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0V015 Biology & Pathology > Nutritional disorders L23 > Flashcards

Nutritional disorders L23 Flashcards

1
Q

What are the three major nutrients?

A

Fats (helps absorb vitamins, energy source, cell membrane, insulation)
Proteins (amino acids for structural support, enzymes, hormones etc,)
Carbohydrates (broken down into glucose to provide ATP)

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2
Q

What is the purpose of vitamins in our diet?

A

They act as co-enzymes.

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3
Q

Which vitamins are fat-soluble and which vitamins are water-soluble?

A

Vitamins A, D, E& K fat-soluble.

Vitamins B & C are water-soluble.

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4
Q

How many minerals does the body contain and what are they?

A 
The body contains moderate amounts of 7 minerals:
Calcium 
Phosphorous 
Potassium 
Sulphur 
Sodium 
Chloride
Magnesium
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5
Q

What are some functions of minerals/trace elements in the body?

A

Calcium in bones
Iron in haemoglobin
Calcium/Sodium/Potassium - nerve impulses

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6
Q

What are the essential nutrients?

A

Molecules that cannot be manufactured within the body from ingested material.

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7
Q

What are the two types of nutritional deficiencies?

A

Primary and Secondary deficiency

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8
Q

What is a primary deficiency?

A

Insufficient intake

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9
Q

What is a secondary deficiency?

A

The intake is normally sufficient but the cells receive because of:

  • failure of intestine to absorb ( Crohn’s disease)
  • increased demand (pregnancy, lactation, growth)
  • presence of antagonists
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10
Q

What is marasmus disease

A

The body compensates for a caloric deficiency by catabolisng body tissue (fat and muscle). The calories derived from the breakdown of these tissues are used to maintain normal cellular metabolism. The result of this is extreme muscle wastage. (can recover quickly as normal cell function retained).

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11
Q

What is kwashikorr disease?

A

Body cannot compensate by catabolising tissues. Normal metabolism fails. The large belly is caused by a failure to maintain serum levels, resulting in oedema.

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12
Q

Where does the body produce vitamin A/retinol from?

A

From diet or from a provitamin (carotene).

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13
Q

Where does dietry retinol come from?

A

Dairy products and liver.

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14
Q

Where does carotene come from in our diet?

A

Leafy green /yellow vegetables

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15
Q

What is nyctalopia?

A

Night blindness

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16
Q

Why does vitamin A deficiency cause night blindness?

A

Vitamin A is an integral part of visual pigments.

Visual pigments are composed of a protein-opsin, bound to 11-cis retinol which is derived from retinol i.e. vitamin A

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17
Q

In night blindness what is affected?

A

The first photoreceptors to be affected are the rods, which underlie scotopic vision. In severe vitamin A deficiency, cone-mediated photopic vision is also affected.

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18
Q

What is scotopic vision?

A

Scotopic vision is the vision of the eye under low-light levels.

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19
Q

What is photopic vision?

A

Photopic vision is the vision of the eye under well-lit conditions.

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20
Q

What is xerophthalmia?

A

Changes in ocular epithelia due to Vitamin A deficiency.

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21
Q

How does Vitamin A deficiency affect epithelia?

A

Squamous epithelia becomes abnormally thickened and excessively keratinised.

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22
Q

Where are ocular covering epithelia present?

A

The cornea and conjunctiva.

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23
Q

What does keratinisation of epithelia in the conjunctiva as a result of vitamin A deficiency cause?

A

It causes the conjunctiva to become wrinkled and dry and leads to the formation of white bitot’s spots (raised keratin plaques).

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24
Q

What does keratinisation of corneal epithelia cause the formation of?

A

Corneal ulcers

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25
Q

What does vitamin A deficiency cause?

A 
Night blindness (nyctalopia)
Epithelial changes ( in oculafr epithelia specifically it is refered to as xerophthalmia) causing Bitots's spots in the conjunctiva and corneal ulcers.
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26
Q

What is the scientific name for a corneal ulcer?

A

Keratomalacia

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27
Q

What is keratomalacia?

A

Corneal ulceration ( corneal ulcer)

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28
Q

What is the scientific name for Vitamin D?

A

Cholecalciferol

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29
Q

How is vitamin D/Cholecalciferol obtained?

A

Diet - it is absorbed by the intestine along with fats

UV sunlight transforms a steroid in the skin (dehydroxycholesterol) to produce it.

30
Q

What is a deciciency of vitamin D usually the result of?

A

Insufficient dietry intake

Lack of sunlight

31
Q

How has vitamin D deficiency been ‘eradicated’ in developed countries?

A

Adding vitamin D to milk. (Fortifying milk with vitamin D)

32
Q

What is the main function of vitamin D?

A

Aiding the absorbtion of calcium thus a lack of Vitamin D causes inadequate calcification of bones.

33
Q

What condition does vitamin D cause in children?

A

Rickets ( soft bones - easily distorted, children become pigeon chested as intercostal muscles pull on the ribs , legs are often bent as bones are soft)

34
Q

What is vitamin D deficiency in adults called?

A

Osteomalacia

35
Q

What is vitamin K required for?

A

Synthesis of blood coagulation factors e.g prothrombin

36
Q

How is vitamin K acquired?

A

Main source of synthesis is by intestinal bacteria ( some derived by leafy green vegetables and dairy products).

37
Q

How can deficiency of Vitamin K occur?

A

Longterm use of antibiotic treatment can kill the intestinal bacteria that syntheisis vitamin K.

