Transcript Chapter 41: Animal Nutrition

Chapter 41: Animal Nutrition
By Josh Ivanir
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.
Herbivores
Omnivores
Carnivores
http://images.nationalgeographic.com/wpf/medialive/photos/000/006/cache/red-tailedhawk_681_600x450.jpg
http://srtherapies.com/files/images/eating-pizza.jpg
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
Concept 41.1 Homeostatic mechanisms manage an animal’s 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.
• 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 protein–
deficient.
• Overnourishment: Excessive food intake.
• Stores excess fat molecules instead of using them.
Fat cells from the abdomen of a human
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.
Appetite- Regulating Hormones
Mouse on Left has defective gene that
produces Leptin.
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
molecules—carbohydrates, proteins, and lipids.
• Animal′s diet must also supply essential
nutrients.
• 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
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”.
Protein deficiency in Haitian boy called
Kwashiorkor
Essential Amino Acids from a Vegetarian
Diet
Essential Fatty Acids
• Certain unsaturated fatty acids that animals
cannot make.
• Fatty Acids have double bonds.
• Deficiencies are rare.
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:
– water–soluble vitamins
– fat–soluble vitamins
Vitamin requirements in Humans
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
Mineral Requirements for Humans
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.
Stages of Food Processing
• enzymatic hydrolysis: The process in digestion that
splits macromolecules from food by the enzymatic
addition of water.
• Absorption: The uptake of small nutrient mol–ecules
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.
Digestive Compartments
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Intracellular digestion: The joining of food vacuoles and lysosomes to allow
chemical digestion to occur within the cytoplasm of a cell.
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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.
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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
Concept 41.4: Each organ of the mammalian digestive system
has specialized food–processing functions
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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.
Human Digestive System
The Oral Cavity, Pharynx, and Esophagus
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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.
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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.
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Bolus: A lubricated ball of chewed food.
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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.
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Esophagus: A channel that conducts food, by peristalsis, from the pharynx to the
stomach.
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.
The Stomach
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.
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.
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.
Stomach and Intestinal Adaptations
• Herbivores generally have longer alimentary
canals than carnivores, reflecting the longer
time needed to digest vegetation.
Symbiotic Adaptations
• Many herbivorous animals have fermentation
chambers where symbiotic micro– organisms
digest cellulose.
Works Cited
• All Images and information from Campbell
biology