Bioenergetics and Digestion

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Bioenergetics and Digestion
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Well be discussing

• Trends and Various Strategies Used by Organisms
  to Process Food
• Process of Digestion in Man
• Disorders of the Human Digestive System

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Core Concepts

• Nutritional requirements
• Animals are heterotrophs that require food for
  fuel, carbon skeletons, and essential nutrients.
• Metabolic rate provides clues to an animals
  bioenergetic strategy.
•  Evolutionary adaptations of feeding mechanisms
  and digestive systems
• Diverse feeding adaptations have evolved among
  animals.
• Structural adaptations of digestive systems are
  often associated with diet.
• Symbiotic microorganisms help nourish many
  vertebrates.
•  Overview of food processing
• The four main stages of food processing are
  ingestion, digestion, absorption, and
  elimination.
• Digestion occurs in specialized compartments.
• The oral cavity, pharynx, and esophagus initiate
  food processing.
• The stomach stores food and performs preliminary
  digestion.
• The small intestine is the major organ of
  digestion and absorption.
• Reclaiming water is a major function of the large
  intestine.
• Hormones regulate digestion.
• Reclaiming water is a major function of the large
  intestine.
• Nutrition and disorders of the human digestive
  system
• A healthful diet provides both fuel and building
  materials.
• Nutritional disorders damage health.

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Keywords

• minerals
• nutrition
• obesity
• pancreas
• peristalsis
• peptic ulcers
• peristalsis
• phagocytosis
• pharynx
• salivary glands
• small intestine
• sphincters
• stomach
• undernutrition
• vesicles
• villus
• vitamins

• absorption
• alimentary canal
• amebocytes
• anorexia
• bile
• bolus
• brush border
• bulimia
• cecum
• chyme
• complete digestive tract
• crop
• digestion
• duodenum
• elimination
• endocytosis
• enzyme
• esophagus

• essential nutrient
• extracellular digestion
• filter feeders
• gallbladder
• gastrovascular cavity
• gizzard
• heterotroph
• ileum
• incomplete digestive tract
• ingestion
• intracellular digestion
• jejunum
• large intestine
• liver
• malnutrition
• microvilli

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Bioenergetics of an animal

• Food
• Fuel
• C-skeletons
• essential nutrients
• ATP powers resting metabolism, activity, and
  temperature regulation
• Excess calories can be used for biosynthesis
• 85-90 of energy from food is lost as heat

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Metabolic rates

• Metabolism
• Anabolism
• Catabolism
• Resting/ Basal Metabolic Rate (BMR)
• energy/unit mass/hr
• Size and relative metabolic rate are inversely
  proportional

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Do plants have digestive systems?

• Carnivorous plants in marshlands have primitive
  digestive systems
• Habitats with N-poor soils
• Adaptation occasionally feed on animals
• CH2O ? Photosynthesis
• N minerals ? insects, etc.

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Evolution of digestion

• Different types depending on diet and lifestyle
• All must accomplish
• Ingestion
• Digestion
• Mechanical breakdown
• Chemical breakdown
• Absorption
• Elimination
• Digestion occurs in specialized compartments

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Intracellular digestion ( 1 ) (evolved in
single-celled protists, retained in simplest
animals)

• Protists
• Paramecium

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Intracellular digestion ( 2 ) (evolved in
single-celled protists, retained in simplest
animals)

• SPONGES

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Extracellular digestion ( by fungi )

• Fungi

• Sedentary heterotrophs living in or on food
  supply
• Saprotroph/parasites
• No internal cavity ? release digestive enzymes

Image from http//www.aber.ac.uk/fungi/graffeg/dec
omp/digestion-by-hypha.jpg
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Extracellular and intracellular digestion1. In
animals with incomplete digestive systems (1)

• Cnidarians
• Hydra

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Extracellular and intracellular digestion 1. In
animals with incomplete digestive systems (2)

• Platyhelminthes
• Planaria and tapeworms

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Extracellular digestion 2. In animals with
complete digestive systems

• Nematoda to Vertebrates
• Earthworms

• 20 cm long with 100 segments
• 1st mouth
• Last anus
• Eats its way through soil

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Feeding adaptations for ingestion
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Comparison of vertebrate digestive systems
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Mammalian digestion General plan
Organs of the GI tract
Accessory digestive organs
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Comparison of mammalian digestive systems(Diet
plays an important role in the length and
structure)
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