters volume of ICF hyperosmotic volume expansion volume of ECF 3.Adding hypotonic solution Adding hypotonic solution volume 444 Note ‫اذا صار في خلل في انتاج ھذا الھرمون زاد‬ ‫انتاجه عن الطبیعي راح یقلل من إدرار البول‬ ‫یعني یقلل خروج الماء من الجسم بالتالي‬ osmolarity ‫تركیز االمالح بیقل والحجم بیزید‬ Liters e.g. Syndrome of inappropriate antidiuretic hormone (SIADH) This hormone helps the kidneys control the amount of water your body loses through the urine.  Edema Edema is: excessive fluid in the tissues which leads to swelling mainly Edema occurs in ECF, but it can happen in ICF as well. Intracellular Edema Extracellular Edema Common clinical cause is excessive capillary fluid filtration From ECF to ICF Extracellular Intracellular Factors controlling fluid filtration across capillary walls Boys slides Hydrostatic pressure: The pressure exerted by blood on the walls of the blood vessel, this pressure pushes fluid outside the capillary Colloid osmotic (oncotic) pressure: Created by the non-diffusible plasma proteins inside the blood vessel, this pressure pulls fluid inside (especially albumin) Movement of fluids across capillary walls depends on the balance of starling forces acting across the capillary walls. Boys slides Causes of Extracellular Edema Boys slides Increased capillary filtration Increased capillary hydrostatic pressure -kidney failure -Heart failure -Venous obstruction Decreased plasma oncotic pressure -Loss of protein (nephrotic syndrom, burns) -Inability to synthesize proteins (liver failure, malnutrition) Increased capillary permeability -Inflammation -Infection. -Immune reactions. Decrease lymph uptake Lymph obstruction -Infection (filaria). -Surgery. -Congenital absence. -Cancer.  MCQs What is the main function of homeostasis? A) Maintain a B) Maintain a C) Change the static external stable internal internal environment D) Disrupt equilibrium environment environment constantly Which of the following is a component of a control mechanism? A) Stimulus B) Effector C) Hormone D) Neuron Which solution is considered isotonic to plasma? A) 0.9% sodium B) 0.45% sodium C) 5% sodium D) 3% sodium chloride chloride chloride chloride What happens to osmolarity in both ECF and ICF during water deprivation? A) No change B) Decreases C) Increases D) Only ECF increases Which of the following is an example of volume contraction? A) High NaCl D) Adding isotonic B) Diarrhea C) SIADH intake NaCl What is a common clinical cause of intracellular edema? B) Excessive C) Increased A) Hyponatremia D) Dehydration sweating capillary filtration 1. B) 2. B) 3. A) 4. C) 5. B) 6. A) Jood Alqosi Bandar Alqahtani Aljoharah Algazlan Abdulaziz Alowaid Dana Alanazi Naser Alnukhylan Maha alghamdi Khalid Alangari Rehad Almutairi Turki Alanazi Danah Alrabiah Rayan Alshahrani Rahaf Metlea Mohammed Almutairi Renad Bin Sanad Faris Aldawood Horia alotaibi Abdullah Alnami Latifah Al-Dossary Yazeed Alqarni Aryam Almotairi Ibrahim Almugrin Jory Alturki Abdullaziz Ibrahim Nada Almuhawwis Shahad alotaibi Basma Al-Bahkly Retaj Alosaimi