Chapter 15 Flashcards
What are some of the main minerals in bone?
calcium and phosphorus
What is hydroxyapatite?
crystal structure that gives bone its strength and rigidity
What is cortical bone?
outer, dense shell
What is trabecular bone?
adds strength without adding much weight
What does collagen do?
allows bone to take impacts
What are osteoblasts?
bone-building cells
What are osteoclasts?
bone-resorption cells found on the bone surface
2 situations where osteoblast activity should exceed osteoclast activity?
-during times of growth
-when bone is placed under stress (weight-bearing activity)
When is peak bone mass reached?
ages 25-30
How does estrogen impact the bones?
inhibits bone breakdown by decreasing osteoclast activity
What is amenorrhea?
absence of menstruation
How does menopause impact estrogen levels?
decreased estrogen levels
Where is most of the calcium in the body found?
99% in bones
Why is the calcium in the blood so important?
helps implement clotting
What are the functions of calcium?
-bone and tooth development and maintenance
-blood clotting
-transmission of nerve impulses
-muscle contractions
-cell metabolism
What happens if blood calcium levels drop?
osteoclasts release calcium from the bone
What happens if blood calcium levels go above normal range?
weaken bones, create kidney stones, interfere with function of heart and brain
What is hypocalcemic tetany?
severely low calcium levels
-lack of parathyroid hormone
effects: numbness and seizures
What is the RDA for calcium for adults?
1000mg/d
What is the RDA for calcium for women over 50?
1200mg/d
Why does RDA for women over 50 increase?
menopause
What are sources of calcium?
dairy products, leafy greens, calcium-fortified foods
What is a Dual Energy X-Ray Absorptiometry (DEXA) scan?
body composition
What factors increase the risk of osteoprosis?
-amenorrhea
-low calcium and vitamin D intake
-low PA
The bones most likely to break when an individual has osteoporosis?
hip, wrist, and bones in spine
What are some steps that can be taken to prevent osteoporosis?
-adequate intake of calcium, vitamin D, phosphorus, magnesium
-weight-bearing PA
What is kyphosis?
hump on back of neck
What is osteopenia?
reduced bone mass
Which vitamin promotes and regulates calcium absorption?
vitamin D
In order for calcium to become active, hydroxyl group need to be added to two organs:
liver and kidney
What are some of the factors that can negatively impact calcium absorption?
-lower levels of active vitamin D
-reduced stomach acid secretion
-chronic diarrhea
-large intakes of oxalic acid, phytic acid, dietary phosphorus (dark soda), and polyphenols
Is blood calcium a good indicator of calcium status?
poor measure of calcium status because it is maintained within a very narrow range
Role of parathyroid hormone in maintaining blood-calcium levels?
pulls calcium from bones
stimulates kidney synthesis of Vitamin D
increases calcium retention
Role of calcitriol in maintaining blood-calcium levels?
increases uptake and decreases output
Role of calcitonin in maintaining blood-calcium levels?
prevents bones from releasing calcium
What happens when blood calcium levels are low?
paraythroid hormone released
What happens when blood calcium levels are high?
calcitonin is released
What is hyperparathyroidism?
overproduction of parathyroid gland
What are the main functions of vitamin D?
-maintains skeletal health
-regulates immune function
-regulates secretion of hormones such as insulin, renin, and PTH
-regulates apoptosis
What is apoptosis?
programmed cell death
-may play a role in cancer prevention
What are the sources of vitamin D?
fatty fish, cod liver oil, fortified milk and breakfast cereal
What is another name for vitamin D2?
ergocalciferol (found in plant foods: mushrooms)
What is another name for vitamin D3?
cholecalciferol (found in animal foods: produced in skin)
dairy, salmon, egg yolks, fortified orange juice
Which form of vitamin D is produced in the skin from cholesterol?
7- Dehydrocholesterol-> D3
Formation of Active Vitamin D (calcitriol)
- Vitamin D3: food, supplements, sun exposure
Vitamin D2: food or supplements - In the liver, Vitamin D converted to calcidiol (circulating form)
- In the kidney, calcidiol is coverted to calcitriol (active form)
What are some potential causes of a vitamin D deficiency?
disease, lack of sunlight, dark-skin pigmentation
What are some of the side effects of a vitamin D deficiency?
rickets and osteomalacia (soft bones)
What is the characteristic sign of the vitamin D deficiency disease seen in children?
rickets (bowed legs)
Why is vitamin D toxicity dangerous?
causes calcium deposits within adipose tissue
What are the functions of phosphorus?
