Anatomical Terminology: Directions and Planes

• Anatomy studies the structure of the body.
• Physiology studies the function of the body parts.
• Pathology studies disease in the body.
• Basic reference systems include directions, planes, cavities, and structural units.

Terms of Direction

• Anterior refers to the front or before.
• Posterior refers to toward the back.
• Superior means above or upward direction.
• Inferior means below or in a downward direction.
• Proximal is the point of attachment near the body's center.
• Distal is the point of attachment further from the center.
• Lateral refers to the side.
• Medial refers to nearest the midline.
• Ventral is the front side.
• Dorsal is the back side.
• Superficial refers to toward the surface.
• Deep refers to toward the interior.

Planes

• Sagittal plane divides vertically into right and left parts.
• Frontal (coronal) plane divides into front (anterior) and back (posterior) parts.
• Transverse plane is a cross-sectional division separating into upper (superior) and lower (inferior) portions.
• Midsagittal plane divides the body vertically into equal right and left portions.

Cavities

• Dorsal cavities include cranial and spinal cavities.
• Ventral cavities include thoracic and abdominopelvic cavities.
• Parietal refers to the walls of a cavity.
• Visceral refers to the covering on an organ.

Structural Units

• Cells are the smallest units of life and perform activities to maintain life.
• Cells perform metabolism, assimilation, digestion, excretion, and reproduction.
• Tissues are made of different types of cells.
• Epithelial tissue covers and protects.
• Connective tissue binds and supports other tissues.
• Muscle tissue facilitates movement.
• Nervous tissue connects sensory structures to motor structures.
• Organs integrate cells into tissues and serve a common function.
• Examples of organs include the liver and stomach.
• A Body System is a group of organs.
• An Organism consists of several body systems that make up a complete living entity.

Integumentary System

• Organs include skin, hair, nails, sweat glands, and sebaceous glands.
• Functions include protection, insulation, and regulation of water and temperature.

Components of the Skin

• Epidermis is the thinnest layer, with no blood vessels or nerve endings, and contains keratin and melanin.
• Dermis is thicker than the epidermis, with fingerprints and footprints.
• Subcutaneous tissue stores fat and energy and acts as a heat insulator.
• Sudoriferous glands regulate body temperature and eliminate waste products.
• Sebaceous glands are oil-secreting glands.
• Hair is dead, keratinized cells.
• Nails protect fingers and toes.

Skin Disorders

• Acne involves oversecretion of sebum, leading to blockage of glands and pustules.
• Eczema is an allergic reaction with an itchy rash.
• Fever blisters are caused by herpes simplex virus (HSV) which may become dormant or activated by stress or illness.
• Fungal infections include ringworm and athlete's foot.

Skeletal System

• Organs include bones, cartilage, and membranous structures.
• Functions include movement, blood production, fat and mineral storage, and protection.

Muscular System

• Organs include muscles, fasciae, tendon sheaths, and bursae.
• Functions include movement, pushing food and blood, and contracting the heart.

Nervous System

• Organs include the brain, spinal cord, cranial and peripheral nerves, sensory and motor structures.
• Functions include control and regulation, and interpreting stimuli.

Endocrine System

• Organs include endocrine glands.
• Works with the nervous system to regulate chemical aspects of the body.

Cardiovascular System

• Organs include the heart, arteries, veins, and capillaries.
• Transports substances to and from cells.

Lymphatic/Immune System

• Organs include lymph nodes, lymph vessels, thymus gland, and spleen.
• Functions include draining tissues of excess fluids, transporting fats, and developing immunities.

Respiratory System

• Organs include nasal cavities, pharynx, larynx, trachea, bronchi, and lungs.
• O2 > CO2 exchange in the blood.

Digestive System

• Organs include the alimentary canal (mouth, esophagus, stomach, small and large intestines, rectum, and anus).
• Associated glands include salivary glands, liver, and pancreas.
• Converts food into absorbable substances and eliminates wastes.

Urinary System

• Organs include kidneys, ureters, bladder, and urethra.
• Functions include chemical regulation of blood, formation and elimination of urine, and maintenance of homeostasis.

Reproductive System

• Women: ovaries, uterine tubes, uterus, vagina.
• Men: testes, seminal vesicles, prostate gland, penis, urethra.
• Maintains sexual characteristics and perpetuates the species.

Homeostasis

• Maintenance of the body's internal environment within varying narrow limits.
• Negative Feedback Loop mechanisms.
• Examples include blood sugar levels and body temperature.

Blood Glucose Regulation

• Levels rise dramatically after a meal.
• Cells take in glucose.
• The pancreas secretes insulin, which moves glucose into the liver for storage as glycogen.
• Between meals, the pancreas secretes glucagon.
• Glycogen is converted into glucose and returned to the blood.
• Glucose levels remain constant because of pancreatic regulation.

Body Temperature Regulation

• Hypothalamus detects increase in body temperature and causes sweating.
• Water evaporates and body is cooled.
• Blood vessels dilate to bring blood near the body surface.

Homeostasis and Feedback Loops

• The body monitors deviations in homeostasis.
• Negative feedback loops elicit responses that revise disturbances in the body’s condition.
• Positive feedback loops Increase function in response to a stimulus, such as uterine contractions during labor.
• Organ systems help control the internal environment.