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CONTROL OF THE INTERNAL ENVIRONMENT CONTROL OF THE INTERNAL ENVIRONMENT • THREE MAJOR AREAS OF CONTROL – HEAT – WATER – WASTE (METABOLIC) CONTROL OF THE INTERNAL ENVIRONMENT • HEAT IS GAINED OR LOST IN FOUR WAYS – CONDUCTION • DIRECT TRANSFER OF THERMAL MOTION (HEAT) BETWEEN MOLECULES – CONVECTION • TRANSFER OF HEAT BY THE MOVEMENT OF AIR OR LIQUID PAST A BODY SURFACE – RADIATION • THE EMISSION OF ELECTROMAGNETIC ENERGY – EVAPORATIVE COOLING • THE LOSS OF HEAT FROM THE SURFACE OF A LIQUID THAT IS TRANSFORMING INTO A GAS CONTROL OF THE INTERNAL ENVIRONMENT • THERMOREGULATION – THE MAINTENANCE OF INTERNAL TEMPERATURE WITHIN NARROW LIMITS – DEPENDS ON BOTH HEAT PRODUCTION AND HEAT GAIN OR LOSS – AS EXTENERAL TEMPERATURE FLUCTUATES, A FAIRLY CONSTANT INTERNAL TEMPERATURE IS MAINTAINED BY: • ALTERING THE RATE OF METABOLIC HEAT PRODUCTION • MAY CHANGE HEAT GAIN/LOSS BY CONDUCTION, CONVECTION, RADIATION, OR EVAPORATIVE COOLING CONTROL OF THE INTERNAL ENVIRONMENT • THERMOREGULATION – DEPENDS ON BOTH HEAT PRODUCTION AND HEAT GAIN OR LOSS – CHANGING BLOOD FLOW AT SKIN ALSO IMPACTS HEAT GAIN/LOSS – COUNTERCURRENT HEAT EXCHANGE • SMALL ARTERIES CARRYING COOL BLOOD INWARD ARE PARALLELED BY SMALL VEINS CARRYING WARM BLOOD OUTWARD FROM THE INNER BODY CONTROL OF THE INTERNAL ENVIRONMENT • COUNTERCURRENT HEAT EXCHANGE CONTROL OF THE INTERNAL ENVIRONMENT • BEHAVIOR OFTEN AFFECTS BODY TEMPERATURE – RELOCATING HABITATS – BATHING – CLOTHING IS UNIQUE BEHAVIOR TO HUMANS CONTROL OF THE INTERNAL ENVIRONMENT • REDUCING THE METABOLIC RATE SAVES ENERGY – TORPOR • A STATE OF REDUCED ACTIVITY IN WHICH BODY TEMPERATURE AND METABOLIC RATE DECREASE AND THE HEART AND RESPIRATORY SYSTEM SLOW DOWN – HIBERNATION • A LONG TERM TORPOR; LIVE OFF OF STORED BODY FAT – ESTIVATION • A TYPE OF SUMMER TORPOR CONTROL OF THE INTERNAL ENVIRONMENT • OSMOREGULATION – CONTROLLING THE GAIN AND LOSS OF WATER AND DISSOLVED SOLUTES – OSMOCONFORMERS • BODY FLUIDS HAVE THE SAME SOLUTE CONCENTRATION AS THE SEAWATER; NO NET GAIN OR LOSS OF WATER – OSMOREGULATORS • USE ENERGY TO CONTROL WATER LOSS OR GAIN CONTROL OF THE INTERNAL ENVIRONMENT • OSMOREGULATORS – LAND ANIMALS MAIN PROBLEM IS LIMITING WATER LOSS (DEHYDRATION) • URINE – WASTE PRODUCT OF THE EXCRETORY SYSTEM • SWEATING – 99% WATER – 2 % WATER LOSS CAN DECREASE AEROBIC ACTIVITY BY 10 % 5 % LOSS CAN LEAD TO SERIOUS HEALTH RISKS CONTROL OF THE INTERNAL ENVIRONMENT • ANIMALS MUST DISPOSE OF NITROGENOUS WASTES (METABOLIC WASTES) – AMMONIA • MOST TOXIC; ONLY FOUND IN AQUATIC ORGANISMS – UREA • 100,000x LESS TOXIC THAN AMMONIA – URIC ACID • LARGELY INSOLUBLE IN WATER; NON-TOXIC CONTROL OF THE INTERNAL ENVIRONMENT • EXCRETORY SYSTEMS CONTROL OF THE INTERNAL ENVIRONMENT • THE EXCRETORY SYSTEM – KIDNEY • MAJOR ORGAN OF THE HUMAN EXCRETORY SYSTEM – URETER • DUCT THAT CONNECTS THE KIDNEY TO BLADDER – URINARY BLADDER • STORAGE SAC FOR URINE – URETHRA • TUBE THAT LEADS FROM BLADDER OUT THE BODY CONTROL OF THE INTERNAL ENVIRONMENT • KIDNEY – FILTERS THE BLOOD; REFINES THE URINE – 2 MAIN REGIONS • RENAL CORTEX • RENAL MEDULLA – NEPHRONS • FUNCTIONAL UNIT OF THE KIDNEY CONTROL OF THE INTERNAL ENVIRONMENT • NEPHRONS – FUCNTIONAL UNIT OF KIDNEY CONTROL OF THE INTERNAL ENVIRONMENT • NEPHRONS – FUCNTIONAL UNIT OF KIDNEY • GLOMERULUS – BALL OF CAPILLARIES ENVELOPED BY BOWMAN’S CAPSULE • BOWMAN’S CAPSULE – RECEIVING END OF KIDNEY • COLLECTING DUCT – CARRIES URINE TO RENAL PELVIS • PROXIMAL TUBULE – REFINES FILTRATE • **LOOP OF HENLE – REFINES FILTRATE** • DISTAL TUBULE – REFOMES FILTRATE CONTROL OF THE INTERNAL ENVIRONMENT • OVERVIEW: THE KEY FUNCTIONS OF THE EXCRETORY SYSTEM ARE FILTRATION, REABSORPTION, SECRETION, AND EXCRETION CONTROL OF THE INTERNAL ENVIRONMENT • OVERVIEW: THE KEY FUNCTIONS OF THE EXCRETORY SYSTEM ARE FILTRATION, REABSORPTION, SECRETION, AND EXCRETION – FILTRATION • WATER AND VIRTUALLY ALL OTHER MOLECULES SMALL ENOUGH TO BE FORCED THROUGH THE CAPILLARY WALL ENTER THE NEPRHON TUBULE FROM THE GLOMERULUS – REABSORPTION • WATER AND VALUABLE SOLUTES, INCLUDING GLUCOSE, SALTS, AND AMINO ACIDS, ARE RECLAIMED FROM THE FILTRATE AND RETURNED TO THE BLOOD – SECRETION • CERTAIN SUBSTANCES ARE REMOVED FROM THE BLOOD AND ADDED TO THE FILTRATE – EXCRETION • URINE PASSES FROM THE KIDNEYS TO THE OUTSIDE VIA THE URETERS, URINARY BLADDER, AND URETHRA CONTROL OF THE INTERNAL ENVIRONMENT • FROM BLOOD FILTRATE TO URINE: A CLOSER LOOK CONTROL OF THE INTERNAL ENVIRONMENT • FROM BLOOD FILTRATE TO URINE: A CLOSER LOOK – DISTAL AND PROXIMAL TUBULES FOCUS ON NUTRIENT REABSORPTION – LOOP OF HENLE AND COLLECTING DUCT FOCUS ON WATER REABSORPTION CONTROL OF THE INTERNAL ENVIRONMENT • KIDNEY FAILURE CAN KILL!! – CAUSES OF KIDNEY FAILURE • HYPERTENSION; DIABETES; ALCOHOL, DRUG USE – KIDNEY DIALYSIS CAN BE A LIFESAVER • DIALYSIS – SEPARATION; ARTIFICIAL KIDNEY • KIDNEY STONES AND GOUT ARE ALSO SERIOUS CONDITIONS CONTROL OF THE INTERNAL ENVIRONMENT • THE LIVER IS A VITAL ORGAN FOR HOMEOSTASIS – SYNTHESIZES UREA FROM AMMONIA – DETOXIFIES MANY COMPOUNDS • HEPATIC PORTAL VESSEL – CONVEYS BLOOD DIRECTLY TO LIVER – MAY BRANCH OF STOMACH OR INTESTINE – GIVES LIVER A CHANCE TO DETOXIFY ALL BLOOD BEFORE IT REACHES HEART – INVOLVED IN BLOOD-SUGAR MAINTENANCE • CONVERTS EXCESS GLUCOSE TO GLYCOGEN CONTROL OF THE INTERNAL ENVIRONMENT • ANOTHER IMPORTANT ASPECT OF HOMEOSTASIS IS KEEPING INTERNAL BALANCE AT ANOTHER LEVEL…FOR INSTANCE, HOW DO YOU CONTROL BLOOD-SUGAR LEVELS?? • THROUGH THE HELP OF THE ENDOCRINE SYSTEM!!!