Hormones Flashcards
Define exocrine gland.
A gland that secretes molecules into a duct that carries these molecules to where they are needed.
Define hormone.
A molecule that is released by an endocrine gland directly into the blood, and that acts as a messenger, carrying a signal from the endocrine gland to the target organ or tissue.
Define target tissue.
Tissue composed of cells which have specific receptors on their cell surface membrane, these having a shape complementary to the shape of a specific hormone molecule.
What is the first messenger?
The hormone that transmits a signal around the body.
What is the second messenger?
A chemical inside cells released in response to a hormone binding to the cell surface membrane. An example of a second messenger is cAMP.
What are the 2 regions that the adrenal glands may be divided into?
Adrenal medulla, adrenal cortex
What does the adrenal medulla do?
Manufactures and releases adrenaline in response to stress.
What does the adrenal cortex do?
Uses cholesterol to produce certain steroid hormones i.e. mineralocorticoids and glucocorticoids.
What do the mineralocorticoids do? Give an example.
Help to control the concentrations of sodium and potassium in the blood. Example: aldosterone.
What so the glucocorticoids do? Give an example.
Help to control the metabolism of carbohydrates and proteins in the liver. Example: cortisol.
What is the role of the pancreas as an exocrine gland?
To manufacture and release digestive enzymes. Tubules join to form the pancreatic duct which carries the fluid containing the enzymes into the first part of the small intestine.
What is the role of the pancreas as an endocrine gland?
Pancreatic α and β cells release glucagon and insulin respectively straight into the blood to control blood glucose concentration.
Define endocrine gland.
A gland that secretes hormones directly into the blood.
