Metabolismo

Definición de metabolismo

• Es la suma de todas las reacciones químicas que ocurren en un organismo

• La actividad metabólica de un animal se relaciona con su temperatura corporal ya que la velocidad de una reacción química aumenta con la temperatura

CALORIMETRÍA

Directa

Indirecta

Tasa Metabólica

BASAL

ESPECíFICA

ACTIVA

ESTÁNDAR

Regulación hormonal y nerviosa

ALGUNAS DEFINICIONES

TMB = aMb a es la ordenada al origenM la masa corporalb exponente empírico

Lavoisier’s direct calorimeter

• Direct calorimetry• Used in 1780

An open respirometer

A closed respirometer

EJERCICIO Y DEUDA DE OXÍGENO

METABOLISMO:

CarbohidratosMonosacáridos (glucosa)Disacáridos (sacarosa)Polisacáridos (almidón)

Glucogénesis y glucogenólisis en hígado Gluconeogénesis (deaminación proteica) Glucosa-6-P en músculo Glucostato hipotalámico Proteínas

Metabolismo hepáticoRegulación hormonal

GrasasÉsteres de AG con glicerolLipólisis Transporte de quilomicronMetabolismo hepáticoControl neural y hormonalHDL y LDL

OBESIDAD

>20-25% CONTENIDO DE GRASA EN EL CUERPO

HipertróficaHiperblástica-hipertrófica

INANICIÓN1) Carbohidratos2) Grasas y proteínas3) Proteínas estructurales

Grasas 9 cal/g – 22% peso corporal – 84% valor combustibleProteínas 4 cal/g – 14% peso corporal – 15% valor combustibleCarbohidratos 4 cal/g – 0,77% peso corporal – 1% valor cvombustible

ACCION DINAMICA ESPECIFICA

ACCION DINAMICA ESPECIFICA

RELACIÓN MASA-SUPERFICIE

TMB y TAMAÑO CORPORAL I

TMB y TAMAÑO CORPORAL II

TMB y TAMAÑO CORPORAL III

TMB = aMb

TAMAÑO CORPORAL Y REQUERIMIENTOS ENERGÉTICOS

TASA METABÓLICAESPECÍFICA

TASA METABÓLICA ACTIVA

TEMPERATURA

Transmisión de calorradiaciónconducciónconvecciónevaporación (transpiración, respiración)

HOMO vs POIQUILOTERMIA

ENDO vs EXOTERMIA

Mecanismostermogénesis tiritantecomportamientograsa blanca / grasa pardacirculacióntranspiración / jadeopiloereccióncontrol nervioso y hormonal

Endotherms and Ectotherms

• Endotherms- have constant body temperature (Tb) and maintain elevated Tb by endogenous heat production– High VO2, high heat production, low

thermal conductivity (good insulation)– high metabolic cost, 5x metabolism of

ectotherms– Mammals, birds some reptiles and insects

•Ectotherms or poikilotherms - thermal condition outside their bodies determine their Tb

- their Tb are high in warm environment, but low in cool environment

- they adjust Tb by means other than heat production and heat loss

- Low VO2, low heat production, and poorly insulated

- fish, reptiles and amphibians

Homeotherms and Heterotherms

Homeotherms – thermoregulate their Tb by physiological means, e.g. the rate of heat production, rather than just by behaviors

- thermoregulation endotherms

Heterotherms

• Exhibit characteristics of endotherms and ectotherms.

• Temporal heterotherms-hibernators, daily torpor in birds and mammals. Some snakes, fish, and insects.

• Regional heterotherms-usually poikilotherm that maintains a high core temperature. Eg., bumble bee.

Pigmy mouse Baiomys taylori

Temperature relations in endotherms

Thermodynamic PrinciplesENVIRONMENT

Radiation

Conduction

Convection

ENVIRONMENT

Radiation

Conduction

Convection

Evaporation

HEAT GAIN HEAT LOSSANIMAL

METABOLISM

Maintenance

Exercise

Growth

Lactation

Feeding

METABOLISM

Milk Removal

Fecal Removal

Urinary Removal

Heat Transfer Between Animals and Their Environment

• Conduction: transfer of heat between objects in contact with each other

• Convection: transfer of heat contained in a mass of gas or liquid by the movement of that mass.

e.g wind• Radiation: transfer of heat by electromagnetic radiation takes place without direct contact

between objects• Evaporation: transfer of heat by allowing water to

evaporate from moist body surface

Thermal neutral zone

• Range of Ta in which endotherm does not need to alter VO2 to maintain constant Tb.

• Upper critical temperature (UCT)-Ta above which energy-requiring heat loss mechanisms are used- sweating, panting.

• Lower critical temperature (LCT)- energy-requiring heat production mechanisms are used- shivering, non-shivering thermogenesis.

Regulación en la zona termoneutral

Countercurrent Heat Exchange

• “opposite flow”

• A process that depends on a specialized morphological arrangement of the blood vessels carrying blood to and from appendages

• Transfer of heat between two closely juxtaposed fluid streams flowing in opposite directionse.g. rete mirabile ---wonderful rete

RETE MIRABILE en el Atún

Q10

• Q10 is the rate of a reaction at a given temperature compared to its rate 10o C lower.

• For most reactions, Q10 is 2-3X

Acclimation

• Laboratory-induced temperature acclimation in ectotherms.

• Acclimation in whole animals occurs through the acclimation of individual cells and tissues.

Supercoolants

• Glycerol, lowers freezing point.

• Antifreeze protein in antarctic fish.

• Antarctic fish are freeze intolerant, but body fluids do not freeze.

Aclimatación en ectotermos

Congelamiento extracelular