1. Introduction to Physiology.pdf

Introduction to Physiology Dr. Arzu Temizyürek Faculty of Medicine Department of Physiology [email protected] SUGGESTED SOURCES Textbook of Medical Physiology (Guyton & Hall) (14th Edition) Review of Medical Physiology (W.F. Ganong) Neuroscience 6th Edition...

Introduction to Physiology Dr. Arzu Temizyürek Faculty of Medicine Department of Physiology [email protected] SUGGESTED SOURCES Textbook of Medical Physiology (Guyton & Hall) (14th Edition) Review of Medical Physiology (W.F. Ganong) Neuroscience 6th Edition (Dale Purve)  Resources Medical Physiology (A.C. Guyton & Hall) Review of Medical Physiology (W.F. Ganong) Vander’s Human Physiology (Widmaier, Raff, Strang) Human Physiology (D. U. Silverthorn) Human Physiology (Stuart Ira Fox) Physiology: with STUDENT CONSULT (Linda S. Costanzo) Syllabus Introduction to physiology, Homeostasis Cell Membranes Transport of substances across cell membrane Cellular Signaling Molecules Regulation of Water & Body Fluids Compartments Regulation of Acid- Base PHYSIOLOGY Physis + logos = Physiology nature science An integrative science The branch of science dealing with the basic functions of living organisms PHYSIOLOGY  Process & Function How do we breathe? Why do we breathe? How does blood flow? Why does blood flow? How do RBCs transport O2? Why do RBC transport O2? Physiological terms; Function: Things to do... Mechanism or process: How to do… PHYSIOLOGY Physiological: “Normal”; not pathological; properties belonging to normal functions of tissues, organs or body Pathophysiological: refers the functional changes associated with or resulting from disease or injury. ‘Abnormal condition’ Example: Resting state blood pressure: 80-120 mmHg (Normal = Physiological condition) 100-180 mmHg (Hypertension = Pathological condition) HOW THE BODY WORKS ???  Levels of structural organization 1. Chemical Level: Atoms combine to form molecules 2. Cellular Level: Cells are made up of molecules 3. Tissue Level: Tissues consist of similar types of cells 4. Organ Level: Organs are made up of different types of tissues 5. Organ System Level: Organ systems consist of different organs that work together closely 6. Organism Level: Human organisms are made up of many organ systems Organization of life: - Cell is the basic unit of life - Hierarchical organization: Cells, tissues, organs, organ systems and organism Levels of Organization and the Related Fields of Study The principal level of focus of physiology is at the level of organs and systems within systems. A system consists of related organs with a common function. HOMEOSTASIS “staying same” or “being almost stable” A process that maintains the stability of the human body's internal environment in response to changes in external conditions. The body will survive and function efficiently only when these internal conditions are properly maintained. Homeostasis requires a sensor to detect changes in the condition to be regulated, an effector mechanism that can vary that condition; and a negative feedback connection between the two.  CENTRAL NERVOUS SYSTEM SENSORY MOTOR DIVISION DIVISION Effector tissue Afferent Efferent neuron neuron Sensory 1. Receptor/sensor – detects stimulus (change) receptors 2- Control/integration center – receives and processes info from receptor 3- Effector - cell/organ provides the means to respond to stimulus to return variable to “setpoint”.  In order to maintain homeostasis, the body must be able to monitor and sense changes in the internal environment. It must also be able to compensate, or make adjustments, for these changes. Homeostatic Regulatory Systems 1. Intrinsic Regulation (Local- Autoregulation Activities of a cell/tissue/organ/system adjust automatically in response to environmental change. Control systems operating within the organs (Local control systems) 2. Extrinsic Regulation Results from activities of nervous or endocrine systems (long-distance communication within the body) Control systems operating throughout the entire body to control the interrelations between the organs.  HOMEOSTASIS requires Cooperative Functioning of Organs and Systems equires Communication Within The Body  Homeostatic Regulation (keeping within set limits) Long-distance communication within the body is accomplished chiefly by: - Nervous system: It uses neural electrical impulses directs rapid, short term, specific responses - Endocrine system: Works through hormones, slow to act but long lasting effects  Homeostatic Regulation Mechanism Feedback loops Components of a feedback system: 1- Receptor/sensor – detects stimulus (change) 2- Control/integration center – receives and processes info from receptor 3- Effector - cell/organ provides the means to respond to stimulus to return variable to “setpoint”.  Negative feedback A pathway in which the response opposes or removes the signal is known as negative feedback. Negative feedback loops stabilize the variable being regulated and thus aid the system in maintaining homeostasis. Control mechanism DECREASES intensity of condition to bring back to "set point" too much X → X too less X → X Oxygen and Carbon dioxide Arterial baroreceptors Blood Pressure Negative feedback - Fluid-Electrolyte Balance  POSITIVE FEEDBACK A few reflex pathways are not homeostatic The output (the product of the process) becomes the stimulus input for the process itself. The initiating stimulus causes more of the same, amplifies with the loop of events and “the response (output) leads to an even greater response (output)”  POSITIVE FEEDBACK Sometimes useful, but sometimes destructive Effectors respond by exaggerating or enhance the stimulus Typically used to deal with threat or stress Positive feedback often results in disease Examples: * Blood clotting – clotting causes more clotting until wound is plug * Birth – Contractions promote more contractions until delivery Thank you