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123 Cards in this Set
- Front
- Back
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What are the 2 groups of organs in the dgestive system"
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organs of the GI tract, and acessory organs
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What are the organs of the GI tract?
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mouth, pharynx, larynx, stomach, small intestine, large intestine
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what are the accessory organs of the digestive system?
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teeth, tongue, salivary glands, liver, gallbladder, pancreas
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What are the 6 basic processes performed by the digestive system?
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Ingestion
secretion mixing, and propultion digestion absorption defecation |
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Descibe ingestion
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eating and drinking
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mixing and propultion
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alternating contractions and relaxation of smooth muscle in the walls of mix food, and se=cretions, and propel them towads the anus.
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What is motility?
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the capability of the GI tract to mix and move material along its length.
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Secretion
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cells in the walls of the GI tract and acessory organs secrete 7L/day of water, acid, buffers, and enymes into the lumen of the GI tract
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What are the 2 types of digestion?
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mechanical, and chemical
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describe mechanical digestion?
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teeth grind food, and smooth muscles of the stomach and small intestine churn it
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describe chemical digestion?
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Large molecules(carbohydrages, lipid, protien, and nucleic acid) in food are split into smaller molecules by hydrolosis. Digestive enzymes catalyze(promote) these catabolic reactioins
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where are digestive enzymes produced?
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salivary glands, tongue,pancreas, and small intestine.
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Absorption
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Fluids, ions, and products of digestion are secreted into epithelial cells lining the lumen of the GI tract. Absorbed substances pass into blood or lymph and circulate into cells throughout the body.
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defecation
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wastes, indigestible substances, bacteria, cells, and digested materials that were not absorbed are eliminated from the body as feces.
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What are the 4 layers of the GI tract?
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1. mucosa
2. submucosa 3. muscularis 4. serosa |
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explain the mucosa
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lines the lumen of the GI tract and is composed of:
1. surface layer of epithelium 2. connective tissue layer(contains blood and lymph vessels) 3. smooth muscle(muscularis mucosae)-creates lots of folds which increase surface area for absorption. |
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Submucosa
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-consits of areolar connective tissue, blood and lymphatic vessels, neurons(submucosal plexes),and glands and lymphatic tissue
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musclularis
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skeletal muscle-mouth, pharyx, superior and middle parts of the esophagus
smooth muscle(rest of tract)-there are 2 sheets: 1. inner circular 2. outer longitudinal |
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what is between the 2 layers of muscularis
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a plexus of neurons called myenteric plexus
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what does musclular tonus mean?
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our muscles shorten extensively while we're alive?
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Serosa?
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-protective outermost layer of the GI tract
-called the visceral peritoneum -the esophagus lacks serosa. |
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what are the 5 major paritoneal folds?
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-greater omentum
-lesser omentum -falciform ligament -mesetery -mesocolon |
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messentery
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binds the small intestine to the posterior abdominal wall. Extends from the posterior abdominal wall to wrap around the small intestine forming a double layer structure which cotains blood, lympatic vessels, lymph nodes
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mesocolon
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a fold of the paritoneum which binds the lg. intestine to the posterior abdominal wall
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falciform ligament
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attaches the liver to the anterior abdominal wall and diaphragm
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lesser omentum
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in the serosa of the stomach and duodenum and suspends the stomach and duodenum from the liver
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greater omentum
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fatty aprom. A double sheet that fold back on itself giving 4 layers. Contains a great amount of adipose tissue.
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what is the difference btw retroparitoneal and intraparitoneal organs?
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retroparitoneal-external to the paritoneal lining of the abdominal cavity.(kidneys and pancreas)
intraparitoneal-completely covered by the paritoneum |
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What are the names of the 3 main salivary glands?
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Parotid glands-inferior to ears
Lingual glands-beneath the tongue ubmandibular glands-floor of the mouth |
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State the function of the esophagus, and describe how food is moved through it?
