Human Excretory Human Excretory SystemSystem

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Excretory SystemExcretory SystemExcretion – removes cellular

waste

The process that collects & removes harmful or useless substances that form in the

body or are taken into the body from the blood, tissues, and

cells.

Excretory SystemExcretory SystemAlthough the urinary system has a major role in excretion, other organs contribute to the excretory function.

Four Organs of the Excretory Four Organs of the Excretory SystemSystem

•The lungs in the respiratory system excrete some waste products, such as carbon dioxide and water. •The skin is another excretory organ that rids the body of wastes through the sweat glands. •The liver (via the intestines) excretes bile pigments that result from the destruction of hemoglobin. It also converts nitrogenous waste from the break down of proteins into urea.•The major task of excretion still belongs to the kidneys, the major organ in the urinary system. If it fails the other organs cannot take over and compensate adequately.

Cellular WasteCellular WasteHeat

WaterSaltsCO2

Urea

W/O excretion poisonous wastes build up in blood, cells, and tissues.

Could lead to serious illness & eventually DEATH!

Liver – Some FunctionsLiver – Some FunctionsFunctions in ExcretionFunctions in Excretion

– Detoxifies BloodDetoxifies BloodFilters Bacteria, alcohol, drugs, toxic Filters Bacteria, alcohol, drugs, toxic substancessubstances

Changes them into inactive or less toxic Changes them into inactive or less toxic forms.forms.

Excretes Bile Contains

Worn-out RBC Bile salts Cholesterol

Liver Produces UreaLiver Produces UreaFunctions in ExcretionFunctions in Excretion

– Forms Forms UreaUreaChanges toxic wastes (ammonia – from Changes toxic wastes (ammonia – from break down of amino acids) to Urea.break down of amino acids) to Urea.

Urea Urea Blood Blood Kidneys Kidneys

Filtered out & excreted in UrinFiltered out & excreted in Urinee

Lungs –Main Function Lungs –Main Function

Alveoli - Exchange O2 & CO2 between air and

blood (through process of diffusion)

Lungs excrete CO2 when you EXHALE

SkinSkinSweat GlandsSweat Glands– Help cool body: Heat escapes through Help cool body: Heat escapes through

millions of pores in skin surfacemillions of pores in skin surface– Excrete perspiration (evap. cooling)Excrete perspiration (evap. cooling)

99% H99% H22OO

Mineral SaltsMineral Salts

UreaUrea

Kidneys & Urinary SystemKidneys & Urinary System

Urinary System – Urinary System – excretes waste and excretes waste and maintains homeostasis maintains homeostasis of body of body fluidsfluids..– KidneysKidneys (main organ of the system) (main organ of the system)– UretersUreters– BladderBladder– UrethraUrethra

Kidneys & Urinary SystemKidneys & Urinary System

KidneysKidneys– Two Two – Fist sizedFist sized– Bean shapedBean shaped

Kidneys- Kidneys- Functional Units & Functional Units & ProductProduct

Nephron Nephron (about one million per kidney)(about one million per kidney)

– Microscopic units that Microscopic units that filterfilter blood of wastes. blood of wastes.– HH22O and waste taken from blood into nephronO and waste taken from blood into nephron

Form URINEForm URINE

Glomerulus (clump of capillaries)

At end of each nephron Network of coiled tubes – diffusion of

wastes - while useful substances & water are reabsorbed Urine

Pale yellow solution Urea, H20, salts, other trace solutions

(toxins…)

Urinary System - continuedUrinary System - continued

UretersUreters– Narrow muscular tubesNarrow muscular tubes– Connect Kidney Connect Kidney Bladder Bladder

Bladder Muscular sac Stores Urine Expand to fill Muscle relaxes

Urine squeezed into Urethra

Urinary System - endpointUrinary System - endpoint

UrethraUrethra– Tube leading from Bladder Tube leading from Bladder outside of outside of

bodybody

Failures of HomeostasisFailures of HomeostasisBladder & Kidney InfectionsBladder & Kidney Infections caused by caused by bacteria from colon/rectum entering bacteria from colon/rectum entering urethra.urethra.

Kidney Stones Kidney Stones - crystallization of mineral - crystallization of mineral salts & uric acid that block passage of salts & uric acid that block passage of urineurine

Kidney Disease Kidney Disease - caused by long term - caused by long term diabetes, infections, & chemical poisoningdiabetes, infections, & chemical poisoning

GoutGout – form of arthritis where excess – form of arthritis where excess production of uric acid leads to deposits production of uric acid leads to deposits of crystals in joints (esp. toes) of crystals in joints (esp. toes)