Fat Soluble Vitamins Flashcards
(132 cards)
1
Q
What elements are vitamins mostly made of?
A
Carbon
Hydrogen
Oxygen
sometimes, Nitrogen.
2
Q
Why are vitamins essential?
A
Body can’t make enough on its own; must be obtained from food. Needed in small amounts for life.
3
Q
Main functions of vitamins
A
Help use macronutrients
Act as coenzymes/cofactors
Support immunity, cell function, and growth.
4
Q
Difference between macronutrients and micronutrients
A
Macronutrients → large amounts (carbs, fats, proteins)
Micronutrients → small amounts (vitamins, minerals).
5
Q
Most common type of vitamin
A
Water-soluble B-complex vitamins.
6
Q
Two major groups of vitamins
A
Fat-soluble (A, D, E, K)
Water-soluble (B-complex, C)
7
Q
Polar or non-polar
A
💛 Fat soluble: HydroPHOBIC (nonpolar)
💙 Water soluble: HydroPHILIC (polar)
8
Q
Absorbed?
A
💛 Fat soluble: NEED normal fat digestion
💙 Water soluble: DO NOT NEED fat digestion
9
Q
Stored in the body?
A
💛 Fat soluble: Liver and adipose tissue.
💙 Water soluble: No, except B12 (stored in liver).
10
Q
Transported?
A
💛 Fat soluble: lipoproteins or binding proteins.
💙 Water soluble: Freely in the blood.
11
Q
Common deficiencies?
A
💛 Fat soluble: LESS PRONE
💙 Water soluble: MORE PRONE
12
Q
More toxic?
A
💛 Fat soluble: YES, especially vitamins A and D.
💙 Water soluble: Less prone to toxicity
13
Q
Excreted?
A
💛 Fat soluble: Mostly through FECES via BILE.
💙 Water soluble: Mostly through URINE after LIVER metabolism
14
Q
Where are all vitamins absorbed?
A
Small intestine.
15
Q
Need for absorption?
A
💛 Fat soluble: Dietary Fat
💙 Water soluble: Water
16
Q
Vitamin A Chemical Structure
A
A polyisoprenoid compound with a cyclohexenyl ring.
17
Q
How is Vitamin A stored in the body?
A
As retinyl esters (e.g., retinyl palmitate) in the liver.
18
Q
A provitamin A with a structure like β-carotene + hydroxyl group (-OH); moderately active.
A
Cryptoxanthin
19
Q
key functions of Vitamin A
A
Antioxidant
Supports vision
Immune function
Cell growth.
20
Q
A carotenoid precursor with moderate activity; less active than β-carotene.
A
α-carotene
21
Q
Good sources of α-carotene
A
Orange/yellow vegetables
22
Q
This is a special as a Vitamin A precursor; Yields 2 molecules of retinol; has the highest Vitamin A activity.
A
β-carotene
23
Q
Foods are rich in β-carotene
A
Carrots
Sweet potatoes
Leafy greens.
24
Q
Similar structure to β-carotene, but yields only 1 molecule of retinol; moderate activity.
A
γ-carotene
25
Common sources of γ-carotene
Orange/yellow fruits and vegetables
26
Structure of Cryptoxanthin
A xanthophyll with a hydroxyl (-OH) group; slightly polar.
27
Vitamin A activity of cryptoxanthin
Moderate; it’s a provitamin A.
28
Good food sources of cryptoxanthin
Oranges
Papayas
Tangerines
Pumpkins
Peppers.
29
Alcohol form of Vitamin A and its functional group
Retinol – contains a CH₂OH group.
30
Aldehyde form of Vitamin A and its functional group
Retinal – contains a CHO group (C=O + H).
31
Acid form of Vitamin A and its functional group
Retinoic acid – contains a COOH group.
32
Plant precursor can be split into two Vitamin A molecules
β-Carotene
33
Form of Vitamin A is found in animal sources
Preformed Vitamin A as retinyl esters (e.g., retinyl palmitate).
34
Animal-source Vitamin A made usable by the body
Retinyl esterase digests retinyl esters → releases retinol
35
Plant sources provide for Vitamin A
Provitamin A carotenoids (e.g., β-carotene, cryptoxanthin).
36
How are plant-source carotenoids used by the body?
converted into active Vitamin A.
37
Where is β-carotene converted to retinol?
