Wvsom Msk - Calcium, Vitamin D, Metabolism #1 & 2

Front 1

Describe the basic functions of calcium & where it is stored

Back 1

calcium salts in bone provide structural integrity of the skeleton: 80% of calcium is found within cortical bone, 19% is found within the sponge-like Trabecular bone.

Calcium ions in extracellular & cellular fluids are essential to normal function of a host of biochemical processes including Neuromuscular excitability, blood coagulation, hormonal secretion, enzymatic regulation.

Front 2

Describe the basic functions of phosphorous

Back 2

ATP, Phosphate bufer system, DNA, RNA, Phospholipids, Nucleotides, Covalent modifications, Signaling molecules

Front 3

Describe the basic function of Vitamin D (Calcitrol)

Back 3

Raises blood calcium in 3 ways

1. Increases Calcium ion absorption b y the small intestines by increasing the transcription of TRPV6 through a steroid receptor.

2. increase calcium & phosphate resorption from the skeleton as it binds to hematopoietic stem cells & cause differentiation of osteoclasts.

3. Weakly promotes the reabsorption of calcium ions by the kidney cells (less Ca+ excreted)

Front 4

Describe the location of Magnesium in the body

Back 4

mineral found in large quantities in bones & muscles

Front 5

Describe the digestion, absorption & food sources of Vitamin D

Back 5

- de novo synthesis & Diet: fatty fish, oils, fortified foods like milk, cereal, & breads

- Age decreases the ability of skin to produce Vitamin D3 due to decreases in kidney & liver function.

- Sunscreen & obesity decrease the body's ability to synthesize Vitamin D3

Front 6

Describe the digestion, absorption & food sources of Magnesium

Back 6

Carrier facilitated process - TRPM6

Simple diffusion: kidneys control the amount of magnesium by altering excretion. Magnesium lactate & Magnesium Chloride are good supplements b/c of their high bioavailability.

Sources: seeds, nuts, legumes, milled cereal grains, milk & dark green vegetables.

Front 7

Describe the digestion, absorption & food sources of Phosphorous

Back 7

- organically bound phosphate is broken down in the intestines by phosphatase

- absorption is dependent on the proximal portion of the duodenum in low pH

- phosphorus from vegetarians is in the form of phytate which is poorly digested by humans

Sources: meats, eggs, nuts, legumes, fortified cereals & grains

- yeast from breads produce phytase which is an enzyme needed to breakdown phytates

Front 8

Describe the digestion, absorption of Calcium

Back 8

Absorption: Duodenum (acidic medium) higher rate of calcium absorption.

- ~30% of dietary calcium absorbed

- largest amount of calcium absorption occurs in the ileum

Actively transport by TRPV6 in the intestines. Vitamin D stimulates transcription of this calcium transporter. Initiated by low serum Calcium levels.

- Calcium is absorbed more efficiently in an acidic environment

Front 9

Describe Food sources of Calcium

Back 9

Dark green leafy vegetables, sardines, canned slamon, Clams, oysters,

fortified foods: orange juice, milk, tofu, breads, ice cream, yogurt, cheese

Dietary fiber (>30g/day), phytates, & oxalates found in foods like rhubarb inhibit calcium absorption

Front 10

List the clinical s/sx & diseases associated with deficiencies of Vitamin D

Back 10

Rickets: disorganized & hypertrophy of chondrocytes, failure of cartilage calcification & endochondral ossification, the metaphyses of rapidly growing bones are widened, uneven, concave or cupped due to the delay or absence of calcification.

Osteomalacia: lack of mineralization (poor osteoid), osteopenia, deep bone pain.

Osteoporosis: cause is related to calcium loss due to high meat protein diets, phosphorylated soft drinks, smoking, lack of exercise, high caffeine intake. Treatment: elimination of risk factors, exercise, calcium supplements, Estrogen administration.

