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Endocrinology

Endocrinology. A quick review Sam Craik. What is endocrinology. B. Paracrine. B. A. The transmission of a hormone message from one cell... Transports via the blood stream. Arrives at a distant cell elsewhere in the body. Triggering a response from this cell. A. Autocrine.

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Endocrinology

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  1. Endocrinology A quick review Sam Craik

  2. What is endocrinology B. Paracrine B A • The transmission of a hormone message from one cell... • Transports via the blood stream. • Arrives at a distant cell elsewhere in the body. • Triggering a response from this cell. A. Autocrine C. Endocrine C

  3. Hormone Types - Peptide • Synthesised from one or more amino acid. • Peptides often produced as inactive pro-hormones. • Can be stored in vesicles for quick release. • Act at target’s plasma membrane. • Second messengers activated. • Rapid response. Examples: Serotonin (amino acid derived) T3, T4 (dipeptide) Insulin (polypeptide)

  4. Hormone Types - Lipid • Derived from lipids: often cholesterol, sometimes fatty acids. • Cholesterol converted to pregnalone. • From here it is converted to steroid hormones. • Slow fluctuations in steroid homone levels. • Lipid soluble - Act on intracellular receptors. • This affects gene expression, slow response. Examples: Testosterone, Oestrogen, Progesterone. Cortisol Prostaglandins (Fatty Acid)

  5. Anterior Pituitary

  6. Posterior Pituitary • Oxytocin – Induction of childbirth, milk ejection. • Vasopressin – Increased water absorption in kidney. • Both are produced in the Hypothalamus and transported down a nerve axon in vesicles to the posterior pituitary where it is released into the blood. This is Neuroendocrine action. A D D. Neuroendocrine

  7. Hypothalamus Hypothalamus GnRH GnRH Ant Pituitary Ant Pituitary FSH FSH Ovary Ovary Oestrogen Oestrogen Feedback • Postive and negative feedback can occur where a hormone within a series acts back on the earlier hormones to activate or inhibit their release. +ve Feedback -ve Feedback

  8. Growth Hormone Hypothalamus • Excess • Gigantism in children, excessive long bone growth. • Acromegaly in adults, epiphyseal fusion occurred already. • Growth in soft tissues and flat bones. • Deficiency • Short Stature • Loss of growth stimulation (bone and muscle growth, fat brakdown) GHRH Ant Pituitary Growth Hormone Liver IGF-1

  9. Thyroid Hormones Control rate of cellular metabolism • Deficiency • Hypothyroidism • Congenital • Iodine Deficiency • Hashimotos (AI) • Tiredness • Weight Gain • Memory problems • Depression • Goitre Hypothalamus • Excess • Hyperthyroidism • Graves Disease (AI) • Restlessness • Weight Loss • Irritability • Goitre TRH Ant Pituitary TSH Thyroid T3 + T4

  10. Glucocorticoids Hypothalamus • Deficiency • Addison’s Disease • Destruction of Adrenal Cortex causes reduction in production of glucocorticoids (eg: Cortisol), mineralocorticoids and sex steroids. • Often autoimmune • Sometimes Tubercolosis • Weight loss • Anorexia • Weakness CRH Ant Pituitary ACTH Adrenal Cortex Cortisol

  11. Glucocorticoids Hypothalamus • Excess • Cushing Syndrome • Can be at hypothalmic, pituitary or adrenal level. • Cortisol has a negative feedback on ACTH. • Can use ACTH levels to detect where problem is. • High ACTH = Hypothalamus or Pituitary, excess ACTH produced. • Low ACTH = Adrenal Cortex, excess Cortisol independent of ACTH, feeds back to inhibit. • Thin limbs (fat/muscle breakdown) • Central weight gain (storage of released fats/glucose) CRH Ant Pituitary ACTH Adrenal Cortex Cortisol

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