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secretes mucus, and transports food into the stomach. it does not produce digestive enzymes, and it is not involved in absorptionof nutrients
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describe deglution
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(swallowing)-there are 3 stages.
1. voluntary-bolus food is forced to the back of the oral cavity and into the oropharynx 2. pharyngeal(involuntary)-bolus causes impulses to be sent to the medulla oblongata and lower pons of the brain stem. These impulses cause the soft palate and uvula to move upward and close off the nasopharynx. 3-esophageal-bolus enters the esophagus and paristalsis moves the bolus along the length of the esophagus. At the end of the esophagus, the sphincter relaxes, and bolus moves into the stomach. |
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describe the location and function of the stomach.
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inferior to the diaphragm
it acts as a mixing chamber, and holding reservoir. Digestion of starch continues, digestion of proteins and triglycerieds begins. Semisolid bolus turns to liquid. |
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what are the 4 main regions of the stomch?
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1. cardia-surrounds the superior opening of the stomach
2. fundus-superior and to the left of the cardia 3. body-inferior to the fundus 4. pylorus-connects the stomach to the duodenum |
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what are the 2 parts to the pylorus?
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pyloric antrum-connects to the body
pyloric canal-connects to the duodenum |
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what are rugae of the stomach?
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when the stomach is empty, the lining forms many fold called rugae.
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Explain mechanical digestion in the stomach
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several minutes after food enters the stomach, perstaltic movements begin. These waves mix the food in with secretions from the gastric glands, and form chyme.(forward and backward motion)
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Explain chemical digestion in the stomach.
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the main chemical activity is protein digestion. Pepsin breaks certain peptide bonds btw amino aids that make up protiens. Pepsin is most effective in a very acidic enviroment, thus it is aided by the presence of HCL.
-a second enzyme(gastric lipase)which splits triglycerides into fatty acids, and monoglycerides, and operates best in a pH of 5-6. |
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what keeps pepsis from digesting the protein in the stomach along with the food?
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pepsin is fist secreted as pepsinogen, so it cannot digest protiens. When it comes in contact with HCL, it is converted to pepsin. Stomach cells are protected by mucus so the stomach is not digested.
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what are the histiological differences of the layers of the stomach from the GI tract?
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muscularis:
-continns 3 layers instead of 2:outer(longitudinal)layer, middle(circular)layer, and inner(deep)layer. Mucosa layer: epithelial cells extend into the lamina propria forming columns of secretory cells called gastric glands. these glands ecrete mucus, intrinsic factor, HCL, pepsinogen, gastric lipase, and gastin into the lumen of the stomach. Thse secretions form gastric joice. |
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what stimulates gastric secretion?
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regulated by both neural and hormonal factors. Sight, sell, and tast of food stimulate parasympathetic nervous system refluxes which increase the secretion of gastric joice y stomach glands.
-the presence of food and a falling pH in the stoamch cells realease the hormone gastrin. |
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what is chyme?
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the semi-liquid mixture of gastric joices and food, that leaves the stomach to enter the small intestine.
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what does gastrin do?
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stimulates the stomach to produce more protein-digesting enzymes(pepsinogens), mucus, and HCL
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what are the 3 regions of the small intestine?
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1. duodenum-stants at the pyloric sphincter and is the shortest segemet
2. jejunum-middle segment 3. ileum-extends to the iliocecal sphinter and is the longest segement |
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what has been broken down when food gets to the small intestine? HOw long of a journey?
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Food that reaches the small intestine is only partially digested. Carbohydrate and protein digestion have been started. Most fats have not been digested at this oint phyme takes 3-6 hoursjourney through the loops of the small intestine.
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How is there a large surface area for digestion?
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glands secrete fluid and mucus and circular fold, villi, microvilli of its wall to provide a large srface area for digestion and absorption of nutrients.
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what are brush-border enzymes?
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enzmes produced by the cells in the mucosa of the small intestines. They id in the digestion of carbs and protien.
