Term
| The gastroinstestinal (GI) tract or alimentary canal extends from what part of the body to another part of the body? |
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Definition
| It begins from the mouth and continues through the pharynx, esophagus, stomach, small and large intestine, rectum, and ending at the anus. |
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Term
| What are the six accessory structures and organs that aid the GI tract in the physical and chemical digestion of food? |
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Definition
| Teeth, tongue, salivary glands, liver, gall bladder, and pancreas |
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Term
| What are the 5 essential digestive processes? |
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Definition
1. Ingestion
2. Propulsions or movement of food (swallowing and peristalsis)
3. Mechanical (chewing, churning of the stomach, segmentation in the intestines) and chemical digestion
4. Absorption of nutrients
5. Defecation |
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Term
| What are the four layers of the GI tract? |
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Definition
| Mucosa, submucosa, muscularis externa, serosa (visceral peritoneum) |
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Term
| Describe the mucosa layer of the GI tract. |
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Definition
| A layer of three tissues that lines the lumen of the GI tract from the mouth to the anus. |
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Term
| The epithelial layer of the mucous layer or membrane of the mouth, pharynx, esophagus, and anal canal is lined with what type of tissue? |
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Definition
| nonkeratinized stratified squamous epithelium |
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Term
| How about the epithelium of the mucous membrane of the stomach, small intestine and large intestine? |
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Definition
| simple columnar epithelium with abundant mucus-secreting goblet cells (mucus protects the organs from own digestive enzymes and eases the passage of food) |
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Term
| What function does the columnar epithelium of the mucosas of the stomach and small intestine specialize in? |
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Definition
Stomach: secretes digestive enzymes
small intestines: absorb digested food |
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Term
| What is the connective tissue layer of the mucous membrane which consists of blood capillaries, lymph capillaries, and lymphatic follicles in the ileum of the intestine? |
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Definition
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Term
| What is the thin smooth muscle called that is responsible for local movement (not peristalsis)? |
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Definition
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Term
| Describe the submucosa layer of the GI tract. |
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Definition
Dense irregular connective tissue that binds the mucosa to the muscularis externa (third layer).
It contains blood and lymphatic vessels, digestive glands, and ANS nerve plexuses that control digestive gland secretions. |
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Term
| Describe the muscularis externa layer of the GI tract. |
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Definition
| Skeletal muscle in the mouth, pharynx, and the first third of the esophagus. |
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Term
| The skeletal muscle is replaced by two layers of what type of muscle? |
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Definition
| Smooth muscle, which lines the last 2/3 of the esophagus, and continue into the stomach, and small and large intestines. |
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Term
| Describe the two smooth muscle layer in the esophagus, stomach, and small and large intestines. |
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Definition
It has an inner circular layer and an outer longitudinal layer.
The ANS myenteric nerve plexuses coordinate the smooth muscle action. |
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Term
| What is the function of the muscularis externa? |
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Definition
| peristalsis and segmentation (dividing and redistributing the bolus) |
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Term
| Describe the serosa layer (visceral peritoneum) of the GI tract. |
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Definition
| A serous membrane that protects the outermost layer of the stomach, small intestine, and large intestine. |
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Term
| The oral cavity includes...? |
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Definition
| lips, teeth, palate, and tongue that are wet with saliva |
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Term
| The mucous membrane of the oral cavity is lined with... |
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Definition
| nonkeratinized stratified squamous epithelium |
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Term
| The teeth are embedded in what sockets of what parts of the skull? |
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Definition
| the alveolar processes of the maxillae and mandible |
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Term
| The alveolar processes are covered by...? |
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Definition
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Term
| What function does the orbicularis oris of the lips and buccinators of the cheeks serve? |
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Definition
| It keeps food between the teeth to chew. |
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Term
| The tongue forces food onto the hard palate during chewing and forms the food into what? |
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Definition
| It forms the food into a bolus (ball of food) and then the tongue pushes the bolus to the back of the mouth. |
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Term
| The posterior soft palate forms the...? |
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Definition
| uvula, which covers the nasopharynx during swallowing. |
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Term
