Endocrine System Flashcards
Functions of Endocrine System
Regulates Growth, Development, Reproduction
Maintains homeostasis
Organs of the Endocrine System
Hypothalamus
Pineal Gland
Pituitary Gland
Parathyroid Gland
Thyroid Gland
Adrenal Gland
Pancreas
Endocrine Communication Definition
Cellular communication through the bloodstream using hormones
3 Features of Endocrine Glands
Ductless glands comprised of endocrine cells
Have good blood supply
Secretes hormones directly into bloodstream
Hormone Definition
Organic Chemical messenger secreted from endocrine cells into the bloodstream
Bind to receptors of target cells to stimulate gene expression/protein synthesis
Risks of anabolic steroids
Stunted growth in teenagers
Damage to liver
Reduced sperm count, infertility in males
Facial Hair, cessation of menstrual cycle in females
3 Types of Hormones
Amino Acid Derivatives
Peptides
Lipid
Types of Amino Acid Hormones
Thyroid - Lipid Soluble
Catecholamines - Water Soluble
Tryptophan Derivatives - Water Soluble
Types of Peptide Hormones
Glycoproteins
Short Polypeptides
Both Water Soluble
Types of Lipid Hormones
Eicosanoids - Water Soluble
Steroid Hormones - Lipid Soluble
Features of Lipid/Water Soluble Hormones
Water soluble can mix with blood but can’t pass through cell membrane
Lipid soluble can’t mix with blood but can pass through cell membrane
Hormone Receptor Locations
On the cell membrane (non-lipid soluble hormones)
Inside the cell (lipid soluble hormones)
Receptor Hormonal Action
Hormone-receptor complex formed
HRC activates G Protein
Activated G Protein activates enzyme adenylate cyclase
Adenylate cyclase converts ATP to cAMP
cAMP activates kinase enzymes
Activated kinases affect target cell
Steroid Hormonal Action
Hormone diffuses through membrane lipids
Binding of hormone to intracellular receptors
Binding of HRC to DNA
Thyroid Hormonal Action
Transport across membrane via diffusion
Binds to receptor on mitochondria/nucleus
Binding of HRC to DNA
Fate of free hormones after secretion
Remain functional for 1 hour
Can be broken down in liver, kidney or plasma enzymes
Fate of Thyroid/Steroid hormones after secretion
Remain in circulation due to being bound to transport proteins
Due to lipid solubility
Enters bloodstream
Hypothalamus Function
Inferface between nervous system and endocrine system
Anterior Pituitary Gland Function
Releases hormones controlling the endocrine system
Acts as Master Gland
Posterior Pituitary Gland Function
Releases ADH and Oxytocin
3 Mechanisms of Hypothalamus Activity
Production of ADH/Oxytocin
Secretion of regulatory hormones to control activity of anterior lobe of pituitary gland
Control of sympathetic output to adrenal medullae
Pituitary Gland Structure
2 Lobes (Anterior/Posterior)
Anterior Lobe contains 3 tissues
Pars Intermedia (Anterior) secretes MSH specifically
Hypophyseal Portal System Pathway
Neurosecretory Neurons at media eminece secrete regulatory factors
Enter fenestrated capillaries in capilllary bed in hyporthalamus
Portal Veins
Capillary bed in anterior pituitary
Feedback Control of Prolactin
Prolactin inhibits PFR
Prolacton also stimulates PIH to inhibit Prolactin secretion
Feedback Control of Growth Factor
GH stimulates Somatomedins secretion
Somatomedins stimulate GH-IH to inhibit GH release
Somatomedins also inhibits GH-RH to stimulate GH release
