2.5.8 Humans: The Digestive System

Question 1

The human digestive system is an example of what?

Answer 1

The digestive system is an example of an organ system in which several organs work together to digest and absorb food

Question 2

Describe the process of digestion

Answer 2

The digestive system is an example of an organ system in which several organs work together to digest and absorb food

Question 3

small soluble molecules (such as glucose and amino acids) are used provide cells with what?

Answer 3

with energy (via respiration), or with materials with which they can build other molecules to grow, repair, and function

Question 4

The human digestive system is made up of the organs that form, what?

Answer 4

alimentary canal and accessory organs

Question 5

What is the alimentary canal

Answer 5

The alimentary canal is the channel or passage through which food flows through the body, starting at the mouth and ending at the anus

Question 6

where does digestion occur

Answer 6

Digestion occurs within the alimentary canal

Question 7

Accessory organs produce substances that are needed for digestion to occur, such as?

Answer 7

enzymes and bile

Question 8

What is the function of the Mouth/Salivary Glands

Answer 8

The mouth is where Mechanical Digestion takes place.

• Teeth chew food to break it down into smaller pieces and increase its surface area to volume ratio
• Amylase Enzymes in saliva start digesting starch into maltose
• The food is shaped into a bolus (ball) by the tongue and lubricated in the saliva so it can be swallowed easily

Question 9

What is the function of the Oesophagus

Answer 9

Tube that connects the mouth to the stomach

• Where the food bolus (ball) goes after being swallowed
• Wave like contractions will take place to push the food bolus down without relying on gravity

Question 10

What is the function of the stomach

Answer 10

Food is mechanically digested by churning actions while protease enzymes start to chemically digest proteins.

• Hydrochloric Acids is present to kill bacteria in food and provide optimum pH for protease enzymes to work.

Question 11

What is the function of the small intestine

Answer 11

The first section is called the duodenum and is where and is where the food coming out of the stomach finishes being digested by enzymes produced here and also secreted from the pancreas

• pH of the small intestine is slightly alkaline - around pH 8-9
• Second section is called Ileum and is where absorption of digested food molecules takes place.
• The ileum is long and lined with Villi to increase the surface area over which absorption can take place

Question 12

What is the function of the Large Intestine

Answer 12

Water is absorbed from remaining material in the colon to produce faeces

• Faeces is stored in the rectum and removed through the anus.

Question 13

What is the function of the pancreas

Answer 13

Produces all three types of digestive enzymes; Amylase, Protease, Lipase

• Secretes enzymes in an alkaline fluid into the duodenum for digestion to raise pH of fluid coming out of the stomach

Question 14

What does alkaline mean?

Answer 14

Alkalinity means that something has a pH higher than 7.

Question 15

What is the duodenum

Answer 15

The first part of the small intestine. It connects to the stomach. The duodenum helps to further digest food coming from the stomach

Question 16

What is the function of the Liver

Answer 16

Produces bile to emulsify fats (break large droplets into smaller droplets) - an example of mechanical digestion

• Amino Acids not used to make proteins broken down here (deamination) which produces urea.

Question 17

What is the function of Gall Bladder

Answer 17

Stores bile to release into duodenum as required.

Question 18

Food taken into the body goes through different stages during its passage through the alimentary canal, what are they?

Answer 18

Ingestion
Mechanical digestion
Chemical digestion
Absorption 
Assimilation 
Egestion

Question 19

What is Ingestion

Answer 19

the taking in of substances, e.g. food and drink, into the body through the mouth

Question 20

What is Mechanical digestion

Answer 20

the breakdown of food into smaller pieces without chemical change to the food molecules

Question 21

What is Chemical digestion

Answer 21

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

Question 22

What is Absorption

Answer 22

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

Question 23

What is Assimilation

Answer 23

the movement of digested food molecules into the cells of the body where they are used, becoming part of the cells

Question 24

What is Egestion

Answer 24

the passing out of food that has not been digested or absorbed (as faeces) through the anus

Question 25

Peristalsis is a mechanism that helps, what?

Answer 25

moves food along the alimentary canal

Question 26

Describe the process of Peristalsis

Answer 26

Firstly, muscles in the walls of the oesophagus create waves of contractions which force the bolus along

Once the bolus has reached the stomach, it is churned into a less solid form, called chyme, which continues on to the small intestine

Question 27

Peristalsis is controlled, what?

Answer 27

by circular and longitudinal muscles

Question 28

Mucus is produced to do what?

Answer 28

To continually lubricate the food mass and reduce friction

Question 29

Dietary fibre provides the roughage required for, what?

Answer 29

the muscles to push against during peristalsis