Week 7 digestive system Flashcards
Transports food from mouth to esophagus
Pharynx
Transports food into Stomach
Esophagus
Organ that Produces Chyme
sromach
Organ that Digest and absorbs food
Small Intestines
where feces is stored
rectum
Organ that Absorbs water, Produces feces and Vit K
Large Intestine
There are two types of motility within the Gastrointestinal tract:
Peristalsis
Segmentation
Motility is possible due to the following:
Plexus located within the digestive organs & Smooth muscle found within the digestive organs
What are the two types of plexus located within the digestive organs?
Submucosal &
Myentric
Where does peristalsis take place?
esophagus and stomach
What is the function of perstalsis?
Moves food down the GI tract ,
Coordinated muscle movement, muscles behind food contract
Random smooth muscle contraction :
SEGMENTATION
submucosal plexus is located where?
the submucosa of the organ
where is myentric plexus located?
muscle of the organ
What is segmentation?
Random smooth muscle contraction
Where is segmentation located?
small intestines
What is the function of segmentation?
Mixes food with digestive secretions
What is chyme?
semi digested food
What are the two main functions of the stomach?
Digestion and storage
How does digestion in the stomach work?
gastric juice breaks down food into semi digested food-chyme
How does storage in the stomach work?
sends food in small segments to the duodenum , storing some
What are the three gastric glands found in the stomach?
Mucus neck cells, parietal cells and chief cells
What do the gastric glands secrete and produce?
gastric juice
Where do the gastric glands secrete their products?
into the gastric lumen
What are mucus neck cells and what are their functions?
Produces mucus which is the alkaline layer and protects against acid
What do parietal cells secrete?
HCl and intrinsic factor
What is the function of HCl?
converts pepsinogen to pepsin
What is the function of the intrinsic factor?
Vitmin b12 absorption
What do chief cells secrete?
Pepsinogen
What is pepsin and its function?
the active form of pepsinogen, pepsin breaks down proteins
The small intestines have three main segments:
Duodenum, jujenum, and illeum
What is the function of the duodenom?
digestion, breaks down macromolecules to monomers
What digestive secretions does the duodenum contain to help with digestion?
Digestive enzymes trypsin, amylase, and lipase. & bicarbonate and bile
The digestive enzymes in the duodenum are produced and released from the _________.
pancreas
What is the function of trypsin?
protein breakdown
What is the function of amylase?
carbohydrate breakdown
What is the function of lipase?
fat breakdown
What is the function of bicarbonate?
neutralizes HCl
What is the function of bile?
lipid emulsification, secreted by the gallbladder, produced by the liver
What is the function of the jejunum and ileum?
absorption
What are the three functions of large intestines?
vitamin K production by bacteria eating food, absorption of water, and production of feces
What are the functions of the liver?
creates plasma (clotting) proteins, creates albumin, it detoxifies chemicals, produces RBCs during fetal life, activates vit D, converts glucose into glycogen, converts amonia to urea, bilirubin metabolism, and creates bile
Bilirubin metabolism steps:
heme oxygenase breaks apart iron and carbon monoxide forming biliderdin, biliverdin is then converted to unconjugated bilirubin via biliverdin reductase, Unconjugated bilirubin is dumped into the blood and binds with albumin, unconjugated bilirubin then goes to the liver and is converted to conjugated bilirubin via glucuronyl-bilirubin transferase, conjugated bilirubin is then dumped into bile, via the bile it travels to small intestines, conjugated bilirubin w/in small intestines converts to urobilinogen, some urobilinogen converts to stercobilin and some goes to the kidneys, urobilinogen in the kidneys is converted to urobilin and is secreted in urine giving it the yellow color
what happens to the stercobilin in the intestines?
secreted in stool giving it the orange-brown color
What is the function of the gallbladder ?
stores bile and secretes it
What is the function of the exocrine portion of the pancreas?
Secretes lipase, amylase, trypsin, and bicarbonate into duodenum.
What are the three phases of digestion ?
Cephalic phase, gastric phase, and intestinal phase
What is the mechanical portion of digestion?
chewing/chomping breaking down food
What is the chemical portion of digestion?
starts in mouth, occurs in stomach and duodenum.
Steps of cephalic phase:
sensory input-> hypothalamus-> stimulates hungar satiety center-> this causes hunger (consequently causing, salvation, gi motility, gastric juices, les relax)-> stomach stretches after eating-> this causes neuropeptide y to be released-> this chemical then goes to hypothalamus stopping hunger
Steps of gastric phase:
Starts once food enters the stomach->Stretching causes Gastrin release-> vagal stimulation causes further broken down of food due to peristalsis and gastric juice ->chyme is produced
What causes the hormone gastrin to be released?
Stomach (stretching & proteins), vagal stimulation
Gastrin is secreted by :
G cells; Stomach, Duodenum & Pancrease
Gastrin secretes :
Hcl, Histamine , K/H ATPase pump (insertion), Increase gastric motility
Parietal cell has 3 receptors:
Musaniric cholinergic receptor for acetylcholine, gastrin receptor for gastrin, H2 receptor for histamine
Parietal cell has three pumps _________________, ___________, ___________, which are all primary active pumps so they require ____.
alkaline tide pump, K/Cl pump, and H/K pump, ATP
ATP production for HCl:
Acetylcholine, Gastrin and Histamine all bind to their receptors -> causes intercellular Ca levels to increase -> Ca activates protein kinase -> protein kinase converts ADP to ATP (adds a phosphate to ADP).
HCL production:
Having CO2 and H20 combine to form H2CO3->
