by jwilli


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What are the primary functions of the digestive system?
Digestion and Absorption
What are the secondary or other functions of the Digestive System?
Motility, Secretion and Storage/Elimination
How is digestion conducted...what type of reactions?


Hydrolysis reactions.  Large molecules  are broken down into monomers
How is absorption specifically done...what is trasported and where?
Monomers are transported across the wall of the small intestine
What two parts of the digestion system conduct absorption?
Lymphatic system and Circulatory system
Motility includes these processes?
Ingestion, Mastication, deglutition and Peristalsis
Secretion involves these two systems?
Exocrine and Endocrine systems
Exocrine secretions include these?
Water, Hydrochloric acid, bicarbonate, and digestive enzymes
Where do endocrine secretions occur?
Stomach and small intestine that secrete a number of hormones
Endocrine secretions are important because they regulate this?
Digestive system
The GI tract is composed of this?
Oral Cavity, pharynx, esophagus, stomach, small intestine and large intestine
How long is the GI tract from mouth to anus?
30 ft (approx)
What are accessory to the digestive organs or viscera?
Teeth, tongue, salivary glands, liver, gallbladder and pancrease
What are the layers of the GI tract?
Mucosa, Submucosa, Muscularis, Serosa
Is digestion happening inside or outside the body?
Outside.  Unless it crosses into the body it is technically outside.
Of the four layers of the GI tract which one is primarily involved in absorption and secretion?
Mucosa:  absorptive and major secretory layer
Which layer of the GI tract is responsible for contractions and peristaltic movement?
Muscularis
Which layer of the GI tract is highly vascularized?
Submucosa

This layer of the GI tract is primarily involved with binding and protection
Serosa (the last layer..furthest from the food)

The GI tract is composed of these basic structures (there are four...very basic)
Esophagus, Stomach, Small Intestine, Large Intestine
Esophagus connects what two areas?
Pharynx and stomach
The terminal portion of the espophagus is called this?
Gastroespophageal sphincter
The Gastroespophageal sphincter prevents this from happening?
Regurgitation of stomach contents into the esophagus
What is regurgitation exactly?
Entry of acidic contents into the espophagus that can lead to heartburn or GERD
Why do infants spit up their food?
The function of the Gastroespophageal sphincter is erratic and this causes them to spit up their food
The stomach empties into this specific region of the small intestine?
Duodenum
What is the function of the stomach?
To store and digest food and gastric juice
What are the function(s) of gastric juice?
To create an acidic environment and to kill microorganisms
What are the three regions of the stomach?
Fundus, Body and pyloric region
Stomach has many Gastric Glands..name all six and what they secrete. (Your a playa if you can do this!)
Goblet cells-->Mucus
Chief cells--> Pepsinogen
Parietal cells-->HCl
Enterochromaffin-like (ECL) --> Histamine
G-cells --->gastrin
D-cells - -> Somatostatin
What is required for the intestinal absorption of vitamin B12?
Intrinsic factor
The parietal cell secretes ____ through these type of pumps?
H+ through H+/K+ ATPase pumps
The parietal cells secrete Cl- through this type of diffusion?
Facilitative
Connect the concept of G-cells, ECL cells and Parietal cells
The G-cells secrete gastrin, and gastrin stimulates the ECL cells to release histamine.  Acetylcholine also stimulates the ECL cells to release histamine.  Histamine then stimulates parietal cells to release HCL, H+ through the H+/K+ ATPase and Cl- through facilitated diffusion.
The stomach creates a very acidic environment and the pH is usually ____, but can sometimes can reach _____, when the Parietal cells are overreactive
pH of 2, sometimes reach 0.8
The acidic condition serves these three functions?
1) Denature proteins
2) Activates or converts pepsinogen to pepsin
3) Provides an ideal condition for pepsin which is more active with a pH of less than 2.0
The small intestine is located between these two locations?
Pyloric sphincter of the stomach and the ileocecal valve opening in the large intestine
The small intestine is the largest portion of the GI tract and is approximately this long?
12ft
The small intestine is divided up into these three sections?
Duodenum, jejunum, ileum
The small intestine is primarily responsible for?
Absorption
The duodenum and jejunum absorbs these?
Carbohydrates, lipids, AA's, calcium and Iron
The Ileum absorbs these?
Bile salts, vitamin B12, water and electrolytes
What is the brush border?
Microvilli that are located on the apical surface of the epithelial cells in the smal intestine
What are the brush border enzymes?
Lactase and Enterokinase
What are the symptoms of lactase intolerance?
Diarrhea, gas, cramping
Why is yogurt more tolerable form of lactase?
It contains lactase from bacteria
How do contractions occur in the small intestine?
They occur automatically by pacemaker cells that are triggered by action potentials originating from Voltage gated Ca+ channels.
What promotes the contractions and motility in the small intestine?
Acetylcholine
Contractions in the small intestine is done by these two major general concepts?
Peristalsis and Segmentation
Where does peristalsis occur in the GI?
Esophagus, stomach and Small Intestine. (Stronger in the esophagus and stomach)
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