Endocrine Part 6 Adrenal Gland Notes PDF

Endocrine 6 Adrenal Gland PSL 300 Helen Miliotis, PhD  Adrenal gland Lecture outline What are the parts of the adrenal gland? What regulates the release & what are the functions of adrenal catecholamines? Why are specific steroids synthesized in different regions of the adrenal cortex? Wh...

Endocrine 6 Adrenal Gland PSL 300 Helen Miliotis, PhD  Adrenal gland Lecture outline What are the parts of the adrenal gland? What regulates the release & what are the functions of adrenal catecholamines? Why are specific steroids synthesized in different regions of the adrenal cortex? What are the functions & what regulates the synthesis of adrenal steroids? Adrenal hormone disorders Textbook reading: Silverthorn 8th ed. 367-368, 730- 736. 7th ed. 367-368, 730-736 (6th ed. 776-782) (5th ed. 758-763; 4th ed. 751-756) Adrenal medulla = modified sympathetic ganglia Adrenal cortex = steroid factory Adrenal Medulla  What regulates catecholamine release from the adrenal medulla? The chromaffin cell is a modified ACh postganglionic Blood vessel sympathetic Preganglionic neuron. Spinal cord sympathetic neuron (c) Catecholamines: To target tissues Adrenal medulla Epinephrine, (Norepinephrine and Dopamine) are released into the Fig 11.8 blood Main hormone is epinephrine because it is secreted in sufficient quantity to exert effects Stimulus for release = activation of the sympathetic nervous system (“fight or flight” response)  What is the role of epinephrine? Answer = Mediate the rapid stress response Liver: glucose release (via enhanced glycogenolysis) Fat: fatty acid release Heart: increases force of contraction Intestine: muscle relaxation Intestine, skin, Kidney: arteriole constriction Muscle: arteriole contraction ( receptors) arteriole relaxation (2 receptors) epinephrine Brain: increases alertness Resp: bronchodilator  Clinical use of epinephrine – Epi Pen Severe allergic reaction – anaphylactic shock Reaction includes: -Bronchospasm (or constriction of the airways)  respiratory failure. -Dangerous decrease in blood pressure Epi-Pen counter-acts the symptoms of anaphylactic shock by promoting: Bronchodilation Vasoconstriction (intestine, skin, kidneys) Vasodilation (skeletal and cardiac muscles) Adrenal Cortex Zones contain different enzymes Main hormones produced by the adrenal cortex 1. Androgens: What are the physiological roles of androgens? Weak androgens (less than 20% activity of testosterone but converted to more potent androgens and estrogens in peripheral tissues) ACTH will increase Androgen production! Children: male prenatal development, also contribute to andrenarche -- pubic hair, body odor, skin oiliness and acne at onset of puberty for both males and females Adult Men: no physiological role Women: maintain pubic and axillary hair, source of estrogens after menopause  Cortisol Is Essential for Life Adrenal cortex secretes steroid hormones, aldosterone (sodium-potassium balance), glucorticoids, sex hormones Cortisol is the main glucocorticoid Control pathway of secretion is the hypothalamic- pituitary-adrenal pathway Continuous secretion, diurnal rhythm Role in the mediation of long-term stress © 2016 Pearson Education, Inc.  Cortisol Is Essential for Life Protective effect against hypoglycemia through permissive effect Metabolic effects – primarily catabolic 1. Promotes gluconeogenesis 2. Causes breakdown of skeletal muscle proteins 3. Enhances lipolysis 4. Suppresses the immune system © 2016 Pearson Education, Inc. ADRENAL HORMONE DISORDERS  Addison’s Disease Also known as: adrenal insufficiency Hyposecretion of adrenal steroid hormones Causes: destruction of the adrenal cortex by autoimmunity, sometimes infection Symptoms: hypotension, hypoglycemia  Adrenal hormone disorders Cushing’s syndrome: Cortisol excess Causes: Disorders tumours cortisol therapy*** Symptoms: hyperglycemia, muscle protein breakdown, lipolysis but build up of fat on trunk and face, increased appetite, mood elevation followed by depression, difficulty with learning and memory  Review question An individual has Cushing’s syndrome caused by a tumour of the anterior pituitary. What would you observe in comparison to normal? a)CRH and ACTH low and cortisol high. b)CRH, ACTH and cortisol low. c) CRH low, and ACTH and cortisol high d)CRH, ACTH and cortisol high. 34  Key Concepts The Adrenal Medulla secretes catecholamines The Adrenal Cortex secretes: – Mineralocorticoids (Aldosterone) Secreted from zona glomerulosa Regulates sodium and potassium levels – Glucocorticoids (Cortisol) Secreted mainly from zona fasciculata Regulates body’s response to stress Regulates metabolism – Sex hormones (Androgens) Secreted mainly from reticularis Regulate reproductive function (e.g. sex drive in females)