1. 2 Lecture 13 Outline (Ch. 48) I.Animal Nutrition Overview II.Essential Parts of Animal Diet III....
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Transcript of 1. 2 Lecture 13 Outline (Ch. 48) I.Animal Nutrition Overview II.Essential Parts of Animal Diet III....
![Page 1: 1. 2 Lecture 13 Outline (Ch. 48) I.Animal Nutrition Overview II.Essential Parts of Animal Diet III. Food Intake IV.Digestive Compartments V.Adaptations.](https://reader030.fdocuments.in/reader030/viewer/2022032804/56649e585503460f94b52094/html5/thumbnails/1.jpg)
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Lecture 13 Outline (Ch. 48)
I. Animal Nutrition Overview
II. Essential Parts of Animal Diet
III. Food Intake
IV. Digestive Compartments
V. Adaptations
VI. Obesity
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Overview: The Need to Feed• Food is taken in, taken apart, and taken up in the process of
animal nutrition • In general, animals fall into three categories:
– Herbivores eat mainly autotrophs (plants, algae)– Carnivores eat other animals– Omnivores regularly consume animals as well as plants
or algal matter
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• Chemical energy, which is converted into ATP and powers processes in the body
• Organic carbon and organic nitrogen • Essential nutrients must be obtained
from dietary sources
Essential Parts of Diet
–Essential amino acids–Essential fatty acids–Vitamins–Minerals
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• Meat, eggs, cheese - provide all nine essential amino acids ( “complete” proteins)
• Individuals eating only plant proteins need specific plant combinations for all essential amino acids
Essential Parts of Diet
Beans and other legumes
Corn (maize)and other grains
Lysine
Essential amino acids for adults
Tryptophan
Isoleucine
Leucine
Phenylalanine
Threonine
Valine
Methionine
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• Animals can synthesize most fatty acids they need• The essential fatty acids are certain unsaturated fatty
acids that must be obtained from the diet
Essential Parts of Diet
• Vitamins: organic molecules needed in small amounts
• 13 essential vitamins for humans• Fat-soluble & water-soluble
B-complex
Biotin
Vitamin C (ascorbic acid)
Vitamin A
Vitamin D
Vitamin E
Vitamin K
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Minerals• Minerals: inorganic nutrients, small amounts needed
Calcium
Phosphorus
Potassium
Sulfur
Chlorine
Sodium
Magnesium
Iron
A diet missing a certain essential part or not enough calories overall leads to malnourishment or undernourishment
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Ingestion: the act of eating
• Suspension feeders - many aquatic animals, which sift small food particles from the water
• Substrate feeders are animals that live in or on their food source
• Fluid feeders suck nutrient-rich fluid from a living host
• Bulk feeders eat relatively large pieces of food
Food Intake
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Humpback whale, a suspension feeder
Baleen
Leaf miner caterpillar, substrate feeder
Caterpillar Feces
Mosquito, a fluid feeder Rock python, a bulk feeder
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• Digestion is the process of breaking food down into molecules small enough to absorb– In chemical digestion, the process of enzymatic
hydrolysis splits bonds in molecules with the addition of water
• Absorption is uptake of nutrients by body cells
• Elimination is the passage of undigested material out of the digestive compartment
Food Intake
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Ingestion Digestion Absorption Elimination
Undigestedmaterial
Chemical digestion(enzymatic hydrolysis)
Nutrientmoleculesenter bodycells
Smallmolecules
Mechanicaldigestion
Food
Piecesof food
1 2 3 4
Food Intake
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Digestive Compartments• Most animals process food in specialized
compartments• Reduces risk animal digesting
its own cells/ tissues
Gastrovascularcavity
Food
Epidermis
Mouth
Tentacles
Gastrodermis
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• More complex animals: digestive tube with two openings (mouth, anus)
• Tube called a complete digestive tract or an alimentary canal
• Can have specialized regions, carry out digestion and absorption stepwise
Digestive Compartments
Esophagus
Mouth
Pharynx
Crop Gizzard
Typhlosole
Intestine
Lumen of intestine
Anus
(b) Grasshopper
Foregut
(c) Bird
(a) Earthworm
Midgut Hindgut
Esophagus RectumAnus
Mouth
Crop
Gastric cecae
Esophagus
Mouth
CropAnus
StomachGizzard
Intestine
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Cecum
Anus Anus
Ascendingportion oflarge intestine
Gall-bladder
Smallintestine
Largeintestine
Smallintestine
Rectum
Pancreas
Liver
Salivary glands
TongueOral cavity
PharynxEsophagus
Sphincter
Stomach
Sphincter
Duodenum ofsmall intestine
Appendix
Liver
Pancreas
Smallintestine
Largeintestine
Rectum
StomachGall-bladder
A schematic diagram of thehuman digestive system
Esophagus
Salivaryglands
Mouth
Digestive Compartments
• Mammalian alimentary canal and accessory glands that secrete digestive juices through ducts
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Larynx
Trachea
Epiglottisup
Pharynx
Tongue
Glottis
Esophagus
Esophagealsphinctercontracted
Food
Tostomach
Tolungs
Epiglottisdown
Esophagealsphincterrelaxed
Glottis upand closed
Epiglottisup
Esophagealsphinctercontracted
Sphincterrelaxed
Relaxedmuscles
Contractedmuscles
Relaxedmuscles
Stomach
Glottisdownand open
Oral Cavity, Pharynx, Esophagus
• Food shaped into a bolus, lubricated by saliva, digestion begins with amylase.
• Pharynx, a junction that opens to both the esophagus and the trachea (windpipe)
• The esophagus conducts food from the pharynx down to the stomach by peristalsis
• Epiglottis blocks entry to the trachea, and larynx.
