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Fig. 41-1
Chapter 41Animal Nutrition
Taken in
Taken apart
Taken up
Fig. 41-4
Fig. 41-6a
Humpback whale, a suspension feeder
Baleen
Fig. 41-6b
Leaf miner caterpillar,a substrate feeder
Mosquito, a fluid feederRock python, a bulk feeder
Fig. 41-18
Incisors
(c) Omnivore
Molars
(b) Herbivore
(a) Carnivore
Canines Premolars
Evolutionary and Adaptations
Fig. 41-9Esophagus
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
Crop
Anus
StomachGizzard
Intestine
Variation in alimentary canals
Fig. 41-19
Cecum
Small intestine
HerbivoreCarnivore
Colon(largeintestine)
StomachSmall intestine
Stomach and intestinal adaptions
Fig. 41-20
Esophagus
OmasumAbomasum
Intestine
Rumen Reticulum1 2
43
Mutualistic adaptation瘤胃
蜂巢胃
重瓣胃皺胃
Concept 41.2: The main stages of food processing are ingestion, digestion, absorption, and elimination
Ingestion Digestion Absorption Elimination
Undigestedmaterial
Chemical digestion(enzymatic hydrolysis)
Nutrientmoleculesenter bodycells
Smallmolecules
Mechanicaldigestion
Food
Piecesof food
1 2 3 4
Fig. 41-10a
Cecum
Anus
Ascendingportion oflarge intestine
Gall-bladder
Smallintestine
Largeintestine
Smallintestine
Rectum
Pancreas
Liver
Salivary glands
TongueOral cavity
Pharynx
Esophagus
Sphincter
Stomach
Sphincter
Duodenum ofsmall intestine
Appendix
Peristalsis
sphincters
Copyright © 2008 Pearson Education Inc., publishing as Pearson Benjamin Cummings
Essential Nutrients
• There are four classes of essential nutrients:
– Essential amino acids
– Essential fatty acids
– Vitamins
– Minerals
Beans and otherlegumes
Corn (maize)and other grains
Lysine
Essential amino acids for adults
Tryptophan
Isoleucine
Leucine
Phenylalanine
Threonine
ValineMethionine
insufficient essential amino acids-----Malnutrition or called protein deficiency
•Vegetarian diet---
Fig. 41-3
Storing protein for growth
Muscle protein
Feather protein
Copyright © 2008 Pearson Education Inc., publishing as Pearson Benjamin Cummings
Essential Fatty Acids
• Animals can synthesize most of the 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
Copyright © 2008 Pearson Education Inc., publishing as Pearson Benjamin Cummings
Unsaturated fatty acids
– Palmitoleic acid (16:1): 棕櫚烯酸
– Oleic acid (18:1): 油酸
– Linoleic acid (18:2): 亞麻油酸
– -Linolenic acid (18:3): α- 亞麻油酸
– Arachidonic acid (20:4): 花生四烯酸
– -Linolenic acid (18:3): γ- 亞麻油酸
– Linoleic acid – Arachidonic acid – eicosanoids -- postaglandins
動物無法合成
植物沒有
Copyright © 2008 Pearson Education Inc., publishing as Pearson Benjamin Cummings
羅倫佐的油
• 羅倫佐得了什麼病？adrenoleukodystrophy (ALD) 腎上腺腦白質退化症
• 過氧化小體 (peroxisome)
– 「非常長鏈飽和性脂肪酸」 (very long-chain fatty acids, VLCFA) 特別是 C24 、 C26的代謝異常
http://www.myelin.org/aboutlorenzo.htm
Copyright © 2008 Pearson Education Inc., publishing as Pearson Benjamin Cummings
Vitamins
• Vitamins are organic molecules required in the diet in small amounts
• 13 vitamins essential to humans have been identified
• Vitamins are grouped into two categories: fat-soluble and water-soluble
Copyright © 2008 Pearson Education Inc., publishing as Pearson Benjamin Cummings
Assessing Nutritional NeedsCan diet influence the frequency of birth
defects?
