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DIG > L09 - Dig and abs of fat - WIP > Flashcards

L09 - Dig and abs of fat - WIP Flashcards

1
Q

Why have fats/ lipids evolved to be the storage depot of choice?

A
  • The most conc depot of energy storage
    1. On avg represent 9.4kcal/ g
    2. Non-polar therefore can be stored in an anhydrous state
  • 1g dry glycogen bound to 2g of water)
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2
Q

Where do most of the body’s fat deposits occur?

A
  1. Exist in the subcutaneous adipose tissue layers

fat also exists to a small extent in muscle and in visceral depots in obese and older people

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3
Q

Which vitamins are fat- soluble?

A

Vitamins A, D, E and K

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4
Q

What do fat-soluble vitamins depend on for intestinal abs?

A

Vits A, D ,E and K depend upon solubilisation within bile salt micelles for intestinal absorption

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5
Q

What can vitamin A deficiency lead to?

A
  • Night blindness
  • Corneal drying (xerosis)
  • Corneal degeneration and blindness (xerophthalmia)
  • Impaired immunity
  • Hypokeratosis
  • Keratosis pilaris
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6
Q

What can an overdose of vitamin A lead to? (Hypervitaminosis A)

A
  • Hair loss
  • Nausea
  • Blurry vision
  • Headaches
  • Muscle and abdominal pain
  • Vomiting
  • Irritability
  • Jaundice
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7
Q

Why can vitamin D be considered as not really a vitamin?

A

Sunlight can be used to generate vit D3 in skin of animals

- Thus, animals with adequate exposure to sunlight do not require dietary supplementation

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8
Q

What are some dietary sources of vitamin D(3)?

A
  • Egg YOLK
  • Fish oil
  • Mushrooms
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9
Q

What are some dietary sources of vitamin A?

A
  • Orange and yellow vegetables and fruits

- Cod liver oil

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10
Q

What can vitamin D deficiency lead to?

A
  • Impaired bone mineralisation
  • Bone softening diseases
  • Rickets in children and osteomalacia in adults
  • Possible contribution to osteoporosis
  • May also be linked to many forms of cancer
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11
Q

What are some dietary sources of vitamin E?

A
  • Veg oils (palm oil, sunflower, corn, soybean and olive oil)
  • Nuts
  • Seeds
  • Green leafy veg
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12
Q

What can an overdose of vitamin D lead to? (Hypervitaminosis D)

A
  • Abnormally high levels of calcium in blood
  • Affect on bones, tissues and other organs
  • Calcification of arteries and soft tissues
  • Kidney stones
  • Kidney failure
  • Heart arrhythmias
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13
Q

What can an overdose of vitamin E lead to? (Hypervitaminosis E)

A
  • Hypertension
  • Vasoconstriction of celebral and systemic vessels –> red of celebral blood flow leading to strokes
  • Aggravation of angina
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14
Q

What can vitamin E deficiency lead to?

A
  • Neurological problems due to poor nerve conduction
  • Muscle dmg
  • Result in loss of feelings in arms or legs
  • Muscle weakness
  • Vision problems
  • Weakened immune system
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15
Q

How many different forms of vit E are there and which one is the most biologically active ?

A
  • 8 different forms
  • a-tocopherol is the most biologically active
    (Vit E aka tocopherol)
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16
Q

What can vitamin K deficiency lead to?

A
  • Inc risk of excessive bleeding (easy bruising)
  • Heavy menstrual periods
  • Bleeding from GIT
  • Blood in urine or stool
  • Inc prothrombin time
  • Excessive bleeding from injuries
  • Risk of massive uncontrolled internal bleeding
  • Cartilage calcification and severe malformation of developing bone
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17
Q

What can an overdose of vitamin K lead to? (Hypervitaminosis K)

A
  • Jaundice in newborns
  • Haemolytic anaemia
  • Hyperbilirubinemia
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18
Q

What are some dietary sources of vitamin K?

A
  • ALSO PROD BY INTESTINAL BACT
  • Green leafy veg
  • Kiwi
  • Tomatoes
  • Prunes
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19
Q

Why is vit K important?

A

Vit K is involved in the carboxylation of specific glutamate residues in proteins to form gamma-carboxyglutamate residues (Gla-residues)
- Gla residue are usually involved in binding calcium

20
Q

Why is vit E important?

A

Vit E has an anti-oxidant role in protection against cardiovascular disease and cancer

21
Q

Why is vit D important?

A

Helps to reg the amount of calcium and phosphate in the body

22
Q

Why is vit A important?

A

Important for normal vision, the immune system, reproduction
- Also helps the heart, lungs, kidneys and other organs to work properly

23
Q

What are the typical symptoms of essential fatty acid deficiency (EFA)?

A
  • Occurs most often in infants whom are fed diets deficient in EFA
  • Scaly dermatitis
  • Alopecia
  • Intellectual disability in children
  • High B
  • High trigylcerides
  • Impaired growth
  • Weakness
  • Tingling sensation
  • Oedema
  • Haemorrhagic dermatitis
  • Skin atrophy
  • Immune and mental deficiencies
24
Q

How many types of vitamin A are there?

