Unit One: Introduction to Physiology: The Cell and General Physiology Chapter 1: Functional Organization of the Human Body and Control of the “Internal Environment” Guyton and Hall, Textbook of Medical Physiology, 12 edition

1. Cells: the living units of the body Human Physiology The attempt to explain the specific characteristics and mechanisms of the human body that make it a living being. 1. Cells: the living units of the body Each organ is an aggregate of many different cells held together by intercellular supporting structures All cells have certain basic characteristics Almost all cells have the ability to reproduce

Extracellular Fluid—The “Internal Environment” Intracellular Fluid-fluid within the cell Extracellular Fluid-found in the spaces outside the cells Constant motion throughout the body Contains the ions and nutrients cells need Called the “internal environment”

Differences Between Intracellular and Extracellular Fluids Contains large amounts of Na+, Cl-, and bicarbonate ions Contains nutrients such as oxygen, glucose, fatty acids, and amino acids Contains carbon dioxide and other cellular wastes Intracellular Fluid: Contains large amounts of K+, Mg+, and phosphate ions

Homeostatic Mechanisms The maintenance of nearly constant conditions in the internal environment. Extracellular fluid transport and mixing system: Blood Circulatory System Origin of nutrients in the extracellular fluid Respiratory system Gastrointestinal tract Liver and other metabolic organs Musculoskeletal system

Homeostatic Mechanisms (cont.) Removal of metabolic end products Removal of carbon dioxide by the lungs Kidneys GI tract and the liver Regulation of body functions Nervous system Endocrine system Protection of the body Immune system Integumentary system Reproduction

Control Systems of the Body Examples of control systems Regulation of oxygen and carbon dioxide in the extracellular fluid Regulation of arterial blood pressure Normal ranges and physical characteristics of extracellular fluid components

Normal Value Range Non-lethal Limits Unit Oxygen 40 35-45 10-1000 mm Hg Carbon dioxide 5-80 Sodium ion 142 138-146 115-175 mmol/L Potassium ion 4.2 3.8-5.0 1.5-9.0 Calcium ion 1.2 1.0-1.4 0.5-2.0 Chloride ion 108 103-112 70-130 Bicarb. Ion 28 24-32 8-45 Glucose 85 75-95 20-1500 mg/dl Body Temp. 37 18.3-43.3 C Acid-Base 7.4 7.3-7.5 6.9-8.0 pH

Control Systems of the Body (cont.) Characteristics of control systems Negative feedback Positive feedback Adaptive control