Topic 15: Digestive System Flashcards
what is included in the digestive system?
-gastrointestinal tract
-accessory organs
what is the gastrointestinal tract?
-tube from the mouth to the anus
what are the accessory organs of the digestive system?
-teeth, tongue, salivary glands
-pancreas
-liver
-gallbladder
what are the 4 processes of the digestion system?
-ingestion
-digestion
-absorption
-defecation
what is ingestion?
-bringing food into the oral cavity
what is digestion? what are the 2 types of digestion?
-when large molecules are broken down into smaller molecules
-mechanical and chemical digestion
what is mechanical digestion?
-physical breakdown + motility
-ex: chewing
what is chemical digestion?
-enzymes
-acid secretions
what is absorption?
-the end products of digestion entering the blood or the lymph
-what is defecation?
-elimination of undigested material
-pooping!
what are the 4 basic layers of the GI tract?
-mucosa
-submucosa
-muscularis externa
-serosa/adventitia
what are the 3 layers of the mucosa in the GI tract?
-epithelium with goblet cells
-lamina propria
-muscularis mucosa
what types of tissue are in the mucosa layer of the GI tract?
-stratified squamous = esophagus and anal canal
-high abrasion in these areas + lower water content in the anal canal
-simple columnar (secretions) = stomach, intestines, rectum
-lower abrasion + higher water content in some areas
what is the purpose of the lamina propria in the digestive system?
-contains blood, lymph vessels, nodules, and tissues for immune purposes
-ingesting things from the external environment
what are the characteristics of the muscularis layer of the mucosa?
-smooth muscle
-allows for movement of mucosa
what are the characteristics of the submucosa?
-areolar CT
-contains blood + lymphatic vessels, and a network of nerve cells
what are the characteristics of the muscularis externa layer of the GI tract?
-smooth muscle (2 layers) separated by a second network of nerve cells
-contractions controlled by the nerve network cause motility (mixing and movement)
what are the 2 layers of smooth muscle in the muscularis externa?
-inner circular layer (contraction constricts lumen)
-outer longitudinal layer (contraction shortens gut length)
what is adventitia? what differs from serosa?
-CT layer that does not allow for movement
-serosa allows for movement
what are the structures of the digestive system?
-oral cavity
-salivary glands
-dentition (teeth)
-oropharynx + laryngopharynx
-esophagus
-stomach
-small intestine
-large intestine
what is included in the oral cavity?
-lips, cheeks, palate, tongue
what creates your hard palate?
-2 maxillae
-2 palatine bones
what creates your soft palate? what is associated with the soft palate?
-skeletal muscle
-posterior projection called the uvula
what is the purpose of the uvula?
-rises to close the nasopharynx when swallowing
what are the structural characteristics of the tongue?
-attached to the hyoid bone
-made of skeletal muscle
-projections of mucosa called papillae (taste buds)
how many pairs of salivary glands are there? what are they called?
-3 pairs
-parotid
-submandibular
-sublingual
where are the parotid salivary glands located?
-inferior + anterior to ears
where are the submandibular salivary glands located?
-floor of the mouth (below the mandible)
where are the sublingual salivary glands located?
-below the tongue on the floor of the mouth
what is saliva made of?
-99.5% water
-0.5% solutes (enzymes)
where do your teeth come off of?
-maxillae + mandible
what are primary + secondary dentition?
-primary = child (deciduous)
-secondary = adult (permanent)
how many central incisor teeth do children + adults have in each quadrant? total?
-both have 1 in each quadrant
-4 in total
how many lateral incisor teeth do children + adults have in each quadrant? total?
-both have 1 in each quadrant
-4 in total
how many canine teeth do children + adults have in each quadrant? total?
-both have 1 in each quadrant
-4 in total
how many premolar teeth do children + adults have in each quadrant? total?
-children = 0
-adult = 2 in each quadrant, 8 total
how many molar teeth do children + adults have in each quadrant? total?
-children = 2 in each quadrant, 8 in total
-adult = 3 in each quadrant, 12 in total
what are the total amounts of teeth in children + adults?
-children = 20
-adult = 32
what are the structural components of a tooth?
-crown
-root
-neck
-periodontal ligaments
-root canal + pulp cavity
what is the crown of a tooth?
-above the gums (visible)
-made of dentin with an enamel overlay
-dentin is the majority of a tooth
what is enamel?
-acellular (lacks cells)
-very thin but strong
-highly calcified (HARD)
what differs between enamel, dentin, and cementum with bone?
-very similar
-avascular
what is the root of a tooth?
-dentin + cementum overlay
what is the neck of the tooth?
-enamel + cementum boundary (gums)
what is the purpose of the periodontal ligaments?
-attaches the root to underlying bones
what is contained within the root canal and pulp cavity?
-CT
-blood + lymph vessels
-nerves
what is the lining of the oropharynx and laryngopharynx?
-only muscularis externa (skeletal muscle) + stratified squamous epithelium
what are the characteristics of the esophagus?
-posterior to the trachea
-passes through the diaphragm entering the abdominal cavity
what are the exceptions in the histology of the esophagus?
-muscularis externa composition
-upper 1/3 = skeletal muscle
-middle 1/3 = skeletal muscle + smooth muscle
-lower 1/3 = smooth muscle
-has adventitia within the thoracic cavity and serosa within the abdominal cavity
what are the 4 regions of the stomach?
-cardiac region (cardia)
-fundus
-body
-pyloric region (pylorus)
what region of the stomach is attached to the inferior esophagus?
-cardiac region
where is the fundus region of the stomach located?
-superior to the esophageal entrance
what is in the pyloric region of the stomach? what is its purpose?
-pyloric sphincter
-regulates release of stomach contents into the small intestine
what is the body of the stomach?
-middle portion
what is the purpose of the stomach?
-stores, partially digests, and regulates emptying of chyme into the small intestine
-chyme = food + gastric juice
what is special about the stomach’s mucosal surface?
-formed exclusively by mucous cells
-has many gastric pits connected to underlying gastric glands
-has rugae
-3 muscularis externa layers (for churning)
what are gastric pits? what are gastric glands?
-invaginations of the epithelium
-exocrine glands that secrete gastric juice into gastric pits to enter the lumen of the stomach
what do chief cells secrete?
-enzymes for protein and fat digestion
what do parietal cells secrete? what does this do?
-HCL
-lowers the stomachs pH
what do G cells (enteroendocrine) secrete?
-secrete a hormone into the blood that regulates activity of parietal cells and other digestive processes
what are rugae?
-folds of the mucosa and submucosa
-visible when the stomach is empty
how is rugae created in the stomach? what does it allow for?
-created due to contractions of muscularis mucosa
-allows for stomach expansion without tearing
what is special about the muscularis externa of the stomach? what is its overall function?
-3 layers instead of 2
-inner oblique
-middle circular
-outer longitudinal
-function = churning of cyme
where does the small intestine extend to?
-pyloric sphincter to the ileocaecal valve
what are the 3 segments of the small intestine?
-duodenum
-jejunum
-ileum
what are the characteristics of the duodenum?
-first fold of the intestine
-short
-retroperitoneal
-extra glands that secrete alkaline mucous
-ducts of accessory organs enter here
what is the purpose of the alkaline secretion in the duodenum?
-protects against the stomach acid
what section of the small intestine is the jejunum?
-middle section
where does the ileum attach?
-the caecum (part of the large intestine)
what is the special characteristic of the ileum
-has a group of lymph nodules called peyer’s patches
what is the purpose of the peyer’s patches in the ileum?
-prevents infection of the small intestine
-prevents bacteria from entering the blood
what are the specialized characteristics of the small intestine? what is the overall purpose?
-plicae circulares
-villi
-microvilli
-the purpose is to increase absorption surface area
what are plicae circulares?
-large folds of the submucosa
what are villi? what do they contain?
-projections of the the mucosa into the lumen of the intestine
-contains blood capillaries + lacteals
what are lacteals?
-lymph capillaries that can absorb larger fats
what are microvilli?
-projections of the enterocytes cell membranes
-extend into the lumen of the small intestine
what do the microvilli form on the surface of the mucosa?
-fuzzy “brush border”
what are the accessory organs of the small intestine? what is their purpose?
-pancreas
-liver
-gall bladder
-release exocrine and/or endocrine secretions involved in digestive processes
what retroperitoneal mean?
-posterior to the parietal peritoneum
-peritoneum only lines one side of the organ
-anterior surface is covered by the parietal peritoneum
-posterior surface is covered by adventitia (connects organ to the body wall)
what are the parts of the pancreas? what else does it contain?
-head, neck, body, tail
-contains exocrine glands (secrete pancreatic juice)
-contains endocrine glands (secrete hormones)
what cells are present in the exocrine glands of the pancreas?
-acinar cells (most)
-duct cells
what do the acinar cells in the pancreas secrete?
-digestive enzymes into the ducts
what do the duct cells of the pancreas secrete?
-alkaline fluid to neutralize stomach acid
what creates pancreatic juice?
-digestive enzymes + alkaline fluid
what cells are present in the endocrine glands of the pancreas?
-islets of langerhans (between clusters of acinar cells)
what do the islets of langerhans secrete?
-insulin (beta cells)
-glucagon (alpha cells)
what is the purpose of glucagon and insulin?
-regulate blood sugar levels
how many lobes does the liver have?
-4
-right, left, quadrate, and caudate
-only the right and left can be seen anteriorly
what are the cells in the liver?
-hepatocytes
what is the purpose of the liver?
-metabolic and digestive roles
-processes, modifies, and detoxifies absorbed material from the GI tract before its transported
-produces bile
what is bile used for?