A
  1. Preformed vitamin A
    - Found in meat, poultry, fish
  2. Provitamin A
    - Found in fruits, veg and other plant based products (most common is beta-carotene)
25
Q

What are the 3 physiological processes that Gla-proteins have a key role in?

A

Key roles in reg of:

  1. Blood coagulation
  2. Bone metabolism
  3. Vascular biology or deposition of insoluble calcium salts in the arterial vessel walls
26
Q

Why are essential fatty acids an important dietary requirement?

A
  • They cannot be derived endogenously, therefore must be obtained from the diet
27
Q

What are the two main essential fatty acids?

A
  1. Alpha-linolenic acid (an w-3 FA)

2. Linoleic acid (an w-6 FA)

28
Q

What are some of the derivatives from alpha-linolenic acid?

A
  • EPA (eicosapentaenoic)

- DHA (docosahexaenoic)

29
Q

What are some of the derivatives from linoleic acid?

A
  • Gamma-linolenic acid (GLA)

- Arachidonic acid (AA)

30
Q

What are some of the important functions of EFA?

A

Important in lots of cellular and organ processes

  1. Formation of healthy cell membranes
  2. Dev and functioning of the brain and NS
  3. Prod of eicosanoids
  4. Responsible for reg BP, blood viscosity, vasoconstriction, immune and inflammatory responses
31
Q

What is the structure of a tri-glyceride molecule?

A
  • Glycerol bound to 3 fatty acid molecules bound by ester bonds (formed during condensation reaction)
32
Q

What are the 4 major phospholipids found in the plasma membrane?

A
  1. Phosphatidlycholine
  2. Phosphatidylethanolamine
  3. Phosphatidylserine
  4. Sphingomyelin (type of sphingolipid)
33
Q

What does phosphatidylethanolamine, phosphatidylcholine and phosphatidylserine have in common?

A
  • Esterified at the first and second two positions of the glycerol backbonae to fatty acids
  • The third position is esterified to a phosphate which in turn in esterified to a head group (i.e phosphatidylcholine)
34
Q

What is the difference between sphingolipids and the other phospholipids?

A

Sphingolipid has a serine rather than glycerol backbone

35
Q

Where are the endogenous lipids in the GI lumen from and what does it contain?

A

Predominantly from bile, which contains:

  1. Phospholipids (phosphatidylcholine)
  2. Unesterified cholesterol
  3. Membrane lipids from desquamated cells
  4. Lipids derived from dead colonic bacteria
36
Q

Emulsification of food can take place by what processes? What is the effect?

A
  1. Food prep (i.e. blending and cooking)
  2. Chewing and gastric churning which allows mixing lingual and gastric juices
  3. Squirting of gastric contents into the duodenum
  4. Intestinal peristalsis mixes luminal contents with pancreatic and biliary secretions
    (These mech processes reduce the size of the lipid droplets and inc their ratio of SA:V)
37
Q

Why do the lipid particles not coalesce?

A
  1. Coating the emulsion droplets with memb lipids, dentaured protein, dietary polysacc, prod of dig (FA and monoglycerides) and biliary PPL and cholesterol
  2. Polar groups (hydrophilic) of the PPL project into the water, thus prevent coalescence of the emulsion particles
  3. Core of the emulsion particle is composed of triglyceride which also contains cholesteryl esters and other non-polar lipids
38
Q

Where does lipid digestion begin and which enzyme is it mediated by?

A
  • Lipid dig begins in mouth, mediated by lingual lipase
39
Q

Which enzymes are responsible for lipid digestion in the stomach?

A

Both lingual lipase and gastric lipase (chief cells in response to gastrin/ ACh) digest large amounts of lipid
- Lingual and gastric lipase release a single FA from triglycerides, leaving behind intact diglycerides

40
Q

Why are the released long chain fatty acids from lipid digestion not absorbed in the stomach, how about for medium-short chain fatty acids?

A
  • They are insoluble at acidic pH and thus remain in the core of the triglyceride droplets
  • Medium-short chain FA are mainly ionised at the acidic gastric pH, remain in solution and are passively abs across the gastric mucosa into portal blood
41
Q

What does CCK stimulate?

A
  1. The flow of bile into the duodenum by gallbladder contraction and relaxation of the sphincter of Oddi
  2. The secretion of pancreatic enzymes, including lipases and esterases
42
Q

What triggers the release of CCK?

A

Secretion stimulated by intro of HCl, aa, FA into the stomach or duodenum

43
Q

Which cells secrete CCK?

A

I cells in the duodenal mucosa secrete cholecystokinin (CCK)

44
Q

What does full lipolytic activity of pancreatic lipase require?

A
  1. Colipase (essential for ligand binding conformation; secreted as pro-colipase and activation as normal)
  2. Alkaline pH
  3. Bile salts
  4. Fatty acids
45
Q

What is the major lipolytic enzyme?

A

Pancreatic lipase - digests all dietary triglycerides not hydrolysed in the stomach

DIG (31 decks)

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