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Block 3 Week 3 Meg > Ward: Small and Large Intestine II > Flashcards

Ward: Small and Large Intestine II Flashcards

1
Q

Three features of the small intestine that increase surface area

A

circular concentric Kirkring folds (3x)
villi (30x)
microvilli on villi (600x)

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2
Q

The (blank) on the microvilli surface of enterocytes is the location of numerous enzymes that provide the final stages of protein and carb breakdown for absorption.

A

glycocaylax

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3
Q

The presence of enzymes on the microvilli surface ensures that the final stages of (blank) occur at the same point where contents are (blank)

A

intestinal content breakdown

absorbed

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4
Q

Presence of the enzymes on microvilli reduce the possibility of (blank)

A

osmotic diarrhea

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5
Q

Each villi of the small intestine receives (blank) and has blind ended (blank) from the lymphatic system

A

blood supply; lacteals

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6
Q

This layer contracts and relaxes in the small intestine

A

muscularis externa

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7
Q

Blood and lymphatic supply to the villi ensure optimal removal of absorbed (blank)

A

peptides, AAs, sugars, fats

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8
Q

To ensure maximal absorption to the small intestine, it undergoes (blank) to ensure proper mixing of the lumenal contents

A

segmentation

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9
Q

3 major sources of carbohydrates

A 
disaccharides
polysaccharides
other carbohydrates (amylose, glycogen...)
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10
Q

Contributes to 3-5% of the hydrolysis of carbohydrates

A

oral amylase

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11
Q

In the stomach, hydrolysis continues for up to 1 hour and results in what percentage of starches being hydrolyzed to maltose?

A

30-40%

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12
Q

This enzyme is released following neutralization of chyme that enters the proximal duodenum (by bicarbonate secretion). Pancreatic secretion of (blank) continues the digestion of carbohydrates, producing maltose, maltotriose and a-limited dextrins

A

amylase

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13
Q

Digestion of starch and other disacchs are further broken down by enzymes located at the (blank) of the membrane

A

brush border

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14
Q

Final breakdown of carbs: Enzymes located near the (blank) mechanism, so free glucose goes into the enterocyte and does not cause (blank)

A

transport; osmotic diahrrea

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15
Q

Enzymes on the brush border of the enterocytes are continually (blank)

A

synthesized

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16
Q

Enzymes found in brush border

A

lactase
sucrase
maltase
a-dextrinase

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17
Q

(blank) dependent carrier system takes glucose and galactose from the brush border into the cell

A

Na+

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18
Q

Glucose and Galactose are absorbed by secondary active transport via a (blank) dependent carrier system

A

Na+

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19
Q

Lactose intolerance exists due to a lack of membrane bound enzymes resulting in malabsorption of (blank)

A

carbohydrates

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20
Q

Undigested lactose causes (blank) changes. (blank) is further increased by the production of lactic acid by intestinal bacteria acting on the lactose.

A

osmolality; osmolality

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21
Q

So, essentially, lactose intolerance is a (blank) deficiency. It is popular in (blank) populations.

A

enzymatic; Asian

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22
Q

Upon admin of lactose, a flat lactose tolerance curve or failure of blood glucose to rise indicates low (blank) activity

A

lactase

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23
Q

These form an important addition to the bulkiness of stool and reduce the transit time of feces

A

dietary fibers

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24
Q

Almost all proteins require (blank) before (blank). There is one exception.

A

digestion; absorption

newborns with gamma globulins from milk

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25
Q

A second source of protein is derived from the (blank) that is continually sleuthed off into the lumen. This accounts for (blank) percent of dietary protein.

A

intestinal mucosa; 50%

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26
Q

A third source of protein are the many (blank) that are secreted into the GI tract

A

enzymes

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27
Q

T/F: Different classes of AAs are absorbed best at different concentrations

A

True

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28
Q

At the final stage of digestion of proteins, the (blank) co-transporter ultimately takes amino acids into the enterocyte and then into the bloodstream

A

Na+/glucose

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29
Q

Enterokinase, located on the brush border of duodenal enterocytes, is activated by the presence of (blank)

A

trypsinogen

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30
Q

The absorption of amino acids is coupled to the transport of (blank) similar to that described for the absorption of monosaccharides.

A

Na+

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31
Q

Gastric pepsin and pancreatic peptidases digest proteins into (blank)

A

di and tripeptides

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32
Q

T/F: there are different carrier systems for different amino acids

A

True

33
Q

Lumenal digestion of a protein meal results in approx (blank) free AA’s and (blank) small peptides.

A

40%; 60%

34
Q

gluten sensitive enteropathy, a specific fraction of wheat protein attacks the microvilli of the mucosa, denuding it of these cells

A

celiac sprue

35
Q

Cystic fibrosis
Hereditary Pancreatitis
Cystinuria
Hartnup disease

A

diseases associated with protein absorption

36
Q

phospholipids
sterols
hydrocarbons
waxes

A

dietary lipids

37
Q

There is little to no absorption of fat in the stomach. (blank) slows gastric motility when fats are in the small intestine. This causes the pancreas to secrete (blank) and the gallbladder to secrete (blank)

A

CCK; lipase; bile

38
Q

4 major events of fat absorption

A

(i) Secretion of bile and various lipases.
(ii) Emulsification.
(iii) Enzymatic hydrolysis of ester linkages.
(iv) Solubilization of lipolytic products within bile salt micelles

39
Q

a suspension of fat droplets, held apart by lecithin, bile salts, fatty acids and other agents

A

emulsification

40
Q

Lipid droplets suspended in water. Micelles can be presented to the enterocyte by a passive process then enter the lacteal as (blank)

A

chylomicrons

41
Q

Pancreatic lipase is inhibited by (blank)

A

bile salts

42
Q

Micelles diffuse across the unstirred layer and present fatty acids and monoglycerides to the enterocytes. This is mostly a (blank) process. (blank) are not absorbed across this layer, and are recyled to form new micelles.

