Metabolismo - unq.edu.arcronos.unq.edu.ar/fisgen/metabolismo 2014.pdf · Metabolismo hepático...
Transcript of Metabolismo - unq.edu.arcronos.unq.edu.ar/fisgen/metabolismo 2014.pdf · Metabolismo hepático...
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
• También se relaciona con la masa corporal
CALORIMETRÍA
Directa
Indirecta
Tasa Metabólica
BASAL
ESPECíFICA
ACTIVA
ESTÁNDAR
Regulación hormonal y nerviosa
ALGUNAS DEFINICIONES
TMB = aM b a es la ordenada al origen
M la masa corporal
b exponente empírico
Lavoisier’s direct calorimeter
• Direct calorimetry
• Used in 1780
An open respirometer
A closed respirometer
METABOLISMO:
Carbohidratos
Monosacáridos (glucosa)
Disacáridos (sacarosa)
Polisacáridos (glucógeno)
Glucogénesis y glucogenólisis en hígado
Gluconeogénesis (deaminación proteica)
Glucosa-6-P en músculo
Glucostato hipotalámico
Proteínas
Metabolismo hepático
Regulación hormonal
Grasas
Ésteres de AG con glicerol
Lipólisis / Lipogénesis
Transporte de quilomicron
Metabolismo hepático
HDL y LDL
Control neural y hormonal
COCIENTE RESPIRATORIO
C6H12O6 + 6O2 6CO2 + 6 H2O Para la glucosa: Rq = VCO2 / VO2
Rq = 1
ACCION DINAMICA ESPECIFICA
ACCION DINAMICA ESPECIFICA
TMB y TAMAÑO CORPORAL
TMb = aMb
a es la ordenada al origen
M la masa corporal
b exponente empírico
TMb = aMb = aM(b-1)
M M
log TMb = log a + b (log M)
TASA METABÓLICA
ESPECÍFICA
TMB y TAMAÑO CORPORAL
TMB = aM b
TMB y TAMAÑO CORPORAL
RELACIÓN MASA-SUPERFICIE
TMB y TAMAÑO CORPORAL I
TMB y TAMAÑO CORPORAL II
TEMPERATURA y TASA METABÓLICA
Transmisión de calor
radiación
conducción
convección
evaporación (transpiración, respiración)
HOMO vs POIQUILOTERMIA
ENDO vs EXOTERMIA
Mecanismos
termogénesis tiritante
comportamiento
grasa blanca / grasa parda
circulación
transpiración / jadeo
piloerección
control nervioso y hormonal
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
HOMEOTERMIA y POIQUILOTERMIA
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
• 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
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
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
directions
e.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