• Insights into human nutrition have come from
epidemiology, the study of human health and disease in populations
• Richard Smithells
-Women who had had one or more babies with neural tube defect.
Fig. 41-5
•Neural tube defects :a deficiency in folic acid in pregnant mothers
Table 41-1: Vitamin, mineral, and 中興大學研發乳鐵蛋白鉻有助新陳代謝症
Copyright © 2008 Pearson Education Inc., publishing as Pearson Benjamin Cummings
Dietary Deficiencies
• Undernourishment
• Malnourishment
• Overnourishment
Fig. 41-21
Homeostasis:90 mg glucose/100 mL blood
Stimulus:Blood glucose
level risesafter eating.
Stimulus:Blood glucose
level dropsbelow set point.
Hometic regulation of cellular fuel
Role of blood glucose in providing energy
Absorptive phase
Postabsorptive state
Fig. 41-12
Interior surfaceof stomach
Esophagus
Chief cells
Small intestine
Epithelium
Stomach
Sphincter
Parietal cell
Pepsinogen and HClare secreted.
HCl convertspepsinogen to pepsin.
Pepsin activatesmore pepsinogen.
Chief cell
Folds ofepithelialtissue
Pepsin
Sphincter
Pepsinogen
HCl
H+
Cl–
Parietal cells
Mucus cells
Gastric gland
1
2
2
3
3
1
5 µ
m
Fig. 41-UN1
Bloodstream
Veins to heart
Lymphaticsystem
Small intestine
Esophagus
StomachLipids
Mouth
Hepatic portal vein
Absorbed food(except lipids)
Absorbedwater
Secretions fromthe gastric glandsof the stomach
Secretions from the pancreas and the liver
Liver
Rectum
Anus
Largeintestine
Fig. 41-10b
Anus
Liver
Pancreas
Smallintestine
Largeintestine
Rectum
Stomach
Gall-bladder
A schematic diagram of thehuman digestive system
Esophagus
Salivaryglands
Mouth
Fig. 41-12b
Interior surfaceof stomach
Chief cells
Epithelium
Parietal cell
Pepsinogen and HClare secreted.
HCl convertspepsinogen to pepsin.
Pepsin activatesmore pepsinogen.
Chief cell
PepsinPepsinogen
HCl
H+
Cl–
Parietal cells
Mucus cells
Gastric gland2
3
1
1
2
3
•Helicobacter pylori
Fig. 41-15
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
The structure of the small intestine
Fig. 41-13
Oral cavity,pharynx,esophagus
Stomach
Lumen ofsmall intes-tine
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)
Fig. 41-13a
Oral cavity,pharynx,esophagus
Stomach
Lumen ofsmall intestine
Epitheliumof smallintestine(brushborder)
Carbohydrate digestion
Polysaccharides
Smaller polysaccharides,maltose
Polysaccharides
Maltose and otherdisaccharides
Disaccharides
Pancreatic amylases
Salivary amylase
Disaccharidases
Monosaccharides
(starch, glycogen) (sucrose, lactose)
Fig. 41-13b
Stomach
Lumen ofsmall intestine
Epitheliumof smallintestine(brushborder)
Protein digestion Proteins
Polypeptides
Smallerpolypeptides
Pancreatic trypsin andchymotrypsin
Pepsin
Dipeptidases, carboxypeptidase,and aminopeptidase
Monosaccharides
Small polypeptides
Amino acids
Pancreatic carboxypeptidase
Amino acids
Small peptides
Fig. 41-13c
Lumen ofsmall intestine
Epitheliumof smallintestine(brushborder)
Nucleic acid digestion
DNA, RNA
Nucleotides
Pancreaticnucleases
Nucleosidasesandphosphatases
Nucleosides
Nucleotidases
Nitrogenous bases,sugars, phosphates
Fig. 41-13d
Lumen ofsmall intestine
Fat digestion
Fat globules
Fat droplets
Pancreatic lipase
Bile salts
Glycerol, fattyacids, monoglycerides
Mechanisms that help regulate body weight
Homeostatic mechanisms
Hormonessatiety center
Hormonal control of digestion
Secretinand CCK
Stomach
GallbladderLiver
+
Duodenum ofsmall intestine
Bile
Gastrin
Secretin
Pancreas
CCK
CCK
Key
Stimulation
Inhibition
+
–
+
++ –
Cholecystoknin
aa
FA
+
Chyme (fat) –
Hormonal control in the Digestive system: Gastric hormones
GASTRIN:
Secretion: By enteroendocrine (G) cells in gastric pits of the mucosa.
