Transcript chapters 6 and 7 temperature and temperature

CHAPTERS 6 AND 7
TEMPERATURE AND
TEMPERATURE REGULATON
“THERM” DEFINITIONS
• HOMEOTHERM= MAINTAINS HI BODY
TEMP;MUST REMAIN ACTIVE IN COLD
SURROUNDING
• ENDOTHERMS= MAINTAIN TEMP BY
INTERNAL HEAT PROD.
• ECTOTHERM= MAINTSINS BODY TEMP
BY USING BEHV. ADAP. Ex. Lizard in sun
TEMPERATURE VS. RATES OF
BIOLOGICAL ACTIVITY
• MOST ANIMALS LIVE WITHIN A ZONE
OF TOLERANCE
• CHEMICAL RXN INVOLVE MOLECULAR
COLLISIONS THEREFORE HEAT MAY
CHANGE TIER CHARACTERISTICS
Q 10 RULE
• MEANS THE INCREASE IN RXN
VELOCITY CAUSED BY A 10 DEGREE
RISE IN TEMP
• SOME EXAMPLES: Q10 FOR ENZYME RXS
RANGES 2-3, FOR COAGULATION OF HGB
13.8
• GENERAL RULE A 10 DEGREE TEMP
INCREASE CAUSES 2-3 FOLD OXYGEN
USE INCREASE
Q 10 RULE CON’T
• IF THE RATE DOUBLES Q10 = 2
• IF THE RATE TRIPLES Q10 = 3
• EXAMPLE: STARTING WITH A Q10 OF 2
AND ATEMP OF 0 DEGREES C AT 10
DEGREES THE RATE WOULD DOUBLE;
• AT 20 DEGREES THE RATE WOULD
QUADRUPLE; AT 30 DEGREES IT WOULD
INCREASE 8x
PHYSIOLOGIC COMPENSATION
FOR RATE LIMITING TEMP
EFFECTS
• AT THE MOLECULAR LEVEL LIFE
PROCESSES ARE GOVERNED BY Q10,
THE LOGARITHMIC LAW RELATING
VELOCITY OF RXN TO TEMP
• ANIMALS HAVE EVOLVED
COMPENSATORY MECHANISM TO BEAT
THE Q10 RULE
TEMPERATURE
COMPENSATION IN
POIKILOTHERMS
• THREE TYPES OF COMPENSATION:
• ACCLIMATION OR ACCLIMATIZATION
• BODY TEMPERATURE ADJUSTMENT OR
REGULATION
• GENETIC OR EVOLUTIONARY
ADAPTATION
• POIKS = TEMP FLUCT W ENVT.
TEMPERATURE
COMPENSATION IN
POIKILOTHERMS
• BIOCHEMICAL AND CELLULAR
ADJUSTMENTS
– NORMALLY INVOLVES ENZYMES, PROTEIN
STRUCTURES,WATER CONTENT OF TISSUES
– ORGANIZATION OF LIPIDS
– CONTROL OF METABOLIC TOXINS
PRODUCED
TEMPERATURE COMENSATION
IN POIKILOTHERMS
• WATER
CONTENT,SUPERCOOLING,”ANTIFREEZE”
– GRADUAL TEMP CHANGE MUCH LESS DAMAGING
– PREVENTION OF INTRACELLULER WATER
CRYSTALLIZATION, BECOME HYPERTONIC
– ICREASE IN OSMOTIC CONTENT OF BODY FLUIDS
TO DEPRESS FREEZING POINT
TEMPERATURE
COMPENSATION IN
POIKILOTHERMS
– GLYCEROL IS A SUBSTANCE THAT DEPRESSES THE
FREEZING POINT OF VARIOUS SOLUTIONS; BUFFER
TERT AND QUAT. PROTEIN STRUCTURE CHANGE
– GLYCOPROTEINS ALSO
– OTHER PROTEINS ALSO OCCUR IN ARCTIC FISH
– MECHANISM THROUGH GROUPS BONDING TO
DEPRESS FREEZING PT
TEMP CONPENSATION IN
POIKS CONT
– GYLCOPRPTOEINS MOST COMMON
– ACT BY PREVENTION OF ADDITOIN OF WATER
CRYSTALS TO ICE LATTICE
– SEVERAL HUNDRED TIMES MORE EFFECTIVE
THAN SODIUM OR GLUCOSE
– ALL HAVE THE AMINO ACIDS ALANINE,
THREONINE, IN COMMON
TEMPERATURE