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what is segmentation in the small intestine?
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mixing chyme with digestive juices and bringingfood into contanct with the mucosa for absoprption
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what are the functions of the small intestine?
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-mix chyme w/digestive juices
-propel chyme through the small intestine -complete the digestion of carbs, proteins, lipids and begins and completes the digestion of nucleic acids. -absorption of 90% of nutrients and water occurs in the small intestine. |
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where does the jejunum end, and the ileum begin?
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there is no distint separation btw the jejunum and the ileum, but the diameter is usually greater and its walls are thick and more vscular and more active than the ileum
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what are the overall functions of the large intestine?
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completion of absorption, production of certain vitamins, formation of feces, andexpulsion of feces from the body.
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Where is the large intestine attached?
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it is attached to the posterior abdominal wall by the mesocolon, a double layer of the paritoneum
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What are the 4 anatomical regions of the lg. intestine?
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1. cecum
2. colon 3. rectum 4. anus |
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Where is the cecum locate?
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in the RLQ, right iliac region. It is continuous with the ascending colon.
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where does the ascending colon travel?
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upward from the cecum, to the level of the liver; abruptly turns, to form the colic(hepatic)flexture. It is in the RUQ
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Where is the transverse colon located?
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runs horizontally across the upper abdomen towards the sleen. It turns inferiorly to form the left colic flexure. It is in the LUQ; lateral and inferior to the spleen
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what is the location of the descending colon and the sigmoid colon?
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courses inferiorly along the left side of the abdoen
-sigmoid makes an s shape, and travels medially toward the ML. It terminates as the rectum |
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How long is the nal canal?
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2-3 cm of rectum
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how is the anus kept closed?
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by 2 sphincter muscles called the nternal and external anal sphincters.
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What are the functions of the large intestine?
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-Where the final stages of digestion occur
-bacteria in the LG intestine convert protiens into amino acids -haustral churning, perstalsis, and mass peristalsis drive the contents of the colon into the recutm -absorbs some water, ions, and vitamins. -ferments remaining carbs, and produces gas. -waste products from digestion are converted to feces and prepared for eliination. |
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Descrive the panreas?
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soft, comma shaped retroparitoneal organ
-divisions of the head, body, and tail -hooklike extension of the head is called the uncunate process |
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where does the head of the pancreas lie?
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within the c-shaped curve of the duodenum
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where does the body of the pancreas lie?
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to the left of the pancreatic head, posterior to the antrum of the stomach
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where does the tail of the pancreas lie?
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causedal to the body of the stomach
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What is the duct of santarini(accesory duct)
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it runs in the head of the pancreas, and is shorter than the pancreatic duct. IT inters the duodenum superior to the ampulla of vater.
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What are the 2 main ducts that run within the pancreas?
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-pancreatic duct(duct of wirsung)-runs through the center of the pancreas, and joins the CBD.
-accessory duct-shorter than pancreas |
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What is the ampulla of vater?
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Where the pancreatic duct joins the CBD, it dialates slightly and is called the ampulla of vater.
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How is the passage of pancreatic juice into the small intestine regulated?
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by a mass of smooth muscle called the sphincter of oddi.
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What kind of cells is the pancreas made up of?
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small clusters of glandular epithelial cells.
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what are the portions of the pancreas?
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exocrine portion-99% of the pancreas which is made of clums of cells called acini(secrete fluid and digestive enzymes called pancreatic juice)
Endocrine-1%-called islets of langerhans(secrete hormones(glucago, nsulin, somatostatin, and pancratic polypeptide)) |
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How much pancreatic jois is produced daily?
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1200-1500mL
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What is the make-up of pancreatic juice?
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clear, colorless liquid, consisting mostly of water, salts, sodium bicarbonate, and several enzymes.
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What enzymes does pancreatic juice contian?
