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What substance can be partially digest in the oral cavity?
Starches (by salivary amylase)
How are drugs absorbs into the blood stream via oral cavity?
Some drugs (lipid soluble) can be absorbed underneath the tongue where the mucosa of the oral cavity is very thin.
How peristalsis moves content through the GI tract?
- Longitudinal muscle contract ahead of the bolus and the circular muscle contract behind the bolus Which push it forward.
- This happens in a wavelike motion throughout the GI tract.
Where the myenteric and the submucosal plexuses located and what they control?
- The myenteric plexus located in the muscolaris, it controls muscular involuntary muscular contraction in the GI tract.
- The submucosal plexus located in the submucosa layer, in controls digestive secretions of the GI tract
What two nerve plexuses components of the enteric nervous system?
- Submucosal plexus
- Myenteric plexus
Is the muscularis a skeletal muscle or smooth?
What directions the muscle layers run in the muscularis?
- Longitudinal muscle (outermost layer) runs at the long axis of the GI tract.
- The circular muscle runs around the lumen.
What type of epithelium are found in different areas of the GI tract?
- Stratified squamous epithelium in the beginning (oral cavity, pharynx and upper part of the esophagus) and the end part (anus).
- Simple columnar epithelium in the rest of the GI tract.
How is mechanical break down different from chemical break down?
- Mechanical breaks down solid chunks of food into smaller peaces (Bolus) by the teeth and tongue.
- Chemical breakdown (digestion) breaks down chemical bond (Big molecules of food into smaller molecules) by enzymes.
What are the functions of the digestive system?
- Ingestion: food and liquid enter via oral cavity.
- Mastication:(chewing) mechanical break of solid food.
- Propulsion: move food doown th GI tract via perisltalsis.
- Digestion: chemical breakdown.
- Absorption: nutrients, vitamins, water, ions,etc.
- Elimination: waste lost in feces
Which structures it the digestive system considered accessory structures?
Liver, pancreas, salivary glands, and gallbladder.
What stimulate the release of gastrin?
Gastrin release stimulated by arrival of undigested proteins and/or caffeine in the stomach
Where do the nutrients that are absorbed in the small intestine go?
- To the rest of the body cells as needed.
- Small sugars and amino acids via blood vessels.
- Lipids via lectile.
What are the functions of the small intestine?
Digestion and nutrient absorption
What occurs as result of the gastrointestinal phase?
Decrease gastric secretion.
What initiates the gastrointestinal phase?
Emptying of the stomach
What occur as result of the gastric phase?
- Trigger digestion in the stomach.
- Increase gastric secretion.
What will initiate gastric phase of regulation?
Stretch in the stomach walls due to arrival of food.
How will gastric secretion change as result of cephalic phase?
Thoughts, smell, and taste of food will trigger gastric secretion in preparation for the arrival of food to the stomach.
What trigger cephalic phase of gastric secretion?
Thoughts, smell, and taste of food.
Why is acidic environment in the stomach is so important?
- Deactivate salivary enzymes.
- Activate pepsinogen that become pepsin.
- deteriorates proteins (start proteins break down)
- Effect plant walls (make them softer)
- Kills microorganism
List the steps that occur during the formation of HCl in the stomach.
- CO2 enters the parietal cell from the blood stream.
- CO2 combine with H2O and become H2CO3 (carbonic acid)
- H2CO3 disassociate to HCO3 and H+. HCO3 (bicarbonate) Move out of the parietal cell in exchange to Cl- (alkaline tide).
- H+ is pumped via ion pump to the gastric pit in exchange to K+.
- The Cl- defuse into the gastric pit. There the Cl- and the H+ combine = HCl.
Why mucus produced in the stomach wall important?
T protect the cells in the stomach walls from Hydrochloric acid.
Why does little to no nutrients absorbed in the stomach?
- Not enough digestion occur in the stomach.
- Mucus that protects the wall of the stomach from the HCl, prevent nutrients absorption through the stomach walls.
List the major functions of the stomach.
