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Digestion > 4B: Anatomy, Physiology, and Path of the S. Intestine (Part 2) > Flashcards

4B: Anatomy, Physiology, and Path of the S. Intestine (Part 2) Flashcards

1
Q

What is emulsification?

A

First step of digestion in the SI.

Fat globule is broken up and coated by lecithin and bile acids.

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2
Q

What is fat hydrolysis?

A

Emulsification droplets are acted upon by pancreatic lipase, which hydrolyzes the first and third fatty acids from triglycerides, usually leaving the middle fatty acid.

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3
Q

What is a good Emulsifying agents?

A

Bile acids

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4
Q

How are micelles formed?

A

Several types of lipids form micelles coated with bile acids

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5
Q

What do pancreatic lipase and colipase do?

A

Chew up fat droplets and the reason why we do emulsification.

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6
Q

Intestinal cells absorb lipids from micelles, resynthesize triglycerides & package triglycerides, cholesterols, and phospholipids into what?

A

Into protein-coated chylomicrons

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7
Q

What packages chylomicrons into secretory vesicles?

A

The Golgi complex

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8
Q

Chylomicrons are released from basal cell membranes by what?

A

exocytosis and enter the lacteal (lymphatic capillary) of the villus

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9
Q

Once the chylomicrons (CM) enter the lymphatic circulation where are they transported?

A

Upward through the thoracic duct and emptied into the venous circulation at the junction of the jugular & subclavian veins.

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10
Q

When does Lipemia usually occur?

A

Within an hour after eating a fatty meal

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11
Q

Why does plasma usually become clear within a few hours?

A

Because Chylomicrons have a short half-life (<60 min)

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12
Q

How are Chylomicrons are removed from the blood?

A

As they pass through the capillaries of adipose tissue and the liver

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13
Q

Capillaries of adipose tissue and liver both contain large quantities of what?

A

Lipoprotein lipase

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14
Q

Lipoprotein lipase is especially active where?

A

In the capillary endothelium, where it hydrolyzes the TGs of chylomicrons into fatty acids & glycerol, which diffuse into adipocytes (storage) & hepatocytes (re-packaged into lipoproteins & exported to blood)

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15
Q

What are the 5 classes of lipoproteins?

A

1) Chylomicrons
2) Very low density lipoproteins (VLDL)
3) Intermediate density lipoproteins (IDL)
4) Low density lipoproteins (LDL)
5) High density lipoproteins (HDL)

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16
Q

Chylomicrons are synthesized by_____________, while VLDL, IDL, LDL, & HDL are synthesized by____________________

A

Enterocytes

Liver hepatocytes

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17
Q

The naming of lipoproteins is based on what?

A

The results of ultracentrifugation by which the lipoproteins are separated according to their density

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18
Q

VLDL contains what?

A

high TGs/moderate cholesterol & phospholipids

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19
Q

IDL contains what ?

A

moderate TGs, cholesterol & phospholipids

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20
Q

LDL’s contain what?

A

low TGs/ high cholesterol & phospholipids

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21
Q

HDL’s contain what?

A

low TGs, cholesterol & phospholipids

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22
Q

Which lipoproteins are the the only one routinely monitored and used to screen of atherosclerosisis, MI & stoke risk, heat disease, etc.

A

LDL-C & HDL-C

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23
Q

What is the role of LDLs?

A

(bad cholesterol) is to transport cholesterol and other lipids from the liver to the peripheral tissues, making them available (via receptor) mediated endocytosis) for membrane or steroid hormone synthesis.

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24
Q

What is the function of HDLs?

A

(good cholesterol) is to transport excess cholesterol from peripheral tissues to the liver, where it is broken down and becomes part of the bile

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25
Q

What are the most effective drugs currently in use for treating elevated LDL-C ?

