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Digestion and nutrition
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Digestion and nutrition



Digestive System

Digestive System



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    Digestion and nutrition Digestion and nutrition Presentation Transcript

    • Digestion and Nutrition Pua Karen Joy D. 1 PSY 4
    • 2 types of species:
      • Autotroph
      • – producers in food chain(i.e. plants).
      • – organisms that only need inorganic compounds from their surroundings to acquire nutrition.
        • Phototrophs – organisms that carry out photosynthesis.
        • Chemotrophs –organisms w/c gain energy from inorganic chemical reactions.
    • 2 types of species:
      • Heterotroph
      • – consumers (i.e. almost all of animals).
      • – takes in autotrophs as food.
    • Animal division according to dietary habits
      • Herbivorous – plant eating animals.
      • Carnivorous – herbivore/carnivore eating animals.
      • Omnivorous – animal and plant eating animals.
      • Saprophagous – animals who eat decaying organic matter.
    • Food processing
      • Ingestion – food taken by mouth or mouth-like structure.
      • Digestion – breaking down of food particles.
      • Absorption – digested food particles are absorbed to the circulatory system & transported to body’s tissues.
      • Excretion – waste products not needed for the body is egested in feces.
    • Feeding Mechanisms
      • Feeding on particulate matter
          • feeding on food particles.
      • Feeding on Food Masses
          • feeding on solid food.
      • Feeding on Fluids
          • Feeding on liquid substance.
    • On particulate matter
      • Suspension feeding
          • Organisms w/c use ciliated surfaces to produce currents that draw food to their mouth.
          • Filter feeding –organisms having filtering structure w/c feeds by straining food particles from water.
      barnacles fan worms Spiral tube worms
    • On particulate feeding
      • Deposit feeding
        • obtaining nutrients from particles suspended in soil.
      earthworm Amphitrite ornata
    • On Food Masses
      • Carnivorous animals use their teeth for seizing and has a retractable stomach for large intake of intact preys.
      • Invertebrates (birds) have teeth-like structures (bills, beaks) for seizing preys.
      Dasypeltis Raven (generalized bill) Cardinal (seed cracker) Parrot (nut cracker)
    • On Food Masses
      • Mammals are the only beings who chew their foods.
        • has 4 different types of teeth:
          • Incisors –biting, cutting, stripping.
          • Canines –seizing, piercing, tearing.
          • Premolars –grinding & crushing.
          • Molars –grinding & crushing.
    • On Fluids
      • Common organisms that feed on fluids are parasites.
      • 2 kinds:
        • Endoparasites (internal parasites) –feeds upon inside the unknowing host.
        • Ectoparasites (external parasites) –feeds outside of the host’s body.
      hookworms leech lamprey Ectoparasites Endoparasites
    • Other ectoparasites have piercing and sucking mouthparts just like mosquitoes and lampreys.
      • Life cycle of lamprey
      • Sucking mouth part of mosquito
      • The process of digestion is mechanically and chemically breaking down of solid foods into small particles for absorption.
      • Solid foods must be broken down first to their simplest molecular form for it to be assimilated.
    • Types of digestion
      • Intracellular digestion
        • Digestion w/in a cell.
        • Food particle is enclosed by food vacuole via phagocytosis.
        • Exclusively used by sponges and protozoa.
    • Types of digestion
      • Extracellular digestion
        • Digestion outside the cell.
        • Digestion of large food masses.
        • Mouth-to-anus alimentary system.
        • Practiced by arthropods and vertebrates.
        • Ingested food is exposed to mechanical, chemical & bacterial treatments, to diff. acidic & alkaline regions, & to digestive juices added throughout passing the alimentary canal.
    • Digestive enzymes
      • Are hydrolytic enzymes or hysrolases.
      • Food molecule is split by process of hydrolysis .
      • Hydrolysis -a chemical reaction in which a compound reacts with water, causing decomposition and the production of two or more other compounds, e.g. in the conversion of starch to glucose.
      • **Enzymes –important biochemical catalyst.
    • Motility in Alimentary Canal
      • Food is moved by cilia or specialized musculature .
      • *cilia – tiny projecting thread that beats rhythmically to aid the movement of a fluid past the cell or movement of the organism through liquid.
      • Characteristic gut movement:
        • Segmentation – alternative constriction of rings of smooth muscle of the intestine that constantly divide & squeeze contents back & forth.
    • Motility in Alimentary Canal
      • Characteristic gut movement:
        • Peristalsis – sweeps food down the gut w/ waves of contraction of circular muscle behind and relaxation in front of the food mass.
      peristalsis segmentation
    • Regional function of Alimentary Canals
      • 5 major regions of alimentary canal
        • Reception
        • Conduction and storage
        • Grinding and early digestion
        • Terminal digestion and absorption
        • Water absorption and concentration of solids
    • I. Reception
      • Buccal cavity
        • Mouth.
      • Pharynx
        • throat
          • Salivary gland
