The Endocrine System Flashcards
What is an endocrine gland?
• it is a gland that secretes hormones directly into the blood
• they have no ducts
• the hormone has to travel to target cells
- it will bind to glycoprotein receptors on target cells which have a complementary shape
What is an exocrine gland?
- it is a gland that secretes molecules into a duct
* the duct takes the product directly to target cells/organ
What is a hormone?
- They are molecules that are released by endocrine glands directly into the blood
- they act as chemical messengers, carrying a signal from the endocrine gland to a specific target organ or tissue
What is a target tissue?
- target tissues consist of target cells the possess specific receptors on their plasma membrane
- the shape of the receptor is complementary to the shape of the hormone molecule
- only these cells will respond to the specific hormone
Explain the action of adrenaline with reference to cyclic AMP (cAMP)
• adrenaline in the blood bonds to its specific receptor on the cell surface membrane, the receptor is complementary to the adrenaline
- the adrenaline molecule is known as the first messenger
• when the adrenaline binds to the receptor it activates the enzyme adenyl cyclase which converts ATP cyclic AMP
• the cAMP is a second messenger molecule, it can then activate other enzymes inside the cell (cascade effect)
Describe the function of the adrenal medulla
- the medulla is found in the centre of the adrenal gland
- the cells in the medulla manufacture and release the hormone adrenaline in response to stress e.g. pain or shock
- the effects of adrenaline are widespread and most cells have adrenaline receptors e.g. Increasing heart rate, increasing blood pressure, dilate pupils
Describe the function of the adrenal cortex
• the adrenal cortex uses cholesterol to produce certain steroid hormones which have a variety of roles in the body e.g. Maintaining concentrations of sodium and potassium in the blood
