The Human Body: An Orientation Anatomy The study of the structures or parts of the body. Physiology The study of the function of the body. (How the parts work.)

Anatomy – Levels of Study Gross Anatomy Large structures Easily observable

Anatomy – Levels of Study Microscopic Anatomy Very small structures Viewed with a microscope

Levels of Structural Organization Atoms form molecules Molecules form cells (the smallest units of living things) A tissue consists of cells working together to perform a common function

Levels of Structural Organization An organ consists of 2 or more tissues working together An organ system is a group of organs working together An organism consists of organ systems working together

Organ Systems Integumentary System Forms the external body covering and protects the internal organs from infection. Includes skin, hair and nails.

Organ Systems Skeletal System Functions in Movement and Support Includes bones, cartilage, ligaments

Organ Systems Muscular System Functions in movement of the body and through the body Includes three types of muscles Skeletal, cardiac and smooth (visceral)

Organ Systems Nervous System Fast acting control system Also functions in communication Includes brain, spinal cord and nerves

Organ Systems Endocrine System Slower acting control system of the body Glands secrete hormones to regulate the body

Organ Systems Cardiovascular System Transports materials through the body via the bloodstream Includes heart and blood vessels

Organ Systems Lymphatic System Returns tissue fluid to blood vessels Important in immunity

Organ Systems Respiratory System Supplies oxygen and removes carbon dioxide Includes lungs, trachea, etc.

Organ Systems Digestive System Digestion of food for absorption of nutrients Includes stomach, intestines, etc

Organ Systems Urinary System Filters toxins from the blood Includes kidneys, bladder, etc.

Organ Systems Reproductive Systems Produces offspring Includes male and female genitalia

Homeostasis Maintenance of a stable internal environment Temperature, fluid levels, pH, etc. Must be maintained for normal functioning and to sustain life Homeostatic imbalance – can result in disease or death

Maintaining Homeostasis The body communicates through nervous and endocrine systems consisting of 3 basic components 1) Receptor Detects a stimulus 2) Control center Analyzes information Determines appropriate response 3) Effector (Muscles or glands) Responds to the stimulus

Maintaining Homeostasis Metabolism – all chemical reactions within the body Production of energy Making body structures

Feedback Mechanisms Negative feedback Includes most homeostatic control mechanisms The response shuts itself off when it reaches the setpoint. Example: Household thermostat

Feedback Mechanisms Positive feedback Increases the intensity of the original stimulus until ultimate goal is reached In the body, this only occurs in blood clotting and birth of a baby