digestion in humans

Question 1

What is the alimentary canal?

Answer 1

A tube going through the body from the mouth to the anus

Question 2

Mouth
3 points

Answer 2

-Where food is ingested and chewed
-mixing with saliva that contains amylase enzymes
-Results in food being formed into ball known as bolus

Question 3

Oesophagus
2 points

Answer 3

-Carries food to the stomach (helped by peristalsis)
-fabricated by mucus from saliva

Question 4

What is peristalsis?

Answer 4

-Food is moved through the digestive system by a process called peristalsis

Question 5

Stomach

Answer 5

-Muscular walls churn the food to ensure that it is mixed well with digestive enzymes

Question 6

Hydrochloric acid in stomach

Answer 6

-Hydrochloric acid is important to provide a suitable low PH for the activity of protease enzymes
-Acid also kills bacteria and other pathogens

Question 7

Bile
liver…gallbladder…duodenum…lipids

Answer 7

-Bile is produced in the liver
-Is stored in the gallbladder
-Bile enters the duodenum
-Bile emulsifies lipids, breaking them into smaller droplets
-lipase breaks down the large lipids molecules

Question 8

Bile alkali

Answer 8

-Bile neutralises the acid materials from the stomach, providing a suitable pH for digestive enzymes in the small intestine

Question 9

Pancreas

Answer 9

-Digestive enzymes are secreted from the pancreas into the duodenum
eg: amylase, proteases and lipases

Question 10

Small intestine

Answer 10

-Food is churned by the action of peristalsis
-Keeps food constantly in contact with the villi

Question 11

Role of villi:
2 pointz

Answer 11

-Site for secretion of enzymes
-Site of absorption of smaller food (molecules)

Question 12

Large intestine

Answer 12

-By the time the food reaches the colon, most of the nutrients have been absorbed
-Large quantities of water are absorbed back into the body
-Waste material is known as faeces

Question 13

Rectum

Answer 13

Faeces is stored in the rectum and passes out of the anus (egestion)

Question 14

Summary of chemical digestion in the gut:

Answer 14

Starch+amylase =maltose (+glucose) in mouth and intestine

Maltose+Maltase =glucose in small intestine

Proteins+pepsin=peptides in the stomach (with low PH)

Peptides+protease=amino acids in the small intestine

Lipids+lipase= fatty acids+glycerol in the small intestine (needs to be emulsified by bile)

Question 15

Absorption

Answer 15

Stage which small molecules are absorbed into the body

Question 16

properties of villi:

Answer 16

-Provide a large surface area inside the intestine
-Move constantly, helping food to keep moving and mixing it with enzymes
-Richly supplied with blood (in the capillaries) so can absorb food and carry it away

Question 17

What is absorbed into capillary

Answer 17

-amino acids
-simple sugars (glucose)

Question 18

What is absorbed into lacteals

Answer 18

-Glycerol and fatty acids