Urinary/Excretory System Descending aorta Inferior vena cava Urinary System (Excretory System) Renal vein Adrenal gland Renal artery Right kidney Left kidney Ureter Ureter Bladder Urethra

Urinary System Organs Kidneys (primary excretory organ) Ureters Bladder Urethra Functions Remove nitrogenous waste product of protein metabolism and other harmful substances Eliminates them in the form of ammonia, uric acid or urea Eliminates controlled amounts of water and salts to maintain the internal environment **Function is NOT to make urine Function is to maintain homeostasis of blood (excrete wastes, absorb nutrients, maintain electrolytes, pH balance)

Rugae

Sends blood to arterioles Receives 15-20% of systemic blood at rest

Nephron Functional Unit of Kidney Glomerulus Afferent arteriole Efferent arteriole Renal Corpuscle Renal papilla

Nephron Up to 1 million in kidney Functions Filtration removes dissolved substances from glomerulus (blood supply) what remains is called the filtrate Reabsorption Substances from filtrate leave nephron Reabsorb from tubule into blood or interstitial fluid Secretion Releases substances from blood supply or interstitial fluid into tubule (opposite direction from reabsorption)

Filtration Blood pressure forces water and dissolved substances out of the glomerulus blood into Bowman’s capsule Dissolved substances (filtrate): H2O, glucose, amino acids, electrolytes, and wastes (no proteins or cells) Averages 125 ml/min for both kidneys (180 liters/day) The vast majority of the filtrate (99%) must be taken back to body’s blood supply. Urinate (wastes) on avg. 1500 ml/day (0.4 gallons)

Reabsorption The return of substances from filtrate in the nephron tubule to the blood or interstitial fluid Major Substances: H2O - osmosis NaCl - active transport Glucose, amino acids - active co-transport Some urea and other salts PCT – most reabsorption Descending loop – reabsorb H2O Ascending loop & DCT – reabsorbs salt Collecting duct – reabsorbs H2O

Secretion Secreted Substances: toxins and drug residues The active release of substances INTO the nephron tubule. Purposes: Secreted Substances: toxins and drug residues Electrolyte balance: K+ exchanged for Na+ Acid-base balance: H+ , NH3 Antidiuretic hormone (ADH): produced by posterior pituitary, increases water permeability of the DCT and collecting duct Cranberry juice – acidifies urine to help discourage bacteria and some types of kidney stones; decrease UTI by inhibiting bacteria from adhering to urinary tract walls

Osmotic Pressure (Osmolarity)

Urine Micturation – process of urination Normal Urine Abnormal Urine H2O 95% Glucose Recent intake of sugary foods, Nitrogeneous wastes urea, uric acid,   diabetes melitis (Glycosuria) ammonia, creatine Protein Physical exertion, high protein; Electrolytes Na+, NH4+, K+, hypertension, glomerulonephritis (Proteinuria) Cl-, PO4-3, SO4-2 Ketone bodies Starvation, untreated diabetes mellitus Toxins bacterial poisons Hemoglobin Hemolytic anemia, severe burns Pigments products of breaking down RBC, Bile pigments Hepatitis, cirrhosis, bile obstruction filtered from food and drugs Erythrocytes Bleeding due to trauma, kidney stones, Hormones infection, cancer (Hematuria) Leukocytes Urinary tract infection

Disorders and Diseases Pyuria – pus in urine Dysuria – painful urination Polyuria – large amounts of urine Oliguria – very little urine Anuria – absence of urine Renal Calculi – crystallized calcium in renal pelvis or calyx (kidney stones) Neurogenic bladder – involuntary urine retention, bulging bladder, burning sensation Overactive bladder – frequent urination, pain, oliguria UTI: bacterial infection Urethritis: inflammation of urethra; result of gonorrhea and Chlamydia; most common in males Cystitis: inflammation of bladder; more common in females due to shorter urethra Nephritis: inflammation of kidney Pyelonephritis – inflammation of renal pelvis Renal Failure – kidney failure