Biochem Evals 12 Set M

SUBJECT: BIOCHEMISTRY TOPIC: EVALS 12 SET M LECTURER: DR.BALLESTEROS DATE: MARCH 2011 Micronutrients (5 pts.) are the only ones included in this evaluation. (nos. 56-69) item number

answer

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 (by excessive vomiting, severe diarrhea, using laxatives, and having callous adenoma)! Also, excretion of K could also be by urination (diuretics, Conn’s tumor, licorice, Cushing’s 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.

explanation

IODINE is the mineral most essential in synthesis of thyroxine, a thyroid hormone. Here’s the table for other microminerals: Elements Chromium Cobalt Copper

Metabolic Function Potentiate the effect of insulin Constituent of B12 Constituent of oxidase enzymes Iron Absorption metabolism

Fluoride Iodine Iron

60

d Manganese Molybdenum Selenium

Zinc

61

a

SUBJECT: TOPIC

Deficiency Impaired glucose metabolism Macrocytic anemia Microcytic hypochromic anemia

and

Constituent of bone and teeth Constituent of thyroid hormone Constituent of heme and non-heme compounds Cofactor for number of enzymes eg. Arginase and carboxylase Constituent of xanthine oxidase, sulfite oxidase and aldehyde oxidase Antioxidant, cofactor for glutathione peroxidase, protects against cell membrane, lipid peroxidation Cofactor for enzymes in DNA, RNA and protein synthesis, constituent of insulin, carbonic anhydrase, carboxypeptidase, alcohol dehydrogenase

Depigmentation skin and hair Dental Carries

of

Cretinism, goiter Microcytic anemia Not well defined Xanthinuria Cardiomyopathy

Growth failure, impaired wound healing and loss of appetite

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). PTH’s 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

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Ca absorption by the intestines.

d

LYSYL OXIDASE’s 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

d

SELENIUM 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

a

CHROMIUM potentiates the effect of Insulin, that is why it is known to be the Glucose Tolerance Factor. (Refer to table.)

d

ALL OF THE ABOVE. Calcitriol’s 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 KIDNEY Increases Ca retention via:  (+) Transcription of genes encoding proteins involved in Ca++ uptake and transport 3. 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.

d

ALL OF THE ABOVE.  Tobacco smoking, malnutrition, and estrogen deficiency are risk factors for osteoporosis. Osteoporosis Prevention:  A balanced diet rich in o 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

62

67

68

The answer should’ve 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…

69 (hmmm)

BONUS

SUBJECT: TOPIC

Hypercalcemia o Serum calcium level exceed 11.0 mg/dL  Normal serum calcium level is 9-11 mg/dl o Causes:  Primary hyperparathyroidism: most common for OPD -May be due to o Familial o Hyperplasia – increase in the number of chief cells in parathyroid gland o 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 tumors o Haematological malignancies  Drug Induced  Other endocrine causes  Overdosage

Hypocalcemia o Serum calcium level less than 8.5 mg/dl o 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)  Osteoporosis o Adult Bone loss o Condition where the bones become fragile and porous o Characterized by low bone mass and structural deterioration of bone tissue, leading to bone fragility and increase susceptibility to fractures of the hip, spine & wrist o “Silent disease”: no symptoms until a fracture occurs o Higher rate of bone resorption compared to bone deposition

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