38
Q

What will vitamin K deficiency cause?

A

Excessive bleeding as blood doesn’t clot.

39
Q

What is the scientific name for vitamin E?

A

tocopherol

40
Q

What does tocopherol act as?

A

Vitamin E acts as an anti-oxidant

41
Q

Why are free radicals dangerous?

A

They are highly reactive and can damage cells by penetrating the cell wall and damaging DNA.

42
Q

How are free radicals produced?

A

Oxidation reactions result in the loss of electrons. These reactions are crucial however can produce free radicals.

43
Q

What is an antioxidant?

A

A molecule capable of slowing or preventing oxidation of other molecules.

44
Q

What can vitamin E deficiency cause?

A

Haemolytic anaemia

also neuromuscular degeneration

45
Q

What is haemolytic anaemia?

A

Hemolytic anemia is a form of anemia (low heamoglobin) due to hemolysis, the abnormal breakdown of red blood cells.

46
Q

What is the scientific name for Vitamin C ?

A

Ascorbic Acid

47
Q

What is vitamin C required for?

A

It is required for the manufacture of collagen and ground tissue - specifically tropocollagen.

48
Q

What is tropocollagen?

A

the basic structural unit of collagen

49
Q

What is a consequence of vitamin C deficiency?

A

Increased fragility of blood vessels (which contain alot of tropocollagen) leading to bleeding , including haemorrhages in the eyelids, anterior chamber , vitreous cavity and retina.
(Bleeding of the gums is also common)

Vitamin C can also lead to old scars reopenning and bone abnormalities.

50
Q

How can vitamin C deficiency been seen by optometrists?

A

Haemorrhaging in the eyelids, anterior chamber, vitreous cavity and retina.

51
Q

What disease is a lack of vitamin C refered to as?

A

Scurvy

52
Q

What is Vitamin B?

A 
It is a family of vitamins:
Thiamine 
Riboflavin 
Niacin
Vitamin B6
Folate 
Vitamin B12

(cornflake vitamins- all present in cornflakes)

53
Q

What is thiamine (vitamine B1) responsible for?

A

It is a co-enzyme responsible for decarboxylation of pyruvate consequently a lack of it results in impaired enery production. It also helps in the production of acetylcholine.

54
Q

What can a deficiency of Thiamine lead to?

A

Beriberi, nutritional disorder caused by a deficiency of thiamin (vitamin B 1) and characterized by impairment of the nerves and heart. 70% of all beriberi patients have ocular problems (dry eyes).

55
Q

What is vitamine B2/riboflavin responsible for?

A

It is responsible for energy transfer (Electron transfer).

56
Q

What effects on the eyes does a deficiency of Riboflavin have?

A

Vascularisation of the cornea, followed by corneal opacities, ulceration of the cornea followed by eventual blindness.

57
Q

What is niacin responsible for?

A

Oxidation/reduction reactions. Ocular abnormalities follwoing a deficinecy of niacin are rare but may result in optic neuritis and retinitis.

58
Q

What is vitamin B6 ( pyridoxine) responsible for?

A

It is a coenzyme in many of the body’s enzyme systems and has a role in GABA synthesis.

59
Q

What can a deficiency in B6 lead to?

A

Blepharirits (inflammation of the eyelids)

60
Q

What does a lack ofn folic acid and vitamin B12 cause?

A

They are responsible for nucleic acid synthesis. A lack causes disrupted DNA synthesis resulting in megaloblastic anaemia.

61
Q

What are sodium, potassium and calcium needed for?

A

Action potential generation,synaptic transmission , muscle contraction,etc,

62
Q

What is iron needed for?

A

Haemoglobin, A lack results in anaemia.

63
Q

What does a deficiciency of iodine result in?

A

Decreased thyroid hormone output

64
Q

What is fluoride needed for?

A

Maintanance of teeth.

65
Q

What are clacium and phosphate needed for?

A

Bones

66
Q

What are magnesium, zinc copper and selenium used for?

A

Several functions including enzymatic activity. Zinc is an anti-inflammatory however in high concentrations is toxic to the eye.

67
Q

Are there any ocular benefit to nutritonal supplements?

A

The age related eye disease study (AREDS)n showed that people who took antioxidants Vitamin C, Vitamin E and beta carotene along with coppper had less vision loss and were less liekly to develope AMD than control groups.

However, the results of some studies are contradictory .

However, the AREDS formulation had no effect on catarax.

In summary, the available evidnece does not support the use of antioxidant vitamin and mineral supplements by healthy patients to preevent or treat cataracts.

68
Q

What is retinal macular pigment a mixture of?

A

Carotenoids Zeaxanthin and lutein.

69
Q

Why is macular pigment important?

A

It absorbs blue light which is a good thing as blue light tends to get scattered more and is more prone to chromatic aberation which tends to lessen image quality.

Carotenoids (in macular pigment i.e. Zeaxanthin and lutein also remove wavelengths most damaging to the retina and act as antioxidants.

70
Q

What do lutein and Zeaxanthin levels decrease with?

A

Age hence low levels are associated with diseases such as catarct and macular degenration.

71
Q

How can carotenoids be obtained?

A

Only from dietry intake - increased intake results in a high macular pigment density.

72
Q

Should smokers take supplements?

A

NO. Smoking is one of the biggest risk factors for causing AMD. Beta carotene which protects against AMD (found in supplements) increases risk of lung cancer in smokers and ex-smokers by 24%.

0V015 Biology & Pathology (57 decks)

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