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Digestion in the Stomach• The stomach stores food and secretes gastric
juice, which converts a meal to acid chyme
• Gastric juice - hydrochloric acid (parietal cells) and the enzyme pepsin (chief cells)
• Mucus protects the stomach lining from gastric juice
Interior surfaceof stomach
Esophagus
Chief cells
Small intestine
Epithelium
Stomach
Sphincter
Parietal cell
Chief cell
Folds ofepithelialtissue
Pepsin
Sphincter
Pepsinogen
HCl
H+
Cl–
Parietal cells
Mucus cells
Gastric gland
1
2
3
5 µ
m
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Digestion in the Small Intestine • The small intestine: longest section of alimentary canal• Major organ of digestion and absorption
• First is the duodenum - acid chyme from the stomach mixes with digestive juices from the pancreas, liver, gallbladder, and the small intestine itself.
pancreas
proteases trypsin & chymotrypsin
amylase & lipase
neutralizes the acidic chyme
liver/gallbladder
bile aids digestion and absorption of fats
small intestine
lining of duodenum (brush border) produces several digestive enzymes
jejunum and ileum mainly absorb water & nutrients
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Digestion in the Small Intestine
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Oral cavity,pharynx,esophagus
Stomach
Lumen ofsmall intestine
Epitheliumof smallintestine(brushborder)
Carbohydrate digestion
Polysaccharides
Smaller polysaccharides,maltose
Polysaccharides
Maltose and otherdisaccharides
Disaccharides
Protein digestion Nucleic acid digestion Fat digestion
Proteins
Small polypeptides
Pepsin
Pancreatic amylases
Salivary amylase
Disaccharidases
Monosaccharides
Small peptides
Amino acids
Amino acids
Polypeptides
Smallerpolypeptides
Pancreatic trypsin andchymotrypsin
Pancreatic carboxypeptidase
Dipeptidases, carboxypeptidase,and aminopeptidase
DNA, RNA
Pancreatic nucleases
Fat globules
NucleotidesFat droplets
Nucleosides
Nitrogenous bases,sugars, phosphates
Nucleotidases
Nucleosidasesandphosphatases
Glycerol, fattyacids, monoglycerides
Bile salts
Pancreatic lipase
(starch, glycogen) (sucrose, lactose)
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Absorption in the Small Intestine• small intestine has huge surface area, from villi and
microvilli exposed to the intestinal lumen• enormous microvillar surface greatly increases rate
of nutrient absorption
Muscle layers
Microvilli (brushborder) at apical(lumenal) surface
Vein carrying bloodto hepatic portal vein
Villi
Intestinal wall
Key
Nutrientabsorption
Largecircularfolds
Bloodcapillaries
Epithelialcells
Villi
Lymphvessel
Basal surface
Lacteal
Epithelial cells
Lumen
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Absorption in the Small Intestine
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Absorption in the Large Intestine• The colon of the large intestine is
connected to the small intestine• The cecum aids in
fermentation of plant material, connects where the small and large intestines meet
• Human cecum has extension (appendix), plays a minor role in immunity
Feces stored in rectum until eliminated
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• The colon houses strains of the bacterium Escherichia coli, some of which produce vitamins
• Two sphincters between the rectum and anus control bowel movements
– Smooth muscle sphincter (involuntary)– Striated muscle sphincter (voluntary)
Absorption in the Large Intestine
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• Herbivores generally have longer alimentary canals than carnivores, reflecting the longer time needed to digest vegetation
Cecum
Small intestine
HerbivoreCarnivore
Colon(largeintestine)
StomachSmall intestine
Adaptations
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Mutualistic Adaptations• Many herbivores have symbiotic microorganisms
that digest cellulose• The most elaborate adaptations in ruminants
Esophagus
OmasumAbomasum
Intestine
Rumen Reticulum1 2
4 3
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Energy Sources and Stores• Animals store excess calories as glycogen in the
liver and muscles• Energy secondarily stored as adipose, or fat, cells• When fewer calories are taken in than are
expended, fuel is taken from storage and oxidized
100 µm
Fat cells
• Obesity is due to excessive intake of food energy, excess stored as fat
• Obesity contributes to diabetes (type 2), cancer of the colon and breasts, heart attacks, and strokes
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Homeostasis:90 mg glucose/100 mL blood
Stimulus:Blood glucose
level risesafter eating.
Stimulus:Blood glucose
level dropsbelow set point.
Energy Sources and Stores
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LeptinPYY
Insulin
Ghrelin
Energy Sources and Stores
• The complexity of weight control in humans is evident from studies of the hormone leptin
• Mice that inherit a defect in the gene for leptin become very obese
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Obese mouse with mutant ob gene (left) next to wild-type sibling mouse.
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Obesity and Evolution
• The problem of maintaining weight partly stems from our evolutionary past, when fat hoarding was a means of survival
• A species of birds called petrels become obese as chicks; in order to consume enough protein from high-fat food, chicks need to consume more calories than they burn
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31A plump petrel
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Lecture 13 Summary
1. Essential Nutrients (Ch. 48)- Amino acids, fatty acids, vitamins, minerals
2. Types of Food Intake and Digestive Tracts (Ch. 48)- Suspension, substrate, fluid, bulk feeders- Gastrovascular, simple, complex digestive cavities
3. Digestive Tract and Enzymes/Secretions (Ch. 48)
- Mouth
- Stomach
- Auxiliary Organs
- Small Intestine
- Large Intestine
4. Adaptations and Control (Ch. 48)- Diet and digestive tract- Mutualisms- Obesity and Energy Stores