Option D unit D1

Question 1

Types of digestion + goal of digestion

Answer 1

Goal of digestion: breaking down food and nutrients into smaller pieces so it can be digested

1. physical/mechanical - breaking down to medium size pieces
   - Usually happens first
   - Chewing
   - Mixing
   - Churning
2. chemical digestion - breaks to really small pieces
   - Usually happens second
   - Enzymes
   - Acid

Question 2

Structures and functions:

Answer 2

• Mouth - mechanical and chemical digestion
• Esophagus - peristalsis action -> muscle movement to push food through organs. Mechanical digestion
• Stomach - rugae, lumen, mucous coating -> mechanical and chemical digestion
• Small intestine - villi and microvilli increase area for absorption of nutrients → chemical digestion
• Large intestine - water balance, vitamin absorption
• Pancreas - production of enzymes → chemical digestion
• Liver - production of bile → chemical digestion
• Gall bladder - storage of bile → chemical digestion

Question 3

Typical pH values found throughout the digestive system:

Answer 3

• Mouth: 5.5 - 7.5 (slightly acidic)
• Stomach: 1.0 to less than 4.0 (very acidic)
• Small intestine: 6.0 - 8.0 (neutral)
  (Proper pH is needed to allow for efficient enzyme reactions.)

Question 4

enzymes that are responsible for digestion

Answer 4

carbohydrates, fats and protein from the mouth to the small intestines

Enzymes are specific to the type of molecule they digest
* Carbohydrates: salivary amylase, pancreatic amylase
* Fats: pancreatic lipase + bile( Bile is produced by the liver and is involved in the digestion of fats)
* Proteins: pepsin, trypsin

Question 5

The need for enzymes in digestion: (7)

Answer 5

• Mechanical digestion does not get food small enough for absorption so we need to chemically digest it to get it small enough
• Enzymes catalyze (allows to happen faster) chemical digestion reactions
  –> Body temp is fairly low which allow chemical reactions to occur fast enough
  
  • Enzymes allow reactions to happen at lower activation energy (energy needed to trigger reaction)
  • With less energy required, reactions can happen more frequently
• Smaller molecules are more soluble → absorption
• Once digestion happens the molecules can be absorbed into the bloodstream in the small intestine
  (Absorption only happens in Small Intestine)

Question 6

absorption of nutrients

Answer 6

• Glucose → Carbs
• Amino Acids → Protein
• Fatty acids → lipids

Question 7

How glucose goes across the lumen to the bloodstream:

Answer 7

• Active transport through a cotransporter to enter the cytosol of the villi cell
• Facilitate transport through a channel protein to enter blood stream

Question 8

How amino Acids goes across the lumen to the bloodstream:

Answer 8

• Active transport through a co-transporter to enter the cytosol of the villi cell
• Simple diffusion to enter bloodstream

Question 9

How fatty acids goes across the lumen to the bloodstream:

Answer 9

• Diffusion to enter the cytosol of the villi cell (No ATP)
• Simple diffusion to enter lacteal/lymphatic system