Digestive system

Question 1

What are the 6 main nutrients the cells in the body require?

Answer 1

Simple sugars 
Amino acids 
Fatty acids 
Vitamins 
Minerals 
Water

Question 2

What will occur to our cells if we do not get these nutrients?

Answer 2

Without these things our cells and therefore body would not function properly!

Question 3

Where do the 20 amino acids come from?

Answer 3

Essential amino acids– from foods directly (9)

Non Essential amino acids– synthesised from foods (11)

Question 4

What bond holds the amino acids?

Answer 4

Amino acids are joined by a peptide bond.

Question 5

What are 4 functions of lipids?

Answer 5

High energy source (energy reserves)
Insulation
Protection of organs
Structural (cell membrane)

Question 6

What is digestion?

Answer 6

The process in which carbohydrate, protein and fat molecules are broken down to products small enough to be absorbed into the blood and into the cells

Question 7

What are the 6 steps of digestion in the digestive system?

Answer 7

Ingestion of food

Mechanical digestion of food (physical)

Chemical digestion of food (involves enzymes)

Movement of food along the alimentary canal

Absorption of digested food and water into lymph and blood

Elimination of material that is not absorbed

Question 8

What is the alimentary canal?

Answer 8

Most of the parts of the digestive system are arranged to form a continuous tube running from the mouth to the anus

Question 9

What are the organs called that are not part of the alimentary canal, but still help with digestion?

Answer 9

There are also other organs called accessory organs that help with digestion.

Question 10

What are carbohydrate enzymes called?

Answer 10

amylase

Question 11

What are protein enzymes called?

Answer 11

Protease

Question 12

What are lipid enzymes called?

Answer 12

lipases

Question 13

What happens in ingestion of food: Digestion in the Mouth? Mechanical and chemical

Answer 13

Mechanical: Action of jaw and teeth breaks food into smaller particles.
Canines(2)- tearing
Incisors(4)- bite
Premolars(4)/Molars(6)- crushing and grinding

Chemical: Salivary glands secrete saliva which contains mucus and salivary amylase (begins starch breakdown)

Question 14

What happens in ingestion of food (physical): chewing and swallowing?

Answer 14

After chewing in the mouth, the food is formed by the tongue into a rounded lump called a bolus. Swallowing then occurs, the tongue moves upwards and backwards to push the bolus into the back of the mouth, the pharynx.The pharynx leads to the oesophagus

Question 15

What happens in ingestion of food: Peristalsis?

Answer 15

The wall of the oesophagus has a double layer of muscle, circular and longitudinal

As food enters the oesophagus the circular muscle behind it contracts to form a constriction. The contraction of successive bands of muscle moves the food along.

Question 16

What is peristalsis?

Answer 16

A wave of muscular contraction that pushes food along

Question 17

What is the stomach lining?

Answer 17

The stomach lining (mucosa) is specialised for the secretion of gastric juice which contains hydrochloric acid, mucus and digestive enzymes

Question 18

What happens in Mechanical digestion of food (physical)?

Answer 18

Mechanical: waves of muscular contraction that move along the stomach wall.
Circular, longditudinal and oblique muscles (muscle contracts in a variety of ways to churn food and mix it with enzymes)

Question 19

What happens in Chemical digestion of food in the stomach?

Answer 19

Chemical: Gastric juice secreted by gastric glands located in tube-like structures called gastric pits.
Starts protein digestion Gastric Protease

Question 20

What occurs in the stomach when food comes?

Answer 20

Lower end of the stomach muscle constriction
Pyloric sphincter: prevents movement of food too early

The food is converted into a thick, soupy liquid called chyme

After 2-8 hours the stomach contents are pushed into the next part of the alimentary canal, the small intestine.

Question 21

What occurs in the first part of the small intestine?

Answer 21

called the duodenum, Food enters the small intestine from the stomach is only partially digested. Most of the organic molecules are still too large to be absorbed into the blood and must be further broken down.

Question 22

What are the three main fluids that helps digest the food in the small intestine?

Answer 22

There are three main fluids that help digest the food in the small intestine.

Pancreatic juice (from the pancreas) 
Bile (from the liver/gall bladder) 
Intestinal juice (from the small intestine)

Question 23

What enzymes are in the Pancreatic juice (from the pancreas) ?

Answer 23

Pancreatic amylase: breaks down starch (polysaccharides) to disaccharides

Pancreatic protease (trypsin): breaks down proteins to small peptide chains

Pancreatic lipases: breaks down fats into fatty acid and glycerol

Nucleases: breaks down RNA and DNA

Question 24

What is bile (from the liver/gall bladder)?

Answer 24

Produced by the liver stored and secreted by the gall bladder

No digestive enzymes

Contains bile salts

Emulsify fats, breaking them down into tiny droplets
MECHANICAL DIGESTION

Increases surface area for fat chemical breakdown.

Question 25

What enzymes are in Intestinal juice (from the small intestine)?

Answer 25

Amylases: disaccharides to monosaccarides simple sugars

Peptidases: small peptides to amino acids

Lipases: Lipids to fatty acids and glycerol

Question 26

Where does Absorption of digested food and water occur?

Answer 26

Through the wall of the small intestine into the blood

Question 27

Why does absorption occur in the small intestines?

Answer 27

Large surface area needed
Long (6m)
Mucosa has folds
Small finger-like projections called villi (1mm)
Cells covering the outside of the villi have tiny microscopic projections called microvilli

Question 28

Describe the process of absorption

Answer 28

Inside Villus is a lymph capillary called a lacteal, which is surrounded by a network of blood capillaries.
Continual movement of villi enhance absorption
Nutrients move via simple diffusion and active transport
Simple sugars, amino acids, water and water-soluble vitamins into blood capillaries
Fatty acids and glycerol into lacteals

Question 29

What occurs in the large intestine?

Answer 29

Remaining water is absorbed

Bacteria in the Large intestine break down much of the remaining organic compounds. Some bacteria produce vitamins, which are absorbed through the walls into the blood.

Minerals are absorbed

Stores faeces (water, undigested food material (cellulose), bacteria, bile pigments, remains of cells of the internal lining of the alimentary canal)

Defecation

Question 30

What is the large intestine?

Answer 30

No Villi
No digestive juices secreted
Slow movement 18-24 hours

Question 31

What the 13 main structures of the digestive system?

Answer 31

Mouth

Salivary glands

Oesophagus

Stomach

Liver

Pancreas

Gall bladder

Duodenum

Small intestines

Large intestine

Appendix

Rectum

Anus

Question 32

What happens when nutrients enter the body?

Answer 32

Water, vitamins and minerals are small molecules and don’t need to be broken down by the body, they just enter the cells.
The remaining body requirements need to be broken down because they are eaten as larger more complex molecules that cannot enter the cells as they are.

Question 33

What 3 parts of the digestion system have mechanical digestion?

Answer 33

Mouth: chewing

Stomach: grinding

Duodenum: Bile-breaks down fat

Question 34

What 4 parts of the digestion system have chemical digestion? State the enzymes.

Answer 34

Mouth: salivary amylase - starch

Stomach: Gastric protease - proteins

Duodenum-(from pancreas) pancreatic amylase, protease and lipase

Small intestines - intestinal amylase, protease and lipase

Question 35

What absorption occurs in the stomach?

Answer 35

No nutrients are absorbed in the stomach due to thick mucus layer
Some alcohol and a few other drugs are absorbed