Digestion of foods in mammalian systems

Question 1

What are the four main steps of digestion

Answer 1

Ingestion: intake of food
Digestion: major biomolecules are broken down
Absorption: nutrients absorbed into the bloodstream
Elimination: excretion of waste

Question 2

Outline digestion in the mouth

Answer 2

chemical: enzymes in saliva break down substances
teeth: mechanical digestion

tongue: forms bolus to swallow

Question 3

Outline digestion in the stomach

Answer 3

hydrochloric acid chemically breaks down food
stomach contractions: physical digestion
pancreas and gall bladder add enzymes and bile to aid with digestion

after this process is finished, the resulting substance is called chyme

Question 4

outline digestion in the small intestines

Answer 4

three main portions: duodenum (beginning), jejunum(middle, most absorption), ileum(end)

villi are key for absorption as they high SA:V and one cell thickness provides efficient diffusion. They have high blood supply as it needs to take up nutrients such as glucose and amino acids for the whole body

amino acids, fatty acids, glucose and glycerol all absorbed

Question 5

outline digestion int he large intestine

Answer 5

water is reabsorbed and “good bacteria” helps with final steps of digestion

Question 6

What is the purpose of chemical and mechanical digestion

Answer 6

mechanical: breaks down into smaller pieces –> higher SA:V ratio –> more efficient absorption
chemical: breaks down larger molecules into simpler biomolecules

Question 7

Outline role of liver, gallbladder and pancreas in digestion

Answer 7

gall bladder: provides bile to dissolve fats for digestion
Liver: processes digested nutrients after absorbed into the bloodstream
Pancreas: supplies enzymes to help with digestion