BIOL112 1st Edition Lecture21 Outline of Last Lecture I. Air ProcessingII. VocalizationIII. Oxygen TransportIV. CO2 ExchangeOutline of Current LectureV. Breathing ControlVI. Oxygen SensitivityVII. The KidneysCurrent LectureI. 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 re-quires proper connections to nervous system to function properly•Upper levels in brain can stimulate or inhibit activities of respiratory centerThese 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 alsopH 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 in-crease 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 lifeEXCRETORY SYSTEMIII. 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, es-pecially 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, fe-ces, urine•Kidney Osmoregu-lation•Concentrationsof electrolytes•pH of fluidsthrough regula-tion of H+, HCO3- concentrations•Amount of solvent (water)•This regulation is achieved through ac-tive transport & control of passive dif-fusion and facilitated diffusionIV. Excretory System Structures•Kidney•Cortex - Filtering Structures•Medulla - Collecting Tubules•Pelvis (of the kidney) - Cavity in centerof 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 kid-neys•Blood Components:•Glomerulus: Bundle of capillarieswith high local blood pressureand special “pores” in endothelialcells.•Pertibular Capillaries : Wrappedaround bundles of tubular com-ponents of nephron•Tubular Components:•Bowman’s Capsule: wrappedaround glomerulus, collects fil-trate•Proximal Convoluted Tubule•Loop of Henlé: Extends from cor-tex down to bottom of medulla and back up•Distal Convoluted Tubule•Collecting Duct: Extends from cortex through medulla to emptyin pelvis•Filtrate generated by glomerulus, collected by Bowman’s Capsule, moves through proximal tubule, loop of Henlé, distal tubule, and through collecting duct. Processed in tubules from filtrate into