| The salivary glands secrete saliva which contains... |
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Definition
| mucus and salivary amylase (digestive enzyme) |
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Term
| What function does saliva serve in digestion? |
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Definition
| Saliva keeps mucous membranes moist, dissolves some food chemicals so that they can be tasted by taste buds, moistens food to help form a bolus, and begins the chemical breakdown of starchy foods. |
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Term
| What glands secrete most of the saliva? |
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Definition
| The parotid, submandibular, and sublingual glands |
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Term
| The flow of these salivary glands is controlled by what parasympathetic cranial nerves? |
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Definition
| Cranial nerve VII (facial) and IX (glossopharyngeal) |
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Term
| The tongue pushes the bolus from the oral cavity to what part of the digestive system? |
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Definition
| oropharynx, then the uvula closes off the nasopharynx |
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Term
| After the food moves past the oropharynx it passes through the...? |
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Definition
| laryngopharynx into the esophagus as the epiglottis closes off the larynx |
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Term
| What is the esophagus and what does it pass through? |
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Definition
It is a muscular tube, 10 inches long and posterior to the trachea.
It passes through the mediastinum and then through the opening in the diaphragm (esophageal hiatus). |
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Term
| About three inches into the esophagus, the skeletal constrictor muscles of the pharynx are replaced by...? |
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Definition
| the contractions of longitudinal and circular smooth muscles (peristalsis) that push the bolus through the esophagus. |
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Term
| What is the gastroesophageal (=cardiac) sphincter? |
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Definition
a small smooth muscle valve at the entrance of the stomach where the esophagus joins the stomach
It relaxes during peristalsis allowing the bolus to enter.
The sphincter is not a true sphincter (not a ring of smooth muscle to seal off the opening) |
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Term
| What is the stomach and what function does it serve in the digestive system? |
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Definition
| It's about 10 inches long. It serves as a temporary "storage tank" for the mechanical breakdown of food and the initial chemical breakdown of proteins. |
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Term
| What are the four regions of the stomach? |
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Definition
| Cardia, fundus, body, and pylorus |
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Term
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Definition
| The longitudinal folds in the mucosa when the stomach is empty which allows the stomach to stretch to hold approximately 1.5 liters of food, but as much as 4 liters. |
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Term
| The lining of the stomach mucosa is lined by what kind of tissue? |
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Definition
| simple columnar epithelium, which specializes in glandular cells generally called gastric glands |
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Term
| The gastric juice secreted by the gastric glands consists of...? |
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Definition
| pepsin that digests proteins into amino acids and hydrochloric acid that makes the stomach contents very acidic (pH 1.5-3.5) and helps destroy bacteria |
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Term
| The mucous cells in the stomach make what kind of mucus and for what purpose? |
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Definition
| alkaline mucus to shield gastric cells from the effects of HCl. |
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Term
| Stomach mucosa only absorbs what kinds of substances? |
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Definition
| Water, salts, aspirins, and alcohol. |
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Term
| The muscularis externa has 3 smooth muscle layers that churn stomach contents. What are they? |
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Definition
| circular, longitudinal and oblique smooth muscle layers |
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Term
| Boluses are degraded physically and mixed with gastric juices to become a semifluid mass called ________. |
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Definition
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Term
| Chyme exits from the stomach into the small intestine through via the __________. |
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Definition
| pyloric sphincter (ring of smooth muscle) |
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Term
| What does the pyloric antrum do? |
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Definition
| It squirts small amounts of chyme through the pyloric sphincter into the small intestine. It takes 2-6 hours for the stomach to empty completely. |
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Term
| The small intestine extends from the __________ of the stomach to the __________. |
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Definition
| pyloric sphincter, large intestine |
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Term
| Enzymatic digestion is complete in the ___________. |
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Definition
| Small intestine (90% of all nutrient absorption is in the small intestine) |
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Term
| Name the 3 segments of the small intestine. |
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Definition
| duodenum, jejunum, and ileum |
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Term
| What function does the duodenum serve in the small intestine? |
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Definition
| Most digestion and some absorption of nutrients occur here. |
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Term
| The duodenum has submucosal glands (Brunner's glands) that make what kind of mucus? |
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Definition
| Alkaline mucus (pH of 7.6) that helps neutralize the acidic chyme |
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Term
| What does the jejunum of the small intestine do? |
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Definition
| It is responsible for much of the absorption of nutrients. |
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Term
| What does the ileum of the small intestine do? |
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Definition
| It joins the large intestine to the ileocecal valve. |
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Term
| What does the ileum of the small intestine do? |
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Definition
| It joins the large intestine to the ileocecal valve. |
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Term
| What are "Peyer's patches"? (think immune system) |
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Definition
| also known as aggregated lymphoid nodules; they are large clusters of lymphoid follicles structurally similar to the tonsils. They are located in the wall of the distal portion of the small intestine which destroy bacteria before the can breach the intestinal wall and generate many memory lymphocytes for long-term immunity. |
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Term
| The simple columnar epithelial cells of the mucosa possess ___________ that increases the cell membrane surface area for absorption. |
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Definition
| microvilli (brush border) |
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Term
| The mucosa, itself, has projections called _________ that are 1 mm high, which further increase the surface area for nutrient absorption. |
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Definition
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Term
| The mucosa is folded into ___________ that rotate the chyme. |
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Definition
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Term
| The lamina propria has a ____________, which receives the absorbed nutrients, and ____________ that receive absorbed fats. |
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Definition
| dense blood capillary bed; lacteals (lymphatic capillaries) |
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Term
| The muscularis externa of the small intestine has the ___________ and ___________ layers of smooth muscle for peristalsis. |
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Definition
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Term
| Undigested material enters the large intestine through the _____________. |
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Definition
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Term
| The large intestine is about ___ feet long and ___ inches in diameter and mainly absorbs 90% of ________ in the chyme. |
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Definition
| 5 feet; 2.5 inches in diameter; 90% of water |
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Term
| The large intestine is divided into what 3 structural regions? |
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Definition
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Term
| The lymphatic tissue protruding from the interior surface of the cecum is the _____________. |
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Definition
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Term
| The cecum merges with the colon, which contains what 4 distinct regions? |
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Definition
| ascending, transverse, descending, and sigmoid colons. |
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Term
| The mucosa in the large intestine before the rectum contain _________ _________ epithelium, which has no ________. |
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Definition
| simple columnar; no villi |
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Term
| The mucosa makes mucus that eases the passage of ___________ to the rectum. |
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Definition
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Term
| The longitudinal smooth muscle of the muscularis externa is thickened into three bands, the ____________ . |
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Definition
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Term
| What does the taeniae coli maintain? |
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Definition
| tonic contractions (continual tension), and causes the intestinal wall to pucker into small pocketlike pouches. (haustra [sing. haustrum]) |
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Term
| The rectum is the last ___ inches of the GI tract. |
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Definition
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Term
| The last 1 inch of the rectum is the ___________ which opens to the exterior at the anus, in which this mucosa contains ____________ ____________ _____________ epithelium for abrasion |
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Definition
| anal canal; nonkeratinized stratified squamous epithelium |
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Term
| The ________________ in the rectum is the circular smooth muscle. |
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Definition
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Term
| The ____________________ is a voluntary skeletal muscle associated with the __________________. |
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Definition
| external anal sphincter; perineal musculature |
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Term
| The peritoneum is a _____________ serous membrane in the abdominopelvic cavity that covers most organs, the body wall and creates the ______________ cavity. |
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Definition
| continuous; peritoneal cavity |
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Term
| The ____________ peritoneum covers the surfaces of most digestive organs. |
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Definition
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Term
| The _____________ peritoneum lines the walls of the abdominopelvic cavity. |
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Definition