Intestinal cells and liver.
38
What stimulates β-carotene → retinol conversion?
Thyroid hormones
39
What is the first active form of Vitamin A after conversion?
Retinol (Vitamin A alcohol)
40
Key roles of retinol in the body?
Reproduction
Epithelial differentiation
Mucous production
Bone growth.
41
How does retinol affect bone?
Aids remodeling: activates osteoclasts and supports osteoblasts.
42
Retinol → ? → Rhodopsin (for vision)
Retinal (combines with scotopsin in rod cells)
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Visual pigment in rods (Retinal + Scotopsin)
Rhodopsin
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Retinol → Retinal → ?
Retinoic acid (regulates gene expression)
45
Function of retinoic acid?
Epithelial differentiation
Mucous production
46
3 major forms of Vitamin A
Retinol (alcohol)
Retinal (aldehyde)
Retinoic acid (acid)
47
Major functions of Retinol (Vitamin A1)
👁️ Vision: Forms rhodopsin (11-cis-retinal + opsin) for low-light vision
🧴 Epithelial Health: Supports skin and mucosal cell differentiation
🛡️ Immunity: Maintains barrier integrity against infection
🧬 Reproduction: Needed for spermatogenesis and fetal development
🧯 Antioxidant: Neutralizes reactive oxygen species (ROS)
🔁 Conversion: Precursor to retinal (vision) & retinoic acid (gene regulation)
48
What is the pathway from seeing an object to perceiving it in the brain?
💡 Light Reflection: Light from the object enters the eye through the lens.
🔄 Inverted Image: Image is flipped and projected onto the retina.
📡 Signal Transmission: Retina converts light to signals → sent via optic nerve.
🧠 Visual Cortex: Signals processed in the occipital lobe.
🅰️ Image Interpretation: Brain interprets the signal (e.g., recognizes "A").
49
Main differences between Rods and Cones in the retina
🖤 RODS
🖤 Shape: Long, cylindrical
🖤 Segment: Flattened saccules
🖤 Function: Night vision (scotopic/mesopic)
🖤 Pigment: Rhodopsin
🖤 Light Sensitivity: Very high (1 photon)
🖤 Location: Peripheral retina
🖤Number: ~120 million
💛 CONES
💛 Shape: Short, tapered
💛 Segment: Flattened disks
💛 Function: Color & sharp vision (photopic)
💛 Pigment: Red/Green/Blue opsins
💛 Light Sensitivity: Lower (needs bright light)
💛 Location: Fovea
💛 Number: ~6 million
50
Role of rods and cones in the retina’s layered structure
Retina contains rods & cones in photoreceptor layer
Signal relayed to 4 neuron types:
1.) Bipolar cells
2.) Ganglion cells
3.) Horizontal cells
4.) Amacrine cells
51
Four types of photoreceptors in the retina
🖤 1 Rod type (night vision)
💛 3 Cone subtypes:
🔴 Red-sensitive
🟢 Green-sensitive
🔵 Blue-sensitive
Mnemonic: RGB + R = 4 photoreceptors
52
Photoreceptors made of
Outer segment: Rhodopsin (opsin + retinal)
Inner segment: Mitochondria-rich for energy
🖤 Rods: Saccules
💛 Cones: Disks
53
What is a photon, and how does it interact with rods and cones?
Photon = massless, chargeless light particle
Travels at light speed
🖤 Rod: Activated by 1 photon
💛 Cone: Needs many photons
54
Photosensitive compounds made of?
Opsin (protein) + Retinal (Vitamin A aldehyde)
Retinal → retinol (Vitamin A alcohol)
β-carotene = precursor of both
55
🔄 How is retinol converted to retinal in photoreceptors?
Reaction: Oxidation
Enzyme: Retinol Dehydrogenase (RDH5)
11-cis-retinol → 11-cis-retinal
Transported by IRBP
Used to regenerate rhodopsin
56
How many Vitamin A molecules come from β-carotene?
1 β-carotene → 2 Vitamin A molecules (retinol/retinal)
57
Where is rhodopsin located and what is it made of?
Location:
Rod Photoreceptor Outer Segment Discs
Made of:
Opsin (a 348-AA GPCR protein, aka scotopsin)
11-cis-retinal (vitamin A derivative)
Together: Opsin + 11-cis-retinal = Rhodopsin
58
🧬 What is the structure of rhodopsin?