Stimulus: Stomach distention and acid pH of chyme causes Gastrin.
Action:– 1. increases HCl production in stomach– 2. increases gastric motility– 3. stimulates growth of gastric mucosa– 4. contract lower esophageal sphincter– 5. relaxes pyloric sphincter– 6. relaxes ileocecal sphincter
Hormonal control in the Digestive system: Gastric hormones
Somatostatin:生長抑制素Secretion: By enteroendocrine (D) cells in gastric pits of the mucosa in the pylorus.
Stimulus: continuously released, overridden by Gastrin and nerves
Action:– Inhibition of Gastrin production
Hormonal control in the Digestive system: Small Intestinal hormones
SECRETIN:
Secretion: By Enteroendocrine (S) cells in the Crypts of Lieberkuhn of small intestine.
Stimulus: Acid chyme in small intestine causes secretion of Secretin:
Actions:– stimulate secretion of pancreatic juice and bile that is rich in
bicarbonate ions.
– inhibit production of HCl in stomach
– promote growth and maintenance of the pancreas
– enhance effects of Cholecystokinin (CCK)
– Increases rate of bile secretion by hepatocytes
所有 intestine 的 mucosa ，在 vili 之間仍然有向下凹的構造，稱為 crypt of Lieberkuhn 。
Hormonal control in the Digestive system: small intestinal hormones
CHOLECYSTOKININ (CCK):
Secretion: Enteroendocrine (CCK) cells in the small intestine mucosa Crypts of Lieberkuhn
Stimulus: Chyme rich in amino acids, triglycerides and fatty acids enter the small intestine.
Actions:– increases secretion of pancreatic juice rich in digestive
enzymes– opens the Sphincter of Oddi– contracts the gallbladder– Inhibits gastric secretion and motility– May reduce hunger
Hormonal control in the Digestive system: small intestinal hormones
Gastric Inhibitory Peptide (GIP):Secretion: Enteroendocrine cells in the small
intestine mucosa Crypts of Lieberkuhn
Stimulus: Chyme rich in triglycerides, fatty acids, and glucose enter the small intestine.
Actions:– Stimulates release of insulin by beta cells– Inhibits gastric secretion and motility– Stimulates lipogenesis by adipose tissue– Stimulates glucose use by skeletal muscle cells
Hormonal control in the Digestive system: small intestinal hormones
Vasoactive Intestinal Peptide (VIP):Secretion: Enteroendocrine cells in the small intestine mucosa Crypts of Lieberkuhn
Stimulus: Chyme entering the small intestine.
Actions:– Stimulates buffer secretion: H2O, electrolytes – Inhibits gastric secretion – Dilates intestinal capillaries
– stimulating pancreatic bicarbonate secretion,
STOMACHHORMONAL CONTROL
CHEMICAL DIGESTION
1. Gastrin--stimulates gastric secretions
2. Histamine--stimulates HCl formation3. Somatostatin—inhibits gastric secretions4. Secretin--inhibits gastric secretions5. Gastric inhibiory peptide--inhibits gastric secretions6. Vasoactive intestinal peptide-inhibits HCl production
LIVER GALLBLADDERNEUROLOGICAL CONTROLThe gallbladder is regulated by the autonomic nervous system. The parasympathetic division, using the vagus nerve, is excitatory and the sympathetic division inhibits the gallbladder.
