Honors Anatomy & Physiology

Kidneys Filter 200L of fluid from blood excreting waste as urine Regulate blood volume, balance water & salts, pH Secretes renin (BP) & erythropoeitin (EPO) Renal Cortex – superficial (light) Renal Medulla – deeper (dark) arranged in (8) pyramids Calyces collect urine & empty into renal pelvis

Nephrons Functional units of kidney > 1 million per kidney Glomerulus capillary bed Fed & drained by arterioles High pressure forces fluid & soluted out of blood Peritubular capillaries From efferent arterioles of glomerulus Low pressure reclaims solutes & water

Urine Color Yellow due to urochrome (pigment from Hb) Transparent – cloudy indicator of UTI Odor If left out smells of ammonia from bacteria metabolizing urea (diabetics urine smells fruity) Average pH6 vary (4.5-8) dependent on diet Composition 95% water Urea (from breakdown of amino acids) Uric acid (from breakdown of nucleic acids) Creatinine (from creatine phosphate) Na +, K +, PO4 3-, SO4 2-, Ca 2+ Mg +2,HCO3 -

Ureters Slender tubes propels urine from kidney to bladder 3 layer wall, transitional epithelium & 2 sheets of smooth muscle for peristalsis

Urinary Bladder Collapsable muscular sac temporariliy stores urine Trigone – 3 openings 3 layers: transitional epithelium, intermingled smooth muscle, fiberous adventitia Rugae – folds when empty Full bladder – 5” long – holds 1 pint of urine (max 1L)

Urethra Drains urine from bladder Internal urethral sphincter – involuntary External urethral sphincter – voluntary Females 3-4” long, external urethral orifice Males 8” long, carries urine & semen 3 regions: prostetic urethra 1” (within prostate) Membranous urethra 2cm Spongy urethra 15cm long

Fluid, Electrolyte, & Acid-Base Balance Water: women 50% of mass, men 60%, infants 73% Intracellular fluid – in cells Extracellular fluid – plasma & interstitial fluid (lymph, CSF, eye humors, synovial fluid, etc) Water intake 2.5L/day & metabolic water Water output: lung vapors, perspiration, feces, urine Solutes Nonelectrolytes – organic molecules w/covalent bonds Electrolytes – dissociate into ions in water Ph 7.35 (viens) (arteries) Buffers: bicarbonate, phosphate, protein