            • buccal gland
            • Produce lubricating secretions containing mucus to assist swallowing.
            • Secretes toxic enzymes for struggling preys.
          • Amylse
            • Carbohydrate-splitting enzyme.
            • Begins hydrolysis of plant and animal starches.
    • I. Reception
      • * Maltose –two-glucose fragment.
        • Tongue
          • vertebrate innovation attached to the floor of mouth.
          • Assists in food manipulation and swallowing.
          • Possess taste buds that are used to determine palatability of foods.
          • II. Conduction and storage
      • Esophagus
        • Transfers food to the digestive region.
        • Serves as crop to invertebrates.
        • * crop – food storage before digestion.
    • III. Region of grinding & early digestion
      • Stomach
        • Provides initial digestion, storage & mixing of food w/ digestive juices.
        • Digestive diverticula (pl. diverticulum ) –blind tubules or pouches arising from the main passage.
        • Cellulase –only enzyme that can digest woody cellulose that encloses plant cells.
        • Are U-shaped in carnivores & omnivores.
        • Cardiac sphincter –muscular ring at the orifice between the esophagus and stomach that opens reflexively when food enters and closes to prevent regurgitation back into the esophagus.
    • II. Region of grinding & early digestion
      • Duodenum -1 st region of small intestine.
      • Pyloric sphincter –regulates flow of food into the intestine and prevents regurgitation into the stomach.
      • Deep tubular glands secrete gastric juice 2 liters/day in humans.
        • Goblet cell –secrete mucus.
        • Chief cells –secrete pepsinogen.
        • Parietal/Oxyntic cells –secrete hydrochloric acid.
        • **pepsinogen –precursor of pepsin.
        • *Rennin –milk-curdling enzyme found in stomachs of ruminant mammals.
    • III. Grinding and early digestion
      • Happens in intestine.
        • Villi –minute finger-like projection in the small intestine.
        • Microvilli -a microscopic hair-shaped cell that projects from the surface of the lining of the small intestine.
        • Pyloric sphincter -is a strong ring of smooth muscle at the end of the pyloric canal and lets food pass from the stomach to the duodenum.
        • Pancreatic juice & bile – has high bicarbonate content.
      • Pancreatic enzymes
        • Trypsin & chromotrypsin – highly specific proteases that split peptide bonds deep inside a protein molecule.
        • Carboxypeptidase –removes amino acid from carboxyl ends of polypeptides.
        • Pancreatic lipase –hydrolyzes fats into fatty acids and glycerol.
        • Pancreatic amylase –starch-splitting enzyme.
        • Nucleases –degrade RNA & DNA to nucleotides.
    • IV. Grinding and early digestion
      • Membrane enzyme
        • Aminopeptidase –splits terminal amino acids from amino end of short peptides.
        • Alkaline phosphatase –enzyme that attacks a variety of phospate compunds, nucleotidases & nucleosidases.
      • Bile
        • Is secreted in the bile duct.
        • Collects in the gallbladder between meals.
        • Contains no enzyme.
        • Bile salts –essential for digestion of fats.
            • Bile pigments –produces yellow-green color of bile.
    • V. Region of water absorption & concentration in solids
      • Happens in the large intestine.
        • Large intestine –consolidates remnants of digestion.
          • Rectal gland –absorbs water and ions as needed.
      Large intestine
    • Regulation of Food intake
      • Hunger centers –located in the hypothalamus.
      • Brainstem –regulate the intake of food.
      • Brown fat –dark adipose tissue specialized in generation of heat present in placental mammals.
      • Uncoupling protein –acts to uncouple the production of ATP during oxidative phosphorylation.
      • Thermogenesis –heat production in the body thru metabolic process
      • Leptin –hormone w/c tells the hypothalamus & brainstem how much fat the body carries.
    • Regulation of Digestion
      • Gastrointestinal(GI) hormone
        • Group of hormone secreted by enteroendocrine cells.
        • Gastrin –a polypeptide hormone that stimulates secretion of gastric acid .
        • Cholecystokinin (CCK) –a polypeptide hormone that stimulates gallbladder contraction (increasing bile salts into the intestine), stimulates enzyme-rich secretion in the pancreas, & contributes a feeling of satiety after a meal particular those rich in fat.
        • Secretin –secreted in response to food and strong acid in the stomach and small intestine.
    • Nutritional requirements
      • For Animals:
        • Carbohydrates & fats- fuel for energy.
        • Proteins (amino acids) –synthesis of specific proteins and other nitrogen-containing compunds.
        • Water –solvent for body chemistry, major component of all fluids of the body.
        • Mineral – inorganic elemental atoms that are essential nutrients.
        • Salts –(inorganic) forms structural & physiological components throughout the body.
        • Vitamins - organic compound required as a nutrient in tiny amounts by an organism.
    • Undernourishment/Malnourishment
      • #2 world’s oldest problem & today’s major health problem.
        • *Atherosclerosis – disease that occurs when a diet is high in saturated lipids but low in polyunsaturated lipids.
      • Growing children, pregnant & lactating women are most vulnerable to effects of malnutrition.
      atherosclerosis Malnutrition