Chapter 11.8 - Digestive System Flashcards
Villi are located in the:
small intestine
Why are villi important?
increase surface area of small intestine to increase the efficiency of absorption
On top of each villus, there are tiny projections known as:
microvilli
Function of microvilli
further expand the surface area to help in nutrient absorption
____ are the absorptive cells that make up the villi
enterocytes
Enterocytes are lined with:
microvilli
Crypts
invaginations in the wall of the small intestine
Crypts contain what kind of cells?
those that secrete enzymes and that produce epithelial cells
Within the structure of a villus, there are:
lacteals (blood capillaries and lymphatic capilary)
What is absorbed into villus blood capillary?
glucose and amino acids
What is absorbed into villus lymphatic capillary?
fatty acid and glycerol
When is secretin released?
when chyme enters small intestine
Secretin stimulates:
the panceas to secrete HCO3- (bicarbonate) into duodenum via pancreatic duct
What hormones are released when chyme enters small intestine?
secretin, CCK
CCK function
- slows down gastric emptying
- signals pancreas to release digestive enzymes
- signals gallbladder to release bile
What does bile do?
emulsifies fat into small droplets (mechanical, not chemical digestion!!)
Pancreas secretes what enzymes?
- pancreatic amylase
- pancreatic lipase
- trypsinogen (activated by enteropeptidase to make trypsin)
- chymotrypsinogen (activated by trypsin to make chymotrypsin)
How does the liver perform blood maintenance?
- stores blood
- filters and detoxifies blood coming from the digestive system
- erythrocyte destruction via kupffer cells
- bacteria destruction via kupffer cells
- chemical/drug detox
How does the liver perform glucose metabolism?
via glycogenesis, glycogenolysis, gluconeogenesis
How does the liver perform protein metabolism?
- synthesizing plasma proteins (albumin)
- synthesizing non-essential amino acids
- converts dangerous ammonia to urea for safer excretion
Pathway of digested food in large intestine
cecum –> colon –> rectum –> anus
3 main functions of the large intestine
- water absorption (though 95% absorbed by small intestine)
- mineral absorption
- vitamin production and absorption
Large intestine produces what vitamins?
B and K (via mutualistic relationship with bacteria)
What serves as an entrance to the gastric glands?
Gastric pits in the stomach’s lining
What types of molecules do stomach enzymes mainly serve to help break down?
Fats and proteins
What is the name of the connective tissue that lines the gastric glands?
lamina propria
Where are parietal and chief cells located?
gastric glands
Zymogen
inactive precursor of an enzyme
What triggers the conversion of pepsinogen to pepsin?
Low pH
Why are enzymes that digest proteins produced and stored as zymogens?
so that the enzyme-producing cell does not digest itself
What is a common cause of peptic ulcers?
Acid corrosion
What is the function of stomach acid?
kill bacteria, denature proteins, provide favorable environment for pepsin
What is the optimal pH for pepsin function?
2
What type of cells secrete mucus in order to protect the small intestine?
Goblet cells
Where are bicarbonate ions secreted from?
Pancreas
Which hormone stimulates the pancreas to release bicarbonate ions into the small intestine?
Secretin
What hormone is released by cells in the lining of the duodenum?
CCK (cholecystokinin)
Enteropeptidase is secreted from:
glands in the duodenum
Which enzymes perform similar functions on the same kind of biomolecule?
trypsin and chymotrypsin - both digest proteins into amino acids
Where does most erythrocyte destruction take place?
spleen
What is NOT a component of blood maintenance in the liver?
erythrocyte synthesis
What happens to bilirubin in the liver?
secreted into bile
What process is most active in our liver between meals?
glycogenolysis
What molecules does the liver typically use to synthesize glucose?
glycerol and amino acids
What type of proteins does the liver mainly synthesize?
Plasma proteins (albumin)
Which of the following is not made in the liver? A. Blood clotting factors B. Non-essential amino acids C. Hemoglobin D. Urea
C. Hemoglobin
What is a source of ammonia build-up in the body?
Protein metabolism
What part of the digestive tract is the appendix connected to?
Cecum
At which point of the digestive tract is water absorption completed?
Colon (5% done here)
Where are feces stored prior to being expelled from the body?
Rectum
What is not a function of the large intestine?
Nutrient absorption
What condition occurs when too little water is absorbed?
Diarrhea
What is NOT a function of bacteria in our large intestines?
Producing vitamin D
