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

Human Physiology

The attempt to explain the specific characteristics andmechanisms 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

2. Extracellular Fluid—The “Internal Environment”

• Intracellular Fluid-fluid within the cell

• Extracellular Fluid-found in the spaces outside the cells

a) Constant motion throughout the body

b) Contains the ions and nutrients cells need

c) Called the “internal environment”

Differences Between Intracellular and Extracellular Fluids

Extracellular Fluid:

• 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:

a. Blood Circulatory System

• Origin of nutrients in the extracellular fluid

a. Respiratory systemb. Gastrointestinal tractc. Liver and other metabolic organsd. Musculoskeletal system

Homeostatic Mechanisms (cont.)

• Removal of metabolic end productsa. Removal of carbon dioxide by the

lungsb. Kidneysc. GI tract and the liver

• Regulation of body functionsa. Nervous systemb. Endocrine system

• Protection of the bodya. Immune systemb. Integumentary system

• Reproduction

Control Systems of the Body

• Examples of control systemsa. Regulation of oxygen and carbon dioxide in the extracellular fluidb. Regulation of arterial blood pressurec. Normal ranges and physical characteristics of extracellular fluid components

Normal Value

Range Non-lethalLimits

Unit

Oxygen 40 35-45 10-1000 mm Hg

Carbon dioxide

40 35-45 5-80 mm Hg

Sodium ion 142 138-146 115-175 mmol/L

Potassium ion

4.2 3.8-5.0 1.5-9.0 mmol/L

Calcium ion 1.2 1.0-1.4 0.5-2.0 mmol/L

Chloride ion 108 103-112 70-130 mmol/L

Bicarb. Ion 28 24-32 8-45 mmol/L

Glucose 85 75-95 20-1500 mg/dl

Body Temp. 37 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

a. Negative feedback

b. Positive feedback

c. Adaptive control