Feast to Famine: Physiological Review of Burmese Python Digestion By: Hamid Safi & Nardin R. Moniri Abstract: Burmese pythons live without food for months. Survival is therefore challenging. To cope, these pythons down regulate their systems; most prominently their digestive system. In this manner, they save very precious energy by lowering maintenance cost of these tissues and organs. However, once a prey is captured, it is swallowed as a whole and digestion starts rapidly. These animals, therefore, have great plasticity in their digestive system. Penning the Krogh Principle, August Krogh wrote, ‘For such a large number of problems there will be some animal of choice or a few such animals on which it can be most conveniently studied’ (Krogh, 1929). The Burmese python with their great and rapid anatomical and functional change between fasting and digesting are an attractive model organism for researchers. For example, ingestion of a meal considerably reduces stomach pH from 7 to 1.5 in 48 hours (Secor, 2008). In addition, there is an increased in size and functionality of organs such as the stomach, intestine, pancreas, heart, liver and kidney significantly enhancing digestion during the feeding phase (Secor, 2008). Within few days of feeding, nutrient uptake and enzyme activity increases by 6‐ 26 folds and the metabolic rate is improved by 17 times (Stark & Beese, 2001). On average, digestion, absorption and excretion occurs within 8‐14 days post feeding and via enhanced cardiac output this increased metabolic rate is supported (Stark & Beese, 2001). This paper will start by providing a brief general background on Burmese pythons followed by an in depth analysis of organ remodeling and its implications on specific dynamic action. It will be followed with a commentary on implications of digestion on blood pH and blood micronutrients composition. Lastly, changes within cardiovascular system will be analyzed which aid in such energetically expensive yet quick digestion occurring. In summary, this paper will provide a review of the physiological mechanisms that these marvelous creatures utilize to be able to cope with their extremely intermittent feeding mode. 1
Table of Contents: 1. Introduction 1.1. Classification and Characteristics 1.2. Habitat 1.3. Mode of Life and Diet 2. Organ remodeling 2.1. Stomach 2.2. Small Intestine 2.3. Pancreas, Gall bladder, Liver, Kidney 2.4. Effect of Meal Size 3. Specific Dynamic Action 3.1. Introduction and Significance 3.2. Determinants 3.2.1. Meal Size 3.2.2. Nutritional Composition 3.2.3. Temperature 4. Alkaline Tide and Blood Micronutrient Composition 4.1. Alkaline Tide 4.2. Blood Composition of micronutrients 5. Cardiovascular System 5.1. Heart Anatomy and Differential pressure 5.2. Role of Histamines and Fatty Acids 5.2.1. Histamines 5.2.2. Fatty Acids 2
1. Introduction The sit and wait foraging Burmese pythons demonstrate exceptional regulation in their gastrointestinal and cardiovascular performance upon feeding after long episodes of fasting (Secor, 2008). For pythons, fasting triggers an integrative down‐regulation of tissue performance along with reduction in their rate of metabolism and energy expenditure (Secor, 2008). Given that during fasting physiological processes is down regulated, pythons experience organ remodeling, tissue up‐regulation and increased metabolic activity during their feeding phase (Secor, 2008). We will first introduce the species with its characteristics, habitat, and mode of diet. This will be followed by a look at how these organisms are able to remodel their organs between fasting and feeding phases to conserve energy during fasting. Next, the topic of energy expenditure will be discussed in detail with regards to specific dynamic action and its ...
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