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enzymes that digest:
-starch(pancreatic amylase) -proteins(trypsin, chomyotrypsin, carboxypeptidase, and elastase) -triglycerides(pancreatic lipase) -nucleic acids(rionuclease, and eoxyribonuclease) |
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What are the 3 cells of islets of langerhans, and what do they do?
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alpha cells-synthesize and secrete glucogon
beta cells-snynthsize and secrete insulin delta cells-synthesize and secrete soatostatin |
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What does sodium bicarbonate do?
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neutralizes the HCL produced in the stomach
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What reguates the release of pnacreatic juice?
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nervous and endocrine systems
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what do parasympathetic impulses do for the pancreas?
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stimulate the pancreas to release digestive enzymes
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What does peptide hormone secretion do for the pancres?
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stimulates the pancreas to secrete large quantities of fluid when acidic chyme enters the duodenum
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What causes dialation of the biliary system?
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tumors in the head compress ducts and cause dialation of the biliary system
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What is the falciform ligament?
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a fold of preitoneum that separates the rt and lt loes and suspends the liver from the diahragm and anterior abdominal wall.
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where is the quadrate lobe located?
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inferior portion of the liver near the gallbladder.
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where is the causdate lobe located?
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posterior and near the ivc
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what is the porta hepatis?
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the area where the 4 lobes meet, and blood vessels and ducts enter or leave the liver
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what is glisson's capsule?
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thin connective tissue that surrounds the entire liver, and is thickest around the IVC
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What is the hepatoduodenal ligament?
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surrounds the porta hepatis, main portal vein, proper hepatic artery, and common bile duct
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falciform ligament
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separates rt, and lt love of liver-broad thin fold of the parietal peritoneum
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ligamentum teres
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obliterated umbilical vein that ascends from the umbilicus to the free edge of the falcifom ligament. travels from the porta hepatis within the liver as the ligamentum venosum.
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What does the right intersegmental fissure divide?
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the right love into anterior and posterior segments.
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Descrive the panreas?
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soft, comma shaped retroparitoneal organ
-divisions of the head, body, and tail -hooklike extension of the head is called the uncunate process |
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What is the ampulla of vater?
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Where the pancreatic duct joins the CBD, it dialates slightly and is called the ampulla of vater.
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What is the make-up of pancreatic juice?
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clear, colorless liquid, consisting mostly of water, salts, sodium bicarbonate, and several enzymes.
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What enzymes does pancreatic juice contian?
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enzymes that digest:
-starch(pancreatic amylase) -proteins(trypsin, chomyotrypsin, carboxypeptidase, and elastase) -triglycerides(pancreatic lipase) -nucleic acids(rionuclease, and eoxyribonuclease) |
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What are the 3 cells of islets of langerhans, and what do they do?
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alpha cells-synthesize and secrete glucogon
beta cells-snynthsize and secrete insulin delta cells-synthesize and secrete soatostatin |
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What does sodium bicarbonate do?
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neutralizes the HCL produced in the stomach
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What regulates the release of pancreatic juice?
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nervous and endocrine systems
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what do parasympathetic impulses do in regards to the pancreas?
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stimulate the pancreas to release digestive enzymes.
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What does the peptide hormone do?
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stimulates the pancreas to release large quantities of fluid when acidid chyrme reaches the stomach.
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Where does the liver lie in relation to the dome?
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directly inferior to the dome of the diaphragm
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where is the quadrate lobe located?
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inferior portion of the liver near the gallbladder
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Desribe the fissures of the liver, and what runs within each
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right intersegmental fissure-divides the right lobe into anterior and posterior segments. The right hepatic vein runs in it.
Main lobar fissure-separates the right and left lobe-middle hepatic vein runs in it Left intersegmental fissure-separtes the left lobe into lateral and medial segments. The left hepatic vein runs in it cranially, the ascending branch of the portal vein runs in it medially, and the ligamentum teres runs within it caudally |
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What is a lobule?
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a hexagonal structure that consists of specialized epithelial cells called hepatocytes.
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how are hepatocytes arranged in a lobule?
