3 Types of Excretion in Animals PDF

Excretion and Homeostasis: Waste Management in Living Systems This Photo by Unknown Author is licensed under CC BY Introduction to Excretion Excretion is the process of removing waste products from an organism's body Crucial for maintaining homeostasis (inte...

Excretion and Homeostasis: Waste Management in Living Systems This Photo by Unknown Author is licensed under CC BY Introduction to Excretion Excretion is the process of removing waste products from an organism's body Crucial for maintaining homeostasis (internal balance) Prevents accumulation of toxic substances Regulates body fluid composition and volume Importance of Excretion for Homeostasis Maintains optimal internal environment Removes metabolic waste products (e.g., urea, carbon dioxide) Regulates water balance Controls electrolyte levels Helps maintain pH balance in the body Types of Excretion in the Human Body Urinary excretion (kidneys) Respiratory excretion (lungs) Perspiration (skin) Defecation (digestive system) Each system removes specific waste products to maintain homeostasis The Urinary System: Key Players Kidneys: Main excretory organs Ureters: Transport urine from kidneys to bladder Urinary bladder: Stores urine Urethra: Conducts urine out of the body Thi s Photo by Unknown Author i s l icensed under CC BY-SA-NC  Filter blood (about 180 liters per day) Role of Remove waste products (urea, creatinine) Regulate water balance Kidneys in Control electrolyte levels (sodium, potassium, calcium) Homeostasis Maintain acid-base balance (pH) Produce hormones (e.g., erythropoietin, renin) Deamination: An Essential Process Definition: Removal of amino groups (-NH₂) from amino acids Location: Primarily in the liver Purpose: Converts excess amino acids into energy or fat Product: Ammonia (NH₃), which is toxic and must be converted to urea (100’s of times less toxic than Ammonia so it can be stored until excretion) Deamination Process Amino acids enter liver cells Enzymes remove amino groups Ammonia (NH₃) is produced Ammonia is converted to urea in the urea cycle Urea enters bloodstream and is excreted by kidneys Forms of Deamination in Land Animals Mammals (including humans): Urea Birds and reptiles: Uric acid Amphibians: Mix of urea and ammonia Adaptations based on water availability and habitat Excretory Systems in Multicellular Organisms Protonephridia: Flame cells (e.g., flatworms) Metanephridia: Segmented tubules (e.g., earthworms) Malpighian tubules: Insect excretory system Kidneys: Vertebrate excretory system Excretion in Worms Earthworms: Metanephridia Pair of tubules in each segment Collect waste from fluids in the Coelom (body cavity Flatworms: Protonephridia (flame cells) Network of tubules with ciliated cells Remove excess water and some metabolic wastes Excretion in Insects Malpighian tubules: Blind-ended tubes extending from gut Filter hemolymph (insect blood) Remove nitrogenous wastes, excess water, and ions Rectum: Reabsorbs water and essential ions  Excretion in Arachnids Coxal glands: Located near leg bases Remove nitrogenous wastes Malpighian tubules (some species): Similar function to insects  Excretion in Birds Kidneys: Three lobes, more compact than mammalian kidneys Produce more concentrated urine to conserve water Uric acid: Main nitrogenous waste product Excreted as a paste with feces Salt glands: In marine birds, help excrete excess salt  Conclusion: Diversity in Excretory Systems Excretion is vital for homeostasis across all organisms Excretory systems have evolved to suit different habitats and lifestyles Common themes: waste removal, water balance, ion regulation Understanding excretion helps us appreciate the complexity of life and adaptations to different environments