Chapter 7 contin..

Question 1

What is the Alimentary canal?

Answer 1

The Alimentary canal is a tube running through the body. Food is digested here.

Question 2

What is Mucus?

Answer 2

Mucus is a slimy liquid that lubricates the lining of the canal, protecting from wear and tear.
It also protects the lining from attack of digestive enzymes.

Question 3

What are the 5 processes that occur in the Alimentary canal?

Answer 3

Ingestion, Digestion (Mechanical & Chemical), Absorption, Assimilation and Egestion.

Question 4

What is Ingestion?

Answer 4

Ingestion is taking in substances through the mouth.

Question 5

What is Mechanical Digestion?

Answer 5

Mechanical digestion is the breakdown of food into smaller pieces without chemical change. (By teeth)

Question 6

What is Chemical Digestion?

Answer 6

Chemical Digestion is the breakdown of large insoluble molecules into small soluble ones. (By enzymes)

Question 7

What is Absorption?

Answer 7

Absorption is the movement of the small molecules through the intestine wall into the blood.

Question 8

What is Assimilation?

Answer 8

Assimilation is the movement of digested food molecules into cells where they are used and become part of the cells.

Question 9

What is Egestion?

Answer 9

Egestion is the removal of undigested or unabsorbed food, as faeces through the anus.

Question 10

What is Peristalsis?

Answer 10

• Peristalsis is the wave of contraction that passes along the canal, pushing food through it.
• It is one contraction after another, causing a wave.
  *Antiperistalsis would be vomiting.

Question 11

What is Diarrhoea?

Answer 11

Diarrhoea is the loss of watery faeces.
This is caused by bacterial or viral infections.

Question 12

How is Diarrhoea caused?

Answer 12

• It caused by the bacteria that damage the intestines.
• This results in too much fluid secreted into the colon.
• Undigested food moves too quickly, and theres not enough time to absorb water from it.
• This causes dehydration.

Question 13

What is ORT/ORS?

Answer 13

Oral Rehydration Therapy/Solution is the treatment for Dehydration.
This involves drinking a solution of water and salts with electrolytes to build back the water concentration in the body.

Question 14

What is Cholera? (points)

Answer 14

Cholera is a disease caused by the bacteria Vibrio Cholera.
- It causes Acute Diarrhoea, that cant be treated with ORS.
- Treatment involves injecting a solution or using Tetracycline to kill the bacteria.
- It can also cause Kidney failure.

Question 15

How is Cholera caused?

Answer 15

It is caused by taking in impure water. The bacteria Vibrio Cholera are in it, and once ingested, they multiply in the SMALL INTESTINE, and then release toxins that damage it.
- This results in secretion of large amounts of water and salts.

Question 16

Why is food first mechanically digested?

Answer 16

• Physical digestion increases the
  surface area of food for the action of enzymes in chemical digestion.
• This is done by the teeth, stomach and BILE in duodenum.

Question 17

What are the 4 types of teeth?

Answer 17

These are:
- Incisors; chisel shaped, bite off food
- Canines; more pointed, bite off food
- Premolars; 2 points/cusps, 1-2 roots. Tear and grind food
- Molars; 4-5 cusps, 2-3 roots. Chew and grind food

Question 18

What is the structure of a tooth?

Answer 18

The tooth has enamel, dentine, pulp cavity, nerves and blood vessels and cement.

Question 19

What is the crown and root?

Answer 19

The crown is the tooth visible (above the gum line).
The root is the rest of the tooth in the jaw bone.

Question 20

How is the tooth embedded in the gums?

Answer 20

The enamel layer is replaced with cement in the root, which allows the tooth to grip to its bony socket in the jaw.

Question 21

How is dental decay caused?

Answer 21

Dental decay causes cavities.
This occurs when bacteria feed on sugar on our teeth, respiring them and producing acid.
The acid dissolves calcium salts in the Enamel, and then the dentine.
The acids cause toothache and irritate nerve endings.

