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Special sense BIO > Vitamin A > Flashcards

Vitamin A Flashcards

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Biology 101 flashcards
1
Q

بسم الله الرحمن الرحيم وبه نستعين
_________________________
MentioN Characteristics of Fat soluble vitamins

A

Absorbed with dietary fat
Transported in blood in Lipoproteins + sepcific binding proteins
Not readily excreted as significant amount are stored in liver and adipose tissue so excess in take can cause toxicity
KEDA

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2
Q

Anti xeroptlamic
anti night blindeness vitramins is ?

A

Vitamin A

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3
Q

Show structure of vitamin A

A

Polyisoprenoid compound
Hydrocarbon + B-Ionone ring

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4
Q

Preformed Vitamin A is ?

A

Retinyl Ester in animal foods also stored in liver
Retinyl ester =Retinol + fattay acid

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5
Q

Mention active forms of Vitamin A

A

Retinol
Reitinal
Retinoic Acid

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6
Q

The reversible reaction in vit A active form transormation

A

Retinol to Retinal is Reversed by reduction reaction

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7
Q

Preformed vit A is ?
ProVit A is ?

A

Preformed =Reinyl ester from animal
ProVit = B carotence percursor of vitamin A by Carotenase

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8
Q

Mention soruces of Vitamin A

A

الجزر غني عني التعريف ^_^
_____________________
=Animal sources Retinyl ester preformed vit A :- Liver- cod liver oil - kideny- butter -cream -egg yolk
=Plant sources Provit A or B carotene :- ? Carrots - dark green leafy vegetables + fruits
peaches + apricot + sweet potato

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8
Q

why conveseion of B carotene into Retinal is non efficent ?

A

Due to low activity of the enzyme carotenase or carotene dioxygenase and the retionl formed from it represnts only 1/12 of the yield retionl

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9
Q

The only Vit A form that is not carried by RBP but carried by….. ?

A

It is Retinoic acid
carried by albuimen

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10
Q

Explain Absoprtion and transport of Vitamina A

A

When RE reaches the Intestine the ester disscoiates leaving the Retionl which is incroprated with B carotene in the miscelle ( Phosplipids- Cholesterol- Fattay acids - MOno acyl glycerol )
The miscelle enters the intestinal eipthelial cells where:-
B carotene converted into 2 retinal by Carotenase or carotene dioxygenase and some escapes the enzyme then retinal reduced into retionl
The retinol released already from miscelle + Retionl from B carotene are Esterified into REs which are incorporated into Chylomicrons with the ecaping B carotene
then CM enters lymph then blood converted into CM remenatns then to liver where retinyl ester becomes retionl to reach its target cell or the retiol will be stored as Reinyl palmitate
B carotene is carried By VLDL to be stored in Adipose tissue

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11
Q

What is the fate of B carotene in intestine ?

A

Absorbed in miscleele into the intestinal cell then:
1-Carotenase works on it to form 2 retinal then reduced to 2 retionl
2- Escapes carotenase to be in CM directly
_____________
after reaching liver carried in VLDL to be sotred in adipose tissue

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12
Q

stored from of vit A in liver?

A

Retinyl palmitate

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13
Q

Daily requirements of Vit A is > ?

A

RDA for adults 900 retional activity equivalent RAEs for male
700 RAEs for females
1 RAEs= 1 ug Retionl = 12 ug B carotene

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14
Q

Mentione Role vitamin A in vision ?

A

It is compnent of visual pigment of photorecpeotr cells of reds and cones which absop light causing chemical changes and nerve impulse discharge!

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15
Q

Mention function ofMet Rhosopsin

A

Metrhodopsin fromed G protein stimulation causing hyperpolarization of receptors casuing finally depolarization of nerves ( optic nerve) to brain

15
Q

Explain Viscual cycle of dim light
or Explain Rhodopsin cycle

A

11 Cis retinal + Oposin ( Rhodopsin )
when light Fall on this complex
Oposin disocciate from 11 cisretinal
and Metrhodopsin fromed G protein stimulation causing depolarization of nerves to brain
11 cis retinal disscoiates as All Trans RetinAl
then redcued to All trans RetinOl THEN transported to ? Retinal pigment epithelium where its is esterfied into All trans RE then isomer formed ( 11 cis RetinOl )
then Oxidized to 11 cis retinal (required ) enter the Rod cell to attach to opsin formin Rhodsopsin complex and the cycle completed

