Human organ systems

1. Cardiovascular system: blood circulations with heart and blood vessels

2. Digestive system: processing food with mouth, stomach and intestines

3. Endocrine system: communicating within the body using hormones

4. Immune system: defending against disease-causing agents

5. Integumentary system: skin, hair and nails

6. Lymphatic system: structures involved in the transfer of lymph between tissues and the bloodstream

7. Muscular system: moving the body

8. Nervous system: collecting, transferring and processing information with brain and nerves

9. Reproductive system: the sex organs

10. Respiratory system: the organs used for breathing, the lungs

11. Skeletal system: structural support and protection through bones

12. Urinary system: the kidneys and associated structures involved in the production and excretion of urine

The anatomical position

In human and zoological anatomy (sometimes called zootomy), several terms are used to describe the location of organs and other structures in the body of bilateral animals. These terms are listed and explained here. Generally the words are derived from Latin.

In some cases, the terminology in human anatomy may differ from that in general anatomy, which also applies to other species (where some very different organs occur).

The anatomical position holds more relevant information on relations and terms of location for human anatomy.

Animals typically have one end with a head and mouth, with the opposite end often having the anus and tail. The head end is the cranial end; the tail end is the caudal end. Within the head itself, rostral refers to the direction toward the end of the nose, and caudal is still used to refer to the tail direction.

The surface or side of the body normally oriented upwards, away from the pull of gravity, is the dorsal side; the opposite side, typically the one closest to the ground when walking on all legs, swimming or flying, is the ventral side. For example: in vertebrates, the spine or nerve chord is located on the dorsal side of the organism. A dolphin's dorsal fin is, unsurprisingly, on the dorsal side. A cow's udder is on the ventral side.

On the limbs or other appendages, a point closer to the main body is "proximal"; a point farther away is "distal".

The right and left side (sometimes in Latin: dexter - right, and sinister - left) are always given as viewed from the animal that is described.

In human anatomy, the body and its parts are always described using the assumption that the body is in anatomical position (main article), i.e. standing upright.

Portions of the body which are closer to the head end are "superior" (Latin "upper"); those which are farther away are "inferior" ("lower") -- superior corresponds to cranial (at the skull'), and inferior to caudal ('at the tail'). Objects near the front are "anterior"; those near the rear are "posterior" -- these correspond respectively to "ventral" and "dorsal".

The terms "anterior" and "posterior" should not be used when referring to most animals however, and are particularly incorrect for quadrupeds. In this case, rostral/cranial and caudal are more appropriate.

However the word posterior is commonly used (not in anatomical jargon) as a substantive meaning the buttocks or an adjective referring to them, as in 'posterior discipline' (such as spanking)