Pigs are non-ruminants

Definition of a non-ruminant Single stomach Eat feed low in fiber Humans are also non-ruminants

Parts of the digestive tract 1. Mouth 2. Esophagus 3. Stomach 4. Small Intestine 5. Large Intestine

What does the digestive system do? Breaks down feedstuffs into ….. simple chemical parts….. so the pig can absorb….. and utilize them .

What does the mouth do in digestion? Breaks down feed stuffs by chewing Adds saliva to help in digestion

What does the esophagus do? Muscles contract to move the food down to the stomach

What does the stomach do? Adds digestive juices to break down food

What does the small intestine do?

The small intestine…. Mixes secretions Absorbs nutrients

What does the large intestine do? Storage and formation of feces Absorption of water Secretion and reabsorption of electrolytes

Digestive System of a Pig

Non-ruminant Abomasum- true stomach depends on digestive enzymes pepsin, rennin, trypsin, chymotrypsin, HCL Needs energy (fat and CHO), protein (a.a.), minerals (Ca:P 1.2:1 to 1.5:1), vitamins, water, antibiotics and other additives

Swine Gastrointestinal Physiology 11/04

Digestive secretions: saliva Functions of saliva in non-ruminants: Lubricates food to facilitate swallowing Contains antibodies and lysozyme Some amylase in saliva of swine and rats, but much less than in humans Functions of saliva in ruminants: Maintains fluid consistency of rumen Slightly alkaline; helps neutralize acids formed by fermentation May help prevent frothing in rumen

Gastric pits in gastric mucosa Gastric pits are openings to ducts into which gastric glands empty their secretions

Exocrine gland Any gland that directs its secretions through a duct into a compartment that is contiguous with the exterior of the body

Glandular regions of simple stomach Cardiac Fundic Pyloric

Glandular regions of equine, porcine and ruminant stomachs Cardiac, fundic and pyloric gland regions are glandular Esophageal regions (“E”) are non-glandular epithelium

Cardiac gland region (cardiac mucosa) Fundic Pyloric

Fundic gland region Mucous neck cells Parietal cells Chief cells Cardiac Mucous neck cells Parietal cells Chief cells Fundic Pyloric

Fundic gland region Mucous neck cells secrete mucus Parietal cells secrete: HCl Intrinsic factor (not in cats); necessary for absorption of Vitamin B12

Fundic gland region Chief cells secrete pepsinogen HCl converts pepsinogen into pepsin Pepsin is a proteolytic enzyme (breaks down proteins into peptides)

Pyloric gland region Mucous secreting cells G cells Pyloric Cardiac Fundic Pyloric

Pyloric gland region G cells are endocrine gland cells – secrete the endocrine hormone, gastrin Endocrine cells secrete hormones into the bloodstream – travel to a distant part of the body where they produce an effect on another cell type

Substances that stimulate HCl secretion by parietal cell Gastrin may interact with either receptor Gastrin Acetylcholine Histamine Histamine secreted by ECL cells in gastric mucosa

Rennin Enzyme secreted by abomasal mucosa of young ruminant Acts to coagulate milk protein, which facilitates its digestion

Hormone secretions of small intestine: cholecystokinin Site of secretion Stimuli for secretion Actions Primarily duodenal mucosa Chyme with a: High amino acid concentration High fatty acid concentration Low pH Inhibits gastric emptying ↑ secretion of pancreatic enzymes and HCO3- Stimulates gall bladder contractions

Hormone secretions of the small intestine: secretin Site of secretion Stimuli for secretion Actions Duodenal mucosa Chyme with a: Low pH High fatty acid concentration ↓ HCl production in stomach ↑ pancreatic HCO3- secretion ↑ biliary HCO3- secretion

Exocrine pancreatic secretions Liquid rich in HCO3- Pancreatic digestive enzymes Both are secreted into duodenum

Pancreatic digestive enzymes Pancreatic proteolytic enzymes (pancreatic proteases) are secreted as proenzymes (zymogens)

Activation of pancreatic proteases in small intestine CCK stimulates duodenal mucosal cells to produce enteropeptidase Proelastase Elastase

Absorption of amino acids from small intestine