BODY-PLANES-CAVITIES-ORGANS-AND-ORGANS-SYSTEMS

1. Body Planes

Body planes are imaginary lines used to divide the body or organs into sections, providing a reference for anatomical descriptions.

  1. Sagittal Plane (Median/Midsagittal/Parasagittal):

    • Divides the body vertically into right and left parts.

    • A midsagittal or median plane divides the body exactly in the midline.

    • A parasagittal plane divides the body into unequal right and left parts.

  2. Frontal Plane (Coronal Plane):

    • Divides the body vertically into anterior (front) and posterior (back) parts.

  3. Transverse Plane (Horizontal Plane/Cross-Section):

    • Divides the body horizontally into superior (upper) and inferior (lower) parts.

2. Body Cavities

Body cavities are spaces within the body that contain and protect internal organs. They are classified into two main groups:

  1. Dorsal Body Cavity:

    • Located on the posterior (back) side of the body.

    • Cranial Cavity: Contains the brain.

    • Vertebral (Spinal) Cavity: Contains the spinal cord.

  2. Ventral Body Cavity:

    • Located on the anterior (front) side of the body.

    • Thoracic Cavity: Superior portion, separated from the abdominopelvic cavity by the diaphragm.

      • Pleural Cavities (2): Each surrounds a lung.

      • Pericardial Cavity: Surrounds the heart.

      • Mediastinum: The central partition of the thoracic cavity (contains heart, thymus, esophagus, trachea, major blood vessels); not a cavity itself, but the region containing the pericardial cavity.

    • Abdominopelvic Cavity: Inferior portion, extends from the diaphragm to the groin.

      • Abdominal Cavity: Superior portion (contains stomach, spleen, liver, gallbladder, small intestine, most of large intestine).

      • Pelvic Cavity: Inferior portion (contains urinary bladder, reproductive organs, part of large intestine).

3. Organs

An organ is a structure composed of two or more different types of tissues that work together to perform a specific function. Examples include the heart, lungs, stomach, and brain.

4. Organ Systems

An organ system is a group of organs that cooperate to perform major functions of the body. There are 11 major organ systems in the human body:

  1. Integumentary System: Skin, hair, nails, sweat and oil glands.

    • Function: Protection, temperature regulation, sensation.

  2. Skeletal System: Bones, cartilage, ligaments, joints.

    • Function: Support, protection, movement, mineral storage, blood cell formation.

  3. Muscular System: Skeletal muscles, smooth muscles, cardiac muscle.

    • Function: Movement, posture, heat production.

  4. Nervous System: Brain, spinal cord, nerves, sensory organs.

    • Function: Communication, coordination, control.

  5. Endocrine System: Glands (e.g., pituitary, thyroid, adrenal).

    • Function: Hormone production, control of growth, metabolism, reproduction.

  6. Cardiovascular System: Heart, blood vessels, blood.

    • Function: Transport of nutrients, oxygen, hormones, and waste products.

  7. Lymphatic System: Lymph vessels, lymph nodes, spleen, thymus, tonsils.

    • Function: Immunity, fluid balance.

  8. Respiratory System: Lungs, trachea, bronchi, larynx, pharynx, nasal cavity.

    • Function: Gas exchange (oxygen and carbon dioxide).

  9. Digestive System: Mouth, esophagus, stomach, intestines, liver, pancreas.

    • Function: Food breakdown, nutrient absorption, waste elimination.

  10. Urinary System: Kidneys, ureters, bladder, urethra.
    - Function: Waste filtration, fluid and electrolyte balance.

  11. Reproductive System: Gonads (testes/ovaries) and associated organs.
    - Function: Production of offspring, hormone production.