HORMONAL CONTROL
The liver is stimulated by secretin to produce bile more rapidly. Cholecysto-kinin stimulates the gallbladder to contract and hepatopancreatic sphincter to relax, so that bile can enter the duodenum.
PANCREAS
HORMONAL CONTROL
The pancreas is regulated hormonally by secretin and cholecystokinin (CCK). CCK induces the acinar cells to secrete the enzymes found in pancreatic juice. Secretin causes bicarbonate ions to form.
segmentation
MECHANICAL DIGESTION
In segmentation, nonadjacentsegments of the intestinealternately contract andrelax, moving the chyme forward and then backwardresulting through mixing. Thisresults in the chyme being well mixed with the enzymes from the liver and the pancreas.
peristalsis
PROPULSION 推動
Propulsion is the result of peristalsis. This causesadjacent segments to alternately contract and relax.
- Adipocytes (fat cells) secrete
hormones (leptin) that regulate
appetite and body weight.
Role of Hormones in Appetite Regulation
- Hormones from GI:
cholecystokinin: suppressantghrelin: stimulantPYY: suppressant
(Science 299:846-849 2003)
Fig. 41-23
LeptinPYY
Insulin
Ghrelin
The appetite –regulating hormoneby affecting a “satiety center’ in the brain
Lose weight, ghrelin increases
Body fat decreases, leptin levels fall
An appetite suppressant that counters the ghrelin
Suppresses appetite
PYY and GhrelinPeptide YY is a short (36-amino acid) protein released by cells in the ileum and colon in response to feeding. In humans it appears to reduce appetite.
also known as PYY, Peptide Tyrosine Tyrosine, or Pancreatic Peptide YY3-36.[1]
PYY exerts its action through NPY receptors, inhibits and increases water and electrolyte absorption in the colon.[6] PYY may also suppress pancreatic secretion. It is secreted by the neuroendocrine cells in the ileum and colon
in response to a meal, and has been shown to reduce appetite. PYY works by slowing the gastric emptying; hence, it increases efficiency of digestion and nutrient absorption after meal.
Ghrelin is a hormone produced mainly by the fundus of the human stomach and pancreas that stimulates hunger.[1]
Ghrelin levels increase before meals and decrease after meals.
It is considered the counterpart of the hormone leptin, produced by adipose tissue, which induces satiation when present at higher levels.
In some bariatric procedures, the level of ghrelin is reduced in patients, thus causing satiation before it would normally occur.
Overnourishment and Obesity
Obesity
contributes to diabetes (type 2), cancer of the colon and breasts, heart attacks, and strokes
Fig. 41-24a
Obese mouse with mutantob gene (left) next to wild-type mouse.
EXPERIMENT
OB /DB X Wild type
Coleman Revealed a Satiety Factor in Mammals
Ob+ gene:
produce leptin (the satiety factor)
Db+ gene:
produce leptin receptor
Parabiosis連體共生
X
Feature Investigation
Fig. 41-24b
Ob+ gene:
leptin (the satiety factor)
Db+ gene:
leptin receptorMost obese humans like db mice –
produce leptin but fail to respond to it
Wild type
ob+, db+
X
ob+, db
Leptin's effects. Because of a gene defect, the boy doesn't make leptin, but treatment with the hormone, begun when he was 3.5 years old (top), brought his weight down to normal levels, as shown at age 8.
(Science 299:846-849 2003)
What if ?
There are two groups of obese people. In one group, the leptin levels are abnormally high; in the other group, they are abnormallyLow.
Q: How would each group’s leptin levels changes if both groups were placed on a low-calorie diet for an extended period? Explain.
gastroileal reflexgastrocolic reflex
