Mechanical and Chemical Digestion

Question 1

Mechanical Digestion: Muscular Action of Digestion

Answer 1

• main function do GI
• involves the physical breakdown of food into smaller pieces
• involves the mixing and propulsion of material by muscular contractions

Question 2

Mechanical Digestion: Intestinal Action - Peristalsis

Answer 2

• propulsive movement
• involves the contraction/ relaxation of the circular and longitudinal muscles of the intestines
• keeps the chyme moving through the intestines

Question 3

Mechanical Digestion: Intestinal Action - Segmentation

Answer 3

• circular muscles contract rhythmically
• “chops” up the chyme into even smaller pieces
• as smaller pieces, it promotes closer contact with digestive juices

Question 4

Chemical Digestion

Answer 4

• breaking down of food into simpler nutrients so that can be used by cells
• involves use of chemical and enzyme secretions from GI tract

Question 5

Enzyme Shape

Answer 5

• made of amino acids (proteins)
• the chain of amino acids food and produce a very unique shape
• this unique shape will only allow it to interact with SPECIFIC substances
• enzyme remains unchanged after the reaction
• similar time lock and key

Question 6

Enzyme Function

Answer 6

• (each nutrient posses a different shape and needs a different enzyme to break it down)
• function as protein catalyst
• allow reactions to occur that would normally not proceed
• they may either:
a) combine molecules to produce a new product
b) break a molecule into smaller parts

Question 7

Secretions of Digestion: Pancreas

Answer 7

1. Pancreatic Juices
   • eg. trypsinogen, pancreatic lipase
2. Bicarbonate
   • creates an alkaline solution
   • neutralizes chyme (acidic from gastric acid) as it enters duodenum

Question 8

Mechanical Digestion: Teeth (Chewing)

Answer 8

• breaks large pieces into smaller pieces

* food that has been chewed is referred to as a “bolus”

Question 9

Types of Stomach Muscles

Answer 9

• circular
• longitudinal
• diagonal

Question 10

Mechanical Digestion: Stomach Action

Answer 10

• muscles act to generate churning action
• churning liquefies the “food” into chyme
• liquefied chyme pushes toward and through the pyloric sphincter

Question 11

Mechanical Digestion: Sphincter Contractions

Answer 11

• muscular gateway
• opens/closes to allow the contents of the GI tract to move at a controlled pace
• prevents reflux
• occurs when sphincters malfunction and chyme flows backwards (causes burning sensation)

Question 12

Chemical Digestion: GI Secretions (Digestive Juices)

Answer 12

• water
• acids
• electrolytes
• mucus 
• salts
• enzymes
• bicarbonate 
- all these chemicals facilitate break down of food

Question 13

Secretions of Digestion: Saliva

Answer 13

• salivary glands produce saliva

• contains water, salts, mucus, enzymes
• ie. salivary lipase, amylase

Question 14

Secretions of Digestion: Stomach

Answer 14

• gastric juices
• gastric glands
• contains water, enzymes (ie. Pepsin, gastric amylase)
• HCI (very strong acid)
- enzymes of stomach work best in strong acidic environment
• mucus protects the stomach walls from damage

Question 15

Secretions of Digestion: Liver

Answer 15

• bile

- breaks fat globules into smaller droplets