Flashcards in Digestive System Deck (81):
What is ingestion?
Taking of food and liquid into the mouth
What is mechanical digestion?
Physically ripping nutrients apart
What performs mechanical digestion in the mouth, stomach, and small intestine?
Mouth - teeth
Stomach - rugae
Small intestine - churning
What is chemical digestion?
Breaking of larger molecules into smaller particles via hydrolysis through enzymes
What is absorbtion?
The moving of ingested and secreted fluids into the epithelial cells lining the lumen of the GI tract
What is defecation?
Shit: waste composed of indigestible substances, bacteria, sloughed off cells and digested materials that are not reabsorbed
What is propulsion?
Alternate contractions and relaxations of smooth muscle in the walls of the GI tract, mixes food and secretions
What intestinal function is included in propulsion?
What is the name of the action of chewing with your teeth?
What is salivary amylase?
An enzyme in saliva that begins chemical breakdown of starch
What is lingual lipase?
Salivary enzyme the begins breakdown of fats
What are the three general layers of the tooth?
The crown, the neck, and the root
List the teeth
2 incisors, 1 canine, 2 bicuspids, 3 tricuspids
What is the mechanism of tasting?
Via taste buds called papillae
What is the name of the sense of taste?
Which 3 glands control salivation?
Parotid, submandibular, and sublingual
What are the 4 layers of GI tract histology?
Serosa, muscularis externa, submucosa, mucosa
What is the role of the serosa?
To hold organs in place and cover them
What is the role of muscularis externa in the stomach?
3 different layers of muscle which aid in churning food and controlling movement of chyme
What do chief cells secrete?
What do parietal cells secrete?
HCl and intrinsic factor
What is the function of intrinsic factor?
Vitamin B12 absorption
In what disease is vitamin B12 missing?
What is the role of mucous cells in the stomach?
To secrete mucus to protect the stomach from HCl
What is pepsin?
An enzyme that digests proteins, severs peptide bonds between amino acids
What is does HCl do in the stomach?
Partially unfolds protein and stimulates secretion of hormones that promote the flow of bile and pancreatic juice; activates pepsinogen to pepsin
What protects the stomach from digesting itself?
What does the stomach break proteins into?
Tripeptides and bipeptides
What is the relationship between carbohydrate digestion and the stomach?
There is minimal carb digestion in the stomach
What are the 2 main fluids secreted by the pancreas?
Enzymes and bicarbonate
What is the role of bicarbonate?
Raise pH of SI
Is the pancreas endocrine or exocrine?
Exocrine (uses ducts and tubes)
What is the role of proteases?
Break down proteins in different locations along the amino acid chain
What is trypsin?
Initially trypsinogen, activated by enterokinase in the duodenum
What is chymotrypsin?
Secreted initially as chymotrypsinogen, activated by trypsin in duodenum
What is carboxypeptidase?
Initially procarboxypeptidase, activated by trypsin in duodenum
In the pancreas what breaks starches into disaccharides and trisaccharides?
What breaks down emulsified triglycerides into fatty acids and monoglycerides in the pancreas?
What is the role of deoxyribonuclease?
Breaking DNA into nucleiotides
What is the role of ribonuclease?
Breaking RNA into molecules
What is the primary role of the liver?
To form and secrete bile - bile acids help break down fats
What is emulsification?
The process of breaking fat into smaller globules, creating a larger surface for enzyme attack
What is the primary detoxifying organ in the body?
The liver - detoxs and processes nutrients just absorbed by the intestines
What kind of problems can liver damage cause?
Jaundice, low immunity, abdominal pain
What proteins does the liver manufacture and what would the loss of them cause?
Albumin and immunoglobins - loss would cause low albumin with swelling and low immunity
Trace the path of a nutrient into the liver
- absorbed in SI to epithelial cells
- cross cells to capillaries
- capillaries merge
- move in portal vein
- in liver which decides how to process them
Trace the path of fats through the body
- absorbed through epithelium
- into lacteals
- then into lymph vessels
What are the primary liver infections?
Hepatitis A, B, C, D, and E
What is Hepatitis A?
Food-borne, acute, common, blood carries it
Which form of Hepatitis is less common?
How is Hep C transmitted?
Blood transfusion, drug needles; chronic, slow progression
Where is bile stored?
How long is the SI?
What is segmentation?
The rhythmic contraction of circular muscles, causes sloshing and mixing of chyme with intestinal fluids; sloshes chyme against mucosa to increase absorption
Does segmentation move food along the intestines?
How long is the Large intestine?
What is the function of the appendix?
Unknown, perhaps immunity
What is the difference between chronic and acute appendicitis?
Chronic is less common and dull pain, acute is intense
Trace the pathway of a carbohydrate
- converted to ATP
- stored in liver and muscles
- polysaccharides broken into sugars (mono and di)
- give energy
Why do lipases need to remove fatty acids from triglycerides?
We can't absorb the whole triglycerides into the intestinal cells
Does glycerol get absorbed alone?
NO, it must have at least one fatty acid attached
What nutrient do fats help us absorb?
What do proteins provide for the body?
Structures (hair, muscles, ect.), enzymes, antibodies, albumin, etc
What does fiber do?
Helps move bulk stool through the intestines
How are Carbs absorbed?
Glucose and galactose are absorbed in the SI via active transport (requires energy)
How is fructose absorbed?
In the SI via facilitated diffusion and then into the bloodstream
How is protein absorbed?
In the SI via active transport (amino acids, dipeps., tripeps.)
How are triglycerides absorbed?
In the SI via simple diffusion, then into a lacteal of a villus
What are the three distinct phases of digestion?
1. Cephalic reflex
2. Gastric reflex
3. Intestinal reflex
How does the cephalic reflex phase work?
See/smell food and brain triggers start of digestive reaction (saliva, gastric juice)
How does the gastric reflex phase work?
Stomach distends, peristalsis wave begins, gastric juice flows, happens because stretching triggers stretch and chemoreceptors which cause the release of HCl
What activates paristalsis?
Parasympathetic nervous system
How does the intestinal reflex phase work?
Food enters intestines, distends duodenum, stomach acid production stops, pyloric sphincter closes, cholecystokinin triggers secretion of pancreatic juice and bile, promotes satiety, secretin releases bicarbonate from pancreas into duodenum
What is gastrin?
Hormone, released from G cells of gastric glands in response to stomach distension, contracts LES to prevent reflux; Increases mobility of stomach and relaxes pyloric sphincter
What is secretin?
Hormone; released from S cells of SI crypts, releases bicarbonate to buffer acid in chyme from stomach; inhibits secretion of gastric juices
What is CCK?
Cholecystokinin; hormone, causes secretion of pancreatic juice/enzymes and bile, promotes satiety; slows gastric emptying through contractions of pyloric sphincter
What is the difference between typical flatulence and "stink bombs"?
Flatulence = maldigestion of carbs
Stink bomb = maldigestion of proteins
What happens in constipation and diarrhea?
Bowel Transit Time increases or decreases
Why is the duodenum the "point central" of digestion?
It is where most digestive juices come together
Where is 80% of the body's immunity located?
In the GALT (Gut Associated Lymphatic Tissue)
e.g. Peyer's patches