Bio 2312 Lab Quiz 3

• The main organs of the digestive system are the oral cavity, pharynx, esophagus, stomach, small intestine, large intestine
• The accessory organs of the digestive system are the teeth, tongue, salivary glands, liver, gallbladder, and pancreas
• The functions of the digestive system are ingestion, mechanical processing, digestion, secretion, absorption, excretion, and storage
• Ingestion occurs when materials digestive tract via mouth
• Mechanical processing is crushing and shearing (segmentation)
• Digestion is the chemical breakdown of food into smaller molecules using enzymes
• Secretion is the release of water, acids, enzymes, salts, and buffers
• Absorption is the process of moving materials across digestive epithelium into interstitial fluid of digestive tract; nutrients absorbed into blood or lymphatic
• Excretion is the removal of waste products from bodily fluids and removes feces
• Saliva contains 99.4% water, electrolytes, antibodies, and enzymes. There are 3 pairs of salivary glands which are parotid, sublingual, and submandibular
• The function of salivary glands is to secrete saliva which lubricates, moistens, and dissolves. It helps to control bacterial population in the oral cavity
• What is the role of salivary glands in carbohydrate digestion?

  It initiates the digestion of complex carbohydrates. It produces salivary amylase which breaks down polysaccharides into smaller polysaccharides
• The cardia part of the stomach connects to the esophagus
• Cells of stomach?

  In the fundus and body of the stomach, there are gastric glands with two types of secretary cells
• The cells of the stomach are parietal cells, chief cells, G cells, D cells, and mucus producing cells
• Parietal cells secrete HCl and intrinsic factors. HCl activates pepsinogen to pepsin
• Chief cells secrete pepsinogen. Pepsin breaks down protein
• G cells produce gastrin (hormone) which stimulates the release of chief and parietal cells
• D cells release somatostatin (hormone) which inhibits release of gastrin
• Lacteal absorb fatty acids
• The small intestine was divided into duodenum, jejunum, and ileum
• The duodenum of the small intestine curves around the head of pancreas, receives chyme from stomach, bile from gallbladder, and digestive secretion from pancreas
• In jejunum, digestion and absorption takes place
• Villi is the fingerlike projections of mucosa
• Microvilli are microscopic projections of columnar epithelial lining cells of mucosa
• Functions of the small intestine play key role in digestion and absorption of nutrients.
• Small intestines have circular folds (plicae circulares) which are transverse folds that help increase surface area
• Mucosa of small intestine has intestinal glands (crypts of lieberkuhn) which is entrance for brush border enzymes
• Brush border enzymes are enteropeptidase and enteroendocrine cells. Enteropeptidase activates pancreatic proenzyme trypsinogen. Enteroendocrine cells produce intestinal hormones such as gastrin, cholecystokinin (CCK), and secretin.
• Functions of the duodenum are to receive chyme from the stomach, receives enzymes and bile, important in chemical digestion to neutralize acids before they can damage the absorptive surfaces of the small intestine
• Functions of the jejunum: most chemical digestion and nutrient absorption
• Function of ileum: absorb vitamin B12, bile salts, etc products of digestion not absorbed by the jejunum
• Which hormone works on the gallbladder pancreas?

  CCK, helps secrete bile from gallbladder and juice from pancreas
• Pancreas exocrine part secretes in bile duct
• Pancreas endocrine excretes inside blood, no bile duct
• Endocrine function is to secrete insulin and glucagon
• Exocrine function is to produce the majority of pancreatic secretions and pancreatic juice is secreted into small intestine.
• Pancreatic juice secretes carbohydrases(to digest carbohydrates), lipases (to digest lipids or fat), nucleases, and proteolytic enzymes (for protein)
• The large intestine is divided into cecum, colon, rectum, and anal canal
• The cecum with appendix collects and stores material from ileum