EXCRETIO N in bacteria, protists, fungi, plants and animals SURVEY THROUGH THE KINGDOMS

EXCRETION  Definition: The process by which organisms remove waste from their cells or bodies to maintain homeostasis.  All organisms produce waste products, as a result of the chemical reactions they perform (metabolism).  Wastes include:  Water  Salts  Carbon dioxide  Nitrogenous wastes (containing nitrogen)

EXCRETION  Some organisms have sophisticated organ systems for this process, others are very simple.  Excretion is necessary in order to maintain the balance of pH, water and salt.  If an organism cannot rid itself of waste, it will die from toxicity.

EXCRETION  Certain organisms, such as bacteria and fungi, remove waste products through the simple process of osmosis and diffusion.  This is the movement of substances from an area of high concentration to low concentration.  Through what organelle is this occurring???

EXCRETION IN PROTISTS  Protists such as amoeba and paramecium use contractile vacuoles (along with diffusion) to remove water and wastes. Ex: Amoeba Paramecium

EXCRETION & RESPIRATION IN PLANTS  Plants use their stoma to take in and remove gases & water.  The stoma are usually found on the underside of the leaves or in the case of cacti, on their stems.

EXCRETION IN INSECTS & SPIDERS  Insects and spiders use malpighian tubules that are found in the blood-filled body of these organisms.  The wastes are filtered into the tubules by diffusion and active transport and released by the anus.

EXCRETION IN WORMS  Worms use a special structure called the nephridia (excretory tubules)to excrete wastes and excess water.  The movement of the nephridia as it filters the wastes looks like a flickering flame and is often called a flame cell.  The waste is eliminated through pores on the body.

DIAGRAM OF NEPHRIDIA

EXCRETION IN CRUSTACEANS  Crayfish and other crustaceans have two types of excretory organs: Gills and antennal glands.  Gills excrete carbon dioxide and the antennal glands excrete water, salts and ammonia. (They also use these to obtain oxygen through respiration!)

EXCRETION IN VERTEBRATES  There are 3 types of nitrogenous wastes in vertebrate animals:  Ammonia  Urea  Uric acid.  All can be toxic!  Vertebrate animals use kidneys to rid their system of nitrogenous wastes.

THE NEPHRON OF THE KIDNEY  The kidney is made up of many functional units called nephrons.  There are 1 million nephrons in each adult human kidney!  Their job is to filter the blood as it passes through the kidneys and collect it in the bladder for elimination.

OTHER EXCRETORY ORGANS  Lungs:  Excrete carbon dioxide—a waste gas.  Skin:  Excretes water, salts and urea.

 Look at the slide of the stoma under the microscope.  Draw and label the stoma and guard cell.  Use arrows to show what gases enter and leave through the stoma. ACTIVITY 12: STOMATA

 Many aquatic animals such as crayfish have gills. 1.What are they used for? 2.What structures do other animals (like ourselves) use instead of gills for this purpose? 3.What is another life process that uses the gills? 1.Hint: it may be one that we haven’t discussed yet. ACTIVITY 13: GILLS