Excretory System
Ewww! Giggle, giggle
Excretion
• • • • Digestive System Respiratory System Skin Urinary System • • • • H2O, undigested food H2O, CO2 H2O, salts H2O, salts, poisons
• Why do we need to drink lots of water?
Regulating Fluids
• • • • Hypothalamus – in mid-brain Detects fluid levels in blood Sends hormone into bloodstream Kidneys respond by increasing/decreasing urine output.
Kidneys
• • • • • Main organs of excretory system Bean-shaped Red – because of blood supply Back of abdomen near waist Filter all blood every 5 minutes
Human Kidney
Filtration – Step 1
• • • Blood from renal (kidney) artery → Capillaries (all wadded up) → Nephron – cup and tube (duct)
– Water, sugar, salt, waste → cup – Red cells, proteins left in capillary – Liquid → tubule
Filtration – Step 2
• Most sugar, salt, H2O reabsorbed from tubules to capillaries • → renal vein • →main circulatory system
Urine
• Left behind in tubules • Excess water, wastes • Urea
– excess amino acids – NH3+ CO2
• Average 1 liter/day
Liver
• Broken-down blood cells – bile • Digestive fluid
Diseases
• Imbalances
– Fluids – Salts
• Blockages
– Kidney stones – Ultrasound blasts
• Infections - Nephritis • Urine tests
– for glucose (diabetes) – protein (heart disease)
Dialysis
• • • • • Kidney failure – excess fluid Patients can’t urinate Artificial kidney filters blood 2-3 times weekly 2-4 hours at a time
Transplant
• Kidney failure • Live or dead donor • Blood matches needed
Preventing Kidney Diseases
• Diet • Exercise • Blood Pressure
The Rest of the Story
• • • • • Tubules Ureters Bladder (up to ½ liter) Urethra Sphincter muscle