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110 Cards in this Set
- Front
- Back
Gastrointestinal Tract
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AKA Alimentary Tract
-includes mouth, most of pharynx, esophagus, stomach, small & large intestine |
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how long is the gastrointestinal tract?
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5-7 meters long (16-23 feet)
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Accessory organs include:
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teeth, tounge, salivary glands, liver, gallbladder, pancreas
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What is deglutition?
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its the movement of food from mouth to stomach
-it involves the mouth, pharynx, and esophagus |
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3 stages of deglutition:
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1) voluntary stage
2) pharyngeal stage 3) esophageal stage |
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voluntary stage of deglutition:
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-use teeth for mastication (chewing) and get the food into a bolus (takes about 25 munchings)
-bolus then passes into oropharynx |
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pharngeal stage of deglutition:
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-begins involuntary passage of bolus through the esophagus into stomach
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esophageal stage of deglutition:
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-esophagus to stomach
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What is GERD?
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Gastoesophageal Reflux disease: when stomach acid moves into the esophagus and errods away the wall of esophagus, causing heart burn
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name the 4 regions of the stomach:
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-cardia
-fundus -body -pylorus |
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cardia of stomach:
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surrounds superior opening of the stomach
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fundus of the stomach:
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rounded, superior portion, next to cardia
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body of the stomach:
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large, central portion
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pylorus of the stomach:
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connects to duodenum/small intestine
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name the 2 regions of the pylorus:
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-Pyloric Atrium
-Pyloric Sphincter |
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pyloric atrium:
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part that connects to the body of the stomach
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pyloric sphincter:
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connects to the duodenum
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Layers of the stomach:
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1) mucosa
2) aerolar connective 3) advendita |
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Mucosa layer of the stomach:
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-deepest inner lining
-has AEROLAR CONNECTIVE TISSUE, gastric glands, gastric pit... -gastric juices -proton pump -ATP -Carbonic Anhydrase |
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gastric juices:
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contains pepsinogen which helps to digest proteins, gastric lipase digests gas, and gastrin digests sugar
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proton pump:
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pumps ions into leumen of stomach
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ATP is
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Active Transport Pump
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Carbonic Anhydrase:
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need this to make protons for ATP
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Carbonic Hydrase Reaction:
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CO2 + H2O --> H2CO3 --> H + CO3
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What does the bicarbonate ion do?
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it helps to buffer blood
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why do you need hydrochloric acid?
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you need this in the stomach to kill microbes, and it denatures proteins, also stimulates hormones and promotes the secretion of bile and pancreatic juices
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Pepsin:
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-the inactive form of Pepsinogen
-digests protein, breaking peptide bonds that hold amino acids together |
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Gastric Lipase:
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-splits triglycerides into monoglycerides (a glycerol and a fatty acid)
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Pancreas:
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-located retroperitoneal, its a gland
-its 12-15 cm long -its connected to duodenum -its a series of ducts, secreting islet cells |
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Pancreatic ducts:
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make and secrete pancreatic juices, that empty into the first part of small intestine
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Islet cells:
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ENDOCRINE hormone portion , about 1%
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Asini:
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make pancreatic juices EXOCRINE, about 99 %
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Islet cells release:
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insulin, glucagon, somatostatin, pancreatic polypeptide
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how are insulin and glucagon released?
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in a paracrin fashion
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how are somatostatin and pancreatic polypeptides relased?
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in an autocrine fashion
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how much pancreatic juice is released in a day?
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1200-1500mL
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Pancreatic juice contains:
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H2O, salts, sodium bicarbonate (basic), enzymes....
*the sodium bicarbonate gives a slightly alkaline pH (basic) and since stomach is acidic, this helps to buffer gastric acid |
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Enzymes if pancreatic juices:
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-pancreatic amylase
-trypsin -chemotrypsin -carbxy peptidase -elastace -pancreatic lipase -ribonuclease -deoxyribonuclease |
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which enzymes digest starch?
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-pancreatic amylase
-trypsin -chemotrypsin -carbxy peptidase |
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which enzymes digest DNA?
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-ribonuclease
-deoxyribonuclease |
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what does elastace digest?
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muscle tissue
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what does pancreatic lipase digest?
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monoglycerides
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how many lobes in the liver?
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2
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what are the two sections of the liver?
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-Quadrate
-Caudate |
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what are the two lobes of the liver connected by?
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Falciform Ligament
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Coronary Ligaments:
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suspend liver in place
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3 regions of the gall bladder:
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-fundus: projects inferiorly beyond liver
-body: central portion covered by liver -neck: tapered portion |
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Hepatocytes:
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functional cells of liver and gall bladder
-make up 80% of cells |
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what are the hepatocytes function? and what do they secrete?
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function is to secrete, metabolic, and endocrine
-they secrete bile |
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Bile Canaliculi:
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ducts between hepatocytes
-they emerge to form right and left hepatic ducts, then merge to R. and L. hepatic ducts, then to common bile ducts |
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Hepatic Sinusoids
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blood capillaries that surround hepatocytes; they are highly permeable
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What makes up the functional portion of the liver?
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-hepatocytes
-bile canaliculi -hepatic sinusoids |
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Blood drainage from liver:
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-hepatic sinusoids
-liver sinusoids - venules -central vein -hepatic vein -inferior vena cava -right atrium... |
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What is Bile?
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its a digestive enzyme, excretory product
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what does the liver do for the body?
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-functions for carbohydrate metabolism, lipid metabolism, and protein metabolism
-it also processes drugs and hormones |
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what does the liver excrete?
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Bilirubin: helps to recycle iron and globulin
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what does the liver synthesize?
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bile salts. it uses small intestine to absorb lipids
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what does the liver store?
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-glycogens and vitamins (A, B12, D, E, K) these are lipid soluble vitamins... and iron (Fe) and Copper (Cu)
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How does the liver remove old RBC?
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phagocytosis (RBC are old after 120 days)
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What does the liver activate?
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vitamin D
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what does the gall bladder do?
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takes bile salts, forms bile and excretes it into small intestine
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what do the circular folds (ruffles) do in the small intestine?
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they increase surface area of intestine
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Microvilli:
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these increase the surface area of cells in the small intestine
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where does the small intestine begin and end?
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begins at Pyloric Sphincter, coild through the abdominal pelvic cavity and ends at the large intestine
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diameter of small intestine:
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about 1 inch/2.5 cm
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length of small intestine:
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3m/10 feet
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Duodenum:
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extends from pyloric sphincter to jejunm
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Jejunum:
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end of duodenum to ileum; its about 1 meter/3feet
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Ileum:
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about 2m/6ft, joins to large intestine
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Ileocecal Sphincter:
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where small intestine and large intestine join
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Absorptive cells:
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absorb the bile and nutrients necessary for digestion, they are ciliated cells
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Goblet cells:
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secrete mucous
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which cells are the intestinal glands made of?
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S cells, CCK cells, and K cells.
-they all secrete hormones, part of the endocrine system |
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what do the cells of the intestinal glands stimulate?
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they stimulate AcH and increase permeability of cells to absorb nutrients
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how are carbs digested?
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they're digested by enzymes released by SI.
-sucrase digests sucrose -lactase digests lactose -maltase digests maltose |
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Aminopeptidase:
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digests protein, breaks the bonds that hold protiens together
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Dipeptidase:
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digests proteins, breaks disulfide bonds
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how are lipids digested?
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digested by Emulsification: breaking large lipids into smaller lipids
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how are sugars digested?
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glucose and fructose are always absorbed through pores (facilitated diffusion)
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how are amino acids digested?
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they come in through active transport pumps in groups of 2-3 AAs, or one AA
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How are electrolytes digested?
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Na/K pump
(3 Na out, 2 K in) -also diffuse down gradient |
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how are fatty acids digested?
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Micelles! "beads of fatty acids", move in by diffusion
-A,D,E,K |
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how do b vitamins (except b120 and vitamin c absorbed?
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come in through osmosis
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Alcohol absorption:
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-absorbed very rapidly
-the longer it can stay in the stomach , the less it takes to get drunk.. |
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Gastric Alcohol Dehydrogenase:
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-levels are 60% lower in women than in men, it breaks down the alcohol into water, so this is why women get more drunk than men.
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what factors decrease the activity of Gastric Alcohol Dehydrogenase?
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-Estrogen decreases the level of GAD
-the more adipose tissue (fatter) the quicker they absorb the alcohol because body is used to digesting quicker. |
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function of the large intestine:
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-complete absorption of anything left in the digestive material
-production of vitamins -expulsion of feces -formation of feces |
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how long is large intestine?
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about 1.5m/ 5 feet
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what is the diameter of large intestine?
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6.5 cm/2.5 inches
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Mesocolon:
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a double layer of peritoneum, its how it attaches to the abdominal wall (it needs a double layer because its heavier)
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4 regions of the large intestine:
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-Cecum
-Colon -Rectum -Anal Canal |
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Cecum:
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small pouch area, beginning of the large intestine, branching off of it is the Apendix
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Apendix:
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coiled tube, secondary lymphoid organ
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4 regions within the colon:
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-ascending right
-transverse -left decending -sigmoid |
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how long is the rectum?
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last 20cm of the large intestine
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how long is the anal canal?
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terminal 2-3 cm of Large intestine
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Ileocecal Sphincter:
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valve that allows material from small intestine to go to the large intestine
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Anus:
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also a sphincter
-internal anal sphincter: smooth muscle, involuntary -external sphincter: skeletal muscle, voluntary |
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layer of the large intestine:
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-mucosa
-submucosa -muscularia |
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Mucosa layer of the LI
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deepest layer, goblet cells secrete mucous
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submucosa layer of the LI
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areolar connective tissue, has glands that make vitamins
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Muscularia layer of the LI
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Lognitudinal smooth muscle AND circular smooth muscle
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what does the circular smooth muscle do?
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compacts the feces
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what does the longitudinal smooth muscle do?
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allows expulsion to occur
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serosa:
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viseral peritoneum
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Gastroileal Reflex:
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movement of food in digestive tract, forces material into the cecum. It intensifies peristalsis, converts material into chyme
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chyme
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digested food in small intestine
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what is gastrin?
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its a hormone released by the stomach that relaxes the sphincters of the gastrointestinal tract. the stomach releases this when its 1/2 -2/3 of the way full
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What does gastrin do?
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-causes mass peristalsis and opening of sphincters
-signals brain that you are no longer hungry --effects last up to 3 to 4 days --*smoking blocks gastrin release |
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Defecation Reflex:
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-emptying rectum
-there are stretch receptors that signal involuntary reflex, the longitudinal muscles shorten within the anal canal (you don't feel this) -external sphincter recieves signal from somatic motor neuron (this lets you know you need to have a bowel movement) |