1) Amines: Derived from the amino acids tyrosine and tryptophan. Includes the water soluble hormones derived from the adrenal medulla, lipophilic thyroid and pineal glands.

2) Polypeptides and proteins: Proteins are large polypeptides. ADH is an 8 amino acid polypeptide, too small to be considered a hormone. Growth hormone (GH) has 191 amino acids, so it is a protein. Insulin is composed of 2 polypeptide chains derived from a single, larger molecule. Water soluble.

3)Glycoproteins: Consist of a protein bound to one or more carbohydrate groups. ex. FSH and LH. water soluble.

4)Steroids: Lipids derived from cholesterol. Includes testosterones, estradiol, progesterone and cortisol. Lipophilic.

1) Steroid hormones, transported bound to plasma carrier proteins, dissociate from their plasma carriers and pass through the plasma membrane of their target cell, because they are lipophilic.

2) the steroid hormone binds to receptors, which may be in the cytoplasm. 3) The hormone bound receptor translocates to the nucleus, where it binds to DNA.

4) This stimulates genetic transcription, resulting in new mRNA synthesis.

5) The newly formed mRNA codes for production of new proeins, which

6) produce the hormonal effects in the target cell.

1) Thyroxine (T4) carried to the target cell bound to its plasma carrier protein, dissociates from its carrier and passes through the plasma membrane of its target cell, because it is lipophilic. 2) In the cytoplasm, T4 is converted into T3 which

3) uses binding proteins to enter the nucleus.

4) The hormone-receptor complex binds to DNA,

5) stimulating the synthesis of new mRNA.

6) The newly formed mRNA codes for synthesis of new proteins, which

7) produce the hormonal effects in the target cell.

1)The hormone binds to its receptor on the outer surface of the target cell's plasma membrane, because it is water-soluble.

2) G-proteins stimulate the activity of adenylate cyclase on the cytoplasmic side of the plasma membrane (due to the dissociation of the a subunit).

3) This enzyme catalyzes the production of cAMP, which

4) removes the inhibitory subunit from protein kinase.

5) Active protein kinase phosphotylates other enzyme proteins, activating or inactivating specific enzymes and therefore producing the hormonal effects of the target cell.

1) The hormone binds to its receptor in the plasma membrane of its target cell,

2) causing the dissociation of G-proteins.

3) A G-protein subunit travels through the plasma membrane and activates phospholipase C, which catalyzes the breakdown of a particular membrane phospholipid into diacylglycerol and IP3.

4) IP3 enters the cytoplasm and binds to receptors in the smooth ER, causing the release of stored Ca2+. The Ca2+ then diffuses into the cytoplasm, where it  acts a a second messenger to promote the hormonal effects in the target cell.

1) Binding of epinephrine to beta-adrenergic receptors activates adenylate cyclase and leads to the production of cAMP, which

2) activates protein kinase.

3) Binding of epinephrine to alpha-adrenergic receptors leads to a rise in the cytoplasmic Ca2+ concentration, which

4) activates calmodulin. Calmodulin then activates a protein kinase, which, like the protein kinase activated by cAMP,

5) alters the enzyme activity so that glycogen is converted into glucose 6-phosphate.

6) The phosphate group is removed by another enzyme, so that the liver cell secretes free glucose into the blood in response to epinephrine.

The pituitary gland is divided into two parts- the anterior lobe (adenohypophysis) and posterior lobe (neurohypophysis). The anterior lobe consits of two parts, the 1) pars distalis (anterior pituitary) and 2) the pars tuberalis- thin extension in contact with the infundibulum. The anterior pituitary secretes trophic hormones (trophic = "feed") which are 1) Growth hormone (GH) 2) Thyroid-stimulating hormone (TSH) 3) Adrenocorticotropic hormone (ACTH) 4) Follicle-stimulating hormone (FSH) 5) Luteinizing hormone (LH) 6) Prolactin (PRL).

The posterior pituitary (pars nervosa) stores and secretes two hormones, both of which are produced in the hypothalamus: 1) Antidiuretic hormone (ADH) and 2) Oxytocin.

Anterior- Hypothalamic control of the anterior pituitary is acheived through hormonal regulation rather than neural regulation. Releasing and inhibiting hormones are produced by neurons in the hypothalamus, and transported to axon endings in the basal portyion of the hypothalamus (median eminence). Venules that drain the median eminence form a hypothalamo-hypophyseal portal system to the anterior pituitary, and the regulatory hormones secreted by the hypothalamus regulate the secretions of the anterior pituitary. Thyrotropin-releasing hormone (TRH) stimulates secretion of TSH, corticotropin-releasing hormone (CRH) stimulates secretion of ACTH, gonadotropin-releasing hormone (GnRH) stimulates sectretion of FSH and LH, prolactin-inhibiting horrmone (PIH) stimulates secretion of prolactin, and somatostatin stimulates secretion of growth hormone (GH).

Posterior- ADH and oxytocin are produced in neuron cell bodies of the supraoptic nuclei and paraventricular nuclei of the hypothalamus. This means these nuclei are thus endocrine glands, and the hormones they produce are transported along axons of the hypothalamo-hypophyseal tract to the posterior pituitary, where they are stored and later released.

Mineralcorticoids (ex. aldosterone) regulate K+ and Na+ balance by stimulating the kidneys to retain Na+ and water, while excreting K+ in the urine. This increases blood volume and pressure and regulates electrolyte balance. Glucocorticoids- regulate balance of metabolism and glucose; stimulates gluconeogenesis and inhibits glucose utilization which helps raise blood glucose level and promotes lipolysis. Sex steroids- supplement the sex steroids secreted by the gonads; weak androgens.

Secretion of epinephrine and norepinephrine increases cardiac output and heart rate, dilate coronary blood vessels, increase mental alertness, increase respiratory rate and elevates metabolic rate. It is activated durin "fight or flight" and its effects are supported by metabolic actions of epinephrine and norepinephrine. A rise in blood glucose due to hepatic glycogenolysis and rise in blood fatty acids due to stimulation of lipolysis.

Sympathoadrenal system becomes activated with increased secretion of epinephrine and norepinephrine in response to stressors that cause the fight or flight rection.

A major function of the adrenal cortex in response to stress is the rise in glucocorticoid levels. Stress causes a response in the higher brain centers  which causes the hypothalamus to secrete increased amounts of CRH (corticotropin-releasing hormone) which cause the anterior pituitary to secrete higher levels of ACTH (adrenocortico-tropic hormone) which stimulates the adrenal cortex to secrete cortisol. High levels of glucocorticoids supress the immune system, cause atrophy of the hippocampus, catabolizes muscle protein and fat, and stimulates gluconeogenesis, raising blood glucose levels. This antagonizes the actions of anabolic hormones, incuding GH and insulin.

Explain the nature and actions of the receptor proteins for insulin and the growth factors: