Reading...
Play button
Play button
Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
32 Cards in this Set
- Front
- Back
|
Name and describe the four layers of the GI tract.
|
1. Mucosa - innermost layer; contains lamina propria; functions in absorption and secretion
2. Submucosa - loose connective tissue; highly vascularized; functions to nourish mucosal lining 3. Muscularis externa - 2 coats of smooth muscle; functions in peristalsis 4. Serosa - outer covering of loose areolar tissue; mesentary holds tissue in place |
|
|
What are the accessory organs of the GI tract?
|
Salivary glands, pancreas, liver, gall bladder, teeth, lymph nodes and appendix
|
|
|
What is peristalsis?
|
Rhythmic wave-like contractions that move food through the GI tract; circular fibers decrease the diameter and longitudinal fibers shorten the tract
|
|
|
Explain the phases of digestion occurring at the beginning of the GI tract.
|
1. Oral phase is voluntary and forms a food bolus.
2. Pharyngeal and Esophageal phases are involuntary and cannot be stopped |
|
|
What organism commonly causes dental caries?
|
Streptococcus mutans - produces lactic acid in the presence of glucose, fructose, and sucrose
|
|
|
What is gingivitis and periodontitis?
|
Gingivitis is the inflammation of the gingival at the gumline due to host inflammatory response to initial plaque formation - gums are reddened and may bleed upon probin. Periodontitis is caused by a polymicrobial infection - the host immune response leads to the destruction of the gingiva and periodontal ligaments.
|
|
|
How many sets of tonsils are there and what kind of tissue are they?
|
There are 3 sets - made up of lymphatic tissue involved in immune surveillance
1. Lingual - cover root of the tongue 2. Palantine - line either side of inferior soft palate 3. Pharyngeal (adenoids) - superior to soft palate lining posterior wall of pharynx |
|
|
How many sets of salivary glands are there and what is their function?
|
The salivary glands secrete salivary amylase, which begins carbohydrate digestion, along with mucus, which binds and lubricates the food.
1. Parotid - by ear; secrete serous fluid and salivary amylase 2. Submandibular - floor of mouth; combo of serous and mucus cells 3. Sublingual - inferior to tongue; primarily mucus secreting cells |
|
|
What are the functions of the stomach?
|
1. Mix food with gastric juice to form chyme.
2. Begins protein digestion. 3. Limited absorption. 4. Moves food into small intestine. |
|
|
Anatomy of stomach
|
Greater and lesser curvatures
Four regions - cardiac, fundic (temporary food storage), body, pyloric Rugae - longitudinal folds of mucosa Specialized cells in gastric pits |
|
|
Gastric pits - name the cells and what they secrete
|
Goblet cells - secrete mucus
Chief cells - secrete pepsinogen Parietal cells - secrete HCl and intrinsic factor for absorption of B12 G cells - secrete gastrin when proteins enter stomach ECL cells - secrete histamine which stimulates parietal cells to secrete HCl D cells - secrete somatostatin |
|
|
Enzymes and chemicals produced by the stomach
|
1. Pepsin - digests proteins into shorter peptide chains; optimum pH of 2.00
2. Gastric lipase - breaks down fats into fatty acids and glycerol; optimum pH of 2.00 3. HCl - lowers pH to kill bacteria and convert pepsinogen to pepsin 4. Gastrin - stimulated by protein containing foods in stomach; increases produce gastric juices and muscular contractions |
|
|
Discus gastric and peptic ulcers
|
Peptic ulcer - erosion of mucus membrane via acion of HCl
Can be caused by Heliobacter pylori infection Acute gastritis results in acid damage due to histamine released (can be treated with histamine receptor blockers) |
|
|
Anatomy of small intestine
|
3-4 meters long
Plia circulares Villi - fingerlike projections of epithelia of lumen Microvilli - extensions of apical membranes (brush border) |
|
|
Duodenum
|
C-shaped tube surrounding head of pancreas; most active in digestion; secretes thick alkaline mucus, peptidases, disaccharide brush border enzymes, intestinal lipases
|
|
|
Jejunum
|
Proximal 2/5ths of small intestine
Plica circularis - transverse folds of mucosa No peyer's patches Lacteals in villi are lymphatic systems similar to capillary Crypts of Lieberkuhn - invagination of villus where high levels of mitosis occur to replace epithelial cells at tips of villi |
|
|
Ileum
|
Distal 3/5ths of small intestine
Numerous Peyer's patches containing lymph nodes for immune surveillance Ends at cecum at junction joining small and large intestines |
|
|
Functions of large intestine
|
Large diameter - inferior to liver and stomach
1. Reabsorption of water and ions 2. Symbiotic bacteria of intestinal flora producing essential aa's and vits 3. Some absorption of aa's and vits 4. Compaction of chyme 5. Storage of fecal matter |
|
|
Cecum
|
Pouch-like structure that accepts chyme from the ileum
|
|
|
Veriform appendix
|
Narrow, hollow, muscular tube attached to the cecum; lined with patches of lymph tissue for immune surveillance
|
|
|
Anatomy and function of the colon
|
Taenia coli - 3 longitudinal bands of muscle that run the length of the colon
Haustra - pouches formed in the wall of the colon Eiploic appendages - periotneum covered sacs of adipose tissue attached to the serosa of the colon Function - absorbs remaining water; cells have Na+/K+ pumps to establish gradient; water follows cells by osmosis; stimulated by aldosterone |
|
|
Divisions of the colon
|
1. Ascending - begins superior to cecum
2. Transverse - Passes across the body horizontally 3. Descending - along the left wall of the abdomen 4. Sigmoid - S shaped at end of colon where feces are stored before being emptied into the rectum |
|
|
Anatomy of rectum
|
Final 15cm of GI tract; continuous with anal canal
Simple columnar epithelium Distal rectum - stratified simple squamous epithelium Internal anal sphincter - smooth muscle External anal sphincter - skeletal muscle |
|
|
Anatomy of liver
|
Two lobes encased in fibrous connective tissue
Held in place by ligaments (coronary, falciform, lesser omentum) |
|
|
Lobules of the liver
|
Each contains hepatocytes which form hepatic plates; plates are separated by sinusoids that are permeable to even proteins; central vein in middle of lobule
Portal triad - each supplies and empties several lobules 1. Branch of hepatic artery 2. Branch of hepatic portal vein 3. Bile ductile |
|
|
Bloodflow through the liver
|
The hepatic portal vein carries blood from the small intestine to the liver, and the hepatic vein carries blood from the liver to the inferior vena cava. All blodd passes through the liver from small intestine before returning to the heart.
|
|
|
Production of bile in the liver
|
Hepatocytes produce bile that must be transported to the gall bladder for storage
Bile canaliculi collect bile - to hepatic duct - to common bile duct - to gall bladder |
|
|
Liver functions
|
Major metabolic center in the body
1. Carbohydrate metabolism - maintains blood glucose level, stores/releases carbs, converts glucose to glycogen 2. Protein metabolism - processes aa's; transports aa's to skeletal muscle; protein synthesis 3. Lipid metabolism - synthesizes lipoproteins, phospholipids, and cholesterol; oxidizes fatty acids; detox of drugs |
|
|
Gall bladder anatomy
|
Hollow, pear shaped, green
Neck - attaches to ventral surface of cystic duct Body Fundus |
|
|
Gall bladder function
|
Store, concentrate, secrete bile into small intestine
1. CCK released by mucosa of SI due to protein in chyme circulates in blood (hormone) and causes gall bladder to secrete bile into SI 2. Emulsifies fat droplets, absorbs fatty acids, cholesterol, and lipid soluble vits (A, D, E) |
|
|
What is bilirubin?
|
Bilirubin is produced in the spleen, bone marrow, and liver.
Derivative of heme Carried in blood attached to albumin. Free bilirubin combines with glucoronic acid to be secreted in bile. Converted in small intestine to urobilinogen (salvage pathway to reuse) |
|
|
What is bile?
|
Bile is important for the emulsification and absorption of lipids and cholesterol.
Bile acids are formed in the major breakdown pathway for cholesterol (cholic acid and chenodeoxycholic acids). Bile salts aggregate to form micelles to emulsify fats. |
