Unformatted text preview: Friday’s Class: METABOLISM & METABOLIC RATE II Chapter 2 Pages: 39-‐44, 71-‐74 Chapter 2 Pages: 22-‐27, 57-‐60 Factors aﬀecLng metabolic rate •
• Temperature AcLvity DigesLon StarvaLon ReproducLve State Dormancy – (HibernaLon/ AesLvaLon/ Torpor) • Time of Day Factors aﬀecLng metabolic rate: Endotherms: ~37°C Temperature Ectotherms: Body temperature is same as environmental temperature Factors aﬀecLng metabolic rate: InacLve AcLvity 8 7 Raw data 6 SMR Oxygen Consumption (ml/hr) 5 4 3 2 1 0 0 8 6 12 18 24 30 36 42 48 24 30 36 42 48 AcLve 7
0 6 12 18 Time (hours) Factors aﬀecLng metabolic rate: Feeding/DigesLng Speciﬁc Dynamic AcLon (SDA) • Increase in metabolic rate caused by food ingesLon • Also called the heat increment of feeding Factors aﬀecLng metabolic rate: ReproducLon • Humans: MR increases 30% near term – growth of fetus – fetal metabolic requirements – growth of mammary Lssue • Golden-‐mantled ground squirrels – lactaLon takes up 1/3 of yearly energy! Factors aﬀecLng metabolic rate: Time of Day • Metabolic rate is typically higher during acLve period Nocturnal: Diurnal: MR MR night What other factor aﬀects MR? Body Size MR Whole animal MR Mass-‐speciﬁc MR Body mass What other factor aﬀects MR? Body Size * Small animals have higher mass-‐speciﬁc MR’s For a given unit of mass, the MR is greater in smaller animals…1 gram of shrew consumes O2 at 100 Lmes the rate of 1 gram of elephant! The eﬀect of body size on weekly food requirements Costs & Beneﬁts of Endothermic Homeothermy LimitaLon with Body Size Principles in Animal Physiology Shrews & small hummingbirds must maintain enormous mass speciﬁc metabolic rates to regulate their body temperature near 37-‐40°C Can only pack so many mitochondria into a cell & can only supply metabolic fuels up to a certain rate www.nhn.ou.edu Eckert & Randall – Animal Physiology Discussion Friday – Week 2: • CreaLne kinase converts creaLne phosphate to creaLne, phosphorylaLng ADP making ATP (WHAT I SAID IN CLASS WAS CORRECT) • Km vs. substrate binding aﬃnity • Agonist example: nicoLne acLng on ACh receptors • Cell Signaling ReacLon Velocity and SaturaLon KineLcs Low Km = High substrate binding aﬃnity (because takes less substrate concentraLon reach ½ Vmax) Km = indicator of aﬃnity of enzyme
for the substrate The Km is the substrate concentraLon required to reach a velocity that is one half the maximal velocity EvoluLonary AdaptaLon of Enzymes Enzymes have evolved to meet physiological condiLons ConservaLon of Km: Maintain proper binding @ physiological substrate concentraLons Ligand – Receptor InteracLons • Ligand-‐receptor interacLons are speciﬁc • Only the correctly shaped ligand (natural ligand) can bind to the receptor • Ligand mimics • Agonists – acLvate receptors • Because increase response, cell’s response is to decrease receptor # (in aqempts to reduce response) • E.g. nicoLne & Acetylcholine (ACh) receptors • Antagonists – block receptors • Because decrease response, cell’s response is to increase receptor # (in aqempts to increase response) • E.g. caﬀeine & adenosine receptors Principles nimal Pohysiology Figure 4.12 • Many ligand mimics act as of dArugs r poisons Types of Cell Signaling INDIRECT SIGNALING Principles of Animal Physiology Figure 4.2, 4.3 Comparison of diﬀerent cell signaling mechanisms How signaling with hydrophilic and hydrophobic mechanisms diﬀer Monday’s Class NEURONAL STRUCTURE, FUNCTION & DIVERSITY Chapter 5 pp. 154-‐161 Chapter 4 pp. 142-‐148...
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- Winter '15
- Receptor antagonist, Metabolic Rate