digestion and absorption quiz

Question 1

protein digestion begins in…

Answer 1

the stomach

Question 2

Outline the roles of hydrochloric acid in the stomach

Answer 2

• lowers pH to ~2, which denatures proteins
  -The hydrochloric acid in the gastric juice breaks down the food and the digestive enzymes split up the proteins. The acidic gastric juice also kills bacteria. The mucus covers the stomach wall with a protective coating

Question 3

Outline the hormonal and nervous mechanisms that control the secretion, content, and volume of gastric juice

Answer 3

1. Site/ smell of food triggers reflex response
2. Food enters stomach causing distention
3. Impulses from stretch receptors sent to brain
4. Gastrin causes sustained release of gastric juices
5. If pH becomes too low (< 1.5-2.0), gastrin inhibited by hormones
6. Once digested food (chyme) passes into small intestine, duodenum releases hormones to stimulate pancreas to release pancreatic juices

Question 4

Most chemical digestion occurs in…

Answer 4

small intestine

Question 5

Explain the role of the pancreas in digestion (as an exocrine gland, including listing the enzymes it secretes into the small intestine and their functions)

Answer 5

an exocrine gland and makes pancreatic juices called enzymes - breaks down sugars, fats, and starches. trypsin(ogen), lipase, amylase

Question 6

What is the general function of villi and explain how the structure of a villus is related to its function

Answer 6

(last section of small intestine) increases surface area and have a rich blood supply

Question 7

List and explain the different forms of transport used by the small intestine to absorb different nutrients

Answer 7

1. Diffusion: Fatty acids and other small pass through the hydrophobic membranes of epithelial cells through simple diffusion
2. Osmosis: Water diffuses across epithelial cell membranes in response to movement of ions
3. Facilitated Diffusion:
   Protein channels within epithelial cell membranes allow passage of hydrophilic food molecules

Question 8

Outline the role of the large intestine and explain why cellulose and lignin are not digested in humans

Answer 8

Absorption of water (and minerals/ vitamins/ ions)
Highly folded – maximizes surface area for absorption of water into the blood, cellulose and lignin are not digested because humans do NOT possess enzymes (cellulase) or gut bacteria to break them down, bile pigments, epithelial cells, lignin, cellulose, human microflora/ bacteria)

Question 9

Outline the roles of fiber in the diet

Answer 9

helps “clean out” old/ damaged intestinal cells and unabsorbed materials, it provides bulk to keep materials moving

Question 10

Outline the cause, consequences, and treatments for stomach ulcers

Answer 10

H. pylori survives the acidic conditions of stomach by penetrating mucus lining (mucosa), treated with antibiotics and PPI’s