A

passive; bile salts

43
Q

Two pathways involved in re-synthesis of triglycerides

A
  1. monoglyceride acylation

2. phosphatadic acid

44
Q

Enterocytes secrete (blank) and (blank)

A

chylomicrons

VLDL

45
Q

Fat soluble vitamins are absorbed in a (blank) process

A

passive

46
Q

Water soluble vitamins are taken up by a (blank) process

A

active

47
Q

Exception to vitamin absorption; requires R proteins and intrinsic factor for its absorption

A

B12

48
Q

What percentage of the absorptive capacity of the colon is regularly utilized? Not maximized.

A

10-25%

49
Q

Water absorption is achieved by the process of (blank) transport

A

Na+

50
Q

Progressive absorption of (blank) along the GI tract, which results in less Na+ being excreted in feces

A

Na+

51
Q

As you move along the gut, these mechanisms help reabsorb Na+

A

Na+/glucose cotransport
Na+/Cl- cotransport
Na+/H+ cotransport

52
Q

Na+ kept low inside the enterocyte due to this

A

Na+/K+ ATPase

53
Q

In the colon, co-transport is absent, cellular junctions are less leaky, so restricted (blank) becomes very important and is under the control of (blank)

A

diffusion; aldosterone

54
Q

Water absorption is driven by (blank) absorption and is described by the 3 compartment model

A

Na+

55
Q

T/F: Ca+ has calcium binding proteins to control its concentration in the cell.

A

True

56
Q

The process of Ca2+ absorption is localized in the proximal intestine and occurs in 4 major steps

A

(i) Entry at the brush border membrane.
(ii) Regulation of intracellular Ca2+.
(iii) Vitamin D affects at least one of these steps.
(iv) Ca2+ exit must occur at the basolateral side of the membrane.

57
Q

1,25 dihydroxyvitamin D3 inhibits calcium binding proteins and releases Ca+ in the plasma via a Ca+ ATPase. Ca+ in the plasma feeds back on (blank) to reduce the amount of 1,25 dihydroxyvitamin D3

A

parathyroid hormone

58
Q

This disease of unregulated iron absorption leads to generalized iron overload that can eventually impair organ systems and lead to cirrhosis, diabetes, and cardiomyopathy

A

hemochromatosis

59
Q

This creates a gradient along the small intestine with the highest frequency in the duodenum and the lowest in the terminal ileum. This gradient ensures oral to aboral movement of the contents in the lumen of the intestine

A

segmentation

60
Q

When carbohydrates are broken down along the brush border, this allows for their products to be quickly absorbed into the enterocytes so they do not remain in the (blank) for long

A

intestinal lumen

61
Q

How is [Na+] kept low in the enterocyte? Why is it important to keep it low?

A

By the Na+/K+ exchanger; important to keep it low so that Na+ will pass down its gradient from the lumen of the gut into the enterocyte and take with it glucose! This allows glucose to be reabsorbed into blood stream from the gut.

62
Q

The Na+/glucose symporter is driven by high extracellular (intestinal lumen) (blank)

A

Na+

63
Q

Lactose intolerance most common in these groups

A

blacks, orientals, eskimos

64
Q

With lactose intolerance, there will be a build up of carbohydrates in the intestine, which will pull (blank) in, and create a watery stool.

A

water

65
Q

Dietary fiber makes you (blank)

A

poop

66
Q

(blank) starts a cascade of peptidase cleavage by cleaving typsinogen into trypsin

A

enterokinase

67
Q

Proteins are digested to di and tripeptides in the gut lumen, then taken into the enterocytes by Na+ co transport. Then, they are broken down within the cell to (blank) before entering the blood.

A

amino acids

68
Q

Di and tripeptides, as well as free AA’s can enter the enterocyte, but large peptides must be acted on by brush border (blank) before entering

A

peptidases

69
Q

Lipids enter enterocytes by a sequence of chemical and physical events that render water insoluble molecules capable of being absorbed by (blank) diffusion

A

passive

70
Q

(blank) complexes lipase to bile salts. Once co-lipase attaches to a fat droplet, lipase will bind to the co-lipase and carry out its function.

A

colipase

71
Q

Why are micelles important?

A

They solublize dietary fat and present it to the enterocytes for absorption

72
Q

Do bile salts get absorbed into the enterocytes? What happens to them?

A

No! They are recycled to the lumen of the gut!

73
Q

Within the enterocytes, fats presented by micelles become (blank) and are transported into the lacteals or they become very low density lipoproteins and enter the blood

A

chylomicrons

74
Q

In 1 day, 7-10 L of fluid enters small intestine. How much of that enters the colon?

A

1-2 L

75
Q

4 ways to get Na+ into enterocytes

A

restricted diffusion
co-transport with sugars or AA’s
co-transport with Cl-
counter-transport with bicarb

76
Q

In the colon, there is no longer co-transport of Na+. So, (blank) predominates.

A

restricted diffusion

77
Q

About 1g of calcium is taken orally, of which approximately (blank) is absorbed and is an important component in the regulation of whole body Ca2+. What vitamin is important for Ca+ transport?

A

40%; Vit D3

78
Q

Exit of Ca+ from the enterocyte to the blood is (blank) transport, and depends primarily on a Ca+ATPase

A

active

79
Q

Regulation of iron uptake is thought to occur at the level of brush border iron (blank) and the ratio of (blank) to transport protein

A

receptors; ferritin

Block 3 Week 3 Meg (9 decks)

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