Endocrine system Flashcards
What are the basics of the endocrine system?
Chemicals known as hormones are secreted from endocrine glands or tissues into extracellular fluid
Transported by the blood to distant target organs
Where are receptors for hormones found?
On the cell surface
In the cytosol
In the nucleus
What are the two ways hormones can exert signal transduction?
Within seconds (adrenaline) Over hours or days (growth hormone)
What are the 7 classic endocrine glands?
Pituitary- anterior and posterior, thyroid, parathyroids, adrenals- cortex and medulla, ovaries, testes, endocrine pancreas
What are other tissues that can be classed as endocrine?
Hypothalamus, kidneys, heart, GI tract, adipose tissue, liver
What are hormones T3 and T4?
Thyroid gland- produced by follicular cells
Stored extracellularly as a prohormone in colloid
Bind to nuclear receptors and regulate protein transcription
Essential for growth, development and metabolism
What does the parathyroid do?
Synthesises and secretes the peptide hormone parathyroid hormone
Action on bone, GI system and kidneys
Regulates plasma levels of calcium and phosphate
What does the adrenal cortex do?
Releases steroid hormones
Glucocorticoids (cortisol) and mineralocorticoids (aldosterone)
What does the adrenal medulla do?
Chromaffin cells release adrenaline and catecholamines (adrenaline, noradrenaline and dopamine)
What do the ovaries produce?
Cells of the developing follicle produce oestrogen and progesterone
What does oestrogen do?
Stimulated cellular proliferation of the endometrium
What does progesterone do?
Stimulates secretions and maturation of tissues
What cells produce testosterone?
Leydig cells of the testes
What does testosterone do?
Stimulates protein synthesis
Can lead to growth and development
What is the role of the endocrine pancreas?
In islets of Langerhans alpha cells secrete glucagon and beta cells secrete insulin
Both released into portal blood to influence the liver
