Human Biology

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Human anatomy (or anthropotomy) is a special field within anatomy (the study of the shape, form, consistency, and organization of plants and animals). It studies organs and organ systems of the human body. The human body, like the bodies of all animals, is made up of systems, that are made up of organs, that are made up of tissues, that are made up of cells. Anatomy embraces morphology (study of the external features of living organisms), and applies also to the internal features of organs, skeletons, and even cellular detail. Anatomy has been studied by means of dissection, while modern non-destructive means of studying internal structures include body-scanners and x-rays.

The science concerned with the form, structure, and spatial relationships of a living organism, and the relation of structure to function. It originally referred to the cutting up of the body to determine the nature and organization of its parts, but nowadays it includes many other aspects of study. Topographic or gross anatomy deals with the relative positions of various body parts. Systemic anatomy is concerned with the study of groups of related structures (eg the respiratory system).

Circulatory system: the blood circulation with heart and veins In anatomy, the circulatory system or cardiovascular system is the system that circulates blood around the body of humans and many other animals. Its main function is to deliver oxygen and nutrients to all parts of the body and to remove wastes; it also plays an important role in the immune system defending against infections.	Digestive system: processing food with mouth, stomach and intestines Gastrointestinal tract, also referred to as GI tract, refers to the system of multicellular animals that ingests, digests, and egests food, and in the process, extracts energy and nutrients.	Endocrine system: communicating within the body using hormones The endocrine system is a system of ductless endocrine glands that secrete chemicals called hormones that circulate within the body via the bloodstream to affect distant organs. It does not include exocrine glands such as salivary glands, sweat glands and glands within the gastrointestinal tract.
Immune system: defending against disease-causing agents The immune system of a multicellular organism acts as a defense against pathogens, such as viruses, bacteria, parasites, and some poisons. There are several variations of immune systems throughout species, and sometimes more than one immune system within the same organism (for example, the human brain has its own immune system that is separate from the "normal" one). Many species, including mammals, have the following type:	Muscular system: moving the body The muscular system is the biological system of animals that allows them to move internally and externally. The muscular system in vertibrates consists of three different types of muscles: cardiac, skeletal and smooth. Cardiac muscle is a striated muscle that makes up the heart. It is the only type of muscle consisting of branching fibers. Skeletal muscle consists of voluntary muscles attached to the frame of the skeletal system enabling bodily movement. Smooth muscle is the involuntary muscle that enables the movement of internal organs. Movement of all muscles is controlled through the nervous system.	Nervous system: collecting, transferring and processing information with brain and nerves The nervous system of an animal coordinates muscle movement, monitors the organs, constructs and processes impressions from the senses, and initiates actions. In animals with brains, it also generates and conducts thoughts and emotions. Thus it is the system that animates "animals" (sponges are the exception). Chemicals that target the activity of nerves generally are the most rapidly acting toxins, typically causing paralysis and/or or death.
Reproductive system: the sex organs A sex organ or primary sexual characteristic, narrowly defined, is any of those parts of the body (which are not always bodily organs according to the strict definition) which are involved in sexual reproduction. They constitute the reproductive system in an complex organism. More generally and popularly, sex organs are those parts of the body involved in erotic pleasure.	Respiratory system: the organs used for breathing, the lungs The respiratory system is the biological system of any organism that engages in gaseous exchange. Even trees have respiratory systems, taking in carbon dioxide and emitting oxygen.	Skeletal system: structural support and protection through bones In biology, the skeleton or skeletal system is the biological system providing support in living organisms. (By extension, non-biological outline structures such as gantries or buildings may also acquire skeletons.)