Interaction Among the Excretory Organs

Abstract

In this chapter the quantitative interaction of kidney, cloaca, and salt gland will be discussed. For the kidney and cloaca the problem is whether the storage of ureteral urine in the cloaca will modify the excretion rates of salts and water. The problem will be treated separately for three major osmotic situations: hydration, salt loading, and dehydration. Urine flow in the water- and salt-loaded states is large compared with the transmural transport in the cloaca, and approximate calculations will be sufficient. In the case of the dehydrated state, however, the ureteral flow of water and salt is so small that the transmural transport in the coprodeum and large intestine will change the rate of excretion considerably. Therefore, more precise calculations must be made. The problem for birds with salt glands will be treated separately. The major question is whether the salt gland and cloaca interact in conservation of water from ureteral urine.