Digestive system

Question 1

what is the function of a digestive system?

Answer 1

break down food from large, insoluble molecules taken in –> small, soluble substances to be absorbed by body

Question 2

what is physical digestion?

Answer 2

breaking down of food into smaller pieces through physical mechanical means –> crushing, grinding, churning/mixing

Question 3

How does chemical digestion work?

Answer 3

food molecules are hydrolyzed into smaller, soluble molecules through enzymes for easy absorption

Question 4

what are enzymes?

Answer 4

biological catalysts produced by the body that speed up the rate of chemical reactions

Question 5

name the process of digestion of carbohydrates (starch)

Answer 5

amylase maltase
starch ————-> maltose ————> glucose (simple
sugars)

Question 6

name the process of digestion of proteins

Answer 6

proteins ————> polypeptides ———-> amino acids
proteases proteases

Question 7

name the process of digestion of fats

Answer 7

fats ——-lipases——–>fatty acids + glycerol

Question 8

how do simple organisms like amoeba survive (get the nutrients they need)

Answer 8

absorbing nutrients in its environment (diffusion)

Question 9

what nutrients do large organisms like humans require large amounts for a balanced diet?

Answer 9

carbohydrates, proteins, fats, fibre, water, vitamins and mineral salts

Question 10

where does digestion begin and end?

Answer 10

mouth –> stomach –> small intestine

Question 11

what is the alimentary canal?

Answer 11

9m long canal consisting of the mouth, oesophagus, stomach, small intestine, large intestine (colon + rectum) and anus

Question 12

what are the accessory organs?

Answer 12

pancreas, salivary glands, gall bladder and liver

Question 13

which organs carry out chemical and/or physical digestion?

Answer 13

chemical: physical:
mouth mouth
oesophagus -
stomach stomach
small intestine -

Question 14

function of teeth?

Answer 14

• cut and crush food to break it into smaller pieces
• increases surface area to volume ratio of food, allowing faster digestion and easier swallowing

Question 15

function of salivary glands

Answer 15

• secrete saliva which contains salivary amylase
• allows partial digestion of starch
• softens and lubricates food for easy swallowing

Question 16

what is the oesophagus?

Answer 16

• a muscular tube that contracts and relaxes rhythmically to push food down towards stomach from the mouth

Question 17

why is there still chemical digestion in the oesophagus when there is no release of digestive juices?

Answer 17

• starch rom the mouth continues to be digested by the salivary amylase that is mixed in with the bolus

Question 18

function of stomach?

Answer 18

• churns to break food into smaller pieces and mixes it with gastric juices (HCL and proteases)
• HCL kills bacteria, provides the right acidic environment for proteases to act
• proteases digest proteins into polypeptides here
• thick layer of mucus to protect stomach tissues from damage caused by HCL and proteases
• muscles at both ends of the stomach control what enters and leaves

Question 19

function of small intestine?

Answer 19

• fully digest food as it is the main site for chemical digestion due to numerous enzymes released
• partially digested food entering from stomach is mixed with digestive juices from pancreas, gall bladder and intestinal glands
• digested nutrients and most of the mineral salts and water are absorbed into the bloodstream here

Question 20

what enters the large intestine?
function of large intestine?

Answer 20

• only undigested food enters
• remaining water and mineral salts absorbed here
• indigestible food and waste form faeces
• the rectum stores faeces temporarily before it leaves the body

Question 21

function of anus?

Answer 21

• where faeces is expelled from the body

Question 22

uses of glucose?

Answer 22

• used in cells during cellular respiration to release energy
• allows cells to carry out functions and enable body to grow

Question 23

uses of amino acids?

Answer 23

• used by cells to make proteins
• then used for growth of new cells and repair damaged tissues

Question 24

uses of fatty acid and glycerol?

Answer 24

• combine again to form fats which are stored
• keep the body warm
• can be oxidized to release energy

Question 25

what is diabetes?

Answer 25

- overconsumption of carbohydrates, leading to a higher-than-normal level of glucose in blood

Question 26

diabetes occurs when:

Answer 26

- body does not produce sufficient insulin ( hormone that keeps blood sugar levels balanced) - body does not respond properly to insulin

Question 27

diabetes is often linked to:

Answer 27

- obesity - other health issues (e.g. heart attack, kidney problems, high blood pressure, stroke)

Question 28

symptoms of diabetes:

Answer 28

- slow healing of wounds - constant hunger - frequent urination - tingling or numbness in hands and feet - unexplained weight loss - blurred vision

Question 29

how to reduce risk of diabetes?

Answer 29

- regular health screenings - healthy + balanced diet --> whole grains, vegetables, fruit and lean meat - avoid food high in saturated fats, salt and sugar - exercise regularly (at least 30 min a day, 5 days a week) - avoid smoking and drinking alcohol

Question 30

what is constipation? possible causes and prevention?

Answer 30

- when faeces move through the large intestine very slowly - possible causes: stress, consumption of certain medicines, not having enough fibre in diet and not drinking enough water - prevention: eat food high in fibre, having adequate exercise, drinking more water

Question 31

what is gastric pain? symptoms and causes?

Answer 31

- pain experienced due to gastritis , the painful swelling or inflammation of stomach lining - symptoms: upper abdominal pain, nausea and bloating - possible causes: bacterial/viral infection, skipping meals, consuming alcohol, consuming caffeine, consuming too much oily food

Question 32

what is food poisoning caused by? symptoms and effects?

Answer 32

- caused by bacteria-contaminated food - symptoms: diarrhoea/ vomiting (how body gets rid of bacteria - some bacteria could cause life-threatening diseases such as cholera and salmonella infection - however, due to proper sanitation and food hygiene in Singapore, such cases are rare

Question 33

how to handle food safely?

Answer 33

- use separate utensils and crockery for raw and uncooked food - cover food properly before placing in refrigerator (cooked food always above raw food) - keep raw food below 5 degrees Celsius

Question 34

how to choose food carefully?

Answer 34

- check that bottled milk/ drinks tightly sealed - food not expired - do not consume food from badly dented/ bloated cans - do not consume mouldy food - buy food chilled at right temperature (0 - 4 degrees Celsius) - frozen food should be stored below -18 degrees Celsius