Levels of Organization Life is built on successive levels of increasing complexity: Chemical (or Molecular) Cellular Tissue Organ Organ System Organism

Organ Organism System Level Level Organ Level Tissue Level Chemical or Endocrine Cardiovascular Lymphatic Nervous Respiratory Muscular Digestive Skeletal Urinary Integumentary Reproductive Organ Level The heart Cardiac muscle tissue Atoms in combination Tissue Level Heart muscle cell Complex protein molecule Protein filaments Chemical or Molecular Level Cellular Level

Overview of Organ Systems The human body is arranged in 11 organ systems: Integumentary Skeletal Muscular Nervous Endocrine Cardiovascular Lymphatic Respiratory Digestive Urinary Reproductive

The Integumentary System Figure 1-2(a)

The Skeletal System Figure 1-2(b)

The Muscular System Figure 1-2(c)

The Nervous System Figure 1-2(d)

The Endocrine System Figure 1-2(e)

The Cardiovascular System Figure 1-2(f)

The Lymphatic System Figure 1-2(g)

The Respiratory System Figure 1-2(h)

The Digestive System Figure 1-2(i)

The Urinary System Figure 1-2(j)

Male Reproductive System Figure 1-2(k)

Female Reproductive System Figure 1-2(l)

Introduction to Organ Systems The body can be divided into 11 organ systems, but all work together and the boundaries between them aren’t absolute. Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

Homeostatic Regulation Homeostasis Maintains stable internal conditions Temperature Ionic concentrations Blood sugar levels, etc. Utilizes negative feedback mechanisms Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

Homeostatic Regulation Regulation depends on: Receptor sensitive to a particular stimulus Effector that affects the same stimulus RECEPTOR Thermometer STIMULUS: Room temperature rises Normal condition disturbed HOMEOSTASIS room temperature RESPONSE: drops restored EFFECTOR Air conditioner turns on Sends commands to Information affects CONTROL CENTER (Thermostat) 20o 30o 40o Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

Homeostatic Regulation Negative Feedback: Variation outside normal limits triggers automatic corrective response Response negates disturbance RECEPTOR Body’s temperature sensors STIMULUS Body temperature rises above 37.2oC (99oF) RESPONSE Increased blood flow to skin Increased sweating Stimulus removed Homeostasis restored Control mechanism when body rises EFFECTOR Blood vessels and sweat glands in skin Negative feedback Sends commands to Information affects CONTROL CENTER Thermoregulatory center in brain and sweat glands in skin Skeletal muscles falls falls below 37.2oC Decreased blood flow Decreased sweating Shivering

Homeostatic Regulation Positive Feedback: Stimulus produces response that reinforces the stimulus Response rapidly completes critical process Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

Homeostatic Regulation Homeostasis and Disease Failure of homeostatic regulation Symptoms appear Organ system malfunction Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings