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110 Cards in this Set

  • Front
  • Back
Gastrointestinal Tract
AKA Alimentary Tract
-includes mouth, most of pharynx, esophagus, stomach, small & large intestine
how long is the gastrointestinal tract?
5-7 meters long (16-23 feet)
Accessory organs include:
teeth, tounge, salivary glands, liver, gallbladder, pancreas
What is deglutition?
its the movement of food from mouth to stomach
-it involves the mouth, pharynx, and esophagus
3 stages of deglutition:
1) voluntary stage
2) pharyngeal stage
3) esophageal stage
voluntary stage of deglutition:
-use teeth for mastication (chewing) and get the food into a bolus (takes about 25 munchings)
-bolus then passes into oropharynx
pharngeal stage of deglutition:
-begins involuntary passage of bolus through the esophagus into stomach
esophageal stage of deglutition:
-esophagus to stomach
What is GERD?
Gastoesophageal Reflux disease: when stomach acid moves into the esophagus and errods away the wall of esophagus, causing heart burn
name the 4 regions of the stomach:
-cardia
-fundus
-body
-pylorus
cardia of stomach:
surrounds superior opening of the stomach
fundus of the stomach:
rounded, superior portion, next to cardia
body of the stomach:
large, central portion
pylorus of the stomach:
connects to duodenum/small intestine
name the 2 regions of the pylorus:
-Pyloric Atrium
-Pyloric Sphincter
pyloric atrium:
part that connects to the body of the stomach
pyloric sphincter:
connects to the duodenum
Layers of the stomach:
1) mucosa
2) aerolar connective
3) advendita
Mucosa layer of the stomach:
-deepest inner lining
-has AEROLAR CONNECTIVE TISSUE, gastric glands, gastric pit...
-gastric juices
-proton pump
-ATP
-Carbonic Anhydrase
gastric juices:
contains pepsinogen which helps to digest proteins, gastric lipase digests gas, and gastrin digests sugar
proton pump:
pumps ions into leumen of stomach
ATP is
Active Transport Pump
Carbonic Anhydrase:
need this to make protons for ATP
Carbonic Hydrase Reaction:
CO2 + H2O --> H2CO3 --> H + CO3
What does the bicarbonate ion do?
it helps to buffer blood
why do you need hydrochloric acid?
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
Pepsin:
-the inactive form of Pepsinogen
-digests protein, breaking peptide bonds that hold amino acids together
Gastric Lipase:
-splits triglycerides into monoglycerides (a glycerol and a fatty acid)
Pancreas:
-located retroperitoneal, its a gland
-its 12-15 cm long
-its connected to duodenum
-its a series of ducts, secreting islet cells
Pancreatic ducts:
make and secrete pancreatic juices, that empty into the first part of small intestine
Islet cells:
ENDOCRINE hormone portion , about 1%
Asini:
make pancreatic juices EXOCRINE, about 99 %
Islet cells release:
insulin, glucagon, somatostatin, pancreatic polypeptide
how are insulin and glucagon released?
in a paracrin fashion
how are somatostatin and pancreatic polypeptides relased?
in an autocrine fashion
how much pancreatic juice is released in a day?
1200-1500mL
Pancreatic juice contains:
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
Enzymes if pancreatic juices:
-pancreatic amylase
-trypsin
-chemotrypsin
-carbxy peptidase
-elastace
-pancreatic lipase
-ribonuclease
-deoxyribonuclease
which enzymes digest starch?
-pancreatic amylase
-trypsin
-chemotrypsin
-carbxy peptidase
which enzymes digest DNA?
-ribonuclease
-deoxyribonuclease
what does elastace digest?
muscle tissue
what does pancreatic lipase digest?
monoglycerides
how many lobes in the liver?
2
what are the two sections of the liver?
-Quadrate
-Caudate
what are the two lobes of the liver connected by?
Falciform Ligament
Coronary Ligaments:
suspend liver in place
3 regions of the gall bladder:
-fundus: projects inferiorly beyond liver
-body: central portion covered by liver
-neck: tapered portion
Hepatocytes:
functional cells of liver and gall bladder
-make up 80% of cells
what are the hepatocytes function? and what do they secrete?
function is to secrete, metabolic, and endocrine
-they secrete bile
Bile Canaliculi:
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
Hepatic Sinusoids
blood capillaries that surround hepatocytes; they are highly permeable
What makes up the functional portion of the liver?
-hepatocytes
-bile canaliculi
-hepatic sinusoids
Blood drainage from liver:
-hepatic sinusoids
-liver sinusoids - venules
-central vein
-hepatic vein
-inferior vena cava
-right atrium...