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they are arranged in irregular, branching interconnected plates situated around a vein.
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what are sinusoids?
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highly permeable capillaries
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what are kupffer cells?
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fixed phagocytes that destroy old RBC, WBC, and bacteria and other foreign matter in the venous blood from the GI tract
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Where is blood taken from that goes into the lobules?
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blood from the digestive tract(carried in portal veins) brings absorbed nutrients into the sinusoids.
-O2nated blood from hepatic artery mixes freely with blood containing nutrients and then flows through the liver sinusoids and nourishes the hepatic cells |
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What are bile calcaliculi?
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narrow, canals that receive bile secreted from hepatocytes
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describe the flow of bile from canalculi, till it exits the liver
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bile enters canaliculi, and they unite to form bile ducts. These ducts become the right and left hepatic ducts, and these hepatic duts merge to form the common hepatic duct.
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what does bile consit of?
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water, bile salts, cholesterol, lecithin, bile pigments, and ions
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What is billirubin?
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a product of the breakdown of RBC which is a main contributer the the pigment of bile.
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How does bile aid in digestion?
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it acts as an emulsifier, reaking down lare fat molecules into smaller ones for easier digestion.
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Name and expalin the 3 categories of jaundice?
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prehepatic-caused by excess producion of bilirubin
hepatic-caused y congenital liver disease, cirrosis of the liver or hepatitis extrahepatic-caused by blockage of bile drainage by gall stones or cancerous tumors in the bowl or pancreas |
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What is jaundice?
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yelllowish discoloration of th whites of the eyes, skin, and mucous membrane due to a buildup of billirubin
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What sources does the liver recieve blood from?
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-hepatic artery-oxygenated blood,
-hepatic portal vein-deoxygenated lood containing nutrients |
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where do manufactued prodcuts and unused nutrients go from the hepatocyte?
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they are secreted back into the blood.
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Where does blood drain from the contral vein?
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blood drains from the central vein to a hepatic vein, then to the ivc, and eventually into the right atrium of the heart.
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what make up the portal triad?
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the hepatic artery, common bile duct, and portal vein.
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what are the 10 functions of the liver
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1. bile secretion-needed for absorption of dietary fats.
2. carbohydrate metabolism-maintian normal blood glucose level 3. lipid metabolism-store triglycerides, break down fatty acid, synthesize, and use cholesterol 4. protein metabolism-breaks down amino acids, synthesizes plasma protiens. 5. processes drugs and hormones- 6. excretes billirubin-via bile into small intsestines 7. synthesis of bile salts 8. storage-glycogen, vitamins, and minerals 9. phagocytosis 10. activation of vitamin D-synthesize active form of vitamin D |
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according to the 4 segment method, what are the divisions of the liver?
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right anterior
right posterior left medial left lateral |
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according to couinads segmentation, what are the lobes of the liver?
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1. caudate lobe
2. lateral segment of the left lobe(superior) 3. lateral segment of the left lobe(inferior) 4a. medial segment of the left lobe of the liver. (superior) 4b. medial segemet of the left lobe of the liver(inferior) 5. anterior segment of the right lobe(inferior) 6. posterior segment of the right lobe((inferior)) 7. posterior segment of the rt lobe(superior) 8. anterior segment of the rt lobe (superior) |
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where is the gallbladder located?
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in a depression on the inferior, ventral surface of the liver. 10X8X4 cm. Can hold 30-50 mL of fluid.
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What are the 3 layers of the gallbladder?
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-lumen is lined w/epithelial cells, and when emty, the ucosa formes rugae like folds.
-middle layer consists of strong, smooth muscle cells which contract and eject contents into the cystic duct -outer layer formed by visceral peritoneum |
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What forms the CBD?
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the cystic duct and hepatic duct
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what controls the entry of pancreatic juice and bile into the duodenum?
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the sphincter of oddi
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when is bile released into the duidenum?
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when stimulated by chelecystokinin.
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