Answer:
complement is a system of plasma protiens that can be activated directly by pathogens
I guess that is:
Within the capillaries of the lungs, gases are exchanged by diffusion; O2 diffuses from the alveolus to the bloodstream and CO2 diffuses from the bloodstream to the alveolus.
In general, the function of the excretory system is, removal of nitrogen waste products from the bloodstream and transport out of the body through urine. It maintains the balance of fluids and electrolytes, control of red blood cells, regulation of blood pressure and also the formation of red bone marrow.
In humans, the excretory system is responsible for removing waste from the body. Metabolic waste is being removed from the blood and an appropriate amount of water nutrients and water and salt are being retained.
In frogs, the excretory system consists of a pair of ureters, kidney pairs, cloaca, and urinary bladder. Frogs take in liquid waste from kidney which removes wastes and then the extra water becomes urine which then it is collected in the urinary bladder through ureters.
The urinary bladder is present in ventral to return then both open into the cloaca.
