Midterm 1 - Lecture 2

Question 1

Name all the organs of digestion

Answer 1

• Mouth
• Esophagus
• Stomach
• Small Intestine
• Large Intestine
• Accessory Organs ((liver, pancreas, gall
bladder & salivary glands)

Question 2

Fxns of saliva

Answer 2

Digest carbohydrates with salivary amylases
Lubricate (mucous)
Antimicrobial (lysozyme that digests bacterial cell walls)
—Bolus formation—

Question 3

Fxns of Taste Receptors

Answer 3

• Sweet and salt receptors attract us to carbs and salt
• Bitter receptors repel us from toxins
• Sour receptors repel us from fermented (acidic) food
• Umami receptors attract us to protein

Question 4

Interactions between salt, bitter & sour receptors:

Answer 4

attracts us to food

Question 5

Interactions between salt, bitter & sour receptors:

>300mM Na

Answer 5

activates sour & bitter receptors causing aversion

Question 6

Interactions between salt, bitter & sour receptors:

Inactivate bitter or sour receptors

Answer 6

lose aversion to high salt

Question 7

Characteristics of Esophagus

Answer 7

secretes water & mucus

movement by peristalsis

Question 8

Entry to Esophagus controlled by

Answer 8

upper esophageal sphincter

Question 9

Back flow into esophagus controlled by

Answer 9

cardiac (lower esophageal) sphincter

Question 10

Fxns of stomach

Answer 10

• Residence time: 2-3 hr
• solubilize and digest food to acid chyme
• Releases acid (HCl, drops pH to 1-2) and proteases
• Acid denatures proteins (inactivates salivary amylase), hydrolyzes carbs, dissolves minerals (e.g. Ca), kills microbes, activates pepsinogen to pepsin

Question 11

Fxn of parietal cells in stomach

Answer 11

release HCl

Question 12

Fxn of chief cells in stomach

Answer 12

store then release pepsinogen

Question 13

Pepsinogen is activated by acid and becomes:

Answer 13

pepsin

Question 14

Fxn of Surface mucous cells

Answer 14

release mucus: protects stomach lining from acid

and proteases and from inflammation induced by food antigens

Question 15

Infant Stomach/Digestion

Answer 15

lower acid production

Question 16

raw honey in infants

Answer 16

botulism poisoning by spores of Clostridium botulinum (paralyzes muscles)

Question 17

~40% mothers start feeding infants solid food at 4 months. Why is this a problem?

Answer 17

Solid food

Question 18

Chyme flow from stomach -> small intestine is controlled by what sphincter?

Answer 18

pyloric sphincter; Squirts only a few mLs to S.I. at a time so SI can neutralize acid (with NaHCO3) because enzymes in SI need neutral pH

Question 19

What occurs in the small intestine?

Answer 19

Digestion is completed and most nutrients and minerals absorbed in this region.

Question 20

Fxn of Duodenum

Answer 20

releases NaHCO3 from pancreas to neutralize HCl

from stomach

Question 21

Small intestine includes the following 3 components:

Answer 21

Duodenum
Jejunum
Ileum

Question 22

How do the following affect the SI lining?

Malnutrition (starvation), pathogens, chemotherapy or toxins

Answer 22

regeneration is impaired, villi are destroyed and can’t absorb nutrients and get diarrhea

Question 23

Fxns of large intestine

Answer 23

• Absorbs electrolytes (Na/K), water, gases and solidifies mass
• Supports growth of beneficial bacteria
• Secretes undigested plant fibers, animal connective tissue and bacteria.
• Longer in women

Question 24

Beneficial bacteria in the large intestine are responsible for:

Answer 24

producing certain nutrients (Vit K & biotin) and fermenting some undigested material.

Question 25

Fxn of portal vein

Answer 25

* protects blood from toxic compounds in SI (e.g. ammonium) * Portal vein transfers water soluble compounds in SI -> directly to liver: processed and detoxified -> blood * Hydrophobic molecules -> lymphatic system -> blood

Question 26

fxns of Salivary Glands:

Answer 26

secrete mucus, amylase and lysozyme

Question 27

fxns of Liver:

Answer 27

* produces bile for fat absorption, * stores glycogen & lipids, * detoxifies

Question 28

fxns of Gall Bladder:

Answer 28

stores bile from liver then delivers it through bile | duct into pancreatic duct

Question 29

fxns of Pancreas:

Answer 29

produces NaHCO3 & hydrolases (lipases, amylases, chymotrypsinogen & trypsinogen), which mix with bile and are delivered to duodenum; Also endocrine gland: insulin & glucagon

Question 30

The two types of regulators in digestion are

Answer 30

nervous system and GI tract itself

Question 31

How does the nervous system regulate digestion?

Answer 31

cut nerves of test animals and found release of saliva, | swallowing and gastric secretions was affected

Question 32

How does the GI tract itself regulate digestion?

Answer 32

uses peptide hormones

Question 33

Fxn of secretin as a peptide hormone

Answer 33

* Apply acid to SI -> pancreatic secretions into SI * even if nerves were cut -> signal released from SI * Secretin from SI induced pancreas secretions