1 Secretion of erythropoietin, which regulates red blood cell production in the bone marrow. 2  Secretion of renin, which is a key part of the reninâangiotensinâaldosterone system. 3  Secretion of the active form of vitamin D (calcitriol) and prostaglandins.
A: A charter school is a public school that is organized and operated according to the terms of the. charter, or contract. A charter school cannot have admissions criteria or charge tuition. A private school is not subject to state school laws, local board of education policies, or State Board of Education rules.
The number of American charter schools has grown from 500 in 16 states and the District of Columbia to an estimated 6,400 in 2013-14. Over 600 new public charter schools (7%) opened, serving an additional 288,000 students (13%), totaling 2.5 million students. By contrast, some 200 schools closed, for reasons including low enrollment, financial concerns and low academic performance.