Monday 19 September Chapter 11 The Endocrine System

Monday, 19 September Chapter 11 The Endocrine System • • • Classes of hormones The adrenal gland Fates of hormones Renin-Angiotensin-Aldosterone System Control of hormone secretion Hormone interactions (permissive effects)

1 QQ # 6 1. Stress leads to the secretion of epinephrine which alters the metabolism of many cell types. Describe the effects of EPI on two different cell types and explain how these effects are beneficial to the person. 2. Starting with the arrival of carbohydrates in the stomach list the sequence of events, cell types, and hormone(s) that comprise a feedforward mechanism. What is the purpose of this feedforward mechanism? 3. Beginning with the ingestion of a large amount of sugar, list the sequence of events in a reactive hypoglycemic person that ultimately leads to a headache, fast heart rate, and cold, clammy skin.

Endocrine Organs (Table 11 -1) • • • Hormone Pituitary Gland Paracrine agent Thyroid Gland Autocrine agent Pancreas Neurotransmitter Gonads Neuromodulator Gastrointestinal Tract Heart Hormone: chemical messengers carried by blood to target cells Kidney upon which they act. Hypothalamus Liver Only those cells having receptors Etc. Can respond to a given hormone Analogy: SSNs and receptors

3 Chemical Classes of Hormones • 1: – – • 2: • 3: Amine hormones (from amino acid tyrosine) Thyroid hormones Adrenal medullary hormones (catecholamines) Peptide hormones (peptides & proteins) Steroid Hormones (derivatives of cholesterol) Why does the chemical class matter?

Amine Hormones Fig. 11. 01 Thyroid Hormones Not soluble in plasma, bound & free NT Adrenal medulla Catecholamines soluble in plasma NT

Steroid hormones Fig. 11. 03 not soluble in plasma, not storable in vesicles Bound & Free Target cells have intracellular receptors. Changes is gene expression. Timecourse?

Peptide Hormones Soluble in plasma Fig. 11. 02 e. g. Beta cell Guess peptide! Cell surface receptors on target cells Examples of Peptide Hormones: Insulin, glucagon prolactin, erythropoietin, parathyroid hormone, gastrin, leptin, growth hormone, oxytocin, vasopressin, FSH, LH, GHRH, and many more!

Know Table 11 -2 p 323 • • • Hormone class Major form in plasma Location of receptors Signal transduction mechanisms Rate of excretion / metabolism

Questions so far?

Fig. 11. 05 Hormones of the Adrenal Cortex Adrenal Gland Part of Sympathetic Nervous System

Hormones of the Adrenal Cortex Androgens DHEA “Andro” Glucocorticoids Mineralicorticoid What regulates the secretion of cortisol and aldosterone?

Fig. Gonadal Steroids 11. 06 (not adrenal cortex) Estrogens King DS, Sharp RL, Vukovich MD, Brown GA, Reifenrath TA, Uhl NL, Parsons KA. Effect of oral androstenedione on serum testosterone and adaptations to resistance training in young men: a randomized controlled trial. JAMA 1999; 281(21): 2020 -8

What happens to hormones once released? Be able to give Examples. Ex: Renin Fast if free Slow if bound T 4 to T 3 and Testosterone to Estradiol

Renin-angiotensin-aldosterone Renin is an enzyme released from kidney cells into bloodstream, its “substrate” is a plasma protein called Angiotensinogen. Renin Angiotensinogen from liver, an ever-present plasma protein Angiotensin I Angiotensin converting enzyme (ACE) Angiotensin II Zona Glomerulosa of Adrenal Cortex Thirst Arterial smooth muscle … vasoconstriction…increase blood pressure Aldosterone Promotes Na+ retention in Kidney

Blood Pressure (-) Renin from Juxtaglomerular cells in Kidney Multi-step process involving Angiotensin I and II Angiotensin II thirst Aldosterone Na+ reabsorption in kidney Drink Plasma volume vasoconstriction Blood pressure K+ in plasma _______

What happens to hormones once released? Be able to give Examples. Ex: Renin Fast if free Slow if bound T 4 to T 3 and Testosterone to Estradiol

Factors that affect hormone secretion Integrator! Recall example: beta cells of Islets of Langerhans Secretion is usually pulsative, may be diurnal.

Fig. 11. 08 Permissive effect Thyroid hormone stimulates production of beta-adrenergic receptors