Chapter 9: Nutrition and Human Digestive System

Question 1

3 cells in epithelial cells

Answer 1

• chief cell produce pepsinogen
• parietal cell produce hydrochloric acid
• mucous cell produce mucus

Question 2

Digestion of in stomach

Answer 2

Protein + water –> polypeptide

• pepsinogen activated by hydrochloric acid to become pepsin
• pepsin hydrolyses protein into polypeptide

Question 3

function of hydrochloric acid

Answer 3

• prepare an acidic environment for pepsin (1.5-2.0)
• stop the enzymatic action of salivary amylase
• kill bacteria in food

Question 4

how food turn into chyme

Answer 4

• churned by peristaltic action of stomach wall muscle
• form semifluid
• enter duodenum slowly when the sphincter muscle relax

Question 5

digestion in duodenum

Answer 5

1. starch + water –> maltose
   - by pancreatic amylase
2. polypeptide + water –> peptide
   - by trypsin
3. lipid + water –> fatty acid + glycerol
   - by lipase

Question 6

secretion of enzyme to be transported into duodenum

Answer 6

Pancreas

• pancreatic amylase
• trypsin
• lipase

Liver

• produce bile
• stored in gall bladder

Question 7

function of bile

Answer 7

• neutralised the acidic chyme
• prepare an alkali environment (6.7-7.7)
• emulsify lipid by breaking down lipids into tiny droplet to increase the total surface area for lipase

Question 8

content of intestinal juice

Answer 8

• sucrase
• lactase
• maltase
• erepsin
• lipase

Question 9

digestion in small intestine

Answer 9

1. carbohydrate ( sucrose, maltose, lactose)
2. peptide + water –> amino acid
   - by erepsin
3. lipid + water –> fatty acid + glycerol
   - by lipase

Question 10

adaptation of villi

Answer 10

• one-cell-think epithelial tissue accelerate the absorption
• microvilli to increase total surface area
• goblet cells to secret mucus
• network blood capillaries to transport digestive products to whole body
• lacteal to carry fatty acid and glycerol
• intestinal gland secrete intestinal juice

Question 11

absorption in iluem

Answer 11

Lacteal (simple diffusion)

• fatty acid and glycerol recombine via condensation process to form tiny droplets lipid
• vitamin ADEK

Blood capillaries

• fructose (facilitated diffusion)
• glucose and galactose ( active transport)
• amino acid ( active transport)
• vitamin B and C ( dissolve in water)
• water (osmosis)

Question 12

liver cirrhosis

Answer 12

• caused by hepatitis, alcoholic and toxic sustances
• liver cells is replaced by scarred cell
• cause liver failure

Question 13

3 function of liver

Answer 13

1. metabolism of digested food
   - glucose for cellular respiration
   - amino acid for enzyme and plasma protein
   - deamination for excess amino acid to expel in urine
2. detoxification
   - expel toxic substances from blood into urine
3. storage of nutrient
   - excess glucose convert into glycogen stored in liver

Question 14

assimilation in cells

Answer 14

Glucose

• oxidised in cellular respiration to release energy, carbon dioxide and water
• energy used for cell process
• excess glucose stored as glycogen in muscle cells

Amino acid

• synthesis hormones and enzymes
• synthesis new protoplasma and repair damage tissue

Lipids

• phospholipid and cholesterol used to build plasma membrane
• excess fat stored in adipose tissue underneath the skin as energy storage
• oxidised to release energy when glucose insufficient

Question 15

4 function of fibre

Answer 15

• stimulate peristalsis and prevent constipation
• absorb and expel toxic substances
• regulate absorption of glucose
• increase population of beneficial bacteria in large intestine

Question 16

4 diseases in eating habits

Answer 16

• gastritis
• anorexia nervosa
• bulimia nervosa
• muscle dysmorphia