4.1 Digestive System Nutrient Digestion Flashcards

1
Q

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

A

Enzymatically

Monomers (glucose, fructose)

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2
Q

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

A

Pancreatic amylase, brush border enzymes

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3
Q

Brush border enzymes…

A

Complete the breakdown of starch to individual glucose molecules

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4
Q

First step of protein digestion in small intestine

A

Proteolytic enzymes are released from pancreas

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5
Q

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

A

Trypsinogen

Trypsin

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6
Q

Activated pancreatic proteolytic enzymes break proteins into ______ and ______

A

Peptides and amino acids

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7
Q

Brush border peptidases break peptides into…

A

Single amino acids to be absorbed through epithelial cell into blood

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8
Q

Protease proenzymes are activated by….

A

Cleavage

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9
Q

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

A

Micelles

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10
Q

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

A

Pancreatic lipase
Triglyceride
Monoglyceride
Two free fatty acids

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11
Q

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

A

Epithelial cell

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12
Q

What happens in the epithelial cells during lipid digestion?

A

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

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13
Q

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

A

Chylomicron

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14
Q

What happens after chylomicrons are formed?

A

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

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15
Q

How are lipids absorbed into the blood?

A

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

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16
Q

How are packaged lipids absorbed differently than all other nutrients?

A

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

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17
Q

Chylomicrons are taken up by…

A

Fat cells in periphery

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18
Q

VLDL

A

Very bad, similar to chylomicron but made by liver

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19
Q

LDL

A

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

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20
Q

HDL

A

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

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21
Q

Capillary endothelium captures LDLs and HDLs by…

A

Receptor mediated endocytosis

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22
Q

LDL receptor density is a ____ trait

A

Genetic

23
Q

Higher LDL receptor density is associated with..

A

Increased LDL clearance rate -> Better cardiovascular health

24
Q

Amount of HDL production determined by..

A

Both genetics and lifestyle (Diet and exercise)

25
Q

Atherosclerosis is..

A

Formation of plaques in vessels

26
Q

Atherosclerosis: Excess LDL accumulates in and around…

A

Vascular endothelium and smooth muscle cells

27
Q

What happens after the accumulation of LDL?

A

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

28
Q

Foam cells are the basis for

A

An atherosclerotic plaque

29
Q

Two major risks of LDL accumulation

A

1) Narrowing of the vessel lumen

2) Clot formation at the site of the atherosclerotic plaque

30
Q

Phases of Digestion

A

Cephalic
Gastric
Intestinal

31
Q

Cephalic phase

A

Anticipatory and preparatory phase initiated by brain

32
Q

Smell, taste, or thought of food activates…

A

Hypothalamus

  • Limbic System
  • Brainstem
33
Q

Limbic system

A

Hunger due to dynorphin release

34
Q

Brainstem

A

ANS, Activates parasympathetic nervous system

-Anticipatory activation of salivary glands and gastric secretions

35
Q

Gastric phase

A

Food enters stomach for digestion

36
Q

Stretch receptors in stomach activated by…

A

Gastric distension

37
Q

Chemoreceptors in stomach activated by…

A

Increase in pH

38
Q

Local afferent signals of the stomach

A

Submucosal plexus and vasovagal reflex

39
Q

Afferent signals from stomach cause..

A

Increase in parasympathetic NS, activate gastric secretions and gastric motility

40
Q

Gastrin (Hormone from G cells) is stimulated by…

A

Increase in pH, gastric distension, and partially digested proteins

41
Q

Gastrin is secreted into..

A

Bloodstream

42
Q

Effects of gastrin

A

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

43
Q

Intestinal phase

A

Food enter duodenum

44
Q

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

A

Distention of activates enterogastric reflex

45
Q

Enterogastric reflex

A

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

46
Q

Intestinal phase: Enteroendocrine cells release these two major hormones

A

Cholecystokinin

Secretin

47
Q

Cholecystokinin (CCK)

Secretion stimulated by..

A

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

48
Q

CCK stimulates

A
  • Pancreatic enzyme secretion by acinar cells

- Gall bladder contraction

49
Q

Secretin

Secretion stimulated by..

A

Acidic chyme

50
Q

Secretin stimulates

A

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

51
Q

Other effects of CCK and Secretin

A

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

52
Q

Leptin

A

Hormone produced by adipose tissue, stimulates satiety center in hypothalamus

53
Q

Ghrelin

A

Produced by stomach, signals to satiety centers in hypothalamus