BIOL 320 1st Edition Lecture 22 Outline of Last Lecture I Juxtaglomerular Apparatus II Blood Pressure Renal Circulation III Filtration Membrane IV Mechanisms of Urine Formation V Glomerular Filtration VI Glomerular Filtration Rate VII Intrinsic Controls of GFR VIII Extrinsic Controls of GFR IX Other Factor Affecting GFR X Tubular Reabsorption XI Sympathetic Nervous System XII Tubular Secretion XIII Ureters XIV Urinary Bladder Outline of Current Lecture XV Urethra XVI Developmental Aspects of Renal Sysmtem XVII Body Water Content XVIII Fluid Compartments XIX Composition of Body Fluids XX Water Balance ECF Osmolality XXI Regulation of Water Intake XXII Regulation of Water Output XXIII Disorders of Water Balance XXIV Edema XXV Electrolyte Balance Current Lecture Urethra Function to drain urine from bladder Male vs Female male urethra is longer Two sphincters both internal and external both sexes have Male urethra three parts Developmental Aspects of Renal System Embryonic three sets of kidneys 6 only one set developing by week 5 Fetal produced by third month Infants small bladders kidneys can t concentrate urine Childhood voluntary urethral sphincter control develops with nervous system Urinary Tract Infections 80 due to E coli STDs can inflame urinary tract Aging kidney function declines many elderly develop incontinence Congenital horseshoe kidney have notably higher infection rate 1 in every 500 600 hypospadius male urethra is not at tip of penis polycystic kidneys abnormal development of collecting ducts urine filled cysts renal failure Body Water Content function of age body mass gender body fat Infants low body fat low bone mass high water content 73 Healthy males 60 water content Healthy females 45 50 water content Old age 45 Throughout life body water declines Females vs Males females have more fate less muscle males tend to have more muscle mass Skeletal muscle 65 Adipose tissue 20 Fluid Compartments Intracellular fluid Extracellular fluid o Interstitial fluid o Plasma volume Composition of Body Fluids Water the universal solvent Solutes o Non Electrolytes lipids glucose urea creatinine not charged o Electrolytes inorganic salts acids bases proteins Osmotic Power electrolytes draw water more strongly than non electrolytes high osmolality draws water more strongly than low osmolality Composition of compartment linked by blood plasma Compartment exchange regulate by Osmotic Pressure Hydrostatic Pressure Water Balance ECF Osmolality Water in drink 60 food 30 metabolic 10 Water output urine 60 insensible 28 sweat 8 fecal 4 Increases in plasma osmolality trigger 1 Sense of thirst 2 Drinking Regulation of Water Intake Thirst Mechanism o Decrease in plasma volume o Increase in plasma osmolarity Regulation of Water Output Antidiuretic hormone ADH Disorders of Water Balance 1 Dehydration water loss is greater than water in o Ex ECF loss from severe burns prolonged activity diarrhea vomiting blood loss diuretics etc o Extreme can lead to weight loss mental confusion fevers hypovolemic shock etc o Activates compensatory mechanisms ADH keep water thirst drink water 2 Hypotonic Hydration o Cellular over hydration water intoxication o Causes over consumption of water renal insufficiency o Consequences metabolic disturbances especially neurons 3 Hyponatremia low blood sodium concentration water flows into tissues o Consequences swelling of tissues cerebral edema Edema Definition atypical accumulation of fluid interstitially tissue swelling Caused by increased fluid flow out of blood stream and or hindered return blocked lymphatics Factors that accelerate fluid loss increased blood pressure leaky capillaries vessel blockage local incompetent venous valves lack of circulation congestive heart failure Hypoproteinemia low plasma protein concentration causes increased fluid flow out of capillaries results from liver damage kidney damage malnutrition May lead to decreased blood pressure impaired circulation Electrolyte Balance Usually refers to salt Salts are important for 1 Neural function 2 Muscle function 3 Secretory activities 4 Fluid movements 5 Membrane permeability Salts enter the body by ingestion Salts are lost via 1 Urine 2 Feces 3 Sweat Central salt sodium In extracellular fluid 1 90 95 electrolytes sodium 2 Therefore sodium primary cation 3 Therefore sodium exerts significant osmotic pressure In plasma sodium levels effect 1 Blood volume pressure 2 Interstitial intracellular fluid Coupled to sodium transport renal acid base mechanisms