Unit IV: Regulation Urinary System Chapter 24: pp Chapter 23: pp

Water Balance Total body water for 150 lb. male = 40L Fluid compartments –65% ICF –35% ECF 25% tissue fluid 8% blood plasma, lymph 2% transcellular fluid (CSF, synovial fluid)

Water Movement in Fluid Compartments OsmosisCapillary filtration Capillaries; Cells; or Lymphatic System Electrolytes play principle role in water distribution and total water content

Fluid Balance Preformed water

Water Loss Loss varies greatly with environment and activity –respiratory loss  : with cold, dry air or heavy work –perspiration loss  : with hot, humid air or heavy work Sensible water loss –urine and abundant sweating Insensible water loss –breath and cutaneous transpiration Obligatory water loss –Expired air, cutaneous transpiration, sweat, feces, minimum urine output (400 ml/day)

Regulation of Fluid Intake Hypothalamus

Regulation of Output Controlled by urine volume Support existing fluid levels and slow rate of loss Na + reabsorption and ADH Osmoreceptors – group of neurons in hypothalamus, respond to osmolarity

Urinary System 2 kidneys 2 ureters Urinary bladder Urethra

Kidney Functions Primary role in excretion, other functions: Filters blood plasma Regulates –osmolarity of body fluids, blood volume, BP –acid base balance Secretes –erythropoietin and renin –calcitriol Gluconeogenesis

Nitrogenous Wastes Urea –proteins  amino acids  NH 2 removed  forms ammonia, liver converts to urea Uric acid –nucleic acid catabolism Creatinine –creatine phosphate catabolism

Thermometer Shunt Artery Vein Blood pump Bubble trap Cutaway view of dialysis chamber Flow meter To drain Dialysis fluid Dialysis tubing Renal Failure Blood urea nitrogen (BUN) –10-20 mg/dL –azotemia:  BUN, nitrogenous wastes in blood –uremia: toxic effects as wastes accumulate Renal insufficiency –Hemodialysis:

Excretion Separation of wastes from body fluids and eliminating them. –respiratory –integumentary: water, salts, lactic acid, urea –digestive: water, salts, CO 2, lipids, bile pigments, cholesterol –urinary: many metabolic wastes, toxins, drugs, hormones, salts, H + and water

Anatomy of Kidney CT coverings –renal fascia –perirenal fat capsule (adipose capsule) –fibrous (renal) capsule

Anatomy of Kidney Renal Parenchyma: –Renal cortex: outer 1 cm –Renal medulla: renal columns, pyramids - papilla Renal sinus –Minor calyx –Major calyx –Renal pelvis  ureter

Renal vein Arcuate vein Interlobar veins Renal artery Cortical radiate veins Segmental artery Interlobar artery Arcuate artery Cortical radiate arteries Afferent arterioles Glomerulus to efferent arterioles to capillaries of the nephron Renal Circulation

Efferent arteriole Glomerulus in renal corpuscle Afferent arteriole Peritubular capillaries To the cortical radiate vein A cortical nephron Renal Circulation Efferent arteriole Capillaries of the vasa recta Afferent arteriole Peritubular capillaries To cortical radiate vein A juxtamedullary nephron

Nephron Renal Corpuscle Glomerulus and Bowman’s capsule (glomerular) Glomerular filtrate collects in capsular space  flows into renal tubule

Nephron Renal Tubule Proximal convoluted tubule (PCT) –simple cuboidal with brush border Nephron loop - descending and ascending limbs –thick segment (simple cuboidal) –thin segment (simple squamous) –Creates osmotic gradient thru counter-current multiplication Distal convoluted tubule (DCT) –Cuboidal epithelium; end of nephron Collecting duct –simple cuboidal –Papillary duct

Renal medulla The thin descending limb is permeable to water, but impermeable to solutes, including urea. KEY Urea Renal cortex Cl  Na  The thick ascending limb of the nephron loop is impermeable to water and solutes. The DCT and the collecting ducts are impermeable to urea but have variable permeability to water. Water reabsorption Variable water reabsorption Nephron Renal Tubule

Flow of Filtrate –Bowman’s capsule  PCT  nephron loop  DCT  collecting duct  papillary duct  minor calyx  major calyx  renal pelvis  ureter  urinary bladder  urethra Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Renal capsule Collecting duct Nephron (a) (c) Cortical nephron Cortex Medulla Glomerulus Glomerular capsule Renal corpuscle: Nephron loop: Descending limb Ascending limb Thick segment Thin segment Flow of tubular fluid Flow of blood Key (b) Renal cortex Renal medulla Renal papilla Minor calyx Efferent arteriole Afferent arteriole Proximal convoluted tubule (PCT) Distal convoluted tubule (DCT) Collecting duct (CD) Papillary duct Collecting duct Nephron loops Juxtamedullary nephron Convoluted tubules (PCT and DCT)