BIOL112 1st Edition Lecture 21 Outline of Last Lecture I Air Processing II Vocalization III Oxygen Transport IV CO2 Exchange Outline of Current Lecture V Breathing Control VI Oxygen Sensitivity VII The Kidneys Current Lecture I Breathing Control At rest an average breathing rate is 12 tidal breaths min 1 breath cycle 1 inhale 1 exhale takes 5 seconds Cycle is regulated by nerve center in medulla of brain Respiratory Center Contains two cyclic oscillatory centers that mutually inhibit each other constantly battling each other all of your life Nervous connections to respiratory center modulate frequency and strength of inhale and or exhale cycles breathing cycle requires proper connections to nervous system to function properly Upper levels in brain can stimulate or inhibit activities of respiratory center These notes represent a detailed interpretation of the professor s lecture GradeBuddy is best used as a supplement to your own notes not as a substitute Brain monitors concentrations of respiratory gasses CO2 O2 and also pH of blood Each of these contributes independently to activities that regulate the respiratory center II Oxygen Sensitivity Most sensitive Carbon Dioxide Increase in arterial pPCO2 40 mm 45 mm Hg produces 3x increase in breathing rate Next most sensitive pH Change from pH of 7 4 typical plasma pH to 7 2 produces 1 5 X breathing rate Least sensitive Oxygen Special sensors on aorta and carotid bodies but system is poorly responsive to major changes in pPO2 Change pPO2 100 mm 60 mm no change in breathing rate If you walked into a room with no oxygen you would continue breathing at the same rate and run out of oxygen Response of system to changes in pPO2 almost has no significance to sustain life EXCRETORY SYSTEM III The Kidneys One of a series of homeostatic processes Regulation of organism s internal environment in the face of external environmental change Major Functions Excretion elimination of catabolic byproducts of metabolism especially ammonia and related compounds Osmoregulation Control of water and salt content of blood Total human body fluids 401 Input Digestive system metabolism Output skin lungs sweat feces urine Kidney Osmoregulation Concentrations of electrolytes pH of fluids through regulation of H HCO3 concentrations Amount of solvent water This regulation is achieved through active transport control of passive diffusion and facilitated diffusion IV Excretory System Structures Kidney Cortex Filtering Structures Medulla Collecting Tubules Pelvis of the kidney Cavity in center of kidney drains into Ureters Ureters one for each kidney Bladder Urethra Renal Artery Vein to from each kidney Nephron Filtering unity of the kidney approximately 2 4 x 106 per two kidneys Blood Components Glomerulus Bundle of capillaries with high local blood pressure and special pores in endothelial cells Pertibular Capillaries Wrapped around bundles of tubular components of nephron Tubular Components Bowman s Capsule wrapped around glomerulus collects filtrate Proximal Convoluted Tubule Loop of Henl Extends from cortex down to bottom of medulla and back up Distal Convoluted Tubule Collecting Duct Extends from cortex through medulla to empty in pelvis Filtrate generated by glomerulus collected by Bowman s Capsule moves through proximal tubule loop of Henl distal tubule and through collecting duct Processed in tubules from filtrate into urine