Hypocalcemia:

Hypophosphatemia:

Front 11

List the clinical s/sx & diseases associated with deficiencies of Calcium

Back 11

CATS go numb: convulsions, arythmias, tetany, numbness/parasthesias in hands, feet, around mouth & lips

Osteomalacia & colon cancer

Front 12

List the clinical s/sx & diseases associated with deficiencies of Phosphorous

Back 12

Rare

Patients taking drugs called phosphate binders.

- Problems include a decrease in ATP, GTP, UTP, CTP, TTP & other organic phosphates.

- Neural, muscular, skeeltal, hematologic, renal & other abnormalities

Front 13

List the clinical s/sx & diseases associated with deficiencies of Magnesium

Back 13

Rare but includes tremors, muscle spasms, mood swings, anorexia, nausea, vomitting.

Causes: renal disease, diuretic therapy, malabsorption, hyperthyroidism, pancreatitis, Kwashiokor, Diabetes, Parathyroid gland disorders

Front 14

What populations are at risk for Vitamin D deficiencies

Back 14

Breastfed infants, older adults, people with limited sun exposure, darker skin pigments, certain religious groups (sun exposure),

Malabsorption syndrome, severe liver disease, kidney disease, drugs, higher latitudes,

Front 15

List the clinical signs and diseases associated with vitamin D toxicity.

Back 15

Hypercalcemia, hypophosphatemia, calcification of soft tissue, constipation, polyuria, polydipsia, kidney stones, headaches, weakness

Front 16

List the clinical signs and diseases associated with Calcium toxicity.

Back 16

Constipation, Nausea, Poor appetite, vomiting, muscle twitches, weakness.

> 2000 mg per day

Hypercalcemia, calcification in kidneys, malabsorption of other minerals (iron, zinc, magnesium)

Front 17

Explain the importance of calcium and vitamin D for bone health and prevention of osteoporosis.

Back 17

1. Roles in the prevention of: colon & breast cancer
2. Vitamin D allow more calcium to be taken up into the body, and calcium is a necessary component of strong bones = removal of calcium will decrease the density of bone and lead to osteoporosis

Front 18

Define EAR, RDA, AI, UL, DRI

Back 18

Estimated average requirement

Recommended dietary allowance

adequate intake

tolerable upper intake level

Dietary reference intakes

Front 19

Describe the effect of PTH on the kidneys

Back 19

PTH increases Vitamin D synthesis by stimulating 1-alpha hydroxylase activity

stimulates calcium reabsorption yet stimulates phosphorus excretion

Front 20

Describe the effect of PTH on the bones

Back 20

Osteoclasts have no PTH receptors

Osteoblastic stromal cells + RankL receptors + PTH increase generation of active bone resorbing osteoclasts

Front 21

Describe the effect of PTH on the intestines

Back 21

PTH has the secondary effect on calcium absorption through the activity of Vitamin D

Front 22

Describe phosphorus regulation

Back 22

PTH controls phosphorus

Vitamin D controls phosphorus

Front 23

Describe the synthesis of Vitamin D

Back 23

Vitamin D3 synthesis occurs in Keratinocytes in the skin

7-dehydrocholesterol is photoconverted to previtamin D3, then spontaneously converts to Vitamin D3

Pre-vitamin D3 will become degraded by over exposure to UVB light & thus is not overproduced.

1,25-dihydroxy-D (Calcitriol) feeds back to inhibit its production

Front 24

Describe the behavior of Calcitonin

Back 24

secreted from the C-cells in the thyroid

lowers Calcium levels in the blood by promoting the deposition of calcium into bone by inhibiting osteoclasts.

Front 25

Describe the daily recommendations

Back 25

4-8y = 100% Calcium, 150% Vitamin D

14-18y = 130% Calcium, 150% Vitamin D

51-70y = 100% Calcium, 150% Vitamin D

70y+ = 120% Calcium, 133% Vitamin D

100% calcium = 1000 mg

150% Vitamin D = 600 mg