Endocrine System Presentation PDF

Anatomy & physiology PHAS5001 Endocrine system Faye Staniforth (PA-R)  Learning outcomes Why do we have an endocrine system? What are hormones and what do they do? What are the main organs that make up the endocrine system? What are the functions of these org...

Anatomy & physiology PHAS5001 Endocrine system Faye Staniforth (PA-R)  Learning outcomes Why do we have an endocrine system? What are hormones and what do they do? What are the main organs that make up the endocrine system? What are the functions of these organs ? How can we start to relate this to disease processes?  What do you already know? https://create.kahoot.it/v2/share/endocrine- quiz/7a6305eb-cce0-4c32-a2ce-13dcb035087f  Endocrine system - function Overall function of the endocrine system is to maintain homeostasis Chemical messages –hormones, enable cells to communicate and achieve homeostasis Homeostasis : to maintain a stable internal state for optimal functioning  Endocrine system -function Short term Long term Blood pressure Growth pH Reproduction Respiration Metabolism  Hormones A hormone is released in response to a stimulus/signal The action of the hormone restores equilibrium directly or indirectly  Hormone Activity Hormones affect only specific target tissues with specific receptors Water soluble hormones have receptors on cell surface Lipid soluble hormones have intracellular receptors Receptors constantly synthesized and broken Positive and negative feedback  Hormones Ways cells communicate using hormones : Endocrine – transmitted by the circulatory system (distant) Paracrine – produced by endocrine tissue and transmitted in extracellular fluid (local) Autocrine – act on the same cell Neuroendocrine – secreted from nerve cells Classes of hormones : Polypeptides – cannot pass through cell membranes (water soluble) Steroids – Can cross the cell membrane (lipid soluble) Modified amino acids – can cross cell membranes (small water soluble ) Eicosanoids- e.g prostaglandins image from : https://yaledailynews.com/blog/2018/02/13/study-shows-how-cell- types-communicate/ Hormone types – Circulating – circulate in blood throughout body (e.g. insulin) – Local hormones – act locally Paracrine – act on neighboring cells Autocrine – act on the same cell that secreted them (e.g interleukin-1)  Mechanisms of Hormone Action Lipid-soluble hormones bind to receptors inside target cells Water-soluble hormones bind to receptors on the plasma membrane Activates second messenger system Amplification of original small signal Endocrine system image from :https://www.rn.com/clinical- insights/endocrine-system/ Endocrine system image from :https://www.rn.com/clinical- insights/endocrine-system/  Hypothalamic-pituitary axis Considered the central regulatory component of the endocrine system Hypothalamus is sensitive to neural and hormonal stimuli The hypothalamus integrates these stimuli and sends signals to the pituitary  Hypothalamus Location: the base of the forebrain ( diencephalon) Structure: pituitary stalk which is continuous with the posterior pituitary gland. Functions: receives inputs from the circulation (temp , BM, hormones ) and neuronal inputs (autonomic and emotional). Based on these inputs hormones are secreted, which target the anterior or posterior pituitary. Blood supply: superior hypophyseal artery , hypophyseal portal vessels to the anterior pituitary (high hormones concentration), drained by the cavernous sinus  Image from : https://www.thescienceofpsychotherapy.co m/hypothalamus/  Image from : https://teachmeanatomy.info/neuroanato my/structures/pituitary-gland/  Anterior Pituitary Location – lies in the sella turnica. The optic chiasma lies directly superior (pituitary gland tumours can cause visual changes due to compression) Function – release hormones after receiving stimulus from hypothalamus. Hormones act on other endocrine organs. Blood supply – superior hypophyseal artery, hypophyseal portal vessels from the hypothalamus , drained by the cavernous sinus (hormones enter circulation)  Posterior pituitary Location – posterior to anterior pituitary Structure – connected to the hypothalamus by the pituitary stalk Function – release ADH (acts on the collecting ducts of the kidney) and oxytocin Blood supply – inferior hypophyseal artery. Drained by the cavernous sinus (hormones enter circulation )  Example Hypothalamus - Anterior pituatry Low Thyroid Thyrotrophin- TSH( thyroid hormones (T4 , T3) releasing stimulating hormones (TRH) hormone) Hypothalamus Posterior pituitary Anterior pituitary GHRH ADH GH GHRIH Oxytocin TSH CRH ACTH GnRH LH TRH FSH PRF PRL Dopamine Small peptides (Except Small peptides Large peptides and dopamine) glycopeptides  Thyroid gland Location - anterior to the trachea on the lower aspect of the neck Structure - butterfly shaped, two lobes 5cm long , connected by the isthmus. Attached to the trachea. (when patient swallows the thyroid gland moves upwards) Function – releases calcitonin (calcium homeostasis), T3 and T4 which regulate the metabolism of most of the cells. Iodine store (iodine is needed to make thyroid hormones) thyroglobin store( used for thyroid hormone synthesis