GI Flashcards
Foregut structures and blood supply
Week 3 of development
Top portion supplied by celiac artery, gives rise to liver, gallbladder, pancreas, esophagus, stomach, duodenum, spleen
What structures are in Midgut and what is the blood supply?
Supplied by superior mesenteric artery and vitelline duct
3rd & 4th sections of duodenum, jejunum, ileum, cecum, appendix, ascending colon, and proximal 2/3 of transverse colon
Physiologic herniation through umbilical ring
Hindgut
Distal 1/3 transverse colon, descending colon, sigmoid colon, and upper part of anal canal
Microscopic anatomy of gallbladder (inside to outside)
Mucosa contains epithelium (simple columnar cells, highly folded) and lamina propria (dense irregular connective tissue, immune cells, and capillaries)
Tunica muscularis (bundles of smooth muscle randomly oriented
External adventitia connects to the liver and is dense irregular connective tissue
External serosa not attached to liver and made up of loose irregular connective tissue w/ lymphatic vessels, blood vessels, adipocytes, and mesothelium on outside
Microscopic anatomy of esophagus (inside to outside)
Mucosa: Epithelium (stratified squamous non-keratinized cells), Lamina propria (dense irregular connective tissue, and Muscularis mucosa (longitudinal smooth muscle)
Submucosa: dense collagenous connective tissue w/ elastin, blood vessels, lymphatic vessels, nerves, and mucosal glands in lower 1/3
Muscularis Propria: inner circular layer and outer longitudinal layer of muscle, 1/3 upper skeletal, middle 1/3 skeletal & SM, Auerbach plexus
Adventitia: connective tissue attach nearby structure
Serosa: last 1-2 cm simple squamous epithelium
Stomach microscopic anatomy
Cardia:
Mucosa: simple columnar epithelium that form gastric pits w/ cardiac glands secrete mucus and muscularis mucosa consisting of thin layer of SM
Submucosa: dense irregular CT
Muscularis propria: 3 layers of S muscle inner oblique, circular, and longitudinal
Serosa: loose connective tissue
Fundus:
Mucosa: rugae w/ parietal cells (isthmus, secrete gastric acid and Intrinsic factor), mucous neck cells, chief cells (secrete pepsinogen found in base), and G cells that secrete gastrin)
Submucosa: dense irregular CT
Muscularis propria: 3 layers of S muscle inner oblique, circular, and longitudinal
Serosa: loose connective tissue
Pylorus:
Mucosa: gastric pits 1/2, pyloric glands secrete mucus are shorter, small number G, parietal, and stem cells
Submucosa: dense irregular CT
Muscularis propria: 3 layers of S muscle inner oblique, circular, and longitudinal
Serosa: loose connective tissue
Small Intestine microscopic anatomy
All share submucosa (dense irregular CT, meissner’s plexus), muscularis propria (circular, myenteric plexus, and longitudinal), and serosa (loose connective tissue)
Duodenum
Mucosa: long tall villi, enterocytes (simple columnar cells w/ microvilli and goblet cells that secrete mucus), lamina propria (loose connective tissue), crypts of Lieberkuhn (stem cells -> epithelial cells, paneth cells prevent against pathogens), muscularis mucosa
Submucosa: burnner’s glands secrete alkaline mucus
Jejunum
Mucosa: same as duodenum
Ileum
Mucosa: short broader villi, Peyer’s patches within lamina propria, lacteals w/in cores of villi that absorb fat,
Colon Microscopic Anatomy
Mucosa: epithelium (enterocytes simple columnar cells w/ microvilli that absorb water and goblet cells secret mucus), lamina propria (plasma cells, lymphocytes, eosinophils, macrophages), crypts of Lieberkuhn, and muscularis mucosa
Submucosa: dense irregular connective tissue, meissner’s plexus, lymphatic vessels, and blood vessels
Muscularis propria: circular, myenteric plexus, longitudinal, tinea coli
Serosa
Liver Microscopic Anatomy
HEPATOCYTES: Perform metabolic, synthetic, storage, catabolic and excretory functions. Apical surface of hepatocytes face bile canaliculi. Basolateral surface faces sinusoids.
KUPFFER CELLS: Macrophages, form the lining of sinusoids.. Protect against infection and circulating toxins (e.g., endotoxin), but with higher efficiency. Activated Kupffer cells also release cytokines, such as TNF-α, interleukins, interferons and TGFs α and β
STELLATE CELLS: (Ito cells) have specialized storage capacities. Contain fat, vitamin A and other lipid-soluble vitamins. Secrete extracellular matrix components, including collagens, laminin and proteoglycans. In disease states, can make in great excess, leading to hepatic fibrosis and eventually cirrhosis.
