4.1 Digestive System Nutrient Digestion

Question 1

Complex carbohydrates must be ________ digested into ________ before absorption into blood

Answer 1

Enzymatically

Monomers (glucose, fructose)

Question 2

What chemicals are involved in carbohydrate absorption in the small intestine?

Answer 2

Pancreatic amylase, brush border enzymes

Question 3

Brush border enzymes…

Answer 3

Complete the breakdown of starch to individual glucose molecules

Question 4

First step of protein digestion in small intestine

Answer 4

Proteolytic enzymes are released from pancreas

Question 5

Enteropeptidase activates ________ to _______, which then activates other proteolytic enzymes

Answer 5

Trypsinogen

Trypsin

Question 6

Activated pancreatic proteolytic enzymes break proteins into ______ and ______

Answer 6

Peptides and amino acids

Question 7

Brush border peptidases break peptides into…

Answer 7

Single amino acids to be absorbed through epithelial cell into blood

Question 8

Protease proenzymes are activated by….

Answer 8

Cleavage

Question 9

Bile salts released from the liver and gall bladder emulsify lipid droplets to form….

Answer 9

Micelles

Question 10

_________ functions within micelles to digest each ________ into a _________ and ____________

Answer 10

Pancreatic lipase
Triglyceride
Monoglyceride
Two free fatty acids

Question 11

Monoglycerides and free fatty acids enter an _________ _____, while bile says remain in the intestinal lumen to be reabsorbed and recycled.

Answer 11

Epithelial cell

Question 12

What happens in the epithelial cells during lipid digestion?

Answer 12

Triglyceride molecules are reassembled… then wrapped / packaged and then exocytosed

Question 13

In the epithelial cells, lipids are wrapped with protein to form a…..

Answer 13

Chylomicron

Question 14

What happens after chylomicrons are formed?

Answer 14

They are packaged within secretory vesicles and exocytosed grin the cells and absorbed into lacteals

Question 15

How are lipids absorbed into the blood?

Answer 15

Lymphatic lacteals carry chylomicrons back to blood, circle without going directly to liver

Question 16

How are packaged lipids absorbed differently than all other nutrients?

Answer 16

Virtually all other blood borne nutrients pass first through the liver before entering systemic circulation

Question 17

Chylomicrons are taken up by…

Answer 17

Fat cells in periphery

Question 18

VLDL

Answer 18

Very bad, similar to chylomicron but made by liver

Question 19

LDL

Answer 19

Released from fat cell (fat keeps most of the triglycerides).. Delivers triglyceride and cholesterol to tissues

Question 20

HDL

Answer 20

Good, released by tissues and returned to liver (moves cholesterol back to gut / bile)
NET REDUCTION IN CHOLESTEROL

Question 21

Capillary endothelium captures LDLs and HDLs by…

Answer 21

Receptor mediated endocytosis

Question 22

LDL receptor density is a ____ trait

Answer 22

Genetic

Question 23

Higher LDL receptor density is associated with..

Answer 23

Increased LDL clearance rate -> Better cardiovascular health

Question 24

Amount of HDL production determined by..

Answer 24

Both genetics and lifestyle (Diet and exercise)

Question 25

Atherosclerosis is..

Answer 25

Formation of plaques in vessels

Question 26

Atherosclerosis: Excess LDL accumulates in and around...

Answer 26

Vascular endothelium and smooth muscle cells

Question 27

What happens after the accumulation of LDL?

Answer 27

Macrophages attempt and fail to clean up the mess.. become "foam cells"

Question 28

Foam cells are the basis for

Answer 28

An atherosclerotic plaque

Question 29

Two major risks of LDL accumulation

Answer 29

1) Narrowing of the vessel lumen | 2) Clot formation at the site of the atherosclerotic plaque

Question 30

Phases of Digestion

Answer 30

Cephalic Gastric Intestinal

Question 31

Cephalic phase

Answer 31

Anticipatory and preparatory phase initiated by brain

Question 32

Smell, taste, or thought of food activates...

Answer 32

Hypothalamus - Limbic System - Brainstem

Question 33

Limbic system

Answer 33

Hunger due to dynorphin release

Question 34

Brainstem

Answer 34

ANS, Activates parasympathetic nervous system | -Anticipatory activation of salivary glands and gastric secretions

Question 35

Gastric phase

Answer 35

Food enters stomach for digestion

Question 36

Stretch receptors in stomach activated by...

Answer 36

Gastric distension

Question 37

Chemoreceptors in stomach activated by...

Answer 37

Increase in pH

Question 38

Local afferent signals of the stomach

Answer 38

Submucosal plexus and vasovagal reflex

Question 39

Afferent signals from stomach cause..

Answer 39

Increase in parasympathetic NS, activate gastric secretions and gastric motility

Question 40

Gastrin (Hormone from G cells) is stimulated by...

Answer 40

Increase in pH, gastric distension, and partially digested proteins

Question 41

Gastrin is secreted into..

Answer 41

Bloodstream

Question 42

Effects of gastrin

Answer 42

↑ gastric secretions ↑ contraction of lower esophageal sphincter ↑ gastric motility Relaxation of pyloric sphincter, stimulates growth of stomach mucosa

Question 43

Intestinal phase

Answer 43

Food enter duodenum

Question 44

Intestine speeds / slows food volume coming out of stomach via...

Answer 44

Distention of activates enterogastric reflex

Question 45

Enterogastric reflex

Answer 45

Stretch receptors -  Medulla - lowers PNS activity - Reduces gastric motility and gastric emptying

Question 46

Intestinal phase: Enteroendocrine cells release these two major hormones

Answer 46

Cholecystokinin | Secretin

Question 47

Cholecystokinin (CCK) | Secretion stimulated by..

Answer 47

Increase in secretion stimulated by partially digested proteins and fats in chyme

Question 48

CCK stimulates

Answer 48

- Pancreatic enzyme secretion by acinar cells | - Gall bladder contraction

Question 49

Secretin | Secretion stimulated by..

Answer 49

Acidic chyme

Question 50

Secretin stimulates

Answer 50

Bicarbonate secretion by pancreatic intercalated duct cells and hepatocytes (bile)

Question 51

Other effects of CCK and Secretin

Answer 51

Inhibit gastric emptying and gastric secretions, respectively and are pancreatic growth factors

Question 52

Leptin

Answer 52

Hormone produced by adipose tissue, stimulates satiety center in hypothalamus

Question 53

Ghrelin

Answer 53

Produced by stomach, signals to satiety centers in hypothalamus