-component of bones and teeth
-component of ATP
-phosphorylation activation of hormones
-plays role in acid-base balance
What are sources of phosphorus?
milk, cheese, meat, cereals, and dark pop
What are the major functions of magnesium?
-cofactor
-energy and calcium metabolism
-nerve transmission
-heart and smooth muscle contraction
-glucose and insulin metabolism
Why are many plant foods good sources of magnesium?
found in chlorophyll
Sources of magnesium?
green, leafy vegetables
Does the average American consume enough magnesium?
no
What are some of the consequences of a magnesium deficiency?
muscle twitches, tremors, and cramps
What are 2 functions of fluoride?
-supports the deposition of calcium and phosphorus in teeth and bones
-protects against dental caries (cavities)
Most Americans get their fluoride from?
water
What is fluorosis?
small spots on the teeth caused by excess fluoride
What is innate immunity?
nonspecific (things born with)
What is acquired immunity?
specific (develops over time)
What are free radicals?
fight off pathogenic invaders but if not controlled can be damaging
What are antioxidants?
Maintain integrity of cell by stopping chain reactions caused by free radicals
Vitamin E is a family of 8 naturally occurring compounds:
4 tocopherols
4 tocotrienols
Alpha-tocopherol?
form found in foods and is most active form
What are some of the functions of vitamin E?
antioxidant (donates H+ to lipid radicals)
What are a few sources of vitamin E?
plant oils, avocado, nuts, seeds
Deficiency of vitamin E can lead to?
hemolytic anemia
Toxicity of vitamin E can interfere with what process?
blood clotting because is blood thinner
What are some of the functions of vitamin C?
-antioxidant (reactivates vitamin E)
-immune function
-collagen formation
-iron absorption
How does vitamin C impact iron absorption?
creates more acidic environment in stomach to prevent oxidization of ferrous iron
Why is vitamin C so important for wound healing?
involved in collagen synthesis
Why would burn and trauma patients and smokers need more vitamin C?
smokers need 35mg or more (promotes oxidation)
Sources of vitamin C?
citrus fruits, peppers, green vegetables
Vitamin C deficiency can cause?
scurvy
early signs: fatigue and pinpoint hemorrhages
late signs: gums and joints bleed
What is one source of selenium?
oysters
What is one function of selenium?
functions in antioxidant defense network as Glutathione Peroxidase
What is the difference between preformed vitamin A an provitamin A carotenoids?
preformed vitamin A is active form
What is another name for preformed vitamin A?
retinoids
Sources of vitamin A?
liver, fish oils, fortified dairy products, eggs
Retinal
vision
Retinoic acid
immune function and growth
Retinal and retinoic acid are examples of?
preformed vitamin A
What are the 3 provitamin A carotenoids?
alpha-carotene
beta-carotene
beta-cryptoxanthin
Sources of provitamin A carotenoids?
dark green and yellow-orange vegetables and fruit
Lycopene is a carotenoid found in foods like?
tomatoes and pink grapefruit
Lutein and zeazanthin are carotenoids that may protect against eye issues like?
macular degeneration
What is an RAE?
Retinol Activity Equivalents
measurement of Vitamin A
What is an RAE?
Retinol Activity Equivalents
measurement of Vitamin A
Sources of vitamin A?
beef liver, carrots, kale
What are retinyl esters?
inactive until fatty acid is removed; converted to retinol
Vitamin A absorption?
along with fat
animal forms more absorbale
How does the digestion and absorption of preformed vitamin A compare with the digestion and absorption of provitamin A carotenoids?
preformed vitamin A is more easily absorbed
Retinoids are transported bound to?
retinol binding protein which is bound to prealbumin
Where is vitamin A stored in the body?
90% in liver
What are functions of carotenoids?
-antioxidant
-diets high in this decreased risk of eye diseases, cancers, cardiovascular disease
What are the functions of retinoids?
-immune function
-normal growth and development
-vision
-dermatology
Retinal is need to form?
rhodopsin (which absorbs light)
What is the earliest sign of a vitamin A deficiency?
night blindness (nyctalopia)
What is xerophthalmia?
can advance to total blindness
What is xerosis?
dryness
What are bitot’s spots?
white deposit on eye
Acute toxicity of Vitamin A
dizzy
Chronic toxicity of Vitamin A
hemorrhages
Teratogenic toxicity of Vitamin A
fetal malformation or spontaneous abortion
