Homeostasis slides.pdf

A warm welcome for my young doctors. What is Physiology? Physiology is the study of normal body functions. It is the study of the normal functioning of a living organism and its component parts, including all chemical and physical processes..  What is Phy...

A warm welcome for my young doctors. What is Physiology? Physiology is the study of normal body functions. It is the study of the normal functioning of a living organism and its component parts, including all chemical and physical processes..  What is Physiology? ‫علم وظائف األعضاء‬  It is the study of functions of living things.  It tries to answer two Questions:  1: Why a body function takes place? “Purpose of a body process”  2: How that body function takes place? “Mechanism of Action”  Lecture 1 Homeostasis Dr. Nazish Rafique Department of Physiology College of Medicine, IAU  Objectives Appreciate Appreciate the levels of organization in the human body. Understand Understand homeostasis and the concept of internal environment. Describe various homeostatic control systems, including:Positive and negative Describe feedback mechanisms. Explain Explain the effects of disruption in homeostasis Levels of organization in the body Contribution of body systems in maintaining homeostasis  Homeostasis Homeo means ‘the same’; and stasis means ‘to stand or stay’ Maintenance of ‘a relatively or nearly’ stable internal environment is called “HOMEOSTASIS” What is internal environment?  Internal Environment The fluid collectively contained within all body cells is called intracellular fluid (ICF). The fluid outside the cells is called Extracellular fluid (Interstitial fluid and plasma). ECF is the internal environment of the body. NOTE: ECF is outside the cells but inside the body. You live in external environment; your cells live within the body’s internal environment.  Many factors of the internal environment are homeostatically regulated  These factors include Concentration of nutrients and carbon waste other oxygen water salts dioxide products electrolytes various molecules and electrolytes pH Temperature Volume Pressure  Control of homeostasis Negative Positive feedback feedback Negative feedback Positive feedback opposes an initial amplifies an initial change. change. It maintains homeostasis. An output is enhanced. A controlled variable A controlled variable moves in the opposite moves in the direction direction of an initial change. of an initial change. Negative feedback system The commonest control system Components of Negative feedback system Sensor: Monitors the magnitude of a controlled variable. Control center (integrator): Compares a sensor’s input with a set point, and sends orders to oppose or to amplify a deviation. The effector: Makes a response to produce the desired effect. Negative feedback system  Trigger Amna was performing tawaf in the month of June when she started feeling very hot because of increased body temperature. But after a lapse of a few minutes, she sweated profusely and started feeling better. Which mechanism has helped in bringing Amna’s body temperature back to normal and how? Positive Feedback mechanism  Positive feedback Initial stimulus Outside factor required to shut off + feedback cycle Response + stimulus Positive feedback cycle ↑ stimulus  Case scenario of birth of baby A 25 years old full-term pregnant lady started having labor pains, She was taken to the gynecologist, and after being examined she was admitted to the labor room. The intensity and severity of the labor pains kept on increasing, resulting in the dilatation of the cervix. The cervix was dilated fully after strong labor pains of three hours. Finally, she gave birth to a baby girl after a very strong uterine contraction Which mechanism is responsible for causing increased intensity and frequency of labor pains? Positive feedback system ? control system  Feed forward control system Allows the body to anticipate change and maintain stability. Watering of mouth (salivation) as a result of sight, smell, or thought of food. Examples Rise in respiration before exercise. Increased secretion of insulin as a result of the presence of food in the mouth  Disruption in homeostasis can lead to illness and death. Pathophysiology is the abnormal functioning of the body during disease.  Reading Material HUMAN PHYSIOLOGY From cells to systems Lauralee Sherwood Level of organization; concept of homeostasis and control system= Pages 02-18. Questions? Comments? Contact Information Dr. Nazish Rafique [email protected] Extension: 35133 We are happy to help  17:55 Lets make a difference in someone's life THANK YOU 31