HUN - Chapter 11 : The Fat-Soluble Vitamins: A, D, E, and K

what are the stages of xerophthalmia

-At first, the cornea becomes dry and hard because of inadequate mucous production = Xerosis -Then xerosis quickly progresses to keratomalacia, the softening of the cornea that leads to irreversible blindness. = Keratomalcia

Beta-carotene plays two primary roles in the body. what are they?

-First, it serves as a vitamin A precursor -Second, some beta-carotene acts as an antioxidant capable of protecting the body against disease

What are some of the major roles of Vitamin A

-Known to regulate expression of several hundred genes -Promoting vision -Participating in protein synthesis and cell differentiation, thereby maintaining the health of epithelial tissues and skin -Supporting reproduction and regulating growth

Vitamin D raises blood concentrations of bone minerals in three ways

-When the diet is sufficient, vitamin D enhances mineral absorption from the GI tract. -When the diet is insufficient, vitamin D provides the needed minerals from other sources: reabsorption by the kidneys and mobilization from the bones into the blood. -The vitamin may work alone, as it does in the GI tract, or in combination with parathyroid hormone, as it does in the bones and kidneys.

Factors that contribute to vitamin D deficiency include

-dark skin -lack of sun -breastfeeding without supplementation -not using fortified milk

Like vitamin A, vitamin D has a binding protein that carries it to the target organs—most notably, what organs?

-the intestines -the kidneys -the bones

Vitamin D in Other roles

-vitamin D protects against cognitive decline and slows the progression of Parkinson disease -Vitamin D in muscle cells encourages growth in children and preserves strength in adults. - Vitamin D signals cells of the immune system to defend against infectious diseases. -Vitamin D may also regulate the cells of the adipose tissue in ways that might influence the development of obesity. -vitamin D enhances or suppresses the activity of genes that regulate cell growth -it may be valuable in treating a number of diseases. Recent research suggests that vitamin D may protect against metabolic syndrome, type 2 diabetes, tuberculosis, inflammation, multiple sclerosis, macular degeneration, hypertension, and some cancers

These two forms of vitamin D are similar and both must be __________ before they can fully function

Acitivated

What vitamins A precursor

Beta-carotene

Vitamin D is also known as

Calciferol

what does the hydroxylation look like?

First, the liver adds an OH group, and then the kidneys add another OH group to produce the active vitamin.

^^^ Is this process reversible?

Much of the retinal is then converted back to its active cis form and combined with the opsin protein to regenerate rhodopsin

Is Beta-carotene, which is found in a wide variety of fruits and vegetables, converted efficiently enough in the body to cause vitamin A toxicity

NO

Which of the three active forms of Vitamin A support reproduction and is the major transport and storage form?

Retinol

A special transport protein picks up vitamin A from the liver and carries it in the blood. What is the name of this protein?

Retinol-binding protein (RBP)

Beta-carotene instead is stored in the fat just under the

SK=kin

Vitamin D comes in two major forms. what are they?

Vitamin D2 and Vitamin D3

What are the fat soluble vitamins?

Vitamins A, D, E, K

Can eating too much Liver cause Vitamin A toxicity? why or why not?

YES ; Liver is a rich source because vitamin A is stored in the livers of animals, just as in humans.*

What is calbindin?

a protein that binds calcium in the intestinal cells

The cells that break down bone contain what in order to dissolve the minerals and digest the matrix

acids and enzymes

Vitamin D3 derives from

animal foods & synthesis in the skin

Retinoids are compounds that are commonly found in foods derived from plants or animals?

animals

The most studied of the carotenoids with vitamin A activity is

beat-carotene

In vitamin D deficiency, production of

calibindin

who is most vulnerable to toxicity because they need less vitamin A and are more sensitive to overdoses

children

Overt signs of vitamin D deficiency are relatively rare, but vitamin D insufficiency is remarkably

commom

what is preformed vitamin a:

dietary vitamin A in its active form.

one celled glands that synthesize and secrete mucus. This is known as

globet cells

Though called a vitamin, the active form of vitamin D is actually a

hormone

—a compound manufactured by one part of the body that travels through the blood and causes another body part to respond. this is known as

hormone

Where are excess fat soluble vitamin stored

in the liver and adipose tissue

the further conversion of retinal to retinoic acid is

irreversible

Elsewhere in the body, vitamin A deficiency affects other surfaces. On the body's outer surface, the epithelial cells change shape and begin to secrete the protein

keratin

the hard, inflexible protein of hair and nails

keratin

the skin becomes dry, rough, and scaly as lumps of keratin accumulate

keratinization

the softening of the cornea that leads to irreversible blindness.