- Store food
- Mixing food with liquids to make chyme.
- Limited digestion (of proteins)
Why the additional muscle layer in the stomach is important?
The Oblique muscle is additional muscle layer in the stomach. It is important for mixing the chyme.
Connects the liver to the body wall
Connects the appendix to the body wall
Connects the transverse colon to the body wall
Connects the sigmoid colon to the body wall.
Connects the stomach to the intestine.
Connect the stomach to the liver
Connect the small intestine to the body wall.
What is mesentery?
Two layers of peritoneum with connective tissue between them that anchor the the organs of the peritoneum cavity in place.
Where is the peritoneal cavity located?
In the abdominopelvic cavity.
What dose the visceral peritoneum cover?
The organs in the peritoneal cavity.
What does the parietal peritoneum cover?
The abdominopelvic cavity wall.
What are the three phases of swallowing? What occur during each phase?
- Buccal Phase: Chewing (mechanical break down), formation of bolus, move bolus toward oropharynx.
- Pharyngeal Phase: Coordinate movement by the medulla oblongata to move bolus (mainly involuntary).
- Esophageal Phase:Push bolus by wave of perilstasis (Involuntary).
Is swallowing voluntary or involuntary?
Both. The buccal phase and a small part of the pharyngeal phase are voluntary. All the rest is involuntary.
What type of muscle(s) is found in the walls of the esophagus?
- Top 1/3 all skeletal muscles.
- Middle 1/3 smooth & skeletal muscles.
- Lower 1/3 all smooth muscles.
Which are the two sphincters found in the esophagus and what are their functions?
- Upper esophageal sphincter: keeps air out of the GI tact.
- Lower esophageal sphincter: keeps stomach content from back up into the esophagus.
What are the effects of gastric inhibitory peptide?
- Decrease gastric secretion.
- Increase insulin release.
- increase adipose synthesis (make fat cells)
What triggers the release of gastric inhibitory peptide?
Chyme high in fats & carbohydrates
What occur as result of CCK secretion?
- Increase enzyme (that breaks lipids & proteins) secretion from the pancreas.
- Increase bile release from the gallbladder.
- Decrease gastric secretion.
What stimulates the release of CCK (cholecystokinin)?
High lipids and /or proteins in the chyme
What effect visoactive intestinal peptide have?
- Dilate capillaries in the intestinal vili (allow more nutrient obserption).
- Increase intestinal secretion
What trigger the release of vasoactive intestinal peptide?
Any kind of bile in the duodenum.
What are the effects of secretin?
- Increase secretion of aqueous component pancreas (a buffer secreted by the pancreas).
- Increase bile production.
- Decrease gastric secretion
What is the stimulus for the release of secretin?
Arrival of acidic chyme from the stomach to the duodenum.
What occurs in response to an increase gastrin secretion?
- Increased gastric motility (mixing movement)
- Increase gastric secretions (of chief cells ans parietal cells)
- Activated form of the pro-enzyme procarboxypeptidase in the pancreas.
- Carboxypeptidase digests proteins.
- Activated form of the pro-enzyme Trypsinoge in the pancreas (activated by brash border enzyme Enteropeptidases).
- Typsin will activate the rest of the pro-enzymes of the pancreas.
- Hormone secreted by D cells in the stomach that inhibit secretion of gastrin.
- Indirect inhibit gastric secretion
Enzyme secrete in the mouth cavity that breaks down starches & carbohydrates.
Secreted by chief cells in infant's stomach breaks down milk proteins.
brash border enzyme that breaks down sucrose into glucose + fructose
A brash border enzyme that breaks down proteins into amino acids
- The activated form of pepsinogen (activated by HCl).
- Enzyme secreted by adult chief cells in the stomach that breaks down proteins.
Pancreatic alpha amylase
Enzyme secreted by the pancreas that digests carbohydrates & starches.
Hormone secreted by G cells in the stomach that decrease hunger
Enzyme secreted by the pancreas that digests nucleic acids (DNA & RNA)
Brash border enzyme that breaks down maltose into two molecules of glucose
Enzyme in the mouth cavity that begins the digestion of lipids.
