4.1 Digestive System Nutrient Digestion Flashcards Preview

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Flashcards in 4.1 Digestive System Nutrient Digestion Deck (53):
1

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

Enzymatically
Monomers (glucose, fructose)

2

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

Pancreatic amylase, brush border enzymes

3

Brush border enzymes...

Complete the breakdown of starch to individual glucose molecules

4

First step of protein digestion in small intestine

Proteolytic enzymes are released from pancreas

5

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

Trypsinogen
Trypsin

6

Activated pancreatic proteolytic enzymes break proteins into ______ and ______

Peptides and amino acids

7

Brush border peptidases break peptides into...

Single amino acids to be absorbed through epithelial cell into blood

8

Protease proenzymes are activated by....

Cleavage

9

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

Micelles

10

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

Pancreatic lipase
Triglyceride
Monoglyceride
Two free fatty acids

11

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

Epithelial cell

12

What happens in the epithelial cells during lipid digestion?

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

13

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

Chylomicron

14

What happens after chylomicrons are formed?

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

15

How are lipids absorbed into the blood?

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

16

How are packaged lipids absorbed differently than all other nutrients?

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

17

Chylomicrons are taken up by...

Fat cells in periphery

18

VLDL

Very bad, similar to chylomicron but made by liver

19

LDL

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

20

HDL

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

21

Capillary endothelium captures LDLs and HDLs by...

Receptor mediated endocytosis

22

LDL receptor density is a ____ trait

Genetic

23

Higher LDL receptor density is associated with..

Increased LDL clearance rate -> Better cardiovascular health

24

Amount of HDL production determined by..

Both genetics and lifestyle (Diet and exercise)

25

Atherosclerosis is..

Formation of plaques in vessels

26

Atherosclerosis: Excess LDL accumulates in and around...

Vascular endothelium and smooth muscle cells

27

What happens after the accumulation of LDL?

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

28

Foam cells are the basis for

An atherosclerotic plaque

29

Two major risks of LDL accumulation

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

30

Phases of Digestion

Cephalic
Gastric
Intestinal

31

Cephalic phase

Anticipatory and preparatory phase initiated by brain

32

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

Hypothalamus
-Limbic System
-Brainstem

33

Limbic system

Hunger due to dynorphin release

34

Brainstem

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

35

Gastric phase

Food enters stomach for digestion

36

Stretch receptors in stomach activated by...

Gastric distension

37

Chemoreceptors in stomach activated by...

Increase in pH

38

Local afferent signals of the stomach

Submucosal plexus and vasovagal reflex

39

Afferent signals from stomach cause..

Increase in parasympathetic NS, activate gastric secretions and gastric motility

40

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

Increase in pH, gastric distension, and partially digested proteins

41

Gastrin is secreted into..

Bloodstream

42

Effects of gastrin

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

43

Intestinal phase

Food enter duodenum

44

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

Distention of activates enterogastric reflex

45

Enterogastric reflex

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

46

Intestinal phase: Enteroendocrine cells release these two major hormones

Cholecystokinin
Secretin

47

Cholecystokinin (CCK)
Secretion stimulated by..

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

48

CCK stimulates

-Pancreatic enzyme secretion by acinar cells
-Gall bladder contraction

49

Secretin
Secretion stimulated by..

Acidic chyme

50

Secretin stimulates

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

51

Other effects of CCK and Secretin

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

52

Leptin

Hormone produced by adipose tissue, stimulates satiety center in hypothalamus

53

Ghrelin

Produced by stomach, signals to satiety centers in hypothalamus