Question 22

What is the Critical PH?

Answer 22

Critical PH is the PH BELOW which the enamel is attacked (normal PH is 7)
Enamel is under an acid attack for 10 minutes.

Question 23

What is the role of the Stomach?

Answer 23

The stomach plays a part in physical digestion.
- The stomach muscle walls contract to squeeze and mix food to liquify it.

Question 24

What is the role of Bile?

Answer 24

• Bile is produced in the LIVER and stored in the GALL BLADDER.
• It is released through the Bile duct to the Duodenum (first part of S.I):
• It is Alkaline, so it neutralises the HCL from stomach.
• It breaks down large fat droplets into smaller ones. EMULSIFICATION.
• This increases surface area of fat droplets for enzyme action.

Question 25

What is Amylase and where is it produced? (+Maltase)

Answer 25

Amylase is the enzyme that breaks down Starch into Glucose (simple reducing sugars). - Amylase breaks down Starch -> Maltose. - Maltase breaks down Maltose -> Glucose. > Amylase acts in the Mouth and Duodenum (produced by Salivary glands and Pancreas) > Maltase acts in the Lining of S.I

Question 26

What is Protease and its types?

Answer 26

Protease is an enzyme that breaks down Protein into Amino acids. - There are 2 types in the digestive system. Pepsin and Trypsin.

Question 27

What does Pepsin and Trypsin do?

Answer 27

PEPSIN is a protease secreted as inactive Pepsinogen. (By Stomach) - This becomes activated by HCL in Stomach. - This is in Acidic conditions TRYPSIN is a protease secreted as inactive Trypsinogen. (By Pancreas to the Duodenum) - This is in Alkaline conditions. - This becomes activated by Enterokinase- An enzyme secreted by the lining of Duodenum.

Question 28

What are the PH of the organs?

Answer 28

Stomach needs ACIDIC PH Duodenum needs ALKALINE PH Pancreas needs NEUTRAL PH

Question 29

What is Lipase?

Answer 29

Lipase is an enzyme that breaks down Lipids into fatty acids and Glycerol. - This is secreted by the Pancreas into the Duodenum.

Question 30

Where is Amylase, Protease and Lipase produced?

Answer 30

- Amylase is produced in the Salivary glands -> Mouth and Pancreas -> Duodenum. - Protease is produced in the Stomach -> Stomach and Pancreas -> Duodenum. - Lipase is produced in the Pancreas -> Duodenum.

Question 31

What are the functions of HCL?

Answer 31

- It kills harmful microorganisms in food. - It provides an optimum ph for enzyme activity ex: Pepsin.

Question 32

What are the Functions of Bile?

Answer 32

- To emulsify fats. - Bile is an Alkaline mixture that NEUTRALISES acidic mixture of food and gastric juice's from the Stomach. - Enzymes in the small intestine have an Alkaline PH, so enzymes work better.

Question 33

Where does Absorption take place?

Answer 33

Most water is absorbed by the ileum, but some also by the Colon.

Question 34

How is the Ileum adapted for absorption?

Answer 34

- The Ileum is adapted for absorption as it has a highly folded surface with millions of Villi and microvilli. - Lining epithelium is very thin, allowing fluids to pass through rapidly. - There is a dense network of blood capillaries in each Villus.

Question 35

What are Villi?

Answer 35

Villi are tiny finger-like projections. They increase the surface area of the ileum, allowing absorption to take place faster and more efficiently. - Microvilli increase the exposed surface by x20

Question 36

What is the structure of a Villus?

Answer 36

Villus consists of Capillaries, thin surface layer, Micro villi, Villi, Blood vessels and Lacteals.

Question 37

What is the role of Capillaries and Lacteals in the small intestine?

Answer 37

- Capillaries absorb the glucose and amino acids, carrying them AWAY FROM S.I, INTO BLOOD. - Lacteals absorb fatty acids and glycerol AWAY FROM S.I, INTO LYMPH.