Pancreas Microscopic Anatomy
Exocrine: Acini contain secretory cells (pyramid-shaped with rough ER at base and zymogens at apices), centroacinar cell, intercalated duct (simple cuboidal epithelium)
Intralobular duct: stratified cuboidal cells and thicken connective tissue
capsule
Intralobular duct: epithelium that could be simple columnar, stratified columnar, or stratified cuboidal and large CT
Interlobular ducts: epithelium (simple columnar cells, or stratified columnar, or stratified cuboidal) connective tissue
Endocrine: islets of Langerhans (fenestrated capillaries, beta cells, alpha cells, delta cells, and pp cells)
Mastication (mechanism, regulation, and factors)
Mechanism: Food gets broken down via masseter, temporalis, medial pterygoid, and lateral pterygoid. Salivary glands secrete saliva that contains salivary amylase, mineral salts, and mucus. Tongue moves side to side pushing between teeth for extra grinding.
Factors: food in mouth, sight of food
Deglutination (mechanism)
Mechanism: Starts with voluntary movement of the tongue pushing bolus to oropharynx then mechanoreceptors, thermoreceptors, and taste receptors in upper esophagus detect food -> sensory info via trigeminal, glossopharyngeal, and vagus nerve to the medulla -> motor info via vagus->
soft palate and uvula moves up -> epiglottis covers larynx -> upper esophageal sphincter relaxes-> upper esophageal sphincter closes-> vagus -> peristalsis -> lower esophageal sphincter relaxes
Salivary gland (embryology, location, function, innervation, circulation)
Embro: ectoderm
Location:
Parotid- below external acoustic meatus/zygomatic arch, behind masseter, in front of SCM, along angle of mandible, contain facial nerve, retromandibular vein, external carotid artery, superficial temporal artery, facial nerve, parotid duct
Submandibular gland- posterior half of mandible, inferior/deep to body of mandible and superficial/deep to mylohyoid muscle
Function: secrete saliva, keep mouth mucosa hydrated, makes swallowing easier, digestion of starch
Innervation: parasympathetic via glossopharyngeal nerve, sympathetic via superior cervical ganglion
Esophagus (innervation, circulatory pathway,)
Innervation: parasympathetic control peristalsis via vagus nerve, sympathetic vis sympathetic trunk from greater splanchnic nerve T5 to T9
Circulatory pathway: inferior thyroid arteries/vein, thoracic aorta/left gastric vein/esophageal veins, left gastric artery
Pharynx (embryo, circulatory pathway, innervation)
Embryo: pharyngeal pouch
Circulatory: facial artery, maxillary artery, inferior thyroid artery, and superior thyroid artery
Innervation: pharyngeal plexus, pharyngeal branch of vagus nerve, glossopharyngeal
Liver (circulatory pathway and innervation)
Circulatory: hepatic artery and hepatic portal vein
Innervation: hepatic nervous plexus, sympathetic celiac plexus, and parasympathetic from vagal trunk
Pancreas ( circulatory pathway and innervation)
Circulatory: (head and uncinate) superior pancreaticoduodenal artery, inferior pancreaticoduodenal artery, and pancreatic artery (body and tail)
Innervation: parasympathetic vagus, sympathetic greater and lesser splanchnic nerves (T5-T12)
Mastication regulation
Regulation: muscles are innervated by trigeminal nerve, salivary glands are innervated by glossopharyngeal and facial nerve via parasympathetic activation, mechanoreceptors in periodontal ligaments, taste receptors on tongue, salivatory nuclei in brainstem
Mastication factors
Factors: food in mouth, sight of food
Deglutination regulation
Regulation: swallowing center in medulla via vagus and glossopharyngeal
Pancreas function
endocrine: regulate blood sugar levels,
exocrine: pancreatic amylase to breakdown carbs, trypsin & chymotrypsin breakdown proteins, and lipase breakdown lipids, ductal cells secrete NaK and ClHCO3
Liver function
detoxify harmful substances, normal blood glucose level, store Vit A, D, E, K, B12, iron, copper, remove amine group from amino acids, albumin, coagulation factors, regulate lipid metabolism, make VLDL, HDL,), bile synthesis
Pharynx (Micro anatomy)
buccopharyngeal fascia, muscular layer (circular and longitudinal part
Pharynx (location)
cranial base to the inferior border of the cricoid cartilage anteriorly and the inferior border of the C6 vertebra posteriorly