Introduction to Anatomy & Physiology

Overview of Anatomy and Physiology

Anatomy is the study of the structures that make up the body and how those structures relate to each other. The term originates from the Greek meaning "to cut up." Anatomy is divided into:

• Gross Anatomy: Study of body structures visible without a microscope.

• Microscopic Anatomy: Study of structures only visible with a microscope.

Physiology is the study of how the body functions and carries out the activities of life.

Levels of Organization

Hierarchy of Structural Organization

The human body is organized into a hierarchy of structural levels, each building upon the previous:

• Atoms: Smallest units of matter; combine to form molecules.

• Molecules: Groups of atoms bonded together; form organelles.

• Cells: Smallest living units; contain organelles formed from molecules.

• Tissues: Groups of similar cells performing related functions. Four main types:

  • Epithelial tissue

  • Connective tissue

  • Muscular tissue

  • Nervous tissue

• Organs: Composed of two or more tissue types working together (e.g., kidney, liver, brain, heart).

• Organ Systems: Groups of organs performing related functions (e.g., respiratory system, cardiovascular system).

Example: The heart (organ) is made of muscle, connective, and nervous tissues, and is part of the cardiovascular system (organ system).

Anatomical Position and Body Orientation

Standard Anatomical Position

• Standing upright, facing forward

• Feet together

• Palms facing forward

Supine: Lying face up in anatomical position Prone: Lying face down in anatomical position

Body Regions

• Axial: Head, chest, abdomen, pelvis

• Appendicular: Limbs (arms and legs)

Body Planes

Major Anatomical Planes

• Transverse (Cross Section) Plane: Divides the body into superior (upper) and inferior (lower) sections.

• Sagittal Plane: Divides the body into left and right halves.

• Midsagittal Plane: Divides the body into equal left and right halves.

• Parasagittal Plane: Divides the body into unequal left and right halves.

• Frontal (Coronal) Plane: Divides the body into anterior (front) and posterior (back) portions.

Anatomical Directions

Directional Terms

• Superior (Cranial): Above; toward the head (e.g., the leg is superior to the foot).

• Inferior (Caudal): Below; toward the feet (e.g., the foot is inferior to the leg).

• Anterior (Ventral): Toward the front (e.g., the nose is anterior to the ears).

• Posterior (Dorsal): Toward the back (e.g., the ears are posterior to the nose).

• Medial: Toward the midline (e.g., the heart is medial to the lungs).

• Lateral: Away from the midline (e.g., the eyes are lateral to the nose).

• Proximal: Nearer to the trunk or point of attachment (e.g., the elbow is proximal to the wrist).

• Distal: Farther from the trunk or point of attachment (e.g., the wrist is distal to the elbow).

• Superficial (External): Nearer to or on the surface (e.g., the skin is superficial to the muscles).

• Deep (Internal): Farther from the surface (e.g., the muscles are deep to the skin).

Abdominopelvic Quadrants and Regions

Quadrants

• Right Upper Quadrant (RUQ)

• Left Upper Quadrant (LUQ)

• Right Lower Quadrant (RLQ)

• Left Lower Quadrant (LLQ)

Regions

• Right hypochondriac region

• Epigastric region

• Left hypochondriac region

• Right lumbar region

• Umbilical region

• Left lumbar region

• Right inguinal (iliac) region

• Hypogastric region

• Left inguinal (iliac) region

Example: The appendix is typically located in the right lower quadrant (RLQ).

Body Cavities

Major Body Cavities and Their Contents

• Dorsal Cavity

  • Cranial cavity: Contains the brain

  • Spinal cavity: Contains the spinal cord

• Ventral Cavity

  • Thoracic cavity

    • Pleural cavities: Surround the lungs

    • Pericardial cavity: Surrounds the heart

    • Mediastinum: Partition between the lungs

  • Abdominopelvic (Peritoneal) cavity

    • Abdominal cavity: Contains digestive organs and many glands

    • Pelvic cavity: Contains urinary bladder and reproductive organs

Note: The thoracic and abdominal cavities are separated by the diaphragm.

Anatomical Landmarks

Common and Anatomical Terms for Body Regions

Organ Systems of the Human Body

Overview of Major Organ Systems

Example: The respiratory system includes the lungs, trachea, and diaphragm, and is responsible for gas exchange.