1 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Essentials of Anatomy & Physiology Fifth edition Seeley Stephens Tate Chapter 1 Introduction to the Human Body

2 Objectives for Ch. 1 Define Anatomy & Physiology Define & Identify the levels of organization List & describe the characteristics of life Describe homeostasis & the effects of stress Describe anatomical positions & guidelines Utilize correct terminology related to the body plan

3 What is Anatomy & Physiology? Anatomy: The structure and the relationships among structures Physiology: The study of how body structures function

4 Levels of Organization Cells - basic structural & functional unit Tissues - groups of specialized cells Organs - groups of specialized tissues Systems - groups of specialized organs w/a common function Organism - a collection of structurally & functional integrated systems

5 Integumentary System - skin Skeletal System - Bones Muscular System - Muscles Lymphatic System - Immunity Respiratory System - Breathing (gas exchange) Digestive System - Digestion, absorption, & elimination of waste

6 Body Systems Nervous System - Responsiveness Endocrine System - Metabolism, Growth Cardiovascular System - Circulation Urinary System - Excretion Reproductive System

7 Characteristics of Life Organization Metabolism Responsiveness Growth Movement Development Reproduction Respiration Digestion Absorption Circulation Assimilation Excretion

8 Homeostasis: Maintaining physiological limits Homeostasis - a condition in which the body’s Internal environment remains within certain Physiological limits. Body fluids must be maintained precisely at all times

9 Fig. 1.4

10 Stress is any external or internal stimulus that creates an imbalance in the internal environment. Homeostasis mechanisms try to balance the stress. The nervous & endocrine systems provide the regulation using feedback systems. Stress & Homeostasis

11 Feedback Systems A feedback system is a cycle of events in which information about the status of the condition is continually monitored & fed back to a central control system.

12 Examples of Feedback Systems Blood Pressure - Negative Feedback –If a stimulus causes blood pressure to rise, pressure sensitive nerve cells in certain arteries send impulses to the brain. The brain sends impulses to the heart, causing the heart rate to decrease and the return of blood pressure to normal.

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14 Example of feedback systems Labor Contractions - Positive feedback: –When labor begins, the uterus is stretched and stretch-sensitive nerve cells in the cervix of the uterus send nerve impulses to the hypothalamus. The hypothalamus causes the release of oxytocin which stimulates the uterus to contract more forcefully. The cycle continues until the birth of the baby.

15 Predict: 1) Donating a pint of blood reduces blood volume, which results in a decrease in blood pressure. What effect does donating blood have on heart rate? What would happen if a negative- feedback mechanism did not return the value of some parameter such as blood pressure to normal?

16 Predict: 2) Is the sensation of thirst associated with a negative- or a positive-feedback mechanism?

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