2.27 Human Alimentary Canal

Question 1

What is digestion?

Answer 1

A process where relativley large and insoluble molecules in food are broken down into smaller and soluble materials which can be absorbed into the bloodstream and delivered to cells in the body

Question 2

What is the alimentary canal?

Answer 2

The passage through which food flows through the body, starting at the mouth and ending at the anus

Question 3

What are the important parts of the alimentary canal?

Answer 3

-The mouth and the salivary glands
-The oesophagus
-The stomach
-The large intestine
-The small intestine
-The rectum
-The anus

Question 4

What is the function of the mouth and the salivary glands?

Answer 4

-Teeth chew the food down into smaller pieces to decrease its surface area to volume ratio
-Amylase enzymes in saliva start digesting startch into maltose
-This mix of food is shaped into a bolus and lubricated by saliva so it can be swallowed easier

Question 5

What is the function of the Oesophagus?

Answer 5

-It is the tube that connects the mouth to the stomach
-Wave like contractions from muscles inside the Oesophagus pushes the food without relying on gravity

Question 6

What is the function of the stomach?

Answer 6

-Food is mechanically processed by churning actions while protease enzymes start to digest proteins chemically
-Hydrochloric acid is present to kill bacteria in food and provide optimum pH for protease enzymes to work

Question 7

What is the function of the small intestine? (duodenum and ileum)

Answer 7

-The first section is called the duodenum, this is where the digestion of food exiting the stomach is finished by enzymes in the duodenum secreted from the pancreas
-The second section is called the ileum, This is where the absorption of water and digested food molecules take place, the ileum is long and lined with villi to increase the surface area.

Question 8

What is the function of the Large intestine?

Answer 8

-Water is absorbed from the remaining material in the colon and turned into faeces
-The faeces are stored in the rectum and exit the body through the anus

Question 9

What is the function of the pancreas?

Answer 9

-It produced all 3 types of digestive enzymes: Protease, Lipase, Amylase
-It secretes enzymes in an alkaline solution into the duodenum for digestion, which raises the pH of the fluid coming out of the stomach

Question 10

What is the function of the Liver?

Answer 10

Amino acids that are not used to make protein are broken down here and turned into urea
-Produces bile to break down fats

Question 11

What is the function of the Gall bladder?

Answer 11

Stores bile to release into the duodenum

Question 12

What are the 6 stages the food goes through as it passes through the alimentary canal?

Answer 12

-Ingestion
-Mechanical digestion
-Chemical digestion
-Absorption
-Assimilation
-Egestion?

Question 13

What is Ingestion?

Answer 13

The taking in of substances e.g eating food

Question 14

What is Mechanical digestion?

Answer 14

The break down of food into smaller pieces without chemical change to food molecules

Question 15

What is Chemical digestion?

Answer 15

The breakdown of large, insoluble molecules into small, soluble molecules

Question 16

What is Absorption?

Answer 16

The movement of small food molecules and ions through the walls of the intestine into the blood

Question 17

What is Assimilation?

Answer 17

The movement of small digested food molecules into the cells of the body, in which they are used, they get used up, becoming part of the cells

Question 18

What is Egestion?

Answer 18

The Passing out of food that has not been digested or absorbed through the anus

Question 19

How does peristalsis work?

Answer 19

-Contraction of circular muscles behind the bolus push it forwards
-Contration of longitudinal muscles infront of the bolus reduce the length of the bolus
-This pushes the bolus to the stomach

Question 20

What is used to lubricate the bolus during peristalsis?

Answer 20

Muscus