Urinary System and Excretion

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What is homeostasis

The condition in which the body remains relatively constant within physiological limits

To maintain this, the volume and composition of body fluids must be tightly regulated

what are the body fluids

• intracellular fluid - fluid in cell

• extracellular fluid - fluid outside cells

• interstitial fluid - fluid in narrow spaces between cells

• blood plasma

• lymph

• others

What is metabolic waste and what do it include?

All waste products produced from cellular metabolism

• carbon dioxide

• water

• nitrogenous wastes

• acids and phosphates

• excess nutrients

What is excretion and what organs do it

The removal of waste products

• kidneys - remove most metabolic waste

• skin - removes CO2

• liver - removes bile pigments

• lungs/gills - removes CO2

• special structures for salt removal

Kidney development and what system

Develop from Nephric ridges and are associated with reproductive organs

often systems are united and called urogenital system

Pronephros

early developing embryonic kidneymes

mesonephros

develops as pronephros regresses along differentiation of Archinephric duct

opisthonephros

remains as kidney and may be elongated and thin or short and compact (fishes and amphibians

metanephros

transitional kidney that functions as embryo

• begins formation of other urinary structures

• develops in retroperitoneal cavity

• adult kidneys are usually compact structures that may be subdivided into lobes

what is nephron