Digestive System

Question 1

What is the structure of the Digestive System?

Answer 1

• Alimentary Canal, mouth, pharynx, oesophagus, stomach, small intestine, large intestine
• Accessory organs (teeth, gall bladder, pancreas, liver, salivary glands, tongue)

Question 2

What are the 6 key functions of the digestive system?

Answer 2

1. ingestion of food and water
2. mechanical digestion of food
3. chemical digestion of food
4. move food along alimentary canal
5. absorb digested food and water into blood and lymph
6. eliminate materials not absorbed

Question 3

What is digestion?

Answer 3

process where carbohydrates, proteins, and fats are broken down to be absorbed into the blood and cells

Question 4

what is mechanical digestion? + examples

Answer 4

mechanical actions to break down food (biting, chewing, mashing, pummelling, churning)

Question 5

what is chemical digestion? + example

Answer 5

the use of chemicals to break down food (enzymes)

Question 6

what is the function of the mouth?

Answer 6

• chemical digestion: salivary amylase
• mechanical digestion: teeth and tongue turn food into bolus (small rounded mass of substance)

Question 7

what is the function of the oesophagus?

Answer 7

• transport bolus to the stomach via peristalsis

Question 8

what is the function of the stomach?

Answer 8

• involved in mechanical and chemical digestion

Question 9

structure of the stomach?

Answer 9

• lined by specialised mucosal cells which produce gastric acid
• 3 layers of muscle: oblique, circular, longitudinal
• muscle walls churn its contents
• the puloric sphincter

Question 10

What is the puloric sphincter? and its purpose?

Answer 10

• a thickening of the circular of the circular muscles at the bottom of stomach
• prevents stomach contents moving through // except pushed via peristalsis

Question 11

What are rugae?

Answer 11

gastric folds that increase surface area and stretch stomach

Question 12

Structure of chemical digestion?

Answer 12

• gastric glands located in the gastric pits release gastric juice
• gastric juice contains hydrochloric acid, enzymes (pepsin), and mucous
• pepsin carries out the chemical digestion

Question 13

Structure of mechanical digestion?

Answer 13

• 3 layers of stomach muscles
• manual churning of stomach contents
• mixes contents with gastric juice
• takes 2-8 hours for stomach contents to move into the section of alimentary canal

Question 14

function of small intestine in chemical digestion

Answer 14

• digestion and absorption
• chemical digestion:
  -first section of intestine called duodenum
  -duodenum has connections with pancreas and live/gall bladder

Question 15

What does pancreatic juice contain?

Answer 15

amylase (for proteins)
trypsin (for proteins)
nuclease (for DNA and RNA)
lipases (for fats)

Question 16

function of small intestine in mechanical digestion

Answer 16

-gall bladder stores bile secreted by liver
-bile salts mechanically digest fats by breaking them down into smaller droplets (emulsification)

Question 17

function of small intestine in absorption

Answer 17

• digestion leaves us with simple sugars, amino acids, fatty acids, glycerol and nutrients
• absorbed by wall of intestine

Question 18

What is Villi and where is it located?

Answer 18

• located in the lining of the small intestine called the mucosa
• each villi has microvilli
• provides huge surface area
• absorption occurs though simple diffusion and active transport

Question 19

function and structure of the large intestine?

Answer 19

• no villi, no secretion of digestive juices
• lining secreted mucous
• 18-24 hours to pass through
• main role: absorption of water, minerals and vitamins from bacteria