Flashcards in Endocrine System Deck (11):
Exocrine glands release enzymes to the external environment through ducts. Exocrine glands include sweat, oil, mucous, and digestive glands.
Endocrine glands release hormones directly into body fluids.
Is the pancreas an endocrine gland, exocrine gland, or both?
The pancreas acts as both an exocrine gland, releasing digestive enzymes through the pancreatic duct, and an endocrine gland releasing insulin and glucagon directly into the blood.
Endocrine hormones are released into the general circulation. Very low concentrations of hormones int he blood have significant effects on the body.
All hormones act by binding proteins called receptors. Each receptor is highly specific for its hormone. The receptors can regulate hormones through being reduced or increased.
In general, the effects of the endocrine system are to alter metabolic activities, regulate growth and development, and guide reproduction. The endocrine system works in conjunction with the nervous system (many endocrine glands are stimulated by neurons to secrete their hormones).
Peptide hormones are derived from peptides. They are manufactured in the rough ER, and are packaged in secretory vesicles by Golgi. Upon stimulation by another hormone or a nervous signal, the cell releases the vesicles via exocytosis.
Since peptides are water-soluble they can travel freely through the blood but must bind to receptor outside of the wall.
Peptide hormones to know for the mcat
Anterior pituitary hormones: FSH, LH, ACTH, hGH, TSH, Prolactin
Posterior pituitary hormones: ADH and oxytocin
Parathyroid hormone PTH
Pancreatic hormones: glucagon and insulin
steroid hormones are derived from and are often chemically similar to cholesterol. They are made in the smooth ER and the mitochondria. Since they are lipids, they require a protein transport molecule in order to dissolve into the blood stream. Diffuse through cell membrane of their effector.
Combine with a receptor in the cytosol. Receptor transports them into the nucleus, an the steroid acts at the transcription level.
Steroid hormones to know for the mcat
Glucocorticoids and mineral corticoids of the Adrenal cortex: cortisol and aldosterone
The gonadal hormones: estrogen, progesterone, testosterone. (Estrogen and progesterone are also produced by the placenta)
Tyrosine derivatives to know for mcat
Thyroid hormones: T3 (triiodothyronine contains 3 iodine atoms) and T4 (thyroxine contains 4 iodine atoms)
Catecholamines formed in the adrenal medulla: epinephrine and norepinephrine.