E. Scientific terminology, Body organisation and Body systems

Levels of organisation in the human body

The major levels of organisation from simplest to most complex are: chemical, cellular, tissue, organ, organ system, and organism.

Chemical Level

The simplest level of organisation, involving atoms and molecules that make up cells.

Cellular Level

The level of organisation where cells, the basic units of life, are formed.

Tissue Level

A group of similar cells that perform a specific function.

Organ Level

A structure composed of two or more tissue types that work together for a specific function.

Organ System Level

A group of organs that work together to perform complex functions.

Organism Level

The most complex level of organisation, representing a living being.

Major components of the integumentary system

Skin, hair, nails, and associated glands.

Major components of the skeletal system

Bones, cartilage, and ligaments.

Major components of the muscular system

Skeletal muscles, smooth muscles, and cardiac muscle.

Major components of the nervous system

Brain, spinal cord, and nerves.

Major components of the endocrine system

Glands such as the pituitary, thyroid, adrenal, and pancreas.

Major components of the cardiovascular system

Heart, blood, and blood vessels.

Major components of the lymphatic system

Lymph nodes, lymphatic vessels, and spleen.

Major components of the respiratory system

Nasal passages, trachea, bronchi, and lungs.

Major components of the digestive system

Mouth, esophagus, stomach, intestines, liver, and pancreas.

Major components of the urinary system

Kidneys, ureters, bladder, and urethra.

Major components of the reproductive system

Ovaries, testes, uterus, and associated structures.

Body cavities

Spaces within the body that house and protect organs, such as the thoracic cavity, abdominal cavity, and pelvic cavity.

Anatomical position

A standardized posture where the person stands upright, facing forward, arms at the sides, and palms facing forward; used to describe the location of body parts.

Anterior

Referring to the front of the body.

Posterior

Referring to the back of the body.

Superior

Referring to a position higher or above another part.

Inferior

Referring to a position lower or below another part.

Medial

Closer to the midline of the body.

Lateral

Further from the midline of the body.

Renal

Pertaining to the kidneys.

Hepatic

Pertaining to the liver.

Brachial

Pertaining to the arm.

Cephalic

Pertaining to the head.

Orbital

Pertaining to the eye socket.

Gluteal

Pertaining to the buttocks.