Digestive system

Question 1

The structures involved in the digestive system

Answer 1

Mouth, oesophagus, stomach, small intestine, large intestine, pancreas.

Question 2

Function of the mouth

Answer 2

1. Where the mechanical digestion takes place. Teeth chew the food into smaller pieces to increase surface area to volume ratio
2. Amylase enzymes start digesting strach into maltose.
3. food is shaped in a bolus ( ball shaped) by tongue and saliva lubricates it so it can be swallowed easily

Question 3

Function of the oesohagus

Answer 3

1. Tube that connects mouth to stomach. Where the food goes after being turned into bolus and swallowed
2. Wave like contractions will take place to push the bolus down without relying on gravity.

Question 4

Function of the stomach

Answer 4

1. food is mechanically digested by churning actions
2. protease enzymes start to chemically digest protein.
3. Hydrochloric acid present to kill bacteria in food and provide optimum pH for protease enzyme to work.

Question 5

What are the two parts in the small intestine and what is the pH in the small intestine.

Answer 5

Duodenum and ileum. It is slightly alkaline around pH 8-9

Question 6

Function of the duodenum

Answer 6

1. Is where the food coming out of stomach finished being digesting by enzymes produced here and discharged by the pancreas.

Question 7

Function of the illeum

Answer 7

1. Absorption of digested food molecules takes place.

2. Is long and has many villi to increase surface area so more absorption can take place.

Question 8

Function of the large intestine

Answer 8

1. Water is absorbed from the remaining material in the colon to produce faeces
2. Faeces is then stored in the rectum and removed through the anus.

Question 9

Function of the pancreas

Answer 9

1. Produces all type of digestive enzymes.

2. Secretes enzyme in an alkaline fluid in the duodenum for digestion.

Question 10

how food is moved through the gut

Answer 10

By peristalsis. Peristalsis is contraction of two sets of muscles in the walls of the gut. The wave like contractions of these muscles create a squeezing action that pushes food through the gut

Question 11

what are the different digestive enzymes and what they digest.

Answer 11

carbohydrases (am= starch to glucose and maltose
protease = protein to amino acids
lipase = lipids to fatty acids and glycerol

Question 12

What is the purpose of disgestion

Answer 12

to break down large, insoluble molecules (carbohydrates, proteins and lipids) into small, soluble molecules that can be absorbed into the bloodstream

Question 13

How does protease break down protein and where are they made?

Answer 13

Made in stomach pancreas and small intestine.
1.Protein are long chain of amino acids.
2 The protease converts the protein back into amino acids which are then absorbed in the bloodstream.

Question 14

How does Carbohydrase break down strach and where is it produced.

Answer 14

Made in the pancreas, small intestine and salivary glands.

1. Starch(carbohydrate) contains chain of glucose molecules.
2. Starch is broken down by amylase.
3. When carbohydrates digested we produce simple sugars.

Question 15

How does lipase break down lipids and where is it produced.

Answer 15

Made in pancreas and small intestine.

1. Lipid molecule has glycerol and 3 fatty acids.
2. Are digested by lipase.
3. Produces glycerol and 3 fatty acids

Question 16

Function of the liver.

Answer 16

Regulates most chemical levels and excretes bile.

Question 17

Where is bile stored and what is it’s function

Answer 17

Stored in the gall bladder.

1. It is alkaline to neutralise the hydrochloric acid which comes from the stomach. Creates alkaline conditions in the small intestine therefore increases rate of lipid breakdown by lipase.
2. breaks down large drops of fat into smaller ones. This is known as emulsification. this increases the surface area of the lipid droplets therefore increases rate of lipid breakdown by lipase.

Question 18

How is the small intestine adapted for absorption

Answer 18

1. Absorption takes place in the ileum which is very long.
2. It has many folded structures call villi that increase it’s surface area allowing absorption to take place faster and more efficiently
3. Has micro villi on top of the villi to further increase surface area
4. Network of blood capillaries meaning very good blood supply, and the products of digestion are rapidly removed therefore increasing the concentration gradient.
5. Wall of villus is one cell thick meaning that there is only a short distance for absorption to happen by diffusion and active transport

Question 19

Structure of the villi

Answer 19

1. Microvilli on the surface of the villus further increase surface area for faster absorption of nutrients
2. Wall of villus is one cell thick meaning that there is only a short distance for absorption to happen by diffusion and active transport
3. Well supplied with a network of blood capillaries that transport glucose and amino acids away from the small intestine in the blood
4. Lacteal runs through the centre of the villus to transport fatty acids and glycerol away from the small intestine in the lymph