Which of the following substances are bloodborne proteins synthesized in the liver?

Which of the following substances are bloodborne proteins synthesized in the liver?

(A) cholesterol
(B) fibrinogen
© growth hormone (GH)
(D) insulin
(E) renin

Explanation:

(B) Fibrinogen is a protein produced by the liver. Its function is to help stop bleeding by promoting the formation of blood clots. Cholesterol (choice A) is partly synthesized in the liver, it is however a lipid, not a protein. GH (choice C) is made by cells in the anterior pituitary gland. However, much of GH’s action is mediated by insulin-like growth factor-1 (IGF-1), a protein secreted from the liver in response to stimulation by GH. Insulin (choice D) is made in cells of the endocrine pancreas and acts on the liver, but is not produced there. Renin (choice E) is made by cells of the juxtaglomerular apparatus in the kidney. However, its action is to cleave circulating angiotensinogen, which is made by the liver.