Excretory system of frogs
The main organ of excretion is a pair of kidneys. These are compact, dark red and bean like structures situated little posteriorly in the body cavity on both sides of vertebral column. The frog excretes urea thus, is a ureotelic animal. It is carried by blood into the kidney where it is separated and excreted.
Each kidney is composed of several structural and functional units called uriniferous tubules or nephrons.
Ureter emerges from the kidney as urinogenital duct in the male. A common ureter opens into the cloaca. A thin-walled urinary bladder in present ventral to rectum, which also opens into the cloaca. A thin-walled urinary bladder in present ventral to rectum, which also open in the cloaca.
Respiratory system of frogs
In amphibians, respiratory organs include buccopharygeal lining, skin, gills and lungs. While the gills are present in larval stage, the adults breathe by lungs or lungs as well as gills.
Respiration by skin is called cutaneous while the one by lungs is termed pulmonary.
Gills are absent in all reptiles, birdsand mammals, and the only respiratory organs in these vertebrates are the lungs.