Type: G-protein coupled receptor (GPCR)
Shape: 7-transmembrane α-helices (serpentine receptor)
Retinal: Lies parallel to membrane, covalently bound to lysine-296 (in 7th helix)
Orientation: N-terminal (extracellular), C-terminal (intracellular)
59
💡 What happens during photoisomerization of retinal in rhodopsin?
11-cis-retinal (bent) → all-trans-retinal (straight) after light exposure
Activates rhodopsin
Begins the visual signal
60
🔄 What are the steps of the phototransduction cascade?
1. Light → Activates rhodopsin
2. 11-cis-retinal → all-trans-retinal
3. Rhodopsin → Metarhodopsin II
4. Metarhodopsin II activates transducin (G-protein)
5. Transducin activates PDE (phosphodiesterase)
6. PDE: cGMP → 5’-GMP → ↓cGMP
7. ↓cGMP → Na⁺ channels close → hyperpolarization
8. Electrical signal → visual cortex
61
📉 What is the result of Na⁺ channel closure in photoreceptors?
↓Na⁺ influx → Cell hyperpolarizes
Signal → transmitted to bipolar & ganglion cells → to the brain
62
🔁 What are the steps of the rhodopsin-retinal visual cycle?
🩵 Bleaching:
Rhodopsin → Bathorhodopsin → Lumirhodopsin → Metarhodopsin I → Metarhodopsin II
→ Releases all-trans-retinal
🧡 Regeneration:
All-trans-retinal → all-trans-retinol
→ 11-cis-retinol → 11-cis-retinal
Combines with opsin → Rhodopsin reformed
63
🥕 How does vitamin A affect vision?
Needed for 11-cis-retinal production (regenerates rhodopsin)
Vitamin A deficiency → impaired rhodopsin regeneration → night blindness (nyctalopia)
64
💡 What dietary factors impair Vitamin A absorption?
Low dietary fat → ↓ absorption (fat needed for micelle formation)
Inadequate protein → ↓ retinol-binding protein (RBP) synthesis
Low zinc → impairs conversion of retinol → retinal
Vitamin E deficiency → ↓ antioxidant protection for Vitamin A
65
⚠️ How do infections and parasites affect Vitamin A status?
Increased demand for tissue repair & immunity
Impaired absorption and transport
Increased urinary loss
Parasitic infestations → intestinal damage → ↓ absorption
66
🧬 How does Vitamin A control cell differentiation and turnover?
Retinoic acids (all-trans & 9-cis) bind to nuclear receptors
RARs bind all-trans & 9-cis-retinoic acid
RXRs bind 9-cis-retinoic acid
Activate genes → protein synthesis → cell growth & differentiation
67
🛡️ What is the role of Vitamin A in the immune system?
Essential for immune cell differentiation & function
Deficiency → ↓ RBP during infection → ↓ circulating vitamin A → weakened immunity
Even mild deficiency → ↑ infection susceptibility
68
👁️ What are the early eye signs of Vitamin A deficiency?
Nyctalopia (night blindness) – poor mesopic vision (dim light)
Photophobia – light sensitivity
Xerosis conjunctivae – dry conjunctiva
Bitot’s spots – foamy, white lesions (keratin + Corynebacterium xerosis)
69
🔄 What is xerophthalmia and its progression?
General dryness of ocular tissues
Can progress to:
Corneal ulcers
Keratomalacia – cornea softens, risk of perforation
Blindness – from opacities or eyeball collapse
70
🧪 What is keratinizing metaplasia and where does it occur in Vit A deficiency?
All epithelial cells can undergo keratinizing metaplasia → ↓ function
Affected systems:
Respiratory tract → ↑ infections
Kidneys → cornification → renal stones
Glandular ducts → blocked, atrophy
Testes → germinal epithelium loss → sterility
71
🧖♀️ What are the skin signs of Vitamin A deficiency?
Dry, scaly skin
Toad skin = follicular hyperkeratosis
Rough, bumpy papules due to keratin around hair follicles
72
What are two synonyms of Vitamin D and why?
Anti-rachitic vitamin – prevents rickets in children
Sunshine vitamin – synthesized in the skin with UV light
73
⚖️ What dual role does Vitamin D play in the body?
Vitamin
Hormone
74
🦴 What are the key functions of Vitamin D?
Regulates calcium & phosphate (bone mineralization → hydroxyapatite)
Supports immune function, muscle health, reduces inflammation
75
🔄 What is the 2-step activation process of Vitamin D?
1. Liver: Cholecalciferol → 25-hydroxyvitamin D (calcidiol, storage form)
2. Kidney: 25-hydroxyvitamin D → 1,25-dihydroxyvitamin D (calcitriol, active hormone form)
76
🌿 What are the 2 dietary forms of Vitamin D and their sources?
Vitamin D2 (Ergocalciferol): plant-based (UV-exposed mushrooms, fortified plant milks, cereals)
Vitamin D3 (Cholecalciferol): animal-based (fish liver oils), can be synthesized from cholesterol
77
🔬 What are the 3 important forms of Vitamin D in the body and their roles?
1. Calcidiol (25-hydroxycholecalciferol): storage form, made in the liver
2. Calcitriol (1,25-dihydroxycholecalciferol): most active, hormone form, made in the kidney
3. 24,25-dihydroxycholecalciferol: less active metabolite, also formed in the kidney
78
⚙️ Summarize the metabolism of Vitamin D3
Skin: 7-dehydrocholesterol → cholecalciferol (Vit D₃) via UV
Plasma: Transport to liver
Liver: → 25-hydroxycholecalciferol (calcidiol)
Kidney: → 1,25-dihydroxycholecalciferol (calcitriol)
Target tissues: Regulates Ca²⁺ and phosphate, supports bone health
79
Name food sources rich in Vitamin D2
🥛 UV-exposed mushrooms (e.g., maitake, shiitake)
🥛 Fortified foods: milk, plant milks, cereals
(Note: D2 is less potent than D3 in raising blood levels)
80
💡 What is the principal function of calcitriol (1,25-dihydroxycholecalciferol)?
To maintain plasma calcium levels by:
↑ Intestinal calcium absorption
↑ Bone calcium mobilization
↓ Renal calcium excretion (stimulates resorption)
81
🔬 What are the additional functions of calcitriol beyond calcium regulation?
Regulates insulin secretion
Stimulates PTH and thyroid hormone synthesis
Inhibits immune components:
🔬 Interleukins (from T cells)
🔬 Antibodies (from B cells)
🔬 Monocyte → macrophage differentiation
Modulates cell proliferation
82
📉 What hormone has an opposite effect to parathyroid hormone and works against calcitriol?
Calcitonin – produced by the thyroid gland, reduces calcium levels.
82
⚙️ What are the physiologic roles of Vitamin D?
↑ Calcium & phosphate absorption in intestines
Stimulates calcium-binding proteins at brush border
↑ Calcium mobilization from bone
↑ Phosphate reabsorption in renal tubules
Involved in citrate metabolism (bone mobilization + anticoagulant effect)
83
🧪 How does Vitamin D affect citrate metabolism and what is its clinical relevance?
Aids in mineral mobilization from bones
Helps remove calcium from blood
Acts as anticoagulant → prevents fibrin clot formation (useful in plasma/serum prep)
84
🚼 How is Vitamin D essential for growth?
Supports normal skeletal growth in mammals
Ensures adequate mineralization of the bone matrix
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🧩 Mnemonic to recall calcium as a coagulation factor?
Factor IV = Calcium → "calcIVm"
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Pediatric disorder caused by Vitamin D deficiency, leading to defective mineralization of bone and cartilage, resulting in soft, pliable bones and skeletal deformities.
Rickets
87
Outward bowing of the legs, commonly seen in early-stage rickets.
Genu Varum (Bowlegs)
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Inward angling of the knees, often seen in older children with prolonged rickets.
Genu Valgum (Knock-knees)
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Smooth, symmetrical, beadlike swellings at costochondral junctions due to cartilage overgrowth from poor mineralization.
Rachitic Rosary
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Abnormally narrow pelvic cavity caused by soft, deformed pelvic bones; can complicate childbirth later.
Contracted Pelvis
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Late closure of skull soft spots in infants due to poor ossification.
Delayed Fontanelle Closure
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Late appearance of teeth due to impaired calcification.
Delayed Tooth Eruption
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Horizontal indentation of the lower chest wall at the site of diaphragm insertion, from softened ribs
Harrison's Groove
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“Square skull” appearance from thickened frontal and parietal bones in rickets.
