Physiology Block 3 Week 14 05 Digestion

Question 1

End result after digestion of:

• Carbohydrates
• Fats
• Proteins

Answer 1

Carbohydrates:
-end result is poly or disaccharides converted to monosaccharides

Fats:
-TG split into 3 fatty acids + glycerol

Proteins:
-split into AA

Question 2

Carbohydrate Digestion

• Sucrose
• Lactose
• Starches

Answer 2

Sucrose:

• -Disaccharide: Glucose + Fructose
• -Enzyme: Sucrase (intestine)

Lactose:

• -Disaccharide: Glucose + Galactose
• -Enzyme: Lactase (intestine)

Starches:

• -Large polysaccharides from non-animal sources (potatoes, grains): Maltose + 3-9 Glucose Polymers
• -Enzymes: Ptyalin (saliva) and Pancreatic Amylase (pancreas)
• -Secretin (acid secretion) allows pancreatic amylase to continue working

Maltose + 3-9 Glucose Polymers:
–Enzymes: Maltase and alpha-dextrinase

Question 3

Protein Digestion

Answer 3

Pepsin:

• breaks down collagen (connective tissue of meats)
• 10-20% protein digestion
• active at low pH

Pancreatic Secretions:
Trypsin and Chymotrypsin: breaks proteins into smaller peptides
Carboxypolypeptidase: cleaves ends of polypeptides to AA
Proelastase (converted to elastase): digests elastin fibers that hold meat together

Peptidase:

• on brush border of duodenum and jejunum
• results in AA, Dipeptides, and Tripeptides

Inside Enterocytes:
-break down di- and tripeptides into single AA

Question 4

Fat Digestion

Answer 4

Lingual Lipase

• 10% digestion
• from salivary glands

Emulsification:

• agitation in stomach
• Bile: Bile salts and Lecithin

Reduces interfacial tension (between fat and water) and allows to break fats down to smaller components for lipase to work on

Pancreatic Lipase increases surface area 1000x and creates a water soluble environment
–>Results in fatty acids and monoglycerides

Question 5

What form are dietary fats mostly in?

Answer 5

Triglycerides

Question 6

Function of Bile Salts

Answer 6

Without bile salts, can’t absorb fats

Bile salts form micelles and remove monoglycerides and fatty acids and transport them to the brush border for absorption

Bile salts act as a transport mechanism–once breakdown products, need to remove them for absorption before reforms as fat

Question 7

Chronic Pancreatitis

Answer 7

Calcifications outline pancreas on CT

Causes: Alcohol, genetic, elevated TG, hypercalcemia, obstruction

Complications: Pain, malabsorption of fats, proteins, and carbs, which leads to diabetes

***Stones located at sphincter of Oddi = acute pancreatitis, NOT CHRONIC

Question 8

Steatorrhea

Answer 8

Non-solid feces due to malabsorption of fats

Question 9

Bristol Stool Chart

Answer 9

7 types of poop
Want type 3 or 4
Type 1 and 2 = constipation
Type 5, 6, 7 each diarrhea

Question 10

Emulsificatoin

Answer 10

Micelle’s have polar heads that dissolve in water (hydrophilic) and tails that dissolve in fat (hydrophobic)

• -this is because we are mostly made of water
• -if were mostly fat, micelles would form opposite

Bile salts surround the phospholipids

Question 11

Which of the following is NOT a final breakdown product of carbohydrate digestion?

A. Glucose
B. Galactose
C. Sucrose
D. Fructose

Answer 11

C. Sucrose

Sucrose is broken down to fructose and glucose by sucrase in the intestine

Question 12

Peptidases are important in protein digestions. Where are they located?

A. On villi surface
B. On crypts of Lieberkuhn
C. Within micelles
D. Within pancreatic Duct Epithelium

Answer 12

A. On villi surface

**Brush border of duodenum and jejunum