keratomalacia

The epithelial tissues that line the inside of the body are the

mucous membranes

the linings of the mouth, stomach, and intestines; the linings of the lungs and the passages leading to them; the linings of the urinary bladder and urethra; the linings of the uterus and vagina; and the linings of the eyelids and sinus passageways is all made up of

mucous membranes

what coats and protects the epithelial cells from invasive microorganisms and other potentially damaging substances, such as gastric juices

mucus

the person loses the ability to recover promptly from the temporary blinding that follows a flash of bright light at night or to see after dark. this is known as

night blindness

what is one of the first detectable signs of vitamin A deficiency deficiency?

night blindness

Doe plants contain retinoids?

no

is vitamin D an essential nutrient?

no

Is vitamin A beneficial for acne ? what are some meds that contain in?

no; Accutane and Retin-A

Each rhodopsin molecule is composed of a protein called _______ bonded to a molecule of __________

opsin ; retinal

Vitamin D2 derives primarily from

plant foods

To make vitamin D, ultraviolet rays from the sun hit a precursor in the skin and convert it to

previtamin D3

what occurs by vitamin A in the lining of the body surface

protein synthesis and cell differentiation

previtamin D3, which is converted to vitamin D3 with the help of

the body's heat

Vitamin D's special role in bone health is to? *based on minerals

to assist in the absorption of calcium and phosphorus, thus helping to maintain blood concentrations of these minerals. . The bones grow denser and stronger as they absorb and deposit these minerals

As you might expect, diseases affecting either the liver or the kidneys can interfere with the activation of vitamin D and produce symptoms of deficiency. true or false

true

Vitamin A deficiency is responsible for death and cases of blindness. true or false

true

To activate vitamin D—whether made in the body or consumed from the die. what type of reaction (s) must occur?

two hydroxylation reactions

If a person were to stop eating vitamin A-containing foods, deficiency symptoms would not begin to appear until after stores were depleted. how long for a healthy adult? how long for a child?

—1 to 2 years for a healthy adult but much sooner for a growing child

what are the three different forms of vitamin A that are active in the body? and what are they collectively called?

- Retinol - Retinal - Retinoic acid -Collectively they are called retinoids

what are some of the several significant ways vitamins differ from water-soluble vitamins

-Being insoluble in the watery GI tract -The fat-soluble vitamins require bile for their digestion and absorption -Upon absorption, fat-soluble vitamins travel through the lymphatic system within chylomicrons before entering the bloodstreams, -In the bloodstream many of them require protein carriers for transport

why is Vitamin a considered a teratogen

-Excessive vitamin A during pregnancy leads to abnormal cell death in the spinal cord, which increases the risk of birth defects such as spina bifida and cleft palate - High intakes before the seventh week of pregnancy appear to be the most damaging.

Vitamin A status depends on

-Vitamin A status depends mostly on the adequacy of vitamin A stores, 90 percent of which are in the liver -Vitamin A status also depends on a person's protein status because retinol-binding protein serves as the vitamin's transport inside the body

Vitamin A plays two indispensable roles in the eye: what are they?

-it helps maintain a crystal-clear outer window, the cornea, -it participates in the conversion of light energy into nerve impulses at the retina

Excessive Vitamin A and Bone

-may weaken the bones and contribute to fractures and osteoporosis -Vitamin A suppresses bone- building activity, stimulates bone-dismantling activity, and interferes with vitamin D's ability to maintain normal blood calcium.

12 micrograms of dietary beta-carotene counts as how many RAE

1

One microgram of retinol counts as how many RAE

1

The richest sources of the retinoids are foods derived from

Animals-- liver, fish liver oils, milk and milk products, butter, and eggs

what color is beta-carotene

Beta-carotene is a rich, deep yellow, almost orange, compound.

Although plants don't contain any retinoids, many vegetables and some fruits contain Vitamin A precursors---

Carotenoids

Foods derived from plants provide ____________, some of which can be converted to Vitamin A

Carotenoids

The risk of toxicity is greater in water-soluble vitamins or in fat-soluble vitamins? Why?

Fat-soluble vitamins because they are not readily excreted

After absorption via the lymph system, vitamin A eventually arrives at the _________, where it is stored

Liver

Does all of the retinal covert back ?

Some retinal, however, may be oxidized to retinoic acid, a biochemical dead end for the visual process

Do to the deficiency in Vitamin A in developing countries, what did scientist do to the rice?