A

1) Atovastatin (Lipitor)
2) Fluvastatin (Lescol)
3) Lovastatin (Altoprev, Mevacor)
4) Pravastatin (Pravachol)
5) Simvastatin (Zocor)
6) Rosuvastatin (Crestor)
7) Pitavastatin (Livalo)

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26
Q

What is Myopathy?

A

General term for any muscle disease

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27
Q

Myalgia?

A

Refers to muscle pain or weakness without increased creatine kinase , whereas myositis includes elevated CK.

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28
Q

What is Rhabdomyolysis?

A

Is defined as muscle symptoms, very high CK (<10 times the upper limit of normal), and increased serum creatine often with dark urine and myoglobinuria

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29
Q

What are all statins associated with?

A

Myopathy

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30
Q

Approx. 1 in 10 patients taking a statin report complaints of?

A

muscle complaints

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31
Q

What are risk factors for stain myopathy ?

A

1) Elderly
2) Small size
3) high statin dose
4) liver or renal disease
5) diabetes
6) uncontrolled hypothyroidism
7) interacting medications

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32
Q

Niacin was the first what?

A

lipid-lowering agent that was associated with a reduction in total mortality, with some of the earliest studies occurring in the mid 1970s.

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33
Q

What are the 3 basic preparations?

A

1) immediate (refular) release (IR) crystalline niacin
2) Sustained/extended release (SR + ER)
3) No-flush (inositol hexaniacinate; niacin-amide)

34
Q

Drug names of immediate (refular) release (IR) crystalline niacin ?

A

1) Niacor (prescription)

2) Generic (OTC)

35
Q

Drug names of Sustained/extended release (SR + ER)

A

1) Niaspan (prescription) (ER)

2) Slo-Niacin (OTC) (SR)

36
Q

Drug names of No-flush (inositol hexaniacinate; niacin-amide)?

A

Niacinamide or no flush niacin

37
Q

What active ingredient is taken out with no-flush ?

A

They contain NO nicotine acid, which is the active ingredient.

38
Q

Are No-flush drugs useful?

A

No they are WORTHLESS and do NOT affect lipid levels

39
Q

Niacin reduces the production of what?

A

Of VLDL which leads to a secondary reduction in LDL

40
Q

Niacin (Nicotinic Acid, Vitamin B3) is also the most potent agent for ________________

A

raising HDL levels

41
Q

What is the average effect of full dose niacin mono therapy ?

A

5-25% reduction in LDL-C
15-35% increase in HDL-C
20-50% reduction in triglycerides

42
Q

The exact MOA of niacin is _______________

A

Still poorly understood

43
Q

What is the percent increase in HDL when using Statins therapy/intervention?

A

6%-14%

44
Q

What is the percent increase in HDL when using Fibrates therapy/intervention?

A

5% to 15%

45
Q

What is the percent increase in HDL when using Physical activity therapy/intervention?

A

5-30%

46
Q

What is the percent increase in HDL when using Weight reduction therapy/intervention?

A

5% to 20%

47
Q

What is the percent increase in HDL when using smoking cessation intervention?

A

5%

48
Q

Is the intolerance to niacin common?

A

Yes, intolerance is common.
Only 50-60% of patients may be able to take full doses

***Clinicians should warn patients to expect the flush and explain that is it s a harmless side effect

49
Q

Why the intolerance?

A

tingling, flushing & sensation of warmth in the face and/ or upper body typically occurs after each dose when the drug is started or when the dose is increased.

50
Q

What can help relieve the effect of niacin?

A

Taking ASA or other NSAIDs (e.g.- ibuprofen) 30-45 min prior to each niacin dose blunts this prostaglandin mediated effect

51
Q

What are Bile Acid Binding Resins called?

A

Bile Acid Sequestrants

***The resins are the among the OLDEST of the HYPOLIPIDEMIC DRUGS

52
Q

Why are resins considered the safest?

A

Since they are not absorbed from the intestine

53
Q

What are some available resins include?

A

-Colestipol (Colestid)

–Cholestyramine (Questran, Questran Light)

-Colesevelam (Welchol)

54
Q

What forms are resins available in?

