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The Human Body: An Orientation

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

Anatomy—Levels of Study

• 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

Organ System Overview

• Skeletal

• Protects and supports body organs

• Provides muscle attachment for movement

• Site of blood cell formation

• Stores minerals

Organ System Overview

• Muscular

• Produces movement

• Maintains posture

• Produces heat

Organ System Overview

• Nervous

• Fast-acting control system

• Responds to internal and external change

• Activates muscles and glands

Organ System Overview

• Endocrine

• Secretes regulatory hormones

• Growth

• Reproduction

• Metabolism

Organ System Overview

• Cardiovascular

• Transports materials in body via blood pumped by heart

• Oxygen

• Carbon dioxide

• Nutrients

• Wastes

Organ System Overview

• Lymphatic

• Returns fluids to blood vessels

• Cleanses the blood

• Involved in immunity

Organ System Overview

• Respiratory

• Keeps blood supplied with oxygen

• Removes carbon dioxide

Organ System Overview

• Digestive

• Breaks down food

• Allows for nutrient absorption into blood

• Eliminates indigestible material as feces

Organ System Overview

• Urinary

• Eliminates nitrogenous wastes

• Maintains acid-base balance

• Regulates water and electrolytes

Organ System Overview

• 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

Necessary Life Functions

• 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

Necessary Life Functions

• 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

Survival Needs

• 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 systems

• Receptor

• Responds to changes in the environment (stimuli)

• Sends information to control center

Maintaining Homeostasis

• 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

Feedback Mechanisms

• 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

• 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