Biology Digestive System

Question 1

The oral cavity (mouth) is where ___ and chemical digestion begins

Answer 1

mechanical

Question 2

___ is the breakdown of large food particles into smaller particles through physical actions, such as the biting and chewing action of teeth (mastication ) or the churning motion of the stomach

Answer 2

mechanical digestion

Question 3

___ refers to the enzymatic breakdown of macromolecules into smaller molecules and begins in the mouth when the salivary glands secrete saliva

Answer 3

chemical digestion

Question 4

Saliva contains ___ amylase (ptyalin), which hydrolyzes starch to maltose

Answer 4

salivary

Question 5

Once food has been swallowed, it is referred to as ___

Answer 5

bolus

Question 6

The esophagus is the muscular tube responsible for transporting the ___ from the oral cavity to the stomach

Answer 6

bolus

Question 7

The bolus is moved down the esophagus by rhythmic waves of involuntary ___ contractions called peristalsis

Answer 7

muscular

Question 8

Peristalsis is not ___

Answer 8

voluntary

Question 9

The ___ is closed off from the stomach by contraction of a muscular structure called the lower esophageal (cardiac) sphincter

Answer 9

esophagus

Question 10

The lower ___ sphincter (LES) protects the esophagus from the acidic gastric contents

Answer 10

esophageal

Question 11

The esophagus lies within the ___ cavity, which regularly is exposed to negative pressure as the person inhales

Answer 11

thoracic

Question 12

Contrastingly, the stomach is located in the ___ cavity, which has a relative positive pressure

Answer 12

abdominal

Question 13

Therefore, without the actions of the lower esophageal ___, the pressure gradients favor a continual reflux of gastric content into the esophagus, resulting in a condition known as gastroesophageal reflux disease (GERD)

Answer 13

sphincter

Question 14

___ digestion relies on the gastric mucosa, which lines the walls of the stomach and contains the gastric pits and gastric glands

Answer 14

chemical

Question 15

Various cell types in the gastric mucosa produce the chemicals responsible for chemical digestion:
Mucous cells, in gastric pits, secrete mucus to protect the stomach lining from the harshly acidic juices (pH =2) present in the stomach
Chief cells, in the gastric glands, synthesize pepsinogen, which is converted to pepsin upon contact with stomach acid and breaks down proteins
___ cells, also present within gastric glands, synthesize and release hydrochloric acid (HCl), which alters the pH of the stomach, kills bacteria, and produces intrinsic factor (IF), which is necessary for the absorption of vitamin B12

Answer 15

parietal

Question 16

The churning of the stomach, combined with enzymatic activity (chemical digestion) produces an acidic, semifluid mixture of partially digested food known as ___

Answer 16

chyme

Question 17

The chyme passes into the first segment of the small intestine, the ____, through the pyloric sphincter

Answer 17

duodenum

Question 18

Digestion in the small intestine is exclusively chemical and is facilitated by ___ secretions from the pancreas, liver, and local intestinal glands

Answer 18

enzymatic

Question 19

Enzymes utilized in small intestine chemical digestion include lipases, ___, disaccharidases

Answer 19

aminopeptidases

Question 20

Pancreatic secretions create a ___ (high pH) environment in the small intestine

Answer 20

basic

Question 21

Segments of the small intestine: Dow Jones Industrial
Duodenum
___
Ileum

Answer 21

jejunum

Question 22

The ___ is an accessory digestive organ, meaning it is not part of the digestive tract, but instead secretes compounds into it

Answer 22

liver

Question 23

The liver produces ___ that is stored in the gallbladder before being released into the small intestine

Answer 23

bile

Question 24

___ functions to emulsify fats, breaking down large globules into small droplets

Answer 24

bile

Question 25

Emulsification increases the ___ area of the fat, increasing the digestive actions of pancreatic enzymes

Answer 25

surface

Question 26

In the absence of ___, fats cannot be digested

Answer 26

bile

Question 27

The first pass effect: blood from the small intestine containing newly ___ compounds is directly sent to the liver for detoxification before entrance into general circulation

Answer 27

absorbed

Question 28

The first pass effect serves to protect the body from ___ toxins

Answer 28

ingested

Question 29

Non-digestive functions of the liver include storage of glycogen, conversion of ___ to urea, protein synthesis, and cholesterol metabolism

Answer 29

ammonia

Question 30

The pancreas is an accessory digestive ___

Answer 30

organ

Question 31

Upon stimulation, the ___ releases amylase, lipase and trypsinogen

Answer 31

pancreas

Question 32

___ is the precursor of trypsin, a powerful proteolytic enzyme, and is activated by enterokinase, which is produced in the small intestine

Answer 32

trypsinogen

Question 33

Trypsin is only activated once it enters the ___

Answer 33

small intestine

Question 34

Upon trypsin entering the small intestine, trypsin then cleaves and activates the other ___ (enzyme precursors)

Answer 34

zymogens

Question 35

The pancreas also secretes a bicarbonate-rich juice that neutralizes the acidic ___ arriving from the stomach in the duodenum

Answer 35

chyme

Question 36

The ___ enzymes operate optimally at a higher pH

Answer 36

pancreatic

Question 37

The large intestine is approximately 1.5 m long and absorbs ___ and any water not already absorbed by the small intestine

Answer 37

salts

Question 38

Digestive Hormones
Gastrin: produced in the ___ of the duodenum, gastrin primarily functions to stimulate histamine and pepsinogen secretion, as well as increase gastric blood flow. Gastrin also stimulates the parietal cells to produce HCl, which denatures proteins and activates digestive enzymes.
Intrinsic factor: a secretion of the parietal cells that facilitates absorption of vitamin b12 across the intestinal lining
Cholecystokinin (CCK): produced and stored in the I cells of the duodenal and jejunal mucosa. it is involved in stimulation of pancreatic enzyme and somatostatin secretion as well as gallbladder contraction. CCK also acts as a hunger suppressant.
Secretin: synthesized and stored in the S cells of the upper intestine. It stimulates the secretion of bicarbonate-containing substances from the pancreas and inhibits gastric emptying and gastric acid production
Ghrelin: synthesized both in the brain and the gut serves as the “hunger hormone.” Increased levels of ghrelin in central circulation cause increased appetite and feeding behavior.
Leptin: synthesized primarily in adipose tissue 9fat cells) serves as an antagonist to ghrelin. Leptin acts on the brain to reduce hunger and provide a satiated state

Answer 38

G cells