Vertebarate Excretory systems

zExcretory systems regulate the chemical composition of body fluids by removing metabolic wastes and retaining the proper amounts of water, salts, and nutrients. zComponents of the excretory system in vertebrates include the lungs, liver, skin, and kidneys.

Excretory System Functions 1. Collect water and filter body fluids. 2. Remove and concentrate waste products from body fluids and return other substances to body fluids as necessary for homeostasis. 3. Eliminate excretory products from the body.

Waste Production zWhere does waste come from? yCells produce water and carbon dioxide as by-products of metabolic breakdown of sugars, fats, and proteins. yChemical groups such as nitrogen, sulfur, and phosphorous are removed, from the large molecules to which they were formerly attached (deamination etc.)

Types of waste zAmmonia yNitrogen wastes are a by product of protein metabolism. Amino groups are removed from amino acids prior to energy conversion. The NH 2 (amino group) combines with a hydrogen ion (proton) to form ammonia (NH 3 ). yAmmonia is very toxic and gets converted to urea which is then put into the blood and removed by the kidneys.

Waste Production zThe continuous production of metabolic wastes establishes concentration gradient across the plasma membrane of cells, causing wastes to diffuse out of cells and into the extracellular fluid. zMulticellular organisms must have a specialized organ system to concentrate and remove wastes from the extracellular fluid, collect it, and remove it from the body.

The Urinary System

Water and Salt Balance zThe excretory system is responsible for regulating water balance in various body fluids. zKidneys regulate body fluid levels and remove wastes

The Urinary System zThe urinary system is made-up of the kidneys, ureters, bladder, and urethra. zThe nephron is the kidney's functional unit. zWaste is filtered from the blood and collected as urine in each kidney.

The Urinary System zUrine leaves the kidneys by ureters, and collects in the bladder. zThe bladder can distend to store urine that eventually leaves through the urethra.

The Urinary System The Nephron zThe nephron consists of a cup-shaped capsule containing capillaries and the glomerulus, and a long renal tube.

The Urinary System The nephron has three functions: 1. Glomerular filtration of water and solutes from the blood. 2. Reabsorption of water and conserved molecules back into the blood. 3. Secretion of ions and other waste products from surrounding capillaries into the distal tubule.

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