8/7/2019 Biochem Evals 12 Set M

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Micronutrients (5 pts.) are the only ones included in this evaluation. (nos. 56-69)

item

numberanswer explanation

56 a HYPOKALEMIC: The med student is Hypokalemic because she has a serum potassium level of 2.1 mmol/L

which is below normal. (Refer to next number.)

57 b The normal range for plasma K is 3.5-5mmol/L.

58 b

DIARRHEA and VOMITING could cause hypokalemia.

Potassium is the major intracellular cation in the body that is found widely in vegetables which means that we

can take in K by eating high-K foods (RDA=2000mg). This also means that we can lose K through the GIT (byexcessive vomiting, severe diarrhea, using laxatives, and having callous adenoma)!

Also, excretion of K could also be by urination (diuretics, Conns tumor, licorice, Cushings syndrome adrenocortical hyperfunction).Remember that potassium excretion increases when there is excessive dietary intake of sodium.

59 d ALL OF THE ABOVE Sweet potato, banana, orange juice are good sources of Potassium.

60 d

IODINE is the mineral most essential in synthesis of thyroxine, a thyroid hormone.

Heres the table for other microminerals:

Elements Metabolic Function Deficiency

Chromium Potentiate the effect of

insulin

Impaired glucose

metabolism

Cobalt Constituent of B12 Macrocytic anemia

Copper Constituent of oxidase

enzymes

Iron Absorption andmetabolism

Microcytic

hypochromic

anemia

Depigmentation of

skin and hair

Fluoride Constituent of bone and

teeth

Dental Carries

Iodine Constituent of thyroid

hormone

Cretinism, goiter

Iron Constituent of heme

and non-heme

compounds

Microcytic anemia

Manganese Cofactor for number of

enzymes eg. Arginase

and carboxylase

Not well defined

Molybdenum Constituent of xanthine

oxidase, sulfite oxidase

and aldehyde oxidase

Xanthinuria

Selenium Antioxidant, cofactor for

glutathione peroxidase,

protects against cell

membrane, lipid

peroxidation

Cardiomyopathy

Zinc Cofactor for enzymes in

DNA, RNA and protein

synthesis, constituent of

insulin, carbonic

anhydrase,

carboxypeptidase,

alcohol dehydrogenase

Growth failure,

impaired wound

healing and loss of

appetite

61 a

CALCIFEROL stimulates the absorption of calcium.

Calcium absorption is dependent on Vitamin D (Calciferol is the active form), because with its presence,Calcium binding proteins in the intestinal epithelial cells are formed. The body responds to low blood calcium

by producing Parathyroid Hormone (PTH). PTHs primary action is to increase blood calcium by bone

resorption, secondarily by converting Vit D to 1,25-dihydroxycalciferol in the small intestine (duodenum

increase dietary Ca absorption).

Calcium absorption is high during growth, pregnancy and lactation.

On the other hand, high blood Calcium stimulates the thyroid gland to produce Calcitonin. As a result, there is

decreased osteoclastic activity in the bones, increase renal calcium excretion by the kidneys, and decreased

SUBJECT: BIOCHEMISTRYTOPIC: EVALS 12 SET MLECTURER: DR.BALLESTEROSDATE: MARCH 2011

8/7/2019 Biochem Evals 12 Set M

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SUBJECT: TOPIC Page 2

Ca absorption by the intestines.

62 dLYSYL OXIDASEs activity is reduced when there is the deficiency in copper.

Copper is a constituent of oxidase enzymes (Refer to table in no. 60).

63 c

CALCIUM DEFIENCY PRODUCES BRITTLE BONES CALLED SCURVY. (FALSE!)

SCURVY is brought about by the deficiency in Vitamin C not by Calcium.

According to Wikipedia, Ascorbic acid is needed for a variety of biosynthetic pathways, by accelerating

hydroxylation and amidation reactions. In the synthesis of collagen, ascorbic acid is required as a cofactor for

prolyl hydroxylase and lysyl hydroxylase. These two enzymes are responsible for the hydroxylation of the

proline and lysine amino acids in collagen. Hydroxyproline and hydroxylysine are important for stabilizing

collagen by cross-linking the propeptides in collagen. Defective collagen fibrillogenesis impairs wound healing.

Collagen is also an important part of bone, so bone formation is also affected. Defective connective tissue

also leads to fragile capillaries, resulting in abnormal bleeding. (Thanks wiki!! )

64 dSELENIUM has a sparing action on Vitamin E. It forms the active site of glutathione peroxidase. This enzyme in

the presence of selenium converts Vit C and Vit E radicals in their unharmful form.

65 d ALL OF THE ABOVE. Iron, Copper and Cobalt are minerals that can cause anemia. (Refer to table.)

66 aCHROMIUM potentiates the effect of Insulin, that is why it is known to be the Glucose Tolerance Factor. (Refer

to table.)

67 d

ALL OF THE ABOVE.

Calcitriols action to increase plasma calcium is by:

1. Absorption of Calcium from INTESTINE (+) Differentiation of absorptive mucosal cells (+) Transcription of genes encoding proteins involved in Ca absorption and transport

2. Reabsorption of Calcium from KIDNEYIncreases Ca retention via:

(+) Transcription of genes encoding proteins involved in Ca++ uptake and transport3. Mobilization of Calcium from the BONE (bone resorption)

Increases Ca release from matrix via:

(+) osteoclast differentiation and proliferation (+) osteoclast activity (synthesis/secretion of matrix degrading enzyme)

*Calcitriol is the active form of Vitamin D.

68 d

ALL OF THE ABOVE. Tobacco smoking, malnutrition, and estrogen deficiency are risk factors forosteoporosis.

Osteoporosis Prevention:

A balanced diet rich ino Calcium (1000mg 50)o Vitamin D (400 800 mg)

Weight-bearing exercise promotes bone density A healthy lifestyle with no smoking or excessive alcohol intake and Bone density testing and medication when appropriate Hormonal replacement therapy (HRT) in menopausic women: estrogens, calcitonin

69

(hmmm)BONUS

The answer shouldve OSTEOPETROSIS because, unlike osteoporosis, osteomalacia, osteogenesis imperfecta,

and rickets, it is characterized by an increase in bone mass.

Total mukha naming puro calcium tinatanong, ito na oh

Hypercalcemiao Serum calcium level exceed 11.0 mg/dL Normal serum calcium level is 9-11

mg/dlo Causes: Primary hyperparathyroidism: most

common for OPD-May be due too Familialo Hyperplasia increase in the

number of chief cells in

parathyroid glando Tumors (multiple adenomas,

parathyroid carcinoma, solitary

adenoma)o Ectopic Hyperthyroidism

Malignancy-Due to:o Humoral Factors (HHM Humoral

Hypercalcemia of malignancy)o Direct skeletal involvement by the

tumorso Haematological malignancies

Drug Induced Other endocrine causes Overdosage

Hypocalcemiao Serum calcium level less than 8.5 mg/dlo Causes:

Reduction in serum albumin Hypoparathyroidism Renal diseases and renal failure Psuedohypothyrodism Hypoparathyrodism? lolz Osteomalacia and rickets Magnesium deficiency Drug induced (foscarnate:

cytomegalovirus retinitis (AIDS)

Osteoporosiso Adult Bone losso Condition where the bones

become fragile and porous

o Characterized by low bone massand structural deterioration of

bone tissue, leading to bone

fragility and increase susceptibilityto fractures of the hip, spine &

wrist

o Silent disease: no symptomsuntil a fracture occurs

o Higher rate of bone resorptioncompared to bone deposition