Brianna Laplante

Excretion is the process of eliminating waste products of metabolism and other non-useful materials.  It is an essential process in all forms of life.  The process of excretion involves finding and removing waste products from the body.  The excretory system regulates the amount of water and ions present in body fluids. 

The primary organs of excretion are the lungs, liver kidneys and skin.   Waste products gases are carried by blood traveling through veins to the lungs where respiration takes place.  Dead cells and sweat are removed from the body through the skin.  Liquid waste is removed from the body through the kidneys.  During circulation, blood passes through the kidneys to deposit used and unwanted minerals, water, and a nitrogen-rich material called urea.  The kidneys filter waste from the blood, forming urine.  The kidneys funnel the urine into the bladder along 2 seperate tubes called ureters.  The bladder stores the urine until muscular contractions force the urine out of the body through the urethra.  Feces are expelled through the large intestine.  In strict biological terminology, the removal of fecal material is not considered excretion because feces are indigestible foods and they are not metabolic waste.  Removing digestive wastes is done through a process called egestion. 

 The 4 types of metabolic wastes in the human body are water, carbon dioxide, salts and urea. 

*Water is a by-product of dehydration synthesis and respiration

*Carbon dioxide is a by-product of cellular respiration

*Salts are a by-product of neutralization

*Urea is a by-product of protein metabolism, deamination

Trackback URI | Comments RSS