U2:C7: Digestion

Question 1

GI Tract Path (include parts in order)

Answer 1

1. Oral cavity: mastication,
   -Digestion of sugars: salivary glands- amylase (hydrolysis starch to maltose
2. Pharynx: throat, epiglottis prevents food from entering trachea
3. Esophagus: peristalsis
4. Stomach: will go more into detail
   -Accessory organ- gallbladder
   -Digestion of Proteins: pepsinogen->pepsin
   -Kill bacteria and activate zymogen pepsinogen: parietal cells r- HCl and make pH 2.
5. Small Intestine: Major Digestion, Nutrient Absorption
   -Duodenum, Jejunum, Ileum (DJ Intestines)
   Accessory organs- pancreas (pancreatic enzymes function at pH 8.3), liver (bile stored in gall bladder).
   -Digestion of Fats, Proteins, Carbs due to enzymes from pancreatic juice & duodenum.
   -SI pH 7.2 - 8.3
6. Large Intestine: Major water Reabsorption, but not regulator, instead for solidifying feces. Absorbs some salts and vitamins such as K (made from bacteria)

Question 2

What is the product from the stomach? and how and where is it neutralized?

Answer 2

Chyme is acidic, pancreatic juice’s (bicarbonate), and livers (bile) that is secreted into the duodenum neutralizes the chyme in the small intestines.

Question 3

List the fat soluble vitamins, and where they would be digested and absorbed.

Answer 3

Vit A, D, E, K (Kead)
Small intestines, bile emulsifies the fat for digestion and absorption.
-except for vit K which is in the large intestine, bc it is produced by the bacteria there.

Question 4

Carbohydrates are digested where, production, enzyme?

Answer 4

1. Mouth- salivary glands- amylase (starch to maltose)
2. Small intestine- pancreas- amylase (starch to maltose)
   SI- SI glands- Maltase, Sucrase, Lactase
   (maltose -> 2 glu, sucrose-> glu & fru, lactose-> glu & gal

Question 5

Amylase

Answer 5

starch (poly glu) -> maltose (dinomer of glu)

Question 6

Maltase

Answer 6

maltose -> 2 glu

Question 7

Sucrase

Answer 7

sucrose -> glu + fru

Question 8

Lactose

Answer 8

lactose-> glu + gal

Question 9

Proteins are digested where, production, enzyme?

Answer 9

1. Stomach- gastric glands- pepsinogen (zymogen)-> pepsin (with HCl)
2. SI- pancreas- Trypsinogen -> trypsin, Chymotrypsinogen-> chymotrypsin, Carboxypeptidase
3. SI- SI glands- Aminopeptidase, Dipeptidases, Enterokinase

Question 10

Lipids are digested where, production, enzyme?

Answer 10

1. SI- liver- bile (emulsifies fat)

2. SI- Pancreas- lipase (hydrolyzes lipids)

Question 11

Trypsin

Answer 11

hydrolyzes specific peptide bond and converts chymotrypsinogen -> chymotrypsin

Question 12

Chymotrypsin

Answer 12

hydrolyzes specific peptide bond

Question 13

Carboxypeptidase

Answer 13

hydrolyzes terminal peptide bond at carboxyl end

Question 14

Aminopeptidase

Answer 14

hydrolyzes terminal peptide bond at amino end

Question 15

Dipeptidases

Answer 15

hydrolyzes pairs of amino acids

Question 16

Enterokinase

Answer 16

Converts trypsinogen to trypsin

Question 17

Stomach secretes 6 products and include their function (don’t include where they are from)

Answer 17

1. H+ : kill microbes, denatures, proteins, converts pepsiongen into pepsin
2. Pepsinogen: pepsin partially digests proteins
3. Mucus: protects the mucosa
4. Bicarbonate: protects mucosa
5. Water: dissolves and dilutes ingested materials
6. Intrinsic factors: required for normal absorption of vit B-12

Question 18

Stomach contains what glands and what cells, include each of their functions.

Answer 18

1. Gastric glands: mucous cells, chief cells, parietal cells
   a. mucous cells: secrete mucus to protect muscular wall
   b. chief cells: secrete pepsinogen
   c. parietal cells: secrete HCl, activate pepsinogen-> pepsin
2. Pyloric glands: secrete gastrin, which induces stomach to secrete more HCl and churn the food.

Question 19

Digestive Hormones: name and location

Answer 19

Gastrin: secreted by phyloric gland in stomach, causes parietal cells to release HCl
Secretin: secreted by duodenum in SI, regulates the secretion of HCl from parietal cells and bicarbonate in the pancreas.
CCK: secreted by duodenum in SI. stimulates the secretion of bile (from gallbladder) and pancreatic juice (from pancreas)
Enterogastrone: secreted by duodenum in SI. slows down the movement of chyme, to increase lipid absorption.

Question 20

Pancreatic enzymes

Answer 20

starch: amylase
proteins: Trypsinogen, Chymotrypsinogen, Carboxypeptidase
Fats: lipase

Question 21

Intestinal gland enzymes

Answer 21

starch: sucrase, lactase, maltase
Protein: dipeptidase, aminopeptidase, enterokinase

Question 22

How do nonpolar and polar nutrient molecules get absorbed and travel to parts of the body?

Answer 22

1. both need to cross the epilthelial cell of the small intestines, and then into the capillaries of the small intestines
   a. nonpolar: will diffuse directly into the capillaries and go into the blood stream bypassing the liver.
   - once through epithelial tissue, triglycerides and esterfied cholesterol are repackaged as Chylomicron (CM),
   - CM enter lacteals (lymphatic circulation) and through thoracic duct enter the circulatory system.
   - CM in blood is made into LDL (low density lipoproteins)
   - LDL travels to liver and is made into HDL (healthy)
   b. polar: req active or facilitated transport into cell then into capillaries. They are then transported to the liver via hepatic portal (liver regulates blood concentrations).