6.1 Digestion

Question 1

Explain why digestion of large food molecules is essential

Answer 1

Foods are made up of large complex biological polymer molecules. These tend to be insoluble and chemically inert. Therefore, we must break them down into soluble products, so that they can be absorbed, transported and reassembled into new products.

Question 2

Explain the need for enzymes in digestion

Answer 2

Enzymes allow the digestive process to occur at body temperature (37C in humans) and at a sufficient speed to meet the organism’s survival requirements.

Question 3

State the enzyme type of Salivary Amylase

Answer 3

Amylase

Question 4

State the source of Salivary Amylase

Answer 4

Salivary glands

Question 5

State the substrate of Salivary Amylase

Answer 5

Starch

Question 6

State the products which Salivary Amylase produces

Answer 6

Maltose

Question 7

State the optimal pH for Salivary Amylase

Answer 7

pH ~7 (neutral)

Question 8

State the enzyme type of Pepsin

Answer 8

Protease

Question 9

State the source of Pepsin

Answer 9

Secreted by chief cells in stomach lining. Found in gastric juices (stomach).

Question 10

State the substrate of Pepsin

Answer 10

Large polypeptides

Question 11

State the products which Pepsin produces

Answer 11

Smaller peptides and amino acids

Question 12

State the optimal pH for Pepsin

Answer 12

pH ~2 (highly acidic)

Question 13

State the enzyme type of Pancreatic Lipase

Answer 13

Lipase

Question 14

State the source of Pancreatic Lipase

Answer 14

Pancreas

Question 15

State the substrate for Pancreatic Lipase

Answer 15

Tryglycerides

Question 16

State the produces which Pancreatic Lipase produces

Answer 16

Glycerol + Fatty acid chains

Question 17

State the optimal pH for Pancreatic Lipase

Answer 17

pH ~8 (slightly alkaline)

Question 18

State the two major organ groups associated with human digestion

Answer 18

Alimentary Canal and Accessory Organs

Question 19

Describe the Alimentary Canal

Answer 19

Contains organs through which the food actually passes (esophagus, stomach, small intestine, large intestine, etc.)

Question 20

Describe the Accessory Organs

Answer 20

Organs that assist in digestion but no food passes through them (liver, pancreas, gall bladder, salivary glands, etc.)

Question 21

Outline the function of the stomach

Answer 21

Breaks down food into a liquidly mixture called chyme. Secretes HCL to kill off bacteria which could cause food poisoning. Secretes pepsin for protein digestion. Provides optimum pH for pepsin. Slowly empties that chyme into the small intestines.

Question 22

Outline the function of the small intestine

Answer 22

Final stages of digestion occur. All soluble food substances (e.g. nutrients) are absorbed into the bloodstream.

Question 23

State the three sections of the small intestine

Answer 23

Duodenum
Jejunum
Ileum

Question 24

Outline the function of the Duodenum

Answer 24

Food particles broken down into soluble components. Sodium bicarbonate neutralises stomach acid in the chyme. Bile emulsifies large fat droplets into smaller droplets, increasing their surface area, pancreatic lipase breaks them apart.

Question 25

Outline the function of the Jejunum

Answer 25

Majority of absorption occurs. Lined with villi, which are in turn lined with microvilli. These absorb nutrients into the blood via active transport, maximizing absorption.

Question 26

Outline the function of the Ileum

Answer 26

Absorbs bile salts, vitamin B12, and whatever usable products of digestion were not absorbed by the jejunum

Question 27

Outline the function of the large intestine

Answer 27

Absorbs water. Converts what remains from fluid state to semi-solid faeces. Faeces stored in rectum and eliminated out the anus.

Question 28

Define absorption

Answer 28

Movement of fluid or dissolved substance across a membrane. Soluble products of digestion are absorbed into bloodstream, or the lymphatic system in the case of lipids.

Question 29

Define assimilation

Answer 29

When food products become part of the body’s tissue. Products of digestion are absorbed into cells from the blood to be stored or used within cells/tissues.

Question 30

State 6 of the features of the villus which are related to their roles in absorption and transport of products of digestion

Answer 30

Microvilli
Rich capillary networks
Single-cell epithelial layer
Lacteals
Intestinal crypts
Mitochondria

(MRS LIM)

Question 31

Explain how microvilli assist the villus in the absorption and transport of products of digestion

Answer 31

Greatly increase the surface area of the villus, allowing for a greater rate of absorption.

Question 32

Explain how the rich capllary network assists the villus in the absorption and transport of products of digestion

Answer 32

Help to maintain a concentration gradient for absorption by rapidly transporting absorbed products away.

Question 33

Explain how the single epithelial layer assists the villus in the absorption and transport of products of digestion

Answer 33

Ensures minimal diffusion distancebetween the intestinal lumen and capillary network.

Question 34

Explain how the lacteals assist the villus in the absorption and transport of products of digestion

Answer 34

Absorb lipids from the intestine into the lymphatic system (which are later reabsorbed back into normal circulation).

Question 35

Explain how intestinal crypts assist the villus in the absorption and transport of products of digestion

Answer 35

Located between villi and release juices that act as a carrier fluid for nutrients.

Question 36

Explain how mitochodria assist the villus in the absorption and transport of products of digestion

Answer 36

Produce sufficient ATP to enable active transport into cells (contents then passively diffuse into bloodstream).