Digestive Study
Extra: Identify and describe the 6 major processes involved in gastrointestinal activity.
1) Ingestion is the active, voluntary process of placing food into the mouth. 2) Propulsion involves all of the actions involved in moving food along the alimentary canal from the mouth to the anus, including swallowing, peristalsis, segmentation, and mass movements. 3) Mechanical digestion involves all of the activities that break food down into smaller pieces to prepare them for further degradation by enzymes. 4) Chemical digesting, the next step of food breakdown, involves the sequence of steps by which large food molecules are broken down to their building blocks by enzymes. 5) Absorption is the mechanism by which digested end products are moved from the lumen of the GI tract into the blood or lymph. 6) The final process is defecation, which is the elimination of indigestible substances from the body via the anus as feces.
Extra: Describe the four layers of the GI tract.
1. Mucosa is the moist innermost layer; it lines the cavity of the organ. 2. The submucosa is found beneath the mucosa layer. It contains blood vessels, nerve endings, lymph nodules, and lymphatic vessels. 3. The muscular externis is the next layer, which is typically made up of a circular and a longitudinal layer of smooth muscle. 4. The outermost layer is the serosa, which consists of two single layers of cells. The innermost serosa is the visceral peritoneum while the outermost layer is the parietal peritoneum. Between these layers is serous fluid.
Which of these events describes a chemical breakdown of food:
A. enzyme action of maltase acting on starch to break it into maltose
What two organs release secretions into the duodenum of the small intestine?
A. liver and pancreas
Site where starch digestion begins:
A. mouth
Proteins-
A. pepsinogens
The release of food from the stomach into the small intestine is regulated by the:
A. pyloric sphincter (valve)
The enzyme responsible for converting milk protein in the stomach to a substance that looks like sour milk in infants is?
A. rennin
Which of the following is NOT associated with the mouth?
A. rug
The process by which food within the small intestine is mixed with digestive juices by backward and forward movement across the internal wall of the organ is called:
A. segmentation
Amylase is an enzyme that is only able to digest:
A. starch
Which one of the following is NOT a modification (which is designed to increase surface area for absorption) within the small intestine?
B. Peyer's patches
The primary function of the small intestine is:
B. absorption of nutrients
Which one of the following is NOT one of the carbohydrates that the human digestive system is able to break down to simple sugars?
B. cellulose
Which one of the following alimentary segments has NO digestive function?
B. esophagus
Nutrients detour through the liver via the:
B. hepatic portal circulation
Which of the following is the moist innermost layer that lines the alimentary canal?
B. mucosa
Digestion is primarily controlled by the:
B. parasympathetic division of the autonomic nervous system
Protein digestion begins in the:
B. stomach
Transport of digested end products from the lumen of the GI tract into the bloodstream or lymphatic fluid is called?
C. absorption
The organ responsible for drying out indigestible food residue through water absorption and the elimination of feces is the:
C. large intestine
Nucleic acids-
C. nuclease
What is the purpose of mastication:
C. to chew, grind and tear food into smaller pieces while in the mouth
The liver is indicated by letter _____.
D
Tube through which food is propelled but no digestion takes place:
D. esophagus
Fat-
D. lipase
The gallbladder is indicated by letter _____.
E
Proteins are digested to their building blocks which are called?
E. amino acids
Which of the following influences the release of pancreatic juice and bile:
E. cholecystokinin and secretin
The process of swallowing is also known as?
E. deglutition
Primary site of water absorption:
E. large intestine
Site of vitamin K synthesis by bacteria:
E. large intestine
The propulsive process that moves food from one organ to the next is called?
E. peristalsis
The hereditary inability of tissue cells to metabolize the amino acid phenylalanine, which can result in brain damaged retardation unless a special diet low in phenylalanine is followed, is called:
E. phenylketonuria
Which one of the following is NOT absorbed by the human large intestine?
E. protein
The small intestine extends from the:
E. pyloric sphincter to the ileocecal valve
The first nutrient to be chemically digested is:
E. starch
Lactose-
F. lactase
Site where protein digestion begins:
F. stomach
Site where pancreatic enzymes and bile enter the alimentary canal:
G. duodenum
The appendix is indicated by letter _____.
H
Starch-
H. cellulose
Site where defection reflex is initiated:
I. rectum
The large intestine is indicated by letter _____.
J
The pancreas is indicated by letter _____.
L
The stomach is indicated by letter _____.
M
Extra: Explain the role of the hormones cholecystokinin and secretin in regulating the release of bile and pancreatic juices.
When chyme enters the small intestine, it stimulates the mucosa cells to produce the hormones cholecystokinin and secretin. These hormones travel in the bloodstream to their target organs: the pancreas, liver, and gallbladder. The pancreas responds to cholecystokinin by releasing enzyme-rich pancreatic juice and secretin causes the secretion of bicarbonate-rich pancreatic juice. The liver responds to secretin by releasing bile while cholecystokinin stimulates the gallbladder to release stored bile.
The enzyme produced by the salivary glands used in the breakdown of starches is _____.
amylase
Bile is formed by the _____.
liver
The innermost layer of the alimentary canal is referred to as the _____.
mucosa
Hydrochloric acid is necessary in the stomach for the conversion of pepsinogen into its active protein-digesting from called _____.
pepsin
The fingerlike projections of the small intestine increase the surface area and are known as _____.
villi