Through biotechnology, scientists have been able to genetically modify rice to be a significant source of beta-carotene. Commonly called golden rice because of its yellowish tinge

Visual activity leads to repeated small losses of retinal, necessitating its constant replenishment either directly from foods or indirectly from retinol stores. True or false

True

Without vitamin A, the goblet cells in the GI tract diminish in number and activity, limiting the secretion of mucus. With less mucus, normal digestion and absorption of nutrients falter, and this, in turn, worsens malnutrition by limiting the absorption of whatever nutrients the diet may deliver. Similar changes in the cells of other epithelial tissues weaken defenses, making infections of the respiratory tract, the GI tract, the urinary tract, the vagina, and inner ear likely. True or False

True

retinoic acid can stimulate cell growth in the skin and inhibit cell growth in tumors. Cells use vitamin A have special protein receptors for it, and its action within each cell may differ depending on the receptor. This is because True or Flase

True

remodeling. To convert a small bone into a large bone, some bone cells must "undo" parts of the bone before other cells can build new bone. What vitamin places a role in this dismantling?

Vitamin A

what helps protect the skin against damage from sunlight?

Vitamin A and beta-carotene

Vatimin A (right amount in the body) supports immune function and inhibits replication of measles virus. what else does it do>

Vitamin A supplements also protect against blindness and the complications of other lifethreatening infections, including malaria, lung diseases, and HIV (human immunodeficiency virus, the virus that causes AIDS).

Only a few carotenoids have vitamin A activity; the carotenoid with the greatest vitamin A activity is

beta-carotenoid

what would happen to Animals raised on retinoic acid as their only source of vitamin A

can grow normally, but they become blind because retinoic acid cannot be converted to retinal

a process by which each type of cell develops to perform a specific function. is

cell differentiation

The beta-carotene in dark green, leafy vegetables is abundant, but masked by large amounts of the green pigment

chorophyll

All body surfaces, both inside and out, are covered by layers of cells known as

epithelial cells

Vitamin A promotes differentiation of what two types of cells?

epithelial cells and goblet cells

Night blindness is caused by a lack of vitamin A at the back of the eye, the retina; total blindness is caused by a lack of vitamin A at the

front of the eye, the cornea.

Children lacking vitamin A fail to grow; given vitamin A supplements, these children

gain weight and grow taller.

Bright color is not always a sign of vitamin A activity, however. Beets and corn, for example, derive their colors from the red and yellow xanthophylls. does it have vitamin A activity ?

no xanthophylls doesn't

Is vitamin A deficiency common in the U.S? If not, where is it common?

no; in many developing countries

As mentioned, vitamin A also supports reproduction and regulates growth. in women, vitamin A supports

normal fetal development during pregnancy.

The growth of bones illustrates that growth is a complex phenomenon of

remolding

Which of the three active forms of Vitamin A is active in vision and is also an intermediate in the conversion of retinol to retinoic acid

retinal

Because the body can derive vitamin A from both retinoids and carotenoids, its content in foods and its recommendations are expressed as

retinol activity equivalents (RAE).

a measure of vitamin A activity; the amount of retinol that the body will derive from a food containing preformed retinol or its precursor, betacarotene. This is known as

retinol activity equivalents (rae):

Which of the 2 can be converted to other active forms of vitamin A by the cells as needed

retinol and retinal

beta-carotene can be split to form

retinol in the intestine and liver

Which of the three active forms of Vitamin A acts like a a hormone, regulating cell differentiation, growth , and embryonic development

retionoic acid

The conversion of retinol to retinal is

reversible

When light passes through the cornea of the eye and strikes the retina, what responds?

rhodopsin

Some of the photosensitive cells of the retina contain pigment molecules called

rhodospin

The epithelial tissue on the outside of the body is, of course, the

skin

As mentioned, vitamin A also supports reproduction and regulates growth. In men, retinol participates in

sperm development

a substance that causes abnormal fetal development and birth defects

teratogen

^^ As it does, opsin is released and retinal shifts from a cis to

trans configuration

After completing their work, the bone-dismantling cells die, leaving their excavation site to be rebuilt by the bone-building cells. true or false

true

Several proteins participate in the digestion and absorption of vitamin A. True or False

true

With the help of vitamin A, these bone-dismantling cells destroy selected sites in the bone, removing the parts that are not needed. true or false

true

which vitamin was the first fat-soluble vitamin to be recognized

vitamin A

what begins when ll the binding proteins are loaded, and vitamin A is free to damage cells.

vitamin A toxicity

Blindness due to vitamin A deficiency, is known as what?

xerophthalmia

the cornea becomes dry and hard because of inadequate mucous production—a condition known as

xerosis

Although overconsumption of beta- carotene from foods may turn the skin _________, this is not harmful

yellow

can the body synthesize vitamin D? if so, How?

yes; with the help of sunlight, from a precursor that the body makes from cholesterol.

Toxicity is a real possibility when concentrated amounts of preformed vitamin A in foods derived from

•Preformed vitamin A from animal sources •Fortified foods •Supplements