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Introduction to Anatomy and Physiology

The Human Body—An Orientation

Anatomy
Study of the structure and shape of the body and its parts

Physiology
Study of how the body and its parts work or function

Anatomy—Levels of Study

Gross anatomy
Large structures
Easily observable

Microscopic anatomy
Structures cannot be seen with the naked eye
Structures can only be viewed with a microscope

Organ System Overview

Integumentary
Forms the external body covering
Protects deeper tissue from injury
Helps regulate body temperature
Location of cutaneous nerve receptors

Skeletal
Protects and supports body organs
Provides muscle attachment for movement
Site of blood cell formation
Stores minerals

Muscular
Produces movement
Maintains posture
Produces heat

Nervous
Fast-acting control system
Responds to internal and external change
Activates muscles and glands

Endocrine
Secretes regulatory hormones
Growth
Reproduction
Metabolism

Cardiovascular
Transports materials in body via blood pumped by heart
Oxygen
Carbon dioxide
Nutrients
Wastes

Lymphatic
Returns fluids to blood vessels
Cleanses the blood
Involved in immunity

Respiratory
Keeps blood supplied with oxygen
Removes carbon dioxide

Digestive
Breaks down food
Allows for nutrient absorption into blood
Eliminates indigestible material as feces

Urinary
Eliminates nitrogenous wastes
Maintains acid-base balance
Regulates water and electrolytes

Reproductive
Produces offspring
Testes produce sperm and male hormone
Ovaries produce eggs and female hormones

Necessary Life Functions

Maintain boundaries
Movement
Locomotion
Movement of substances

Responsiveness
Ability to sense changes and react

Digestion
Breakdown and absorption of nutrients

Metabolism—chemical reactions within the body
Break down complex molecules into smaller ones
Build larger molecules from smaller ones
Produces energy
Regulated by hormones

Excretion
Eliminates waste from metabolic reactions
Wastes may be removed in urine or feces

Reproduction
Occurs on cellular level or organismal level
Produces future generation

Growth
Increases cell size and number of cells

Survival Needs

Nutrients
Chemicals for energy and cell building
Includes carbohydrates, proteins, lipids, vitamins, and minerals

Oxygen
Required for chemical reactions

Water
60 to 80 percent of body weight
Most abundant chemical in the human body
Provides for metabolic reaction

Stable body temperature
37°C (98°F)

Atmospheric pressure 
Must be appropriate for gas exchange

Homeostasis

Homeostasis—maintenance of a stable internal environment 
A dynamic state of equilibrium
Necessary for normal body functioning and to sustain life
Homeostatic imbalance
A disturbance in homeostasis resulting in disease

Maintaining Homeostasis
The body communicates through neural and hormonal control system

Receptor
Responds to changes in the environment (stimuli)
Sends information to control center

Control center
Determines set point
Analyzes information
Determines appropriate response

Effector
Provides a means for response to the stimulus

Feedback Mechanisms

Negative feedback
Includes most homeostatic control mechanisms
Shuts off the original stimulus, or reduces its intensity
Works like a household thermostat

Positive feedback
Increases the original stimulus to push the variable farther
In the body this only occurs in blood clotting and during the birth of a baby

The Language of Anatomy
Special terminology is used to prevent misunderstanding (see pg. 15 in your book)
Exact terms are used for
Position
Direction
Regions
Structures

Body Planes and Sections
A sagittal section divides the body (or organ) into left and right parts.
A median, or midsagittal, section divides the body (or organ) into equal left and right parts.
A frontal, or coronal, section divides the body (or organ) into anterior and posterior parts. 
A transverse, or cross, section divides the body (or organ) into superior and inferior parts.

Body Cavities

Dorsal body cavity
Cranial cavity houses the brain
Spinal cavity houses the spinal cord

Ventral body cavity
Thoracic cavity houses heart, lungs, and others
Abdominopelvic cavity houses digestive system and most urinary system organs