-fat digestion
what is the gall bladder? what are its features and purpose?
-muscular sac on the inferior surface of the liver
-has rugae + no submucosa
-stores + concentrates bile
-contractions release bile into the duodenum
what part of the small intestine do the accessory organs enter?
-the duodenum via a series of ducts
where does the large intestine extend to?
-ileocaecal valve to the anus
what differs the large intestine from the small intestine?
-no villi or folds in the mucosa
-little absorption
what are the functions of the large intestine?
-absorption of water, electrolytes, and vitamins
-formation and temporary storage of feces
what does the large intestine consist of?
-caecum
-appendix
-colon
-rectum
-anal canal
what are the parts of the colon?
-ascending (right side of abdominal cavity)
-hepatic flexure
-transverse
-splenic flexure
-descending (left side of the abdominal cavity)
-sigmoid
what is a flexure?
-a bend or curve (spaces for organs)
what is special about the colon histology?
-muscularis externa longitudinal layer is incomplete (in bands) called taeniae coli
-contractions form pouches (haustra)
does the rectum contain taeniae coli?
-no
what is the caecum connected to?
-the ileum by the ileocaecal valve
what are the two anal sphincters? what type of muscle creates them? voluntary or involuntary?
-internal (smooth muscle) (involuntary)
-external (skeletal muscle) (voluntary)
what controls the opening and closing of the inferior anal canal during defacation?
-2 anal sphincters
where is the anal canal located? what is the inferior opening?
-last segment of the large intestine
-external to the abdominopelvic cavity
-the anus
what is a portal system?
-blood vessels between 2 capillary beds
-blood does not return to the heart between them
what is the peritoneum?
-serous membrane lining the abdominopelvic cavity and most of the abdominal organs
what are the parts of the serous membrane (peritoneum)?
-visceral peritoneum (against organ wall)
-parietal peritoneum (against cavity wall)
-peritoneal cavity (filled with serous fluid)
what is omenta?
-folds of serosa between organs made of a sheet of 2 fused layers of visceral peritoneum
-contain blood + lymph vessels and nerves
what are examples of omenta?
-greater omentum
-lesser omentum
what is the greater omentum?
-“fatty apron”
-connects the stomach to transverse colon
-forms a large fold that hangs down over the transverse colon and small intestine
what does the mesentery act as?
-entry and exit point for blood vessels, nerves, and lymph vessels
-supply the digestive organs
where is the lesser omentum?
-connects the liver to the stomach
what is the mesentery?
-folds of serosa between the posterior abdominal wall and the intestines made of a sheet of 2 fused layers of parietal peritoneum
what is the mucosa of the oral cavity?
-stratified squamous epithelium and lamina propria
what causes mumps?
-inflammation of 1 or both parotid salivary glands
what cells are contained within the gastric glands?
-goblet cells
-chief cells
-parietal cells
-G cells
what are examples of retroperitoneal organs in the digestive system?
-duodenum
-pancreas
what is GERD?
-gastroesophageal reflux disease
-stomach contents flow into the esophagus
what is appendicitis?
-inflammation of the appendix
-pain in the lower right quadrant
what is cholecystitis?
-inflammation of the gallbladder
-due to blockage of the cystic duct with gall stone
-pain in the upper right quadrant
what is the pathway of the hepatic portal system from the aorta to the inferior mesenteric artery?
-aorta
-inferior mesenteric artery
-capillaries in the large intestine
-inferior mesenteric veins
-splenic vein
-hepatic portal vein
-capillaries in the liver
-hepatic vein
-inferior vena cava
what is the pathway of the hepatic portal system from the aorta to the superior mesenteric artery?
-aorta
-superior mesenteric artery
-capillaries in the large and small intestines
-superior mesenteric veins
-hepatic portal vein
-capillaries in the liver
-hepatic vein
-inferior vena cava
what does the right upper quadrant include?
-liver
-gallbladder
-duodenum
-head of pancreas
-right kidney + right adrenal gland
-hepatic flexure of colon
what does the right lower quadrant include?
-caecum
-appendix
-ascending colon
-right ovary + uterine tube
-right ureter
what does the left upper quadrant include?
-stomach
-spleen
-splenic flexure of colon
-left lobe of liver
-body of pancreas
-left kidney + left adrenal gland
-parts of the transverse and descending colon
what does the left lower quadrant include?
-descending colon
-sigmoid colon
-left ovary + uterine tube
-left ureter
what is the duct system of the pancreas?
-pancreas
-pancreatic duct
-accessory pancreatic duct > duodenum
-hepatopancreatic ampulla > duodenum
what is the duct system of the liver?
-liver
-hepatic duct
-common bile duct
-hepatopancreatic ampulla
-duodenum
what is the duct system of the gallbladder?
-gallbladder
-cystic duct
-common bile duct
-hepatopancreatic ampulla
-duodenum
