Chapter 41: Animal Nutrition

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Chapter 41 Animal Nutrition

• By Josh Ivanir

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Overview

• Three main categories that animals fall in
• -Herbivores  eat mainly autotrophs (plants and
  algae) ex. Gorillas, cattle
• -Carnivores eat other animals
• ex. Sharks,hawks
• -Omnivores regularly consume animals as well as
  plants or algae
• ex. Humans, Bears
• Most animals are also opportunistic feeders,
  foods that are outside their main dietary
  category when these foods are available.
• All animals consume bacteria along with other
  types of food.

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Herbivores
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Omnivores
Carnivores
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For any animal, a nutritionally adequate diet
must satisfy three nutritional needs

•  fuel (chemical energy) which is converted into
  ATP to power cellular processes.
• Organic building blocks, such as organic carbon
  and organic nitrogen, to synthesize a variety of
  organic molecules
• Essential nutrients, which are required by cells
  and must be obtained from dietary sources

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Concept 41.1 Homeostatic mechanisms manage an
animals energy budget

• The flow of energy into and out of an animal's
  body can be viewed as a budget.
• Mostly all of an animal's ATP generation is based
  on the oxidation of energy, carbohydrates,
  proteins, and fats, in cellular respiration.
• Monomers of any of these substances can be used
  as fuel.
• Animals burn proteins only after exhausting
  their supply of carbohydrates and fats.
• Fats are rich in energy.
• Biosynthesis occurs when an animal takes in more
  calories than it needs to produce ATP.
• In humans, the liver and muscle cells store
  energy in the form of glycogen, a polymer made up
  of many glucose units.
• Glucose is an important fuel for cells.

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• When fewer calories are consumed, fuel is taken
  out of storage depots and oxidized.
• This causes the animal to lose weight.
• Most healthy people, even if they are not obese,
  have enough stored fat to sustain them through
  several weeks of starvation.
• Caloric imbalance
• Undernourishment If the diet of a human or other
  animal is chronically deficient in calories.
• body begins breaking down its own proteins for
  fuel, muscles begin to decrease in size, and the
  brain can become proteindeficient.
• Overnourishment Excessive food intake.
• Stores excess fat molecules instead of using
  them.

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Fat cells from the abdomen of a human
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Obesity

• Now recognized as a major global health problem
  by The World Health Organization.
• In the United States, the percentage of obese
  (very overweight) people has doubled to 30 in
  the past two decades.
• Obesity contributes to a number of health
  problems, including the most common type of
  diabetes, cancer of the colon and breasts, and
  cardiovascular disease that can lead to heart
  attacks and strokes.
• Scientists are able to control appetite-regulating
  hormones.
• Inheritance is a major factor in obesity.
• Defective genes can contribute to issues in
  weight loss.

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Appetite- Regulating Hormones
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Mouse on Left has defective gene that produces
Leptin.
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Concept 41.2 An animal's diet must supply carbon
skeletons and essential nutrients

• An animal's diet must also supply all the raw
  materials needed for biosynthesis, in addition to
  providing fuel for ATP production.
• An animal must obtain organic precursors (carbon
  skeletons) from its food to grow, maintain
  itself, and reproduce.
• Animals can fabricate a great variety of organic
  moleculescarbohydrates, proteins, and lipids.
• Animal's diet must also supply essential
  nutrients. 

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• Essential Nutrients materials that must be
  obtained in preassembled form because the
  animal's cells cannot make them from any raw
  material.
• Malnourished an animal whose diet is missing one
  or more essential nutrients.
• Four classes of essential nutrients
•  essential amino acids
•  essential fatty acids
• Vitamins
• minerals

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Essential Amino Acids

• An amino acid that an animal cannot synthesize
  itself and must be obtained from food. Eight
  amino acids are essential in the human adult.
• Animals require 20 amino acids to make proteins.
• protein deficiency form of malnutrition caused
  by insufficient amounts of one or more essential
  amino acids.
• Proteins in animal products are complete, which
  means that they provide all the essential amino
  acids in their proper proportions. 
• Most plant proteins are incomplete.

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Protein deficiency in Haitian boy called
Kwashiorkor
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Essential Amino Acids from a Vegetarian Diet
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Essential Fatty Acids

• Certain unsaturated fatty acids that animals
  cannot make.
• Fatty Acids have double bonds.
• Deficiencies are rare.

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Vitamins

• An organic molecule required in the diet in very
  small amounts. Vitamins serve primarily as
  coenzymes or parts of coenzymes.
•  Vitamin deficiencies can cause severe problems.
• 13 vitamins essential to humans have been
  identified.
• Grouped into two categories
• watersoluble vitamins 
• fatsoluble vitamins 

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Vitamin requirements in Humans
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Minerals

• In nutrition, a chemical element other than
  hydrogen, oxygen, or nitrogen that an organism
  requires for proper body functioning.
• Humans and other vertebrates require relatively
  large quantities of calcium and phosphorus for
  the construction and maintenance of bone.
• Most people eat more salt than needed

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Mineral Requirements for Humans
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Concept 41.3 The main stages of food processing
are ingestion, digestion, absorption, and
elimination

• Ingestion A heterotrophic mode of nutrition in
  which other organisms or detritus are eaten whole
  or in pieces.
• Organic material in food consists largely of
  proteins, fats, and carbohydrates in the form of
  starch and other polysaccharides.
• Cannot use these macromolecules directly for two
  reasons
•  polymers are too large to pass through membranes
  and enter the cells of the animal.
• macromolecules that make up an animal are not
  identical to those of its food.
• Digestion The process of breaking down food into
  molecules small enough for the body to absorb.

