PHYSIOLOGY I n COURSE - PB3203 n COURSE DIRECTOR - J.B. Parker Ph.D. –OFFICE –OFFICE HOURS - As Posted – – –I will see students at any time I’m in my office

PHYSIOLOGY 1 LECTURE 1 Functional Organization of the Human Body and Control of the “Internal Environment”

Functional Organization of the Human Body “Internal Environment” n OBJECTIVES: n 1. The student should be able to define Physiology n 2. The student should be able to explain and diagram the maintenance and control of the internal environment of the body, homeostasis. n 3. The student should be able to define homeostasis.

PHYSIOLOGY 1 n Physiology – n Definition A. historical definition - study of function – How does it work? n B. modern definition – Physiology is the study of all of the physical and chemical factors that are responsible for the origin, development, and progression of life and death

THE IMPORTANCE OF PHYSIOLOGY n Understanding the human body n Diagnosis n Explanations n Patient n Insurance Companies n Fellow Doctors n Understanding research and applications to practice

THE IMPORTANCE OF PHYSIOLOGY n What is the human body?

Internal Environment of the Human Body n A Water Filled Sack- –1. Ranges from 55 to 80 % water 2. 56% of the adult body is water (American population average - actually this is a state of dehydration) Normal fully hydrated should be 72 % 3. Indication of obesity in the American population

Internal Environment of the Human Body B. Fluid Compartments 1. Extracellular Fluid a. 1/3 of total body water b. Is in constant motion mainly via diffusion and osmosis c. Contains: 1. Ions - Na+, K+, Cl- 2. Nutrients - O2, glucose, fatty acids, amino acids d. Cellular waste products - CO 2, H+, Heat

Internal Environment of the Human Body n C. Intracellular Fluid –1. About 2/3 of total body water –2. Contains: a. Ions - Na+, K+, Cl- (Different concentrations than extracellular fluid) b. Nutrients - O2, glucose, fatty acids, amino acids c. Cellular waste products - CO2, H+, Heat

Internal Environment of the Human Body n How is the internal environment of the human body maintained?

HOMEOSTASIS n Homeostasis - The internal variables of the human body are maintained within very tight ranges. Resulting in a constant internal environment consistent with cellular growth and maintenance n (Claude Bernard )

HOMEOSTASIS n Maintenance of Constant Internal Conditions - n Temperature, pH, osmolality, Fluid volume, gases (Blood), Nutrition and waste removal, Metabolism, ion concentrations, etc.

HOMEOSTASIS n How does the human body maintain homeostasis? n Regulation of Homeostasis n 1. Nervous Control n 2. Endocrine Control n 3. Reproduction n 4. Intrinsic Control

HOMEOSTATIC CONTROL SYSTEMS n A. Thousands in the Human body n B. Maintain intra and extracellular environments n C. Are primarily endocrine or neural n D. Regulated by –1. Negative Feedback –2. Feedforward (Adaptive) 3. Positive Feedback E. Prevention of dysfunction

HOMEOSTATIC CONTROL SYSTEMS n Regulation – What are the regulatory methods used by the human body? n Negative Feedback –a. Maintains Homeostasis –b. Acts like a thermostat n 1. Set point n 2. Disturbance –c. Returns factor (variable) to mean value –d. Effectiveness of system = Gain

HOMEOSTATIC CONTROL SYSTEMS n Feedforward or Adaptive n A. Special case of negative feedback –B. Two or more sensors –C. Examples n 1. Temperature regulation n 2. pH regulation

HOMEOSTATIC CONTROL SYSTEMS n Positive Feedback - –a. Stimulus to increase stimulus –b. Leads to an event which stops the process (Event may be death) –c. Usually pathological –d. Examples of nonpathological –1. Blood clot formation –2. Parturition (childbirth) –3. Generation of neural impulses

HOMEOSTATIC CONTROL SYSTEMS n Prevention of Dysfunction –1. Sickness –2. Death