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!!!