Endocrine system

jonny1311
Flashcards by jonny1311, updated more than 1 year ago
jonny1311
Created by jonny1311 over 7 years ago
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Physiology Flashcards on Endocrine system, created by jonny1311 on 06/12/2013.
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Functions of the endocrine system Communication system, vital to homeostasis, regulates long term processes, cells release secretions into extra-cellular fluid, controlled by negative feedback
Glands involved Hypothalamus, pituitary gland, pineal gland, thyroid gland, parathyroid glands, thymus gland, adrenal glands,
Primary organs involved Pancreas, ovaries, testes
Secondary organs/glands involved Heart, thymus, kidneys, adipose tissue, gonads, digestive tract
Methods of stimulation Neural (nerve fibres), hormonal (primary and secondary), hormonal (presence of products in blood)
Hormones- key facts Released into bloodstream for transportation, can alter metabolism (locally or body-wide), calls have specific receptors for each hormone, aim to preserve homeostasis
Three groups of hormones Amino acid derivatives, peptide hormones, lipid derivatives
Recycling of hormones Remain functional for <1 hour, diffuse out of bloodstream and bind to cells, broken down or absorbed by liver and kidneys, broken down by enzymes in plasma and interstitial fluid
Changes hormones make within cells Identity, activities, quantities
Cell membrane receptors Needed for hormones which aren't limited soluble so cannot cross the membrane (adrenaline, peptide hormones etc), receptor proteins on the outer surface, these are first messengers
First/second messengers First messengers lead to second, may act as enzyme activators, inhibitors or cofactors, can change rates of metabolic reactions
Important second messengers Cyclic-AMP (cAMP), cyclic-GMP (cGMP), calcium ions (these are broken down very quickly)
Intra-cellular receptors For hormones which are lipid soluble, receptor proteins on the inner surface of the membrane, commonly involved with DNA and genetic activity
Intra-cellular receptors For hormones which are lipid soluble, receptor proteins on the inner surface of the membrane, commonly involved with DNA and genetic activity
Types of negative feedback Directly- changes in extracellular fluid, indirectly- through hypothalamus
Three ways in which the hypothalamus controls the system Controls the release of adrenal medulla through nerve stimulation, acts as a gland to release ADH and oxytocin into the bloodstream, secretes regulatory hormones to be transported to endocrine cells
Pituitary gland- key facts Regulates many of the endocrine organs, releases 9 different peptide hormones, uses cAMP as a 2nd messenger, divided into anterior and posterior sections
Thyroid gland- key facts Lies anterior to the larynx, consists of two lobes, connected by the isthmus
Parathyroid gland- key facts Regulates blood calcium levels, parathyroid hormone raises calcium ion levels, speeds bone breakdown and slows kidney loss,
Adrenal glands- key facts Lies superior to each kidney, divided into adrenal cortex and adrenal medulla, produces hormones that adjust metabolic rate (corticosteroids)
Pineal gland- key facts Lies posterior of the third ventricle of the brain, synthesizes melatonin
Pancreas- key facts Lies between the stomach and small intestine, contains islets of Langerhans and exocrine cells, responsible for insulin (beta cells) and glucagon (alpha cells)
Testes- key facts Produce androgens in interstitial cells, secretes inhibin (supports differentiation and matures sperm) in nurse cells
Ovaries- key facts Produce estrogen, follicle cells release progesterone and reorganize into corpus luteum after ovulation
Secondary organs- intestines Secrete hormones to control digestion
Secondary organs- kidneys Secrete three hormones e.g. EPO
Secondary organs- heart Specialised muscle cells secrete ANP to lower blood volume or pressure
Secondary organs- thymus Secretes thymosins to control immune system defenses
Secondary organs- adipose tissue (fat) Secretes leptin to control appetite and resistin to reduce insulin response
Three phases of the stress response Alarm phase (fight or flight), resistance phase (long term metabolic adjustments), exhaustion phase (collapse of vital systems)
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