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Term
| Organs that lie posterior to the parietal peritoneum are ______________ (e.g. duodenum and kidney are not in the peritoneal cavity) |
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Definition
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Term
| Peritonitis is an infection of the __________, which can b due by an external wound or rupturing of the GI tract (e.g ruptured appendix). |
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Definition
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Term
| The visceral peritoneum that wraps around an organ can form a double-layered membrane or _____________, which connects to the parietal peritoneum and suspends the organ within the peritoneal cavity. |
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Definition
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Term
| The liver has a larger _______ lobe, a smaller ________ lobe and 2 small lobes, the __________ and __________. |
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Definition
| right; left; caudate and quadrate |
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Term
| The _________________ is the mesentery that suspends the liver from the diaphragm. |
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Definition
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Term
| The liver cells are called ___________ . |
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Definition
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Term
| Hepatocytes secrete _________ a fluid with salts, pigments and choleterol, into the ______________ that leave the liver to enter the _______________ duct. |
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Definition
| bile; bile canaliculi; common hepatic duct |
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Term
| The common hepatic duct merges with the _____________ of the gallbladder to form the ________________. |
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Definition
| cystic duct of the gallbladder; common hepatic duct |
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Term
| The common bile duct and the _______________ merge to empty the bile into the duodenum. |
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Definition
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Term
| Bile's digestive function is _______________ i.e. breaks up fats and oils into small droplets that are easier to digest with enzymes. |
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Definition
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Term
| _____________, a by-product of hemoglobin breakdown in the liver, it is one of the bile pigments that give bile its green color. |
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Definition
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Term
| The _______________ comes from the celiac trunk and supplies oxygenated blood into the liver. |
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Definition
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Term
| The _________________ drains the blood of the digestive tract into the liver. |
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Definition
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Term
| Both the _____________ and ___________ blood mix in the ______________________ of the hexagonally-shaped lobules which are composed of hepatocytes. |
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Definition
| arterial and venous; sinusoidal capillaries |
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Term
| Within the sinusoids are _________________ that remove old RBC's and remove potentially toxic material. |
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Definition
| Kupffer's cells (liver macrophages) |
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Term
| All blood draining from the liver (arterial or venous) enters the _________________ at the middle of the lobule, which merge into venules that empty into the _______________ and then into the _____________________. |
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Definition
| central vein; hepatic veins; inferior vena cava |
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Term
| The liver through its hepatocytes does six more functions. What are they? |
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Definition
1. Convert glucose into glycogens, stores glycogen, or release glycogen into the blood.
2. Stores certain vitamins and iron
3. Converts amino acids into glucose
4. Detoxification of toxic ammonia to urea, drugs (alcohol), amphetamines, and antibiotics such as penicillin.
5. Produces plasma proteins, such as fibrinogen and albumin that are found in the blood.
6. Has Kupffer's cells in the sinusoids that phagocytize bacteria and deteriorated blood cells. |
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Term
| The gallbladder is a thin-walled, green, muscular sax, approximately 3-4 inches long on the inferior surface of the right liver lobe with it's function to store ________. |
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Definition
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Term
| Although the liver continuously secretes bile, a sphincter of the __________________________ prevents the entry of bile into the duodenum unless needed for digestion. |
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Definition
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Term
| The ___________ are the principal digestive enzyme organ. It is 4.5-6 in long, 1inches thick, and retroperitoneal. |
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Definition
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Term
| The ____________ cells comprise 98% of the tissues and secrete digestive enzymes, mainly ____________ and _________, within 1200-1500 ml of _______________ excreted during digestion. |
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Definition
| exocrine; proteases and lipases; pancreatic juice |
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Term
| The juice leaves the pancreas through the _______________ and ___________ ducts to enter the duodenum during digestion. |
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Definition
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Term
| The ____________________ within the pancreas are ___________ and produce the hormones _________, _________ and ___________. |
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Definition
| Islets of Langerhans; insulin, glucagons and somatostatin. |
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