alveoli
alveoli
Air sac
Alveoli
a cell
The smallest functional andstructural unit of kidney is called as -
alveoli. they are the basic functional unit of the lungs. it is where gas exchange occurs.
Capillaries are referred to as the functional unit of the circulatory system.
Because they are the lining of the lungs that begin the process of taking oxygen out of the air and into the blood stream. They are the parts that actually coe into contact with the "air" and are therefore called the functional part of the lungs.
The smallest structural unit of a protein is the amino acid. The smallest functional unit of a protein is a little ambiguous, because some might consider the amino acid to be functional (after all, some can function as neurotransmitters). Or, some might consider the peptide (di, tri, etc) to be a functional unit. One could argue what exactly is the smallest functional unit of a protein.
neuron
myocytes
decibel
nephron.
atom