UrinaryExcretory System Inferior Descending aorta vena cava Urinary

Urinary/Excretory System Inferior Descending aorta vena cava • Urinary System Adrenal (Excretory System) gland Renal vein Renal artery Right kidney Left kidney 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, p. H 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): H 2 O, 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: – – • • H 2 O - osmosis Na. Cl - active transport Glucose, amino acids - active co-transport Some urea and other salts PCT – most reabsorption Descending loop – reabsorb H 2 O Ascending loop & DCT – reabsorbs salt Collecting duct – reabsorbs H 2 O

Secretion • 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+ , NH 3 – 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 H 2 O 95% Nitrogeneous wastes urea, uric acid, Glucose ammonia, creatine Electrolytes Na+, Abnormal Urine NH 4+, Recent intake of sugary foods, diabetes melitis (Glycosuria) Protein Physical exertion, high protein; hypertension, glomerulonephritis (Proteinuria) K+, Cl-, PO 4 -3, SO 4 -2 Ketone bodies Starvation, untreated diabetes mellitus Toxins bacterial poisons Hemoglobi n Hemolytic anemia, severe burns Pigments products of breaking down RBC, Bile pigments Hepatitis, cirrhosis, bile obstruction filtered from food and drugs Erythrocyte Bleeding due to trauma, kidney s 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