Digestive System

Question 1

What does the pancreas secrete?

Answer 1

Bicarbonate ions to naturalize stomach acid
Pancreatic amylase
Pancreatic lipase
Trypsin and Chymotrypsin

Question 2

What is the primary function of bile?

Answer 2

To emulsify fats: breakdown larger fats into smaller droplets to increase the amount of surface area of fats that can react with intestinal lipase and is critical for fats to be fully digested and absorbed

Question 3

What would happen if an individual could not produce bile?

Answer 3

They would have trouble absorbing fats and most other nutrient processing would be unaffected

Question 4

Where is glycogen primarily stored in the body?

Answer 4

In the liver

Question 5

Antibiotics

Answer 5

A group of medications that attack and kill bacterial pathogens

Question 6

What is an affect of taking antibiotics everyday?

Answer 6

Antibiotics are desired to eliminated pathogens only, but the general mechanism is typically deadly to non-pathogenic bacteria as well—> extended use can result in death of natural, symbiotic bacteria in the digestive gut

Question 7

The presence of lipids (and proteins) in the small intestine triggers the release of ______________

Answer 7

Cholecystokinin (CCK)

Question 8

What are the functions of cholecystokinin?

Answer 8

• secreted from the small intestine in response to proteins and fats in the small intestine
• Signals the gallbladder to release bile to the duodenum
• Signals the pancreas to release digestive enzymes to the duodenum (e.g. pancreatic lipase)
• Slows down gastric emptying by decreasing the motility of the stomach so that the duodenum has more time to digest fat

Question 9

What are the two ways the small intestines protects itself from the acidic chyme?

Answer 9

1) goblet cells: secret mucus to protect the epithelial lining

2) neutralization: the small intestine produces secretin (hormone) in response to entry of chyme from the stomach which stimulates the pancreas to release bicarbonate ions (HCO3-) into the duodenum via the pancreatic duct —> bicarbonate is basic and it neutralizes the acidic gastric juice that just entered the small intestine

Question 10

Salivary amylase

Answer 10

Breaks down starch into maltose by breaking starch’s alpha-glycosidic bonds

First sight of chemical digestion

Question 11

What does mastication produce?

Answer 11

Mastication is the physical act of chewing- this creates a bolus which increases the surface area of food and thus exposing it to more enzymes and increasing its moisture in order to facilitate easier swallowing

First site of mechanical digestion

Question 12

Mesenteries

Answer 12

Network of fat and connective tissue that serves the digestive system through structural support, fat storage and by providing a framework through which blood supply, nerves, and the lymphatics can reach various locations

Question 13

Where are the gastric glands of the stomach located?

Answer 13

Within the mucous membrane (also known as the gastric mucosa), specifically within the lamina proportional of the gastric mucosa

Question 14

Mucous cells

Answer 14

• in the stomach
• Secretes mucus that lubricates and protects stomachs epithelial lining from the acidic environment
• mucus is mainly composed of glycoproteins and electrolytes and some cells secrete a small amount of pepsinogen

Question 15

Parietal cells

Answer 15

• Secrete gastric juice (HCl)
• Release intrinsic factor (a type of glycoprotein) that assist ileum in the absorption of B-12
• Posses many mitochondria for energy to establish proton gradient

Question 16

digestion: mouth

Answer 16

• salivary amylase breaks down starch into maltose by breaking starch’s a-glycosidic bonds (chemical digestion)
• chewing creates bolus (and saliva which lubricates the bolus), which is swelled, increasing surface area of food and expposing it to more enzymes (mechanical digestion)

Question 17

digestion: pharynx

Answer 17

• throat
• food (and air) passes through
• contians the epiglottis (flap of tissue) that blocks the trachea so food doesnt enter lungs

Question 18

digestion: esophagus

Answer 18

• muscular tube leading to stomach
• food travels by peristalses (wave-like motion via smooth muscle)
• lubricated by saliva

Question 19

stomach: storage

Answer 19

• contains accordion-like folds that allow 2-4 liters of storage

Question 20

stomach: mixing

Answer 20

• mixes food with water and gastric juice, forming chyme

Question 21

stomach: physical breakdown

Answer 21

• muscles are activated to breakdown food

Question 22

stomach: chemical breakdown

Answer 22

• parietal cells secrete HCl
• HCl activates pepsin from pepsinogen (released by chief cells)
• pepsin digests proteins

Question 23

chief cells

Answer 23

• in the stomach
• secrete pepsinogen (zymogen precursor to pepsin)
• pepsinogen is activated to pepsin by the low pH in stomach and begins protein digestion (protein –> amino acids)
• secretes gastric lipase which breaks down fats to fatty acids and glycerol

Question 24

G cells

Answer 24

• food entering the stomach causes distention
• distention signals G cells to release gastrin (a large peptide hormone which is absorbed into blood)
• gastrin stimulates parietal cells and chief cells

Question 25

villi

Answer 25

* finger-like projections of the small intestine that increases the surface area to allow for greater digestion and absoption * made of enterocytes that are lined by microvilli (increases surface area as well) * each villi has a lacteal

Question 26

lacteal

Answer 26

* lymph vessel surrounded by a capillary network that functions for nutrient absoption * located inside the villus * nutrients such as glucose and amino acids are absorbed into blood capillaries * fats such as fatty acids and glycerol are absorbed into lacteals

Question 27

secretin

Answer 27

* peptide hormone produced by cells lining the duodenum in response to acid in the small intestine (chyme, HCl) * stimulates the pancreas to release basic bicarbonate ions into the duodenum via the pancreatic duct to neutralize chyme

Question 28

grehlin

Answer 28

* secreted from stomach wall * initiates hunger

Question 29

leptin

Answer 29

* secreted from adipose tissue * inhibits hunger

Question 30

peptide YY

Answer 30

* secreted from the small intestine * concerned with hunger and lack of hunger

Question 31

insulin in digestion

Answer 31

* secreted from the pancreas * encourages storage of glucose as glycogen in the liver

Question 32

epinephrine in digestion

Answer 32

* supresses hunger