Excretory System Urinary system

Structures of the Urinary System 2 kidneys – produce urine, filter blood 180 L of blood per 24 hours filtered 2 ureters – tube that leads to the bladder Bladder – stores urine Urethra – tube for eliminating urine

Kidney Function A. filter blood that has collected wastes from cells. B. Excrete waste – urea, uric acid, creatine, ammonium C. Maintain blood volume – regulating water excretion D. Monitor electrolytes in blood E. Monitor blood pH F. Secrete Renin – enzyme to help maintain blood pressure G. Stimulates red blood cell production

Structure of Kidney Renal cortex – outer layer, filtration Renal medulla – middle layer, filtration, absorption Renal pelvis – urine collection and transport Renal artery - Renal vein -

Urine Analysis Lab: Crystals

Lab: RBC’s in urine Will look red under microscope

WBC’s in urine Blue pigment

Production of Urine – Nephron – filtering unit (about 1 million) p Rate of filtration: 125 ml/min or 45 gallons each day. Blood in your whole body gets filtered 20 – 25x per day.

1. Filtration – filters bloodfilters blood  Caused by pressure difference between glomerulus and bowman’s capsule.  Glomerular filtrate – 180L/day, water, sodium, potassium, chloride, sugar, uric acid, creatine.  No red blood cells or large proteins found  Passive transport

Tubular Reabsorbtion - Valuable molecules reabsorb in blood  L reabsorbed (glomerular filtrate back into blood)  active and passive transport o glucose, water (passive), sodium (active) o hormones help reabsorbtion – ADH and aldosterone o diuretics affect this process

Tubular Secretion Small amount of substances (uric acid, ammonium, H ions) move from blood back to nephron

Hormonal Control Antidiuretic Hormone – (ADH) 1. Produced by hypothalamus 2. Stimulates reabsorbtion of water 3. Hydrated – decrease in production of ADH; increase in urine. 4. Dehydrated – increase ADH production 5. Diurectics – inhibit the absorption of water i.e. caffeine, alcohol

Aldosterone A. adrenal hormone, maintains sodium and potassium balance. Increase blood volume

Renin-Angiotensin System Regulates the body’s sodium and water levels for blood pressure. Steps of System:  Glomerular cells secrete renin into blood 2. Angiotensinogen (inactive in blood plasma), 3. In the liver coverts Angiotensinogen to hormone Angiotensin II 4. Constricts blood vessels 5. Also, causes Aldosterone to be secreated to help retain water and decrease renin production.