Caput Quadratum
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Irregular, tender, soft nodules at costochondral junctions caused by Vitamin C deficiency (scurvy), due to subperiosteal hemorrhage from defective collagen.
Scorbutic Rosary
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Difference: Rachitic vs. Scorbutic Rosary
Rachitic: Firm, symmetrical, non-tender beads (Vitamin D deficiency)
Scorbutic: Soft, asymmetrical, tender swellings with hemorrhage (Vitamin C deficiency)
97
Neuromuscular hyperexcitability due to hypocalcemia, often from Vitamin D deficiency.
Tetany
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Painful involuntary spasms of the hands and feet seen in tetany.
Carpopedal Spasm
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Life-threatening spasm of the laryngeal muscles causing breathing difficulty.
Laryngospasm
100
Rapid, jerky, involuntary movements caused by neuromuscular instability in tetany.
Choreiform Movements
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Tetanus vs. Tetany
Tetanus: Bacterial infection (Clostridium tetani).
Tetany: Hypocalcemic disorder due to Vitamin D or calcium deficiency.
102
Another name for Vitamin E?
Anti-aging vitamin.
103
What increases Vitamin E requirement?
High intake of polyunsaturated fatty acids (PUFAs).
104
Richest food source of Vitamin E?
Wheat germ oil
105
Main function of Vitamin E?
Antioxidant protecting cell membranes.
106
Most potent form of Vitamin E?
Alpha-tocopherol.
107
Vitamin E protects which vitamins from oxidation?
Vitamins A
Carotene.
108
Vitamin E’s effect on red blood cells?
Prevents hemolysis by protecting membrane integrity.
109
What does Vitamin E do in the lungs?
Protects lung tissue from airborne oxidants.
110
Vitamin E’s role in muscles?
Maintains muscle health and function.
111
How does Vitamin E support liver health?
Works with selenium to prevent liver necrosis.
112
Selenium dose enhancing Vitamin E effect?
25 mcg per 200 IU Vitamin E.
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Consequence of Vitamin E deficiency in males (animals)?
Testicular degeneration and sterility
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Consequence of Vitamin E deficiency in females (animals)?
Failure of gestation.
115
Neurological effect of Vitamin E deficiency?
Nerve cell degeneration due to fatty acid peroxides.
116
Hematologic disorder from Vitamin E deficiency in humans?
Megaloblastic anemia from RBC hemolysis.
117
Other names for Vitamin K?
Coagulation vitamin, Anti-hemorrhagic vitamin.
118
Major plant form of Vitamin K?
Phylloquinone (Vitamin K1).
118
Form of Vitamin K found in putrid fish meal?
Farnoquinone (Vitamin K2).
119
Synthetic form and parent compound of the Vitamin K series?
Menadione (Vitamin K3).
120
Which form of Vitamin K is synthesized by gut bacteria?
Menaquinones
121
Primary physiologic role of Vitamin K?
Cofactor for gamma-carboxylation of glutamic acid residues in clotting factors II, VII, IX, and X.
122
What happens to clotting in Vitamin K deficiency?
Clotting becomes delayed or impaired.
123
Which bone-related proteins require Vitamin K?
Osteocalcin
Bone matrix Gla protein.
124
What other vitamins are needed for osteocalcin function?
Vitamins C and D.
125
Role of Vitamin K in energy metabolism?
Part of the electron transport chain (Coenzyme Q).
126
Medical use of Vitamin K in anticoagulant toxicity?
Antidote for drugs like dicumarol and warfarin.
127
Classic manifestation of Vitamin K deficiency in infants?
Hemorrhagic disease of the newborn.
128
Conditions causing Vitamin K deficiency?
Malabsorption syndromes
Biliary tract obstruction
GIT sterilization (e.g., prolonged antibiotic use)
Vitamin K antagonists (e.g., dicumarol)
129
Drugs that reduce Vitamin K activity or increase needs?
Antibiotics, warfarin, alcohol, and some anticonvulsants.
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General causes of vitamin deficiencies (incl. Vitamin K)?
Poor intake
Malabsorption
Liver/gallbladder disease
Drug interference
Increased demand (e.g., pregnancy, growth, healing)
Excess loss (bleeding, diarrhea)