What is Bile?
its a digestive enzyme, excretory product
what does the liver do for the body?
-functions for carbohydrate metabolism, lipid metabolism, and protein metabolism
-it also processes drugs and hormones
what does the liver excrete?
Bilirubin: helps to recycle iron and globulin
what does the liver synthesize?
bile salts. it uses small intestine to absorb lipids
what does the liver store?
-glycogens and vitamins (A, B12, D, E, K) these are lipid soluble vitamins... and iron (Fe) and Copper (Cu)
How does the liver remove old RBC?
phagocytosis (RBC are old after 120 days)
What does the liver activate?
vitamin D
what does the gall bladder do?
takes bile salts, forms bile and excretes it into small intestine
what do the circular folds (ruffles) do in the small intestine?
they increase surface area of intestine
Microvilli:
these increase the surface area of cells in the small intestine
where does the small intestine begin and end?
begins at Pyloric Sphincter, coild through the abdominal pelvic cavity and ends at the large intestine
diameter of small intestine:
about 1 inch/2.5 cm
length of small intestine:
3m/10 feet
Duodenum:
extends from pyloric sphincter to jejunm
Jejunum:
end of duodenum to ileum; its about 1 meter/3feet
Ileum:
about 2m/6ft, joins to large intestine
Ileocecal Sphincter:
where small intestine and large intestine join
Absorptive cells:
absorb the bile and nutrients necessary for digestion, they are ciliated cells
Goblet cells:
secrete mucous
which cells are the intestinal glands made of?
S cells, CCK cells, and K cells.
-they all secrete hormones, part of the endocrine system
what do the cells of the intestinal glands stimulate?
they stimulate AcH and increase permeability of cells to absorb nutrients
how are carbs digested?
they're digested by enzymes released by SI.
-sucrase digests sucrose
-lactase digests lactose
-maltase digests maltose
Aminopeptidase:
digests protein, breaks the bonds that hold protiens together
Dipeptidase:
digests proteins, breaks disulfide bonds
how are lipids digested?
digested by Emulsification: breaking large lipids into smaller lipids
how are sugars digested?
glucose and fructose are always absorbed through pores (facilitated diffusion)
how are amino acids digested?
they come in through active transport pumps in groups of 2-3 AAs, or one AA
How are electrolytes digested?
Na/K pump
(3 Na out, 2 K in)
-also diffuse down gradient
how are fatty acids digested?
Micelles! "beads of fatty acids", move in by diffusion
-A,D,E,K
how do b vitamins (except b120 and vitamin c absorbed?
come in through osmosis
Alcohol absorption:
-absorbed very rapidly
-the longer it can stay in the stomach , the less it takes to get drunk..
Gastric Alcohol Dehydrogenase:
-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.
what factors decrease the activity of Gastric Alcohol Dehydrogenase?
-Estrogen decreases the level of GAD
-the more adipose tissue (fatter) the quicker they absorb the alcohol because body is used to digesting quicker.
function of the large intestine:
-complete absorption of anything left in the digestive material
-production of vitamins
-expulsion of feces
-formation of feces
how long is large intestine?
about 1.5m/ 5 feet
what is the diameter of large intestine?
6.5 cm/2.5 inches
Mesocolon:
a double layer of peritoneum, its how it attaches to the abdominal wall (it needs a double layer because its heavier)
4 regions of the large intestine:
-Cecum
-Colon
-Rectum
-Anal Canal
Cecum:
small pouch area, beginning of the large intestine, branching off of it is the Apendix
Apendix:
coiled tube, secondary lymphoid organ
4 regions within the colon:
-ascending right
-transverse
-left decending
-sigmoid
how long is the rectum?
last 20cm of the large intestine
how long is the anal canal?
terminal 2-3 cm of Large intestine
Ileocecal Sphincter:
valve that allows material from small intestine to go to the large intestine
Anus:
also a sphincter
-internal anal sphincter: smooth muscle, involuntary
-external sphincter: skeletal muscle, voluntary
layer of the large intestine:
-mucosa
-submucosa
-muscularia
Mucosa layer of the LI
deepest layer, goblet cells secrete mucous
submucosa layer of the LI
areolar connective tissue, has glands that make vitamins
Muscularia layer of the LI
Lognitudinal smooth muscle AND circular smooth muscle
what does the circular smooth muscle do?
compacts the feces
what does the longitudinal smooth muscle do?
allows expulsion to occur
serosa:
viseral peritoneum
Gastroileal Reflex:
movement of food in digestive tract, forces material into the cecum. It intensifies peristalsis, converts material into chyme
chyme
digested food in small intestine
what is gastrin?
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
What does gastrin do?
-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
Defecation Reflex:
-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)