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Stages of Food Processing
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• enzymatic hydrolysis The process in digestion
  that splits macromolecules from food by the
  enzymatic addition of water.
• Absorption The uptake of small nutrient
  molecules by an organism's own body the third
  main stage of food processing, following
  digestion.
• Elimination The passing of undigested material
  out of the digestive compartment.

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Digestive Compartments

• Intracellular digestion The joining of food
  vacuoles and lysosomes to allow chemical
  digestion to occur within the cytoplasm of a
  cell.
• Begins after a cell engulfs food by phagocytosis
  or pinocytosis.
• Extracellular digestion The breakdown of food
  outside cells.
• Occurs within compartments that are continuous
  with the outside of the animal's body.
• Gastrovascular cavity An extensive pouch that
  serves as the site of extracellular digestion and
  a passageway to disperse materials throughout
  most of an animal's body.
• Animals with relatively simple body plans have a
  digestive sac with a single opening. 
• Complete digestive tract A digestive tube that
  runs between a mouth and an anus also called an
  alimentary canal. An incomplete digestive tract
  has only one opening.

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alimentary canals
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Concept 41.4 Each organ of the mammalian
digestive system has specialized foodprocessing
functions

• The mammalian digestive system consists of the
  alimentary canal and various accessory glands
  that secrete digestive juices into the canal
  through ducts.
• Peristalsis Rhythmic waves of contraction of
  smooth muscle that push food along the digestive
  tract.
• Sphincter A ring like valve consisting of
  modified muscles in a muscular tube, such as a
  digestive tract closes off the tube like a
  drawstring.
• Salivary glands Exocrine glands associated with
  the oral cavity. The secretions of salivary
  glands contain substances to lubricate food,
  adhere together chewed pieces into a bolus, and
  begin the process of chemical digestion.
• Pancreas A gland with dual functions The
  nonendocrine portion secretes digestive enzymes
  and an alkaline solution into the small intestine
  via a duct the endocrine portion secretes the
  hormones insulin and glucagon into the blood.
• Liver The largest organ in the vertebrate body.
  The liver performs diverse functions, such as
  producing bile, preparing nitrogenous wastes for
  disposal, and detoxifying poisonous chemicals in
  the blood.
• Gallbladder An organ that stores bile and
  releases it as needed into the small intestine.

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Human Digestive System
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The Oral Cavity, Pharynx, and Esophagus

• During chewing, teeth of various shapes cut,
  smash, and grind food, making it easier to
  swallow and increasing its surface area.
• Oral cavity The mouth of an animal.
• Oral Cavity triggers a nervous reflex that causes
  the salivary glands to deliver saliva through
  ducts to the oral cavity.
• Humans secrete more than a liter of saliva each
  day.
• Saliva contains a slippery glycoprotein called
  mucin.
• Salivary amylase A salivary gland enzyme that
  hydrolyzes starch and glycogen.
• Bolus A lubricated ball of chewed food.
• During swallowing, the tongue pushes a bolus to
  the back of the oral cavity and into the pharynx.
• Pharynx  An area in the vertebrate throat where
  air and food passages cross in flatworms, the
  muscular tube that protrudes from the ventral
  side of the worm and ends in the mouth.
• Epiglottis A cartilaginous flap that blocks the
  top of the windpipe, the glottis, during
  swallowing, which prevents the entry of food or
  fluid into the respiratory system.
• Esophagus A channel that conducts food, by
  peristalsis, from the pharynx to the stomach.

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The Stomach

• An organ of the digestive system that stores food
  and performs preliminary steps of digestion.
• Gastric juice A digestive fluid secreted by the
  stomach.
• Converts a meal to acid chyme.
• Gastric juice includes hydrochloric acid and the
  enzyme pepsin.

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The Stomach
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 The Small Intestine

• The major organ of digestion and absorption.
•  Acid chyme from the stomach mixes in the
  duodenum with intestinal juice, bile, and
  pancreatic juice.
• Diverse enzymes complete the hydrolysis of food
  molecules to monomers, which are absorbed into
  the blood across the lining of the small
  intestine.
• Hormones help regulate digestive juice secretions.

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The Large Intestine

• Aids the small intestine in reabsorbing water and
  houses bacteria, some of which synthesize
  vitamins.
• Feces pass through the rectum and out the anus.

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Concept 41.5 Evolutionary adaptations of
vertebrate digestive systems are often associated
with diet

• Some Dental Adaptations
• A mammal's dentition is generally correlated with
  its diet.
• Mammals have specialized dentition that best
  enables them to ingest their usual diet.

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 Stomach and Intestinal Adaptations

• Herbivores generally have longer alimentary
  canals than carnivores, reflecting the longer
  time needed to digest vegetation.

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Symbiotic Adaptations

• Many herbivorous animals have fermentation
  chambers where symbiotic micro organisms digest
  cellulose.

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Works Cited

• All Images and information from Campbell biology