Topic 6.1

Question 1

Produce an annotated diagram of the digestive system.

Answer 1

Refer to picture

Question 2

Label the following diagram of the villi

Answer 2

Refer to picture

Question 3

Label the following diagram of the small intestine.

Answer 3

Refer to picture

Question 4

Peristalsis

Answer 4

• Involuntary contraction of circular and longitudinal muscles
• Move food in one direction only (away from mouth)

Question 5

To where does the pancreas secrete enzymes?

Answer 5

• The pancreas secretes enzymes into the lumen of the small intestine

Question 6

List the enzymes in pancreatic juice and their reactions

Answer 6

• Amylase (starch –> maltose)
• Lipase (triglycerides, phospholipids –> glycerol and fatty acids)
• Proteases (proteins/peptides –> amino acids)

Question 7

Outline the function of mouth

Answer 7

• Voluntary control of eating and swallowing
• Mechanical digestion of food by chewing and mixing with saliva
• Chemical digestion of starch with amylase in saliva

Question 8

Outline the function of saliva

Answer 8

• Lubricants
• Enzymes that start starch digestion (amylase)

Question 9

Outline the function of esophagus

Answer 9

• Movement of food by peristalsis from the mouth to the stomach

Question 10

Outline the function of small intestine

Answer 10

• Final stages of digesion of lipids, carbohydrates, proteins, and nucleic aics
• Neutralize stomach acid (in duodenum)
• Absoption of nutrients

Question 11

What are the three parts of small intestine?

Answer 11

Duodenum, jejunum, ileum

Question 12

Outline the function of pancreas

Answer 12

Secretion of lipase, amylase and protease

Question 13

Outline the function of liver

Answer 13

Secretion of surfactants in bile to break up lipid droplets

Question 14

Outline the function of Gall bladder

Answer 14

Storage and regulated release of bile

Question 15

Outline the function of large intestine

Answer 15

• Reasbsorption of water
• Further digestion especially of carbohydrates by symbiotic bacteria
• Formation and storage of feces

Question 16

Bolus

Answer 16

Grinded food (after chewing)

Question 17

Describe the process of swallowing

Answer 17

• Soft palate moves backwards and up to seal the nasal passage
• Trachea moves up and under the epiglottis to prevent choking

Question 18

Cardiac sphincter

Answer 18

• Separates the esophagus and stomach
• Helps to push food into stomach
• Prevent food from backflowing

Question 19

Outline the function of stomach

Answer 19

• Mechanical digestion (churning and mixing with secreted water and acid)
• Kills foreign bacteria and other pathogens in food
• Initial stages of protein digestion

Question 20

Describe the purpose of villi

Answer 20

• Increase surface area of epithelium
• Increase the efficiency of nutrient absorption

Question 21

What does the villi absorb from the lumen?

Answer 21

• Monomers such as glucose, amino acids, fatty acids, nucleotides
• Mineral ions such as calcium, potassium, sodium
• Vitamins such as ascorbic acid

Question 22

Describe how triglycerides are transported across the villus epithelium cells

Answer 22

• Digested into fatty acids and monoglycerides
• Absorbed into villus epithelium cells by simple diffusion
• Fatty acids are also absorbed by facilitated diffusion
• Once inside the cells, fatty acids and monoglycerides form triglycerides to ensure that they don’t diffuse back out into the lumen

Question 23

Describe how triglycerides are transported across the lacteal

Answer 23

• Triglycerides coalesce with cholesterol to form droplets that is coated in phosopholipids and protein (lipoprotein)
• Released by exocytosis through the plasma membrane and enter the lacteal or blood capillaries

Question 24

Describe how glucose is transported across the villus epithelium cells

Answer 24

• Polar and hydrophilic (cannot diffuse across)
• Sodium-potassium pumps creates a low concnetration of socium ions inside the cells (using ATP)
• Socium-glucose cotransporter proteins in the microvilli transfer a sodium ion and a glucose molecule together from the lumen into the cells
• Facilitated diffusion that depends on sodium concentration (established by active transport)

Question 25

Describe how glucose is transported across the blood capillaries

Answer 25

• Glucose channels move the glucose from the cytoplasm to interstitial spaces and then blood capillaries

Question 26

Why can’t we digest cellulose?

Answer 26

We don’t have the bacteria required to make cellulase (enzyme that digests cellulose)