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 SOLUTECONCENTRATION AS THESEAWATER; NO NET GAIN ORLOSS 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 OFTHE EXCRETORYSYSTEM
• SWEATING– 99% WATER
– 2 % WATER LOSS CANDECREASE AEROBICACTIVITY BY 10 %5 % LOSS CAN LEAD TOSERIOUS HEALTH RISKS
CONTROL OF THE INTERNAL ENVIRONMENT
• ANIMALS MUST DISPOSE OF NITROGENOUS WASTES (METABOLIC WASTES)– AMMONIA
• MOST TOXIC; ONLY FOUNDIN 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 ORGANOF THE HUMANEXCRETORY SYSTEM
– URETER• DUCT THAT
CONNECTS THEKIDNEY TO BLADDER
– URINARY BLADDER• STORAGE SAC FOR
URINE– URETHRA
• TUBE THAT LEADS FROMBLADDER 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 THEKIDNEY
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’SCAPSULE
• 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 ONNUTRIENT REABSORPTION
– LOOP OF HENLE ANDCOLLECTING DUCT FOCUSON 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
• KIDNEYSTONES ANDGOUT AREALSO SERIOUSCONDITIONS
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!!!
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