animal nutrition chapter 41. function 1. digestion 2. absorption of nutrients/water –energy...
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Mechanicaldigestion
Chemicaldigestion(enzymatichydrolysis)
Nutrientmoleculesenterbody cells
Undigestedmaterial
INGESTION
DIGESTION
ABSORPTION
ELIMINATION
1
2
3
4
Fig. 41-9
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
Crop
Anus
StomachGizzard
Intestine
General structure
Gastrointestinal tract (tube)Mucosa: inner layer (epithelial)Submucosa: connectiveMuscularis: 2 layers of muscleSerosa: outer layer (connective)Plexues: nerves located in the submucosa
Digestive organs
MouthPharynxEsophagusStomachSmall intestine (duodenum, jejunum, ileum)Large intestine (cecum, ascending colon, transverse colon, descending colon, sigmoid, rectum, anus)
Digestion
MouthTeethGizzard (in birds to help grind food)Salivary glandsSecrete saliva Amylase (enzyme to breakdown starch)
Esophagus
EsophagusMuscular tubeConnects pharynx to stomachPeristalsis:Rhythmic movement of muscle contractions Moves food alongEsophageal sphincter:End of esophagus keeps food in stomach
Stomach
Mucosa lining (epithelial)Parietal cellsSecrete H + Cl ionsChief cellsSecrete pepsinogenPepsinogen is converted to pepsinDigests proteins
Small intestine
ChymeLeaves stomach via pyloric sphincterDuodenum Digestive enzymes from pancreasBile from liver & gallbladderMost digestion occurs in the duodenum & jejunum
Small intestines
Villi along intestine epitheliumMicrovilli“brush border”Aids in absorptionSecretes enzymesBreak disaccharides (sucrose, lactose)
Accessory organs
PancreasSecretes fluids via pancreatic ductExocrine systemTrypsin & chymotrypsin (proteases)Amylase (starch)Lipase (fats)Bicarbonate (neutralizes HCl)Endocrine (insulin and glucagon)
Accessory organs
LiverSecretes bileContains bile pigments & bile saltsBile pigments are waste from break down of RBCEliminated
Accessory organs
Bile salts Emulsify the fatsBile made in liverStored in gall bladderReleased when eat fatty mealGallstones can block release
Small intestines
Monosaccharides, aa are transported to the blood capillariesHepatic portal veinLiverHeart Transported to body
Small intestines
Fatty acids & monoglycerides Villi TriglyceridesChylomicrons: (triglyceride & protein coat) Lymph system
Fig. 41-15bMicrovilli (brushborder) at apical(lumenal) surface
Key
Nutrientabsorption
Bloodcapillaries
Epithelialcells
Villi
Lymphvessel
Basal surface
Lacteal
Epithelial cells
Lumen
Fig. 41-16Lumenof smallintestine
Lacteal
Chylomicron
Phospholipids,cholesterol,and proteins
Triglycerides
Monoglycerides
Triglycerides
Fatty acids
Epithelialcell
Essential nutrients
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)
Large intestines
Absorbs waterAbsorbs vitamin KConcentrates wastesE. coli FecesCloacaCombines feces & urine wastes in some animals
Veins to heart
Lymphatic system
Hepatic portal vein
Liver
Mouth
Esophagus
StomachLipids
Absorbed food(except lipids)
Absorbedwater
Secretionsfromsalivaryglands
Secretionsfromgastricglands
Small intestine
Secretions from liver
Secretions from pancreasLargeintestine
Anus
Rectum
Essential nutrients
Essential aa Minerals VitaminsA, B-complex, C, D, E, KScurvy, rickets, pernicious anemia, bleeding
Abnormalities
UlcersH. pyloriBacteria Treated with antibioticsReflux:Gastric juices go backwards to esophagus