MSS biochem lec1+2+lab

Which of the following mechanisms contributes to a decrease in plasma calcium concentration?

The action of vitamin D on the intestine

B) The action of parathyroid hormone on the intestine

C) The action of parathyroid hormone on the kidney

D) The action of calcitonin on the kidney

When serum calcium (Ca++) is high

A: activity of renal 1 alpha hydroxyls is inhibited

B: expression of intestinal Calbindin-D is increased

C: PTH secretion is increased

D: 24, 25-dihydroxycholecalciferol production decreases

Parathyroid hormone secretion is tightly controlled by the ionized calcium ions. The calcium binds to calcium-sensing cell surface receptors in the parathyroid gland. Which of the following second messenger is activated by calcium-sensing cell surface receptors?

A) cGMP

B) cAMP

C) Phosphoinositol triphosphate

D) Diacylglycerol

Which of the following is the indirect action of parathyroid hormone?

A) Increased bone reabsorption c

b) Increased renal calcium reabsorption

c)Increased intestinal calcium absorption

D) All of the above

Which of the following enzyme is activated by the parathyroid hormone?

A) 25-alpha hydroxylase

B) 1-alpha hydroxylase

c) 24-alpha hydroxylase

D) All of the above

. The following are the characteristic feature of primary hyperparathyroidism, EXCEPT

A) Increased PTH hormone

B)usually caused by parathyroid adenoma

d) Decreased serum concentration of calcium and phosphate

C) Increased urinary calcium reabsorption

E)osteomalacia may develop

Which of the following regarding magnesium effects on Calcium is true(more than one option may be chosen)

Hypomagnesemia activates CaSR and so PTH is suppressed resulting in hypocalcemia

Hyomagnesemia decreases PTH release resulting in hypercalcemia

Hypomagnesemia activates CaSR and so PTH is suppressed resulting in hypocalcemia

Hyomagnesemia decreases PTH release resulting in hypocalcemia

Hypermagnesemia activates CaSR and so PTH is suppressed resulting in hypocalcemia

Hypermagnesemia inhibits CaSR and so PTH is increased resulting in hypercalcemia

Which of the following is true regarding Congenital hypophosphatemia

Vitamin D will increase serum calcium and phosphate and thus will fully treat congenital hypophosphatemia

FGF-23 protein inhibits phosphate excretion through renal tubules

The cause is a mutation in PHEX protein

It is autosomal recessive

Which of the following is wrong regarding melanin and albinism?(more than one option may be chosen)

Due to deficiency in tyrosine hydroxylase in albinism, melanocytes can't hydroxylate tyrosine to L-DOPA and so no melanin is produced

Pheomelanin is synthesized from dopaquinone conjugation with cysteine from glutathione

In addison's disease, there is decreased cortisol and ACTH and so decreased MSH resulting in hypopigmentation

Ocular albinism is rarer than occulocutaneous

Inheritance of albinism is mostly autosomal dominant

Leukoderma is limited wheras albinism involves all of skin

Which of the following statements is false?

In osteogenesis imperfecta, glycine is replaced with bulky side chains resulting in lack of triple helix formation

The major matrix protein in bone is osteocalcin

Cartilage is made of collagen type 2 whereas bone from collagen type 1

The typical sequence of amino acids in a collagen is glycine, lysine/proline, hydroxylysine/hyroxyproline

Cathepsin K degrades type 1 collagen

Which of the following is true ?(more than one option may be selected)

Phosphate is majorly an intracellular ion

Hyperphosphatemia results in metastatic calcifications, renal stones, and hypocalcemia

Hyperparathyroidism is a cause of hypophosphatemia

Renal failure is a cause of hypophosphatemia and hypercalcemia

Hypocalcemia may cause chvostek(spasm of facial muscles when facial nerve is tapped) and trousseau(spasm of hand on inflating cuff)s

Hypercalcemia features include constipation,bone pain, and psychiatric problems

An old male patient complained about fatigue. His laboratory analysis showed that the total calcium level is of 7.8 mg/dl, phosphorus level of 4.6 mg/dl, albumin level of 3 g/dl, and a total protein level of 7 g/dl. What is the corrected calcium level of the patient

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