Regulated by – the anterior pituitary gland (TSH) Blood supply - superior and inferior thyroid arteries (thyroid ima artery supplying the isthmus in some people), drained by the superior and middle thyroid vein, into the internal jugular vein and the inferior thyroid veins into the brachiocephalic vein. Not enough T3 and T4 due to –disease ,Cold , pregnancy (oestrogen) , low t3 t4 , adrenaline  Actions of Thyroid Hormones: vIncrease basal metabolic rate vIncrease body temperature (calorigenic effect) vIncrease the use of glucose and fatty acids vStimulate lipolysis vRegulate development and growth of nervous tissue and bones  Disorders of the thyroid TSH high TSH low T3 low T3 high image from T4 low :https://www.pinterest.co.uk/pin/1632561 T4 high 7382587253/  Parathyroid Located – one pair on the posterior surface of each lobe of the thyroid gland(total 4) (number can vary 2-6) Structure – 5mm in diameter , chief cells, oxyphil cells and adipocytes Function - calcium and phosphate homeostasis Regulated by – negative feedback , calcium levels Blood supply – inferior thyroid arteries  Adrenal glands Location -Paired retroperitoneal glands situated over the superior pole of each kidney Structure- Right gland is pyramidal in shape, contrasting with the semi-lunar shape of left gland. Separated into medulla and cortex Function- Secrete steroid and catecholamine hormones directly into blood Regulated by – adrenal cortex – pituitary gland (ACTH) ,adrenal medulla –sympathetic nervous system  cortex -glucocorticoids – in response to stress (cortisol) -mineralcorticoids- regulate blood volume (aldosterone) -Androgens (sex hormone) medulla -catecholamines -adrenaline and noradrenaline Click to add text  Blood supply - Superior adrenal artery – arises from inferior phrenic artery - Middle adrenal artery – arises from abdominal aorta - Inferior adrenal artery – arises from renal arteries - Right and left adrenal veins drain the glands. Right adrenal vein drains into inferior vena cava, whereas left adrenal vein drains into left renal vein  Aldosterone: principal mineralocorticoid It regulates the homeostasis of 2 mineral ions: K+ and Na+ à regulation of blood pressure Renin-angiotensin-aldosterone pathway Renin-angiotensin-aldosterone pathway -Stimuli: dehydration, haemorrhage, Na+ deficiency -Decrease blood volume à decrease blood pressure -Stimulation of kidney cells to secrete RENIN à converts ANGIOTENSINOGEN into ANGIOTENSIN I -ANGIOTENSIN I is converted into ANGIOTENSIN II by ACE( ACE Inhibitors) -ANGIOTENSIN II (ARB) stimulates the adrenal cortex to secrete ALDOSTERONE -In the kidneys ALDOSTERONE increases the reabsorption of Na+ which in turn causes reabsorption of water by osmosis = less water lost in urine Leads to increase in blood pressure Glucocorticoids: - Cortisol the most abundant. Released in response to stress They have the following effects: 1. Protein breakdown: increase the rate of protein breakdown in the in muscle fibres liberating AA for synthesis new proteins 2. Glucose formation: liver cells convert AA or lactic acid into glucose to be used as energy 3. Lipolysis: breakdown of triglycerides and release fatty acids from adipose tissue for energy 4. Resistance to stress: providing substrates for energy production Click to add textmake the body ready to react 5. Anti-inflammatory effects: inhibits inflammatory response by supressing the immune function (used in treatment of inflammatory conditions)  Catecholamines Epinephrine/adrenaline 80% Norepinephrine/noradrenaline 20% Fight or flight response - Increases HR - More blood to heart, liver and muscles - Dilates airways - Increases energy production  PANCREAS Endocrine- into blood stream (Islets of Langerhans) and exocrine – via ducts (acini) gland  Pancreas Location – retroperiotoneal gland , posterior and inferior to the stomach Structure – islets of langerhans, containing 4 types of cells Function – endocrine and exocrine function Blood supply – body and the tail are supplied by branches of the splenic artery. The uncinate and head are supplied by the creaticoduodenal artery.  Endocrine Each pancreatic islet includes 4 types of hormone-secreting cells: Alpha or α cells 17% cells GLUCAGON = raises BG INSULIN = lowers BG Beta or β cells 70% cells SOMATOSTATIN = inhibits Delta or δ cells 7% cells both glucagon and insulin release F or pp cells The remaining PANCREATIC POLYPEPTIDE = cells inhibits somatostatin and digestive enzymes secretion  Exercise – match the condition to the gland Addisons Adrenal gland Hypothyroidism Thyroid gland Cushings disease Pituitary Diabetes Hypothalamus Conns disease Pancreas Graves disease Acromegaly  Answers Condition Gland Addisons Adrenal insufficiency Hypothyroidism Thyroid gland , low T3 and T4 Cushing disease Adrenal – raised cortisol ( or too much steroid medication) Diabetes Pancreas Conns disease Adrenal – too much aldosterone Graves disease Thyroid – autoimmune , raised T3 and T4 Acromegaly Pituitary – too much growth hormone  Final Quiz https://create.kahoot.it/v2/share/end-of- endocrinology-quiz/a02471e4-7827-4a18- 9c5a-59f560d47f38  Further reading Crash course in Edocrinology – O'Neil Murphy (if interested)