16
Q

mention function of 11 cis retinal

A

attach to Opsin in rods forming rhosopisn for dim light
attach to opsin if cones forming iodopsin for brigh light and colors

17
Q

Mention role in vit A in immunce cells
mention role of Vit A in cell differentiation and turnover

A

Retinoic acid attaches to Nuclear protein receptor then to Element of DNA stimlating transcrioptin of gene to mRNA - protein in cell differentiation and turnover

18
Q

Vit A plays a role in maintanece of healthy epithleum show

A

Retinyl phospate from retionl works as glycosyl carries for synthesis of glycoproteins + Mucopolysaccharides for muscin secretion

18
Q

Mention role of vit A in reproduction

A

Retinol and Retinal plays an imprtant role in sepermatogensis and preventing fetal resprobtipin in felmale rats

19
Q

What happens if animal is only given reinoic acid as a source of Vit A

A

Plays its role in cell differentiation but
no role in reproduction so ?
Sterile Animal and blind

20
Q

What happens if animal is only given reinoic acid as a source of Vit A

A

Plays its role in cell differentiation but
no role in reproduction and visual cycle so ?
Sterile Animal and blind

21
Q

B carotene and health ?

A

It is antioxidant trap free radicals at low oxygen pressure
May protect against? Cancer + heart attack

22
Q

What are the causes of Vit A def and why it is lately mainfested ?

A

1- low vit a in diet
2- low fat diet
3- Abdsoption problems due to biliary obstruction
4- Liver disease causing decreased RBP
___________________________
Lately manifested due to storage in liver for 2-3 months for symptomps to appear

23
Q

Mention effects of the vit A def in eye

A

NXM
1-Night blindness Nyctalopia
2-Xeropthalmia dryness no muscus
3-KeratoMalacia due to ulceration and degenration of cornea causing total blindness
NXK

24
Q

Vit A def and skin and Epithlium

A

Keratiniaztion of Skin causing dry rough keratinized skin with fissure susptible to infection
Keratinzing Metaplasisa of the Epithlium of the Git Respiratory Genitourinary tracts losing Mucin causing susptibility to infection

25
Q

GR/Vit A deficinecy causes sustpibilty to infection

A

Cuz Vit A is responsible for immunce cells differentiation and Turnover
Also
Keratinization of Skin + Keratinziing Metaplasia of the Epithlium of the Git …… losing mucin secetion causing ?suspitibility to infectio n

26
Q

GR/Vit A deficinecy causes sustpibilty to infection

A

Cuz Vit A is responsible for immunce cells differentiation and Turnover
Also
Keratinization of Skin + Keratinziing Metaplasia of the Epithlium of the Git …… losing mucin secetion causing ?suspitibility to infection

27
Q

Retinoic acid is given in dermatological problems as ,,,,+,,,,,,

A

Acne + Psoriasis

28
Q

Excessibe intake of Vit A causes what ?

A

Hypervitaminosis A
Causing Dry skin + alopecia
Liver : Hyperlipidemia and hepatomegaly
Increased Intracranial pressure
Teratogenic in pregnant

29
Q

Skin yellow and Sclera White represnts ?

A

not jaundice but excessive B carotene intake

30
Q

الحمدلله رب العالمين

A
31
Q

Describe non-visual role of vitamin A

A

r2ia
-Role in cell growth and differentiation. Retinoic acid binds to nuclear receptors that bind to response elements of DNA and regulate the transcription of specific genes.
-Role in maintenance of healthy epithelial cells, retinol in converted to retinyl phosphate which serves as glycosyl carrier in synthesis of glycoproteins and mucopolysaccharodes needed for normal mucus formation
-Role in reproduction, retinol & retinal but not retinoic acid support spermatogenesis and prevent fetal resorption in female rates
-Role as anti-oxidant, b-carotene trap free radicals at low O2 pressures. It may protect against cancer amd heart attack.

32
Q

Describe symptoms of vit A deficiency

A

-Blindness, earliest night blindness then xerophthalmia, then corneal degeneration & ulceration (keratomalacia), eventually blindness.
-Dermatological problems: xeroderma
-Increased susceptibility to infection bec of keratinizing metaplasia of epithelial & mucosal cells, and impaired immune system as vit A is imp for immune cell differentiation

Special sense BIO (1 decks)

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