Brash border enzyme that breaks down lactose into glucose + galactose
- Secreted by parietal cells in the stomach.
- Helps in absorption of vitamin B12
Hydrochloric acid in the stomach
Hormone secreted by G cells in the stomach that initiates hunger
Hormone secreted by G cell in the stomach that activates gastric secretions of chief cells & parietal cells.
Enzyme that secreted by chief cells in an infant stomach that digests milk fats.
Enzyme secreted by the pancreas that breaks down elastin protein.
An enzyme secreted by the pancreas that digest proteins
Aqueous pancreatic secretion.
A buffer high in HCO3 that secreted from the pancreas.
Secreted from brunner's glands in the small intestine to rise the PH of the chyme that comes from the stomach.
- Behind the parietal peritoneum layer.
- The pancreas and most of the duodenum located there.
A droplet with hydrophilic portion on the outside.
Production of glucose by carbohydrate metabolism in the liver.
Ripples in the inner walls of the stomach that increase surface area and allow the stomach to stretch.
Fixed macrophage in the liver
Bring food & liquid in the mouth cavity.
HCO3 move out of the parietal cell in exchange to Cl-
How secretion from the major duodenal papilla different from the secretion of the minor duodenal secretion?
- The major duodenal papilla secrets bile & pancreatic secretions into the duodenal.
- The minor duodenal papilla secrets only pancreatic secretion into the duodenum.
Know the pathway of the duct system of the liver.
- Left & right hepatic ducts merge to common hepatic duct (contain bile secreted from the liver).
- Cystic duct contains bile that gos in and out of the gallbladder.
- the cystic & common hepatic ducts merge and become the common bile duct.
- The common bile duct merge with pancreatic duct and become the Hepatopancreatic ampulla.
How pro-enzymes in the pancreas are activated?
- Trypsinogen will be activated by Enterokinase (a brash border enzyme of the duodenum)
- Trypsin (an activated trypsinogen) will activate the rest of the pancreatic pro-enzymes.
- Chymotrisinogen → Chymotripsin
- Procarboxypeptidase → carboxypeptidase
- proelastate → Elestate
Which portion of the pancreas is part of the digestive system?
The Exocrine part: Consist of Acini cells that making digestive secretion of the pancreas.
How bile salts assist with break down of fats?
- Bile salts emulsify big drop of fat into many smaller droplets that increases its surface area.
- This make it easy to pancreatic lipase (a non lipid soluble enzyme) to digest lipid from the surface of the droplets.
Where are alcohol and drugs detoxified?
smooth ER of the liver cells
What can be stored in the liver?
- Vitamins: A, D, E, K, and B12
What happen when the liver deaminatates proteins?
- Deamination = removal of the amino group from amino acid.
- The amino group can be used to make ATP by cellular respiration.
How the liver metabolizes fats?
The liver regulates triglycerides, fatty acids, and cholesterol. If the level of those decrease, liver will break down reserved lipids and release it to the bloodstream. If the level of those increase, the liver remove them from the bloodstream and store them as lipids.
How the liver will respond to increase of blood glucose?
The liver will remove glucose from the blood stream then, the liver, will either store it as glycogen or use it to synthesize lipids that can be stored in the liver or in other parts of the body.
How will the liver respond to decrease of blood glucose?
the liver will break down stored glycogen into glucose and release it to the blood stream.
Where is bile made? Where is it stored?
- Made in the liver
- stored in the gallbladder
Which division of the ANS will increase saliva production?
What are the function of the large intestine (the whole thing)?
1,500 mL enters
- Absorb biotin, vitamin K & B5 (as result of bacteria activity).
- Absorb water (over 1 L per day).
- eliminate waste as feces: 75% water, 5% bacteria, 20% undigested material.
the colon and only 200 mL ejected
as feces = 1,300 mL absorbed
by the colon each day.
A brush border enzyme in the duodenum that activates trypsinogen to trypsin in the pancreas.