Digestion

Question 1

What is the most satiating macronutrient?

Answer 1

Protein

Question 2

What have low satiety value?

Answer 2

Carbs and fat

Question 3

Digestion in the mouth

Answer 3

• cephalic phase – sight, smell or thought of food initiates the digestive
  process with the salivary and gastric responses
• Mechanical digestion = chewing
  -Chemical digestion = saliva

Question 4

How many salivary glands are there?

Answer 4

3

Question 5

What does saliva contain?

Answer 5

• water
• bicarbonate (pH maintenance)
• mucus (lubrication)
• antibodies (protection)
• enzymes e.g. salivary amylase which
  initiates the digestion of starch

Question 6

What is the gastroesophageal sphincter?

Answer 6

separates the esophagus from the stomach; the bolus
(the portion of food shallowed at one time)
cannot slip back, from the stomach to esophagus

Question 7

Digestion in the stomach includes..?

Answer 7

-Mechanical digestion to mix food with gastric juices
-Chemical digestion via gastric juices

Question 8

What is gastric juices?

Answer 8

Digestive secreation containing water, HCL, and enzymes (pepsin)

Question 9

What is chyme?

Answer 9

semi-solid product of mechanical and chemical digestion in the
stomach; partially digested food mixed with water and gastric juices; expelled
by the stomach into the duodenum (the top portion of the small intestine).

Question 10

What does the liver produce?

Answer 10

Bile

Question 11

What does the gallbladder store?

Answer 11

Bile

Question 12

What is bile?

Answer 12

– secreted into duodenum when needed, whenever fat arrives there
– it is an emulsifier: disperses the fat in the water forming an emulsion

Question 13

What is the purpose of the pancreas?

Answer 13

– produces pancreatic juice which flows from the pancreas into the small
intestine through the pancreatic duct

Question 14

What is pancreatic juice?

Answer 14

i) enzymes that act on all 3 macronutrients (amylase for carbohydrates,
protease for proteins, and lipase for fats)
ii) sodium bicarbonate to neutralize acidic chyme as it enters the small intestine

Question 15

What os the major site of digestion?

Answer 15

Small intestine

Question 16

What is the final stage of digestion?

Answer 16

Small intestine

Question 17

What is peristalsis?

Answer 17

-successive waves of involuntary muscular contractions passing along the walls of the GI
tract that push the contents along

• circular and longitudinal muscles contract

-Enhances the absorption along the intestine

Question 18

What is segmentation?

Answer 18

-circular muscles contract, creating segments of chyme within the intestine

Question 19

What is in the small intestine that facilitates absorption?

Answer 19

-Villi
-Microvilli

Question 20

What is Villi?

Answer 20

finger-like projections made up of cells
that found on the folds of the small intestine and
they are in close contact with nutrient
molecules; absorb nutrients and shuttle them
into the bloodstream so they can travel where
thy are needed.

Question 21

What is microvilli?

Answer 21

-Microscopic hair-like projections
-Primary site of absorption of most nutrients

Question 22

What is simple/passive diffusion?

Answer 22

-Pass through the membrane freely
-move along concentration gradient

-High to low

• Lipids and water

Question 23

What is facilitated diffusion?

Answer 23

-Only soluble in water
-requires a carrier protein
-requires concentration gradient (high to low)
-Does not require expenditure of cellular energy

• Water-soluble vitamins, fructose

Question 24

What is active transport?

Answer 24

-Concentration is higher inside than outside
-Requires carrier protein
-requires energy
-glucose and amino acids

Question 25

What is endocytosis?

Answer 25

• small amount of intestinal content engulfed by cell membrane

Question 26

Where does undigested food move through?

Answer 26

In the sphincter called ileocecal valve in the large instestine

Question 27

How long is material stored prior to elimination?

Answer 27

12-24 hours

Question 28

How many live bacteria is needed in a probiotic?

Answer 28

1-10 billion live bacteria

Question 29

What is the use of prebiotics

Answer 29

-Promotes growth of good bacteria within the large intestine

Question 30

What are synbiotics?

Answer 30

-Combination of pro and pre

Question 31

What are postbiotics?

Answer 31

bioactive
compounds (e.g. short chain fatty
acids, Vitamins B and K, amino
acids, etc) that are produced
when probiotic bacteria consume
prebiotic fiber in your colon.

• Boosts immune system, reduce digestive symptoms

Question 32

What is the vascular system?

Answer 32

• Transport of water soluble nutrients through the blood

Question 33

What is the reason for the lymphatic system?

Answer 33

-Lymph = transports of lipids

-transports fat-soluble nutrients
-returns fluid to the blood
-part of the immune system

Question 34

What is the Hepatic portal system?

Answer 34

portal vein (receives first
absorbed water-soluble nutrients)

• ensures liver is first to receive materials absorbed from GI tract
  (“gatekeeper”)

Question 35

What is the major metabolic organ?

Answer 35

Liver = prepares absorbed nutrients for use by rest of body

Question 36

What is homeostasis?

Answer 36

maintain important variables in the face of large environmental changes

Question 37

What is negative feedback?

Answer 37

response to a stimulus in order to reverse or cause the opposite effect of
the original stimulus

Question 38

What is CNS?

Answer 38

-Central nervous system
-main processing area
-Brain and spinal cord

Question 39

What is PNS?

Answer 39

-Peripheral nervous system
-nerves outside CNS
-GI tract component called enteric nervous system

Question 40

What is gastrin?

Answer 40

Hormone produced by G cells in the stomach
-Triggered by entry of food into the stomach
-Promotes the release of HCL from the stomach
-Controls release of pepsin from the stomach

Question 41

What is secretin?

Answer 41

Hormones released from the duodenum when stomach acid contents come to duodenum (when pH is below 4.5)
-Inhibits gastric motility and gastrin
-stimulates bicarbonate secretion from pancrease to neutralize chyme

Question 42

What is CCK?

Answer 42

Cholecystokinin
-Hormone produced by the duodenum due to lipid rich chyme
-Stimulates the release of digestive enzymes from the pancrease and of bile from the gallbladder

Question 43

What is GIP?

Answer 43

Gastric-inhibitory peptide
-hormone produced by duodenum
-inhibits gastric motility and secretion of acid
-stimulates the release of insulin from pancreas in response to glucose infusions