Are there organisms ina re body that we need to live? like certain things?not like organs or blood cells but?

Answer 1

There are lot of organisms which live in and on the body...
Over the skin, in the nose, mouth, oesophagus, intestines..... These are called as "commensals" or "normal flora"

These organisms help in preventing the infections from disease causing bacteria to some extent..
They also help us by synthesising Vitamin K & some B complex Vitamins and also help by metabolising some substances...

This is process is known as Symbiosis, Helping each other..

Some tell that the Mitochondria was once a separate organism which got incorporated into the cells in the process of evolution..

Commensals have very less virulence (ability to cause harm) and usually wont cause disease in healthy individuals...

There are certain conditions where these commensal organisms can cause diseases.. Some of these include:
Improper antibiotic therapy.
Immuno-compromised conditions like AIDS, Diabetes Mellitus, ImmunoSupprassant Drugs, Cancer Chemotherapy, etc....
Valvular Heart Diseases & in Prosthetic Valves...

There are some conditions where organisms like these are tried to remove.. Eg: in Hepatic Encephalopathy...

There are certain compartments which is free from organisms (also called sterile) in normal individuals like CSF, Blood, Joints, Pleura, Peritonium, etc..

Answer 2

Yes like Chechu said, we do have organisms living in sync with us, these are called normal microbiata. The ones in your intestines help to break down and digest food.

Answer 3

of course, we live in symbiosis with organism in our skin and in our intestines. they are cel most like bacterias