Upload
ian-nixon
View
36
Download
0
Embed Size (px)
DESCRIPTION
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. ALGUNAS DEFINICIONES. - PowerPoint PPT Presentation
Citation preview
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
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
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.
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.
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
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.