1. 2 Lecture 13 Outline (Ch. 41) I.Animal Nutrition Overview II.Essential Parts of Animal Diet III....
-
Upload
marianna-king -
Category
Documents
-
view
214 -
download
0
Transcript of 1. 2 Lecture 13 Outline (Ch. 41) I.Animal Nutrition Overview II.Essential Parts of Animal Diet III....
1
2
Lecture 13 Outline (Ch. 41)
I. Animal Nutrition Overview
II. Essential Parts of Animal Diet
III. Food Intake
IV. Digestive Compartments
V. Adaptations
VI. Obesity
VII. Lecture Concepts
3
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
4How does a diet of lean fish help make a bear fat?
5
• 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
6
• 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 otherlegumes
Corn (maize)and other grains
Lysine
Essential amino acids for adults
Tryptophan
Isoleucine
Leucine
Phenylalanine
Threonine
Valine
Methionine
7
Essential Fatty Acids• Animals can synthesize most fatty acids they need• The essential fatty acids are certain unsaturated
fatty acids that must be obtained from the diet• Deficiencies in fatty acids are rare
8
Vitamins• Vitamins: organic molecules, small amounts needed• 13 vitamins essential to humans have been identified• Two categories: fat-soluble & water-soluble
B-complex
Biotin
Vitamin C (ascorbic acid)
Vitamin A
Vitamin D
Vitamin E
Vitamin K
Table 41-1
9
Minerals
• Minerals: simple inorganic nutrients, usually required in small amounts
Calcium
Phosphorus
Potassium
Sulfur
Chlorine
Sodium
Magnesium
Iron
Table 41-2
10
Dietary Deficiencies• Undernourishment – diet consistently low in chemical energy• Malnourishment – long-term absence of essential nutrients
An undernourished individuals use up stores, break down own protein and muscle
Malnourishment can cause deformities, disease, and death
11
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
12
Humpback whale, a suspension feeder
Baleen
Leaf miner caterpillar, substrate feeder
Caterpillar Feces
Mosquito, a fluid feeder Rock python, a bulk feeder
13
• 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
14
Ingestion Digestion Absorption Elimination
Undigestedmaterial
Chemical digestion(enzymatic hydrolysis)
Nutrientmoleculesenter bodycells
Smallmolecules
Mechanicaldigestion
Food
Piecesof food
1 2 3 4
Food Intake
15
Digestive Compartments• Most animals process food in specialized
compartments• Reduces risk animal digesting
its own cells/ tissues
Gastrovascularcavity
Food
Epidermis
Mouth
Tentacles
Gastrodermis
16
• 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
17
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
18
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.
19
Digestion in the Stomach• The stomach stores food and secretes gastric
juice, which converts a meal to acid chyme
• Gastric juice - hydrochloric acid and the enzyme pepsin
• Mucus protects the stomach lining from gastric juice Interior surface
of 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
20
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, protein-digesting enzymes
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
21
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)
22
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
23
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
24
• The colon houses strains of the bacterium Escherichia coli, some of which produce vitamins
• Two sphincters between the rectum and anus control bowel movements
25
• 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
26
Mutualistic Adaptations• Many herbivores have symbiotic microorganisms
that digest cellulose• The most elaborate adaptations in ruminants
Esophagus
OmasumAbomasum
Intestine
Rumen Reticulum1 2
4 3
27
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
28
Homeostasis:90 mg glucose/100 mL blood
Stimulus:Blood glucose
level risesafter eating.
Stimulus:Blood glucose
level dropsbelow set point.
29
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
30
Obese mouse with mutant ob gene (left) next to wild-type sibling mouse.
31
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
32Figure 41.25 A plump petrel
33
Lecture 13 concepts- Name the three nutritional needs that must be met by diet
- Describe the four classes of essential nutrients
- Distinguish among undernourishment, overnourishment, and malnourishment
- Describe the four main stages of food processing
- Distinguish between complete digestive tracts and gastrovascular cavities
- Follow a meal through the mammalian digestive system:
List important enzymes and describe their roles
Compare where and how the major types of macromolecules are digested and absorbed
- Explain where and in what form energy-rich molecules may be stored in the human body
- Make a list of new vocabulary with definitions.