A

Granular form (Colestid, Questran) which can be mixed with water or as tablets (Colestid, Welchol)

55
Q

When Resins bind bile aids in the intestinal lumen what does it lead to?

A

1) Decreased emulsification of dietary fat

2) Prevention of bile acid reabsorption (via enterohepatic circulation)

56
Q

What does prevention of bile acid reabsorption cause?

A

Causes the liver to increase its production of bile acids, using hepatic cholesterol to do so

57
Q

What are statins referred to as?

When do they work best?

A

HMG-CoA reductase inhibitors (shut down endogenous production)

-Work best with life-style changes

58
Q

True or False. Plasma LDL levels can be reduced by up to 30% with maximal doses?

A

True

59
Q

Do Resins have a effect on HDLs and triglyceride levels in the blood?

A

Have little effect

60
Q

What are the MOST common adverse effects related to the GI system ?

A

1) Constipation (in some cases, fecal impaction)
2) bloating/abdominal distention/pain
3) flatulence
4) nausea
5) vomiting
6) dyspepsia

61
Q

When do symptoms (related to GI system) usually decrease?

A

With slow dose titration and tie

62
Q

What may relieve constipation and bloating ?

A

Increased dietary fiber or a fiber supplement (e.g. -Metamucil)

63
Q

Resins can bind to what other drugs/substances and interfere with their absorption?

A

1) Fat soluble vitamins (supplementation should be considered)
2) folate (supplementation should be considered)
3) thiazides
4) tetracyclines
5) warfarin
6) propanolol
7) penicillin

64
Q

How can you avoid some of these drug-drug interactions?

A

To take the resin a few hours after taking medications on the list (e.g., folate, antibiotics, warfarin..etc)

65
Q

All H20 absorption in the small intestine is ____________ and __________ to solute movement

A
  • PASSIVE

- Secondary to solute movement

66
Q

What are some examples of solutes?

A

Electrolytes such as Na+ or non-electrolytes such as glucose

67
Q

What stimulates lots of water absorption?

A

Na+/glucose and Na+/amino acid mechanisms

68
Q

How is K+ absorbed?

A

Passively when luminal [K+] rises because of absorption of water (solvent drag)

69
Q

Where does calcium absorption occur?

A

In the duodenum & jejunum

70
Q

Calcium absorption is regulated by what?

A

Primary regulated by VITAMIN D3 or 1, 25 dihydroxycholecalciferol (AKA “active vitamin D”)

71
Q

What does calcium absorption stimulate?

A

The synthesis of Ca2+ binding proteins called CALBINDINS in ENTEROCYTES

72
Q

How are Fat-soluble vitamins (A, D, E, K) absorbed?

A

Similar to fat absorption

73
Q

What are the MOST wate-soluble vitamins absorbed by?

A

Simple diffusion

74
Q

What does one of the water-soluble vitamins (vitamin B12; cobalamin; CBL) require?

A

Intrinsic factor (IF) for normal absorption

75
Q

What do Ileal cells absorb across the brush border?

A

IF-Vitamin B 12 complexes

76
Q

What does Atrophy of the gastric mucosa result in?

A

In a deficiency of IF and acid secretion that causes vitamin B12 deficiency

77
Q

What do peristaltic contractions do? and where do they occur?

A
  • They propel and mix food along the GI tract

- Occur in the esophagus, stomach & small intestine

78
Q

How long does it take chyme to move through the entire SI via peristalsis?

A

Approx. 3-5 hours

79
Q

What is segmentation?

A

A series of contractile and relate periods that mechanically digests food

80
Q

What are BOTH peristalsis and segmentation controlled by?

A

Autonomic Nervous System.

81
Q

How do sympathetic and parasympathetic nerves affect muscular activity?

A

Sympathetic= INHIBITS

Parasympathetic= EXCITES

Digestion (15 decks)

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