Chapter 24 - Digestive System Flashcards
Organs of the digestive system
esophagus, stomach, small intestine, large intestine, anal canal
Accessory digestive organs
teeth, tongue, salivary glands, pharynx, liver, gallbladder, pancreas
Ingestion
taking foods and liquids into the mouth
Secretion
release water, acid, buffers, and enzymes into the lumen of the GI tract
Motility
Alternating contractions and relaxations of smooth muscle in the walls of the digestive canal mix food and secretions and move them toward the anus
Digestion
process of breaking down ingested food into small molecules that can be used by body cells
Absorption
Movement of the products of digestion from the lumen of the digestive canal into blood plasma or lymph plasma
Defecation
Removal of wastes, indigestible substances, bacteria and materials not absorbed
Four basic tissue layers
Mucosa, submucosa, muscular layer
3 layers of the mucosa
Epithelium, Lamina propria, muscularis mucosae
Myenteric neural plexus
supplies the longitudinal and circular smooth muscle layers of the muscular layer, controls digestive canal motility
Submucosal neural plexus
supply the secretory cells of the mucosal epithelium, controlling secretions of the organs of the digestive canal
5 areas of the peritoneum
Greater omentum, falciform ligament, lesser omentum, mesentery, mesocolon
Minor Salivary glands
glands that open directly, or indirectly via short ducts, to the oral cavity
Three major salivary glands
Parotid glands, submandibular glands, sublingual glands
Three major regions of a tooth
Two enzymes that contribute to chemical digestion in the mouth
Salivary amylase, lingual lipase
Function of salivary amylase
Begin starch digestion by breaking down starch into smaller molecules such as the disaccharide maltose, the trisaccharide maltotriose, and short-chain glucose polymers called a-dextrins
Three parts of the pharynx
Nasopharynx, oropharynx, laryngopharynx
Function of upper esophageal sphincter
regulates the movement of food from the pharynx into the esophagus
Functions of the lower esophageal sphincter
regulates the movement of food from the esophagus into the stomach
Three stages of swallowing
1) voluntary stage, 2) Pharyngeal stage, 3) Esophageal stage
Functions of the stomach
1) Mixes saliva, food, and gastric juice to form chyme
2) Reservoir for food before release into the SI
3) Secretes gastric juice
4) Secretes gastrin into the blood
Four regions of the stomach
Cardia, fundus, body, pyloric part
Enzymes in the stomach
Pepsin, gastric lipase
Function of pepsin
severs certain peptide bonds between amino acids, breaking down a protein chain of many amino acids into smaller peptide fragments
Function of gastric lipase
Splits triglycerides in fat molecules into fatty acids and monoglycerides
Components of the liver
Hepatocytes, Bile Canaliculi, Hepatic Sinusoids
What are hepatocytes
Major functional cells of the liver and perform a wide array of metabolic, secretory, and endocrine functions
What are bile canaliculi
Small ducts between hepatocytes that collect bile produced by the hepatocytes
What are hepatic sinusoids
Highly permeable blood capillaries rows of hepatocytes that receive oxygenated blood from branches of the hepatic artery and nutrient-rich deoxygenated blood from branches of the hepatic portal vein
What makes up the portal triad
Bile duct, branch of the hepatic artery, branch of the hepatic vein
What makes up the hepatic acinus
Hepatocytes, bile duct system, hepatic sinusoids
What supplies blood to the liver
Hepatic artery (oxygenated blood), hepatic portal vein (deoxyegenated blood)
Role of bile
Excretory product and partially a digestive secretion, play a role in emulsification
Functions of the liver (9)
Carbohydrate metabolism, lipid metabolism, protein metabolism, processing of drugs and hormones, excretion of bilirubin, synthesis of bile salts, storage, phagocytosis, activation of vitamin D
3 regions of the SI
Duodenum, jejunum, ileum
4 cell types in the epithelium of the SI
Absorptive cells (contain enzymes that digest food and absorb), Goblet cells (Secrete mucus), Paneth cells (secrete lysosome), Enteroendocrine cells
Purpose of circular folds
Located in the mucosa and submucosa, enhance absorption by increasing surface area
Two types of movement through the SI
Segmentations and a type of peristalsis called migrating motility complexes
What does segmentation do
Mix chyme with the digestive juices and bring the particles of food into contact with the mucosa for absorption
Functions of the LI
Completion of Absorption, production of certain vitamins, formation of feces, expulsion of feces from the body
Movements through the SI
Haustral churning, peristalsis, mass peristalsis
3 phases of digestion
Cephalic Phase, Gastric Phase, Intestinal Phase
Cephalic phase
smell, sight, thought, or initial taste of food activates neural centers in the cerebral cortex, hypothalamus and brain stem, preparing the stomach for food that is about to be eaten
