Hormones and regulation

  • Created by: Saoirse
  • Created on: 09-06-14 23:55

Hormones: molecules released by endocrine glands directly into blood. Act as messengers on specific target cells

An endocrine gland is a gland that secretes hormones directly into the blood. Do not have ducts.

An exocrine gland is a gland that secretes molecules into a duct that carries molecules.

The first messenger is the hormone that transmits a signal around the body e.g adrenaline. Binds to receptor which activates second messenger.

The second messenger e.g cAMP transmits a signal inside the cell.

Functions of adrenal gland:

  • Adrenal medulla - manufactures and releases adrenaline which prepares body for activity and includes the following effects:
    • relax smooth muscle in bronchioles
    • increase stroke volume of the heart
    • increase heart rate
    • cause vasoconstriction to raise blood pressure
    • stimulate conversion of glycogen to glucose
    • dilate pupils
    • increase action of gut
    • cause body hair to erect
  • Adrenal cortex - uses cholesterol to produce certain steroid hormones that can:
    • control concentrations of Na and K in blood
    • control metabolism of carbohydrates and proteins in liver

Regulation of blood glucose

  • The pancreas is both an exocrine and endocrine organ:
    • exocrine = secretion of enzymes through the pancreatic duct
    • endocrine = secretion of hormones from islets of langerhans
  • Islets of langerhans consist of alpha and beta cells:
    • alpha cells secrete glucagon - causes blood sugar levels to rise
    • beta cells secrete insulin - causes blood…


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