Chapter 1: The Human Body—An Orientation

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Anatomy: The study of the structure and shape of the body and its parts, and their relationships to one another. STRUCTURE
Physiology: The study of how the body and its parts function. FUNCTION
Relationship: Anatomy and physiology are closely related because the structure of a body part determines its function. For example, the structure of the heart enables it to pump blood.
Example: The thin walls of the alveoli in the lungs (anatomy) allow for efficient gas exchange (physiology).

Chemical Level: Atoms combine to form molecules.
Cellular Level: Cells are made up of molecules.
Tissue Level: Tissues consist of similar types of cells.
Organ Level: Organs are made up of different types of tissues.
Organ System Level: Organ systems consist of different organs that work together closely.
Organismal Level: The human organism is made up of many organ systems.

Additional info: Each level builds on the previous one, creating increasing complexity.

Integumentary System: Protects the body, regulates temperature, and provides sensory information.
Skeletal System: Supports and protects body organs, provides muscle attachment, and produces blood cells.
Muscular System: Allows movement, maintains posture, and produces heat.
Nervous System: Fast-acting control system, responds to internal and external changes.
Endocrine System: Glands secrete hormones that regulate processes such as growth and metabolism.
Cardiovascular System: Transports blood, nutrients, gases, and wastes.
Lymphatic System: Returns leaked fluids to blood, involved in immunity.
Respiratory System: Supplies blood with oxygen and removes carbon dioxide.
Digestive System: Breaks down food, absorbs nutrients, and eliminates waste.
Urinary System: Eliminates nitrogenous wastes and regulates water, electrolyte, and acid-base balance.
Reproductive System: Produces offspring.

Maintaining Boundaries: Separation between internal and external environments (e.g., skin).
Movement: Includes movement of the body and substances within the body.
Responsiveness: Ability to sense and respond to stimuli.
Digestion: Breakdown of food into absorbable units.
Metabolism: All chemical reactions within the body.
Excretion: Removal of wastes from the body.
Reproduction: Production of offspring at cellular and organismal levels.
Growth: Increase in size of a body part or the organism.

Nutrients: Chemicals for energy and cell building.
Oxygen: Required for chemical reactions.
Water: Most abundant chemical in the body; necessary for metabolic processes.
Normal Body Temperature: Needed for proper metabolic reactions.
Atmospheric Pressure: Required for proper breathing and gas exchange.

Body is erect, feet parallel, arms at the sides with palms facing forward, and thumbs pointing away from the body.

Superior (Cranial): Toward the head or upper part of a structure.
Inferior (Caudal): Away from the head or toward the lower part of a structure.
Anterior (Ventral): Toward the front of the body.
Posterior (Dorsal): Toward the back of the body.
Medial: Toward the midline of the body.
Lateral: Away from the midline of the body.
Proximal: Closer to the origin of the body part.
Distal: Farther from the origin of the body part.

Median (Midsagittal) Plane: Divides the body into equal right and left parts.
Frontal (Coronal) Plane: Divides the body into anterior and posterior parts.
Transverse (Horizontal) Plane: Divides the body into superior and inferior parts.

Body Cavity	Location	Main Organs
Cranial	Within the skull	Brain
Spinal	Within the vertebral column	Spinal cord
Thoracic	Chest area	Heart, lungs
Abdominal	Abdomen	Stomach, liver, intestines, spleen
Pelvic	Pelvis	Bladder, reproductive organs, rectum

Homeostasis: The maintenance of a stable internal environment despite changes in the external environment.
Importance: Essential for normal body functioning and sustaining life. Imbalance can lead to disease or dysfunction.

Definition: A mechanism that reverses a deviation from the set point; the most common homeostatic control mechanism.
Role: Maintains homeostasis by reducing the intensity of a stimulus or shutting it off when the set point is reached.
Example: Regulation of body temperature: If body temperature rises, mechanisms such as sweating are activated to cool the body.

Additional info: Positive feedback mechanisms are less common and amplify the original stimulus (e.g., blood clotting, labor contractions).