From the below posts of my fellow bloggettes one could determine that we were put to the test (literally) on how much biology information we have gleaned over the years. The favorite stumbling block this year seems to be plants and while I will say that on some of the questions for photosynthesis, angiosperms, life cycles, and ATP production I did make a double take but the dumb mistake I made had to do with human physiology, specifically hormone secretion.
The question asked when serum calcium levels fall, an adequate level is restored in humans by secretion of either thyroxine, glucagon, growth hormone, parathyroid hormone, or calcitonin. Now before you jump the gun and pick calcitonin like someone I know lets do a little history. The way that I break it down on a multiple choice question is by looking at each word and separating the meaning from each word...that is what I normally do but in this case I just flippantly picked calcitonin because...calcium is the meaning of the first part. However I digress....so thyroxine.
Thyroxine is a thyroid hormone secreted by the thyroid gland by way of follicular cells which facilitates the stimulation of metabolic processes and influencing physical development. No for calcium levels.
Glucagon - easy to dismiss because of its root word that being glucose. Glucagon is secreted by the pancreas in order to help with glucose levels in the body. When glucose levels are too low (hypoglycemia) the pancreas secretes glucagon into the system causing the liver to convert glycogen into glucose thereby restoring blood glucose levels in the body. Again no calcium.
Growth Hormone - really? no question here it is not for calcium
Parathyroid Hormone - or PTH is secreted by the parathyroid glands and the main function of PTH is regulating serum calcium levels. DING DING DING we have a WINNER!!!
Sorry premature excitement...anyways. PTH regulates calcium levels in three tissues: bone, kidney, and the intestine. When serum calcium levels in the body decrease, the levels are restored by the secretion of PTH. This hormone will either cause calcium levels to increase by increasing the level of bone resorption this is done by indirect stimulation of osteoclasts thereby breaking bone down in order to release calcium into the blood. Calcitonin is the opposite, it works to decrease calcium concentrations in the blood.
Moral of the story is break the word down and drink more milk!!!!!