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Anatomy & Physiology: Digestive System Key Concepts

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Terms in this set (22)

  • Layers of the GI tract

    The five general layers are mucosa (secretion, absorption), submucosa (blood vessels, nerves), muscularis externa (movement), serosa (outer covering), and adventitia (connective tissue in retroperitoneal areas).

  • Functions of the mucosa layer

    The mucosa is responsible for secretion of mucus and enzymes, absorption of nutrients, and protection against pathogens.

  • Muscularis externa layers in GI regions

    Esophagus has 2 layers, stomach has 3 layers, small intestine has 2 layers, and large intestine has 2 layers of muscularis externa.

  • Enteric nervous system divisions

    Includes the myenteric plexus (controls GI motility) and the submucosal plexus (controls secretion and blood flow).

  • Mechanical and chemical digestion in the oral cavity

    Mechanical digestion occurs by chewing; chemical digestion involves salivary amylase breaking down starch and lingual lipase starting lipid digestion.

  • Lingual papillae types

    Include filiform (not for taste), fungiform, circumvallate, and foliate papillae; most contain taste buds except filiform.

  • Phases of deglutition (swallowing)

    The oral phase is voluntary; the pharyngeal and esophageal phases are involuntary reflexes.

  • Stomach mucosa environment maintenance

    Maintained by mucus secretion, bicarbonate, tight junctions, and rapid cell replacement to protect against acid and enzymes.

  • Mechanical vs chemical digestion in the stomach

    Mechanical digestion by muscular contractions; chemical digestion by pepsin (protein) and gastric lipase (lipids).

  • Anatomy of the small intestine subdivisions

    Duodenum (receives bile and pancreatic enzymes), jejunum (major site of absorption), ileum (absorbs bile salts and vitamin B12).

  • Biliary tree components and function

    Includes hepatic ducts, cystic duct, common bile duct; transports bile from liver/gallbladder to duodenum for lipid digestion.

  • Portal triad definition

    The portal triad consists of the hepatic artery, portal vein, and bile duct running together in the liver.

  • Functions of the liver

    Includes bile production, metabolism of nutrients, detoxification, storage of vitamins, and synthesis of plasma proteins.

  • Inactive enzyme (zymogen) purpose

    Proteases are secreted as inactive zymogens to prevent autodigestion and are activated only in the digestive tract.

  • Differences between jejunum and ileum

    Jejunum has thicker walls, more folds, and is the primary site of absorption; ileum has Peyer's patches and absorbs bile salts and vitamin B12.

  • Microanatomy of the small intestine

    Features include villi, microvilli, and plica circularis to increase surface area for absorption.

  • Enzymes involved in macronutrient breakdown

    Salivary amylase, pancreatic amylase (carbohydrates); pepsin, trypsin, chymotrypsin (proteins); lingual, gastric, pancreatic lipases (lipids).

  • Absorption routes for macronutrients

    Carbohydrates and proteins enter blood capillaries; lipids enter lacteals (lymphatic vessels) before reaching bloodstream.

  • Large intestine anatomy and function

    Includes cecum, colon, rectum; absorbs water and electrolytes, forms and stores feces, houses gut microbiota.

  • Endocrine vs exocrine pancreas

    Endocrine pancreas secretes hormones like insulin; exocrine pancreas produces digestive enzymes and bicarbonate.

  • Insulin and blood glucose homeostasis

    Insulin lowers blood glucose by promoting uptake and storage; disruption leads to diabetes mellitus.

  • Type I vs Type II diabetes mellitus

    Type I is autoimmune destruction of insulin-producing cells; Type II is insulin resistance and relative insulin deficiency.