What is NOT an organ?

Before I start, I’d like to mention that my first German Bachelorette Party experience was a fun success and I will post an entry/photo links in a jiffy. However, I’m lost and I need a little help in Anatomy.

Last Thursday in my German class we were to name four different human organs. Being the over achievers that we are, we named more than four:

das Herz
die Niere(n)
die Leber
das (Ge)hirn
die Lunge(n)
die Haut
der Darm
die Blase
die Auge= heart
= kidneys
= liver
= brain
= lungs
= skin
= intestine
= bladder
= eye

But then things started to get a little fuzzy. Is the nose (die Nase) an organ? What about the ear (das Ohr(-en))? I suspected that an eye was not an organ and wrongly deduced, based on our list, that a particular body part is named an “organ” because it is vital to life, without an “organ” one would die. I guess “organ donation” sprung to mind.

However, the internet dictionary’s medical and scientific definitions say that an organ is ‘part of a living thing, distinct from the other parts, that is adapted for a specific function. Organs are made up of tissues and are grouped into systems.’

My class missed these other common animal/human organs:

der Magen
die Milz
das Pankreas or
die Bauchspeicheldrüse
die Gebärmutter= stomach
= spleen
= pancreas
 
= uterus

Since people function without eyes and women are able to live without a uterus, my understanding of what an organ is is wrong. The definition goes further: Animal organs inside the thorax or abdomen are often referred to as internal organs (innere Organe des Körpers). But internal organs do NOT included organs inside the head or other parts of the body. The internal organs collectively are often called viscera (die Eingeweide). Okay fine so far.

BUT then there are organ systems, which are a group of related organs (in any number of ways), but relationships of function are most commonly used.

Organ systems

Herz-Kreislauf-System
der Verdauungsapparat
das Immunsystem
die Körperdecke 
das Lymphgefäßsystem
das Nervensystem
der Geschlechtsapparat
der Atmungsapparat
das Harnsystem = Cardiovascular system
= Digestive system
= Immune system
= Integumentary sys skin, hair, nails
= Lymphatic system
= Nervous system
= Reproductive system
= Respiratory system
= Urinary system

But we’re not done! There is also organ system pairing, for example, the nervous and endocrine (das Endokrines System) systems both operate via a shared ‘organ’, the hypothalamus -which are then combined and studied under neuroendocrine system. Musculoskeletal system, considered a human organ system, is the relationship between muscular and skeletal systems. Yet are muscles (die Muskeln) and bones (der/die Knochen) considered organs, just NOT internal organs?

Even German and English anatomy texts group organ systems differently. For example, in German, the immune system is linked with the cardiovascular system to give Herz-Kreislauf- und Abwehrsystem and the urinary system is linked with reproductive system. Wikipedia in German goes further to name the Sensory system (Sinneorgan) an organ system -therefore the Ears and nose are organs?

It seems to me, defining an organ is subjective and an organ system is not a system of organs+. So cells, glands (die Drüse) or Tissues (die Gewebe) are NOT organs, but organs can be cells, tissue or glands.

This seems almost as bad as defining what’s a fruit or vegetable ugh!