Endocrine, Paracrine, Autocrine & Intracrine Flashcards
What are the 10 endocrine structures?
Hypothalamus Pituitary Thyroid Parathyroid Pancreas Thymus Adnrenal Ovaries Metabolism Pineal
Describe cortisol
Secreted and synthesised by the adrenal cortex
Steroid
Describe regulation of hormone secretion
Maintain homeostasis, hormone secretion must be regulated as needed - accomplished by neural and feedback mechanisms
What are 4 hormones released by the hypothalamus?
Corticotropin releasing hormone (CRH)
Thyrotropin releasing hormone (TRH)
Growth hormone releasing hormone (GHRH)
Gonadotropin releasing hormone (GnRH)
Describe the posterior pituitary and the two main hormones released
Pars nervosa - negative feedback loop stimulated by the anterior pituitary
ADH + Oxytocin
Describe the anterior pituitary and the 6 main hormones released
Pars tuberalis, pars distalis and pars intermedia Hormones and secreted by: TSH - Thyrotrophs FSH - delta / gonadotropic LH - delta / gonadotropic ACTH - corticotrophs GH - somatotrophs Prolactin - lactotrophs
What does ACTH act on?
Adrenal gland
What does TSH act on?
Thyroid gland
What does GH act on?
Liver - somatomedins
What does Prolactin (PRL) act on?
Mammary glands
What does FSH act on?
Testes and ovaries
What does LH act on?
Testes and Ovaries
What does MSH (Melanocyte stimulating hormone) act on?
Melanocytes
What does Oxytocin act on?
Prostate + ductus deferens
Uterine smooth muscle
Describe the pineal gland
Pinealocytes - produce melatonin
Glial cells - bipolar elongated cells that run between nests of pinealocytes - indistinct unless stained
Describe melatonin
Regulates seasonal changes in the body and sleep
Describe the parathyroid gland
- Embedded in the posterior surface of the thyroid
- separated by the dense capsular fibres of thyroid
- Parathyroid hormone PTH calcium homeostasis
Chief cells and Oxyphils
Describe hyperthyroidism
- Increase thyroid stimulating immunoglobulins
- Antibodies to TSH receptors on thyroid follicular cells
- Increase secretion of thyroid hormone and hypertrophy of gland
Causes rapid heart rate , weightloss and goiter
Treatment - Drugs to inhibit thyroid hormone synthesis or surgical removal of the gland
Describe hypothyroidism
- Autoimmune destruction is the most common cause
- antibodies destroy the gland or blockthyroid hormone synthesis
Symptoms - Weight gain, decreased heart rate, periorbital, menstrual dysfunction
Treatment - thyroid hormone replacement
Describe the adrenal gland
Cortex - secretes steroid hormones
medulla - neuroendocrine component - polyhedral
Describe cushings syndrome
- Result of chronic excess glucocorticoids
- Over production of cortisol by adrenal cortex
- Treatment - use meds to block steroid hormone biosynthesis
Describe cholera
Caused by vibrrocholerae Severe diarrhoea Shock and death if fluid not replaced Cholera toxin produced by bacteria that enters the gut binds to G protein that controls adenylate cyclase - Increase adenylcyclase activity - Increase cAMP - Increase active transport by ions by interstitial cells - Increase Na and H2O into the gut
Describe paracrine communication
- Occurs when a cell releases a signalling molecule into its immediate environment
- molecule is bound by and effects neighbouring cells
Describe autocrine communication
- Cell releases a regulatory molecules bound by its own receptors
- Acts on cell which releases it - positive feedback to cell