COMPENSATION
INPOIKILOTHERMS
• LIPIDS, CELL MEMBRANES, ENZYME SYSTEMS
– DIFFERENT BODY LIPIDS MAY BE PRESENT IN
ANIMALS IN DIFFERET CLIMATES
– INCREASING BODY TEMP DECREASES FLUIDITY OF
THE MEMBRANES
– MOST CRITICAL AREAS ARE CELL MEMBRAMES AND
NERVOUS TISSUE LININGS
ENZYME ADJUSTMENTS
• ADAPTIVE RESPONSE OF ENZYMATIC
SYSTEMS IS CRITICAL TO THERMAL
RESPONSE
– ADJUSTMENTS OCCUR AT MULTIPLE STEPS OF THE
REACTION SERIES
– TOXIC METABOLITES , HISTAMINE AND
THROMBOPLASTIC MATERIALS OFTEN ARE FOUND
IN TISUES
• MECHANISM PROBABLY DUE TO PROTEIN
DENATURATION
PHYSIOLOGIC AND
BEHAVIORAL ADJUSTMENTS
• MOST POIKILOTHERMS USE BEHAVIOR
TO AVOID OR MINIMIMIZE TEMP
CHANGES
– INFARED SENORS IN FACIAL PITS OF
RATTLERS CAN DETECT .001 - .005 DEGREE C
DIFFERENCE
– BASKING IN SUNSPOTS
PHYSIOLOGIC SDJUSTMENTS
• CARDIOVASCULAR ADAPTATION
– CUTANEOUS VASOCONSTRICTION IN COLD;
VASODILATION IN HEAT IN POIKS
– AMPHIBIANS MAY SALIVATE IN HEAT, OR DO
EVAPORATIVE COOLING
PHYSIOLOGIC ADJUSTMENTS
• NEUROENDROCRINE
– IN POIKS, APPEARANCE OF ANTIFREEZES AS
WINTER APPROACHES
– THIS IS TIMED BY PHOTOPERIOD IN
ARCCTIC TELEOST FISH
– APPEARS IN FALL, PITUITARY SIGNALS
CHEMICAL CLEARANCE IN SPRING
BODY TEMP BIRDS AND
MAMMALS
– THERE IS A CORE BODY TEMP AND A
PERIPHERAL TEMP
– DURING EXERCISE THE BBBDOY TEMP
MUST ADJUST TO A 10 FOLD RISE IN HEAT
PRODUCTION
– BODY TEMP FOLLOWS LIGHT CYCLE ,
DIURNAL FLUCTUATION
PHYSIOLOGIC ADJUSTMENTS
• CAPACITY FOR ENDOTHERMY
– MAINTANENCE OF RELATIVE CONSTANT BODY TEMP
– SOME TUNAS AND SHARKS DO THIS VIA OPERATION
OF THERMAL EXCHANGE UNITS
PHYSIOLOGIC ADJUSTMENTS
• TYPES OF HEAT EXCHANGERS ( LOCATED IN
TRUNK HEAVY MUSCLES)
– CUTANEOUS OR LATERAL RETIAL
– SERVED BY A CUTANEOUS ARTERY AND VEIN
– IN BLUEFIN TUNA AND LAMNID SHARKS
PHYSIOLOGIC ADJUSTMENTS
• TYPES OF HEAT EXCHANGERS
– CENTRAL OR HEMAL RETIA
– SUPPLIED DIRECTLY BY DORSAL AORTA
– IN SKIPJACKS
PHYSIOLOGIC ADJUSTMENTS
• PRINCIPALS FOR USE OF HEAT
EXCHANGERS
– REGARDLESS OF TYPE: THEY ARE
ELABORATE RETE MIRIBLES, USING
COUNTER CURRENT FLOW
– BLOOD FLOW IS VERY SLOW THROUGH
SUCH AREAS
– COLD BLOOD IS HEATED BY ACTIVELY
METABOLIZING TISSUES
HOMEOTHERM
TEMPERATURE
COMPENSATION
• CRITICAL TEMPERATURE ( HOMEOTHERMS)
IS THE LOWEST AIR TEMP AT WHICH AN
ANIMAL CAN MAINTAIN RESTING OR BASAL
METABOLIC RATE WITHOUT LOWERED CORE
TEMP.
• IN MAN THIS TEMP IS 27-TO,25 DEGREES
CENTEGRADE
• IN ARCTIC FOX -30 TO -40
HEAT PRODUCTION
• IN HOMEOHERMS A MARKED INCREASE
IN MUSCLE TONE AND MUSCULAR
ACTIVITY PRECEEDS SHIVERING.
– MUSCLES GENERATE HEAT= SHIVERING
THERMOGENESIS
– GENERATION OF HEAT BY METABOLIC
PROCESES AND ORGANS = NON-SHIVERING
THERMOGENESIS
HEAT PRODUCTION CON’T
– ANIMALS VARY IN CAPACITY TO GENERATE
HEAT
– IN SOME MAMMALS: CATS, RATS, DOGS AND
SHEEP BASAL METABOLIC RATE IS HIGHER
WHEN THEY ARE COLD ACCLIMATED
BROWN FAT : SPECIAL
THERMOGENIC TISSUE
(MAMMALS)
• MOST EVIDENT IN NEWBORNS,
HIBERNATORS, AND COLD ACCLIMATED
MAMMALS
– RESPONDS TO COLD STRESS BY PRODUCING
HEAT BURSTS
– LOCATED IN NECK AND THORACIC REGIONS
NEAR LARGE VESSELS FOR QUICK HEAT
TRANSPORT
– STIMULATED BY NORADRENALIN
BROWN FAT: CON’T
– NORADRENALIN BINDS TO BETA RECEPTORS
ON PLASMA MEMBRANES OF FAT CELLS
– THESE CELLS HAVE 150,000 OF THESE
RECEPTORS; MUCH HIGHER THAN IN
OTHER CELL TYPES
– CATECHOLAMINES AND CYCLIC AMP
PROMOTE RAPPID LIPOLYSIS
– SOME OF THE FATTY ACIDS ENTER
MITOCHONDRIA FOR IMMEDIATE USE
BROWN FAT :CON’T
– SOME FATTY ACIDS EXPORTED FROM CELL:
MECH STILL NOT CLEAR
– HEAT PRODUCTION IS THE ONLY FUNCTION
OF BROWN FAT
– IT IS VERY VASCULAR WITH HIGH
CONCENTRATIONS OF CYTOCHROMES,
MYOGLOBIN
– HAS HHIGHER CONCENTRATIONS OF
WATER, PROTEINS, CHOLESTEROL,
MITOCHONDRAIL ENZYMES
HEAT LOSS
– CONSTANT BODY TEMP REQUIREMENT:
HEAT LOSS =HEAT GAIN
– CONDUCTION: TAKES PPLACE WHEN
PHYSICAL SUBSTANCES ARE IN DIRECT
CONTACT
– CONVECTION: HEAT MOVEMENT IN FLUIDS
– RADIATION= HEAT TRANSFER IN ABSENCE
OF DIREST CONTACT
HEAT LOSS
• NORMALLY VIA CONDUCTION,
RADIATION, VAPORIZATION
– IN AQUATIC ENVIRONMENTS CONVECTION
MAY ACCOUNT FOR ENTIRE HEAT
TRANSFER
– TERRESTRIAL ORGANISMS NORMALLY
LOSE MOST HEAT BY RADIATION
– IN SMALL BIRDS EVAPORATIVE COOLING
MAY BE THE MAJOR MECHANISM
CONTROL OF HEAT
DISSIPATION: FUR AND
FEATHERS
• ARCTIC SPECIES BETTER INSULATED
THAN TROPICAL
– ANIMALS THAT LACK FUR CAN OBTAIN
INSULATION VIA A COLD SKIN LAYER( PIGS)
COUNTERCURRENT
EXCHANGERS
• EXTREMETIES ARE OFTEN HEAT
LEAKERS: NOT WELL INSULATED
– THESE MUST BE COLD RESISTANTAND ABLE
TO TOLERATE TEMP CHANGES
– EX: CARIBOU LEG AT 8 DEGREES BODY AT 37
DEGREES
– COUNTER CURRENT EXCHANGERS: MAJOR
ARTERIES SURROUNDEDBY THIN WALLED
VEINS IN APPANDAGE
COUNTERCURRENT
EXCHANGERS
– WHEN HEAT IS TO BE CONSERVED
PERIPHERAL CIRCULATION IS RESTRICTED
– WHEN HEAT DISSIPATION IS NEEDE
VASODILATION OCCURS
– USED IN MANY MAMMALS
HEAT : LETHAL
MANIFEATATIONS
– HIGH TEMP DEATH DUE TO:
– DENATURATION OF PROTEINS
– THERMAL ENZYME INACTIVATION
– INADEQUATE OXYGEN SUPPLY
– EFFECTS ON Q10 DEPENDENT MET. RXNS
– TEMP EFFECTS ON MEMBRANE STRUCTURE
ACCLIMATION AND
ACLIMATIZATION
– ACLIMATIZATION OCCURS SEASONALLY,
AADJUSTMENT TO TEMP CHANGES WITH
CLIMATE CHANGE; USUALLY UNDER
INFLUENCE OF PHOTOPERIOD
– ACCLIMATION , WHEN ORGANISM ADJUSTS
TO ARTIFICALLY IMPOSED CONDITION,
USUALLY IN THE LABORATORY
THERMAL ACCLIMATION
– OFTEN AMINALS DO NOT FOLLOW THE
PATTERN PREDICTED BY THE Q10 RULE DUE
TO PHYSIOLOGIC COMPENSATORY MECHS
– BE SURE TO READ THIS IN YOUR BOOK
HIBERNATION TORPITIDY
ESTIVATION
– HIBERNATION: BODY TEMP DROPS, HEART
AND METABOLIC REATE DROP, ANIMAL IS
TORPID= SHOWS LITTLE RESOPNSE TO
ENVIRONMENTAL STIMULI
– NORMALLY DURING WINTER, AT LOW TEMP
– ESTIVATIONINACTIVITY DURING SUMMER
MONTHS
– SSOME ANIMALS AND BIRDS, LIKE HUMERS
GO INTO TORPID STATES OVER NIGHT,
DUING TIME SWHEN FOOD IS LIMLITD