The 'Hormone Parathyroid Hormone' (PTH) is secreted by the parathyroid glands. Its primary effect on blood calcium levels is to: MCQ with Answer and Explanation
The 'Hormone Parathyroid Hormone' (PTH) is secreted by the parathyroid glands. Its primary effect on blood calcium levels is to:
A. Increase them
B. Fluctuate them
C. Have no effect on them
D. Decrease them
Answer: Option A
Solution (By JKSSB Mock Tests)
Parathyroid Hormone (PTH) is a peptide hormone secreted by the chief cells of the four parathyroid glands in response to low blood calcium levels (hypocalcemia). Its primary function is to increase blood calcium levels (hypercalcemic effect). It achieves this by: 1) Stimulating osteoclasts to break down bone, releasing calcium. 2) Increasing calcium reabsorption and stimulating the activation of Vitamin D in the kidneys. 3) Indirectly increasing calcium absorption in the gut via active Vitamin D. It has the opposite effect of calcitonin.
Explanation:
Alveoli are tiny, thin-walled air sacs surrounded by pulmonary capillaries. Oxygen diffuses across the alveolar and capillary walls into the blood, while COâ‚‚ diffuses out. The trachea, bronchi, and nasal cavity are air passages that do not participate directly in gas exchange.
Explanation:
The living state and all vital functions first become evident at the cellular level. While macromolecules are present in both living and non-living systems, it is the organized interaction of these molecules within a cell that manifests life. Cells are the fundamental structural and functional units of life.
Explanation:
Differential centrifugation separates organelles by size and density by spinning homogenized cells at progressively higher speeds. Each pellet is enriched in a particular organelle. Density gradient centrifugation further refines separation. Electrophoresis separates by charge/size, chromatography by differential partitioning, spectrophotometry measures absorbance.
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