9. digestion system

Question 1

mouth;

Answer 1

in the mouth food is chemically and physically broken down. Teeth help break down larger food particles into smaller food particles (physical)

Question 2

role of enzyme amylase & mucus

Answer 2

salivary glands release saliva that contains enzyme amylase & mucus, which breaks down starch into maltose.

Question 3

the bolus;

Answer 3

the mucus helps moisten food & along with chewing and tongue produces a bolus. The tongue pushes the bolus back to the throat (pharynx) and you swallow, the bolus enters the oesophagus.
The oesophagus is a smooth muscle tube that runs from the back of the mouth.
The bolus is moved by muscle contractions called peristalsis.

Question 4

the stomach;

Answer 4

The bolus is mixed with gastric juice. The stomach has muscular walls that mix and churn the food with this gastric juice. Gastric acid contains the enzyme pepsin(pH 2.5).
The walls of the stomach have gastric pit, which contain cells that produce mucus which helps protect the stomach lining from acids and enzymes.

Question 5

what happens as the food exits the stomach;

Answer 5

when the food exits the stomach via the pyloric sphincter, the liquid chime enters the small intestine. Further digestion occurs in the first part called the duodenum, then the digested food is absorbed through the walls of the small intestine. Inside the small intestine are villi, finger like projections that increase the surface area for absorbtion of food.

Question 6

The fat of food;

Answer 6

sugars (glucose) is used for respiration (to make ATP). Some can be stored in glycogen in liver and muscle.

If excess sugar is converted to fats , sent to the fat store.

Question 7

fat;

Answer 7

• can be used for respiration
• required to make some hormones
• insulation
• protection ( fat pads, hands, feet/paws)
• part of the cell membrane

Question 8

proteins;

Answer 8

growth and repair of tissue.
> we cannot store excess amino acids, they are broken down by a process called deamination in the liver.
> protein can be used for respiration but only as a last resort.

Question 9

pancreas;

Answer 9

plays a vital role in digestion, it produces pancreatic juice which contains 3 enzymes required for digestion.
Pancreatic juice + bile from the gallbladder enters the small intestine and helps change acidic chyme to alkaline substance.
> the pancreas also produces 2 hormones (insulin and glucagon) which regulate blood sugar levels.

Question 10

3 enzymes required for digestion (pancreatic juice)

Answer 10

pancreatic amylase
starch —————————————————-> maltose
trypsin
polypeptides ———————————————-> amino acids
lipase
fat ————————————————————> fatty acids +
glycerol

Question 11

the liver;

Answer 11

> all products of digestion regulated by the liver.
If too much of a substance the liver can either store, change or get rid of that substance.
the liver produces bile as a by product from the breakdown of old red blood cells. ~ bile stored in gallbladder.

Question 12

important function of bile in digestion

Answer 12

Bile is classified as a emulsifier and makes large fat droplets into smaller fat droplets, this allows a greater surface area for lipase to work on.

Question 13

large intestine (Colon);

Answer 13

the undigested remains reach the large intestine, water is reabsorbed learning a semi solid waste called faeces. This is stored in the rectum and exists through the anus.