Endocrine System Flashcards
Endocrine Grands
Synthesize and secrete chemical substances called hormones directly into the circulatory system
Exocrine Glands
Secretes substances transported by ducts (gallbladder)
Hypothalamus
The regulatory center of the endocrine system, part of the forebrain, located above the pituitary gland, secretes hormones, regulate the pituitary via negative feedback, ADH/oxytocin
Gonadotropin-releasing Hormone (GnRH)
Stimulates the anterior pituitary to secrete follicle-stimulating hormone FSH and LH
Hypophyseal Portal System
Releasing hormones can immediately reach the anterior pituitary without first entering the circulatory system
Thyrotropin-releasing hormone (TRH)
Stimulates the anterior pituitary to release thyroid hormones, T3 and T4
Growth hormone-releasing (GHRH)
Stimulates the anterior pituitary to release growth hormone
Pituitary Gland
Small, trilobed gland at the base of the brain, anterior and posterior, intermediate
Infundibulum
Connects the hypothalamus to the posterior pituitary gland
Anterior Pituitary
Synthesizes direct hormones and tropic hormones
Tropic Hormones
FSH, LH, ACTH, TSH
Follicle-stimulating (FSH)
Maturation of ovarian follicles, which in turn secrete estrogen, sperm production
Luteinizing Hormone (LH)
Stimulates ovulation and maintenance of the corpus luteum, regulating progesterone secretion, synthesizes testosterone
Adrenocorticotropic hormone (ACTH)
Stimulates the adrenal cortex for glucocorticoids
Thyroid-stimulating Hormone (TSH)
Stimulates the thyroid gland to synthesize and release thyroid hormones
Direct Hormones
Prolactin, Endorphins, Growth hormone, MSH
Prolactin
Stimulates milk production
Endorphins
Pain-relieving
Growth hormone (GH)
bone and muscle growth
Melanocyte-stimulating hormone (MSH)
Sun-inducing darkening of skin
Posterior Pituitary
Does not synthesize hormones, stores and releases peptide hormones oxytocin and antidiuretic hormone
Oxytocin
Uterine contractions, milk secretion
Antidiuretic Hormone (ADH)
Increases water permeability in the collecting duct of the nephron, promoting water reabsorption and increasing blood volume, decreases blood osmolarity
Adrenal Glands
Top of kidneys, adrenal cortex, adrenal medulla
Corticosteroids
Exert their action by determining which genes are transcribed in the nuclei of their target cells and at what rate
Glucocorticoids
Cortisol and cortisone, glucose regulation and protein metabolism, anti-inflammatory effects
Mineralocorticoids
Aldosterone regulates plasma levels of sodium and potassium, active reabsorption of sodium
Androgens
Male sex hormones
Epinephrine
Increases the conversion of glycogen to glucose in liver and muscle tissue, increase metabolic rate, fight or flight effect
Thyroxine (T4)
4 iodine atoms, formed and secreted by the thyroid gland
Triiodothyronine (T3)
Five times more potent than T4, Converted from T4
Hypothyroidism
Thyroid hormones are under secreted or not secreted at all, slowed heart rate, fatigue, weight gain
Hyperthyroidism
Overstimulated, increased metabolic, profuse sweating, weight loss
Parathyroid Glands
Four small pea-shaped structures embedded in the posterior surface of the thyroid, secrete PTH, regulate plasma Ca2+ concentration
Islets of Langerhans
Small glandular structures where endocrine function is performed (alpha,beta,delta) in Pancreas
Alpha cells
Produce and secrete glucagon
Beta cells
Produce and secrete insulin
Delta cells
Secrete somatostatin
Glucagon
Peptide hormone, released when blood glucose levels are low (Pancreas)
Insulin
Protein hormone, is secreted in response to high blood glucose concentrations
Somatostatin
Blocks the secretion of both insulin and glucagon from adjacent cells
Type 1 Diabetes
Less common, younger, presence of islet cell antibodies, autoimmune
Type 2 Diabetes
Most common, older, resistance to insulin, increased hepatic glucose production, obesity
Renin
An enzyme that converts the plasma protein angiotensinogen and angiotensin 1 in kidneys
EPO (erythropoietin)
Glycoprotein produced in the kidney that stimulates red blood cell production
Melatonin
Released by the pineal gland, base of brain, regulation of the circadian rhythms
Peptide Hormones
Amino acids, extracellular, stimulates a receptor, dissolves and travels freely, quick onset, short-lived
Steroid Hormone
Cholesterol, Intracellular, binds to a receptor, bound to a carrier protein, slow onset, long-lived action
