New User Special Price Expires in

Let's log you in.

Sign in with Facebook


Don't have a StudySoup account? Create one here!


Create a StudySoup account

Be part of our community, it's free to join!

Sign up with Facebook


Create your account
By creating an account you agree to StudySoup's terms and conditions and privacy policy

Already have a StudySoup account? Login here

Chapter 17- The Endocrine System

by: Marlee Porter

Chapter 17- The Endocrine System BIOL 20214

Marketplace > Texas Christian University > Biology > BIOL 20214 > Chapter 17 The Endocrine System
Marlee Porter

Preview These Notes for FREE

Get a free preview of these Notes, just enter your email below.

Unlock Preview
Unlock Preview

Preview these materials now for free

Why put in your email? Get access to more of this material and other relevant free materials for your school

View Preview

About this Document

Study guide for Exam 1
Anatomy and Physiology
Mrs. Crenshaw
Study Guide
anatomy, Physiology, Anatomy & Physiology, Endocrine system
50 ?




Popular in Anatomy and Physiology

Popular in Biology

This 12 page Study Guide was uploaded by Marlee Porter on Wednesday February 3, 2016. The Study Guide belongs to BIOL 20214 at Texas Christian University taught by Mrs. Crenshaw in Spring 2016. Since its upload, it has received 32 views. For similar materials see Anatomy and Physiology in Biology at Texas Christian University.


Reviews for Chapter 17- The Endocrine System


Report this Material


What is Karma?


Karma is the currency of StudySoup.

You can buy or earn more Karma at anytime and redeem it for class notes, study guides, flashcards, and more!

Date Created: 02/03/16
Chapter 17­ The Endocrine System Endocrine Glands ­Ductless; release hormones into surrounding tissue; highly vascular  ­Neuroendocrine ­Combined functions associate with both the nervous system and the endocrine  system ­Adipose cells, cardiac cells, and epithelial cells in digestive organs also have minor  endocrine functions  ­Some endocrine organs also have exocrine functions ­Testes, ovaries, liver and pancreas Hormones ­Long­distance chemical signals that target cells all over the body ­Intracellular effects (exocrine extracellular effects) ­Regulate processes such as growth and development, reproduction, metabolism, blood  composition, and mobilization of body defenses by cells ­Compared to: ­Autocrines­ chemicals that exert their effect on the same cells that secrete them ­Paracrines­ chemicals that exert their effect on the cells immediately neighboring          them ­Three Classes: ­Steroid Hormones ­Derived from cholesterol ­Hydrophobic ­Not stored in cells ­Include: aldosterone, androgens, corticosterone, cortisol, estrogens, and  progesterone ­Monoamines (Biogenic) Hormones ­Derived from amino acids ­Subclass= catecholamines  ­Hydrophilic  ­Include: epinephrine/norepinephrine, melatonin, and thyroid hormone ­Peptide Hormones ­Chains of 3­200+ amino acids ­Hydrophilic  ­Subclasses= ­Oligopeptides: ­ADH, GnRH, Oxytocin, and TRH ­Polypeptides: ­ACTH, Calcitonin, CRH, Glucagon, GH, GHRH, Insulin,  PTH, PRL, Somatostatin (GHIH) ­Glycoproteins   ­FSH, LH, TSH ­Secretion ­Source Organ­ an endocrine gland responsible for secreting a particular hormone ­Will secrete a hormone in response to one of three types of stimuli: 1. Humoral Stimulus­ changing solute concentration  2. Hormonal Stimulus­ hormone released by another organ 3. Neural Stimulus­ nervous system stimulation  ­Most hormone secretion is regulated by negative feedback ­increasing levels of a particular hormone in the blood will automatically  inhibit production of the hormone at the source  ­Transport  ­Most hydrophilic hormones travel freely through blood plasma ­Most hydrophobic hormones are bound the transport proteins in the blood to  increase solubility  ­Some hormones are secreted in an inactivated form, and must be activated in the  blood or by the target cell ­Hormone activity is limited by: ­Half­life—length of time for a hormone’s blood level to decrease by ½  ­Transport proteins can prolong half­life ­Some are degraded by enzymes; most are removed from the blood by the  liver or kidneys ­Binding ­Bind specifically to protein receptors of target cells  ­Can be intracellular or extracellular  ­Hormone chemistry dictates what kind of receptor a hormone will bind to ­The more receptors a cell has for a specific hormone, the stronger the response  will be  ­Up Regulation­ target cell increases sensitivity to a hormone by     increasing the number of receptors  ­Down Regulation­ target cell decreases sensitivity to a hormone by     decreasing the number of receptors  ­Location of Receptors: ­Hydrophilic­ bind to extracellular receptors  ­Second­messenger system ­These pathways can activate or inhibit metabolic pathways that  already exist in the cell ­Effects are quick and short­lived  ­Hydrophobic­ diffuse through the membrane to intracellular receptors  ­Steroid hormones and thyroid hormone ­Hormone receptor complex is transported to the nucleus  ­Results in direct gene activation  ­Results in transcription (production of mRNA) and translation (production of proteins)  ­ Effects are slow and require several hours to days to show  ­Actions  ­Amplification cascade­ one hormone can trigger the synthesis/activity of a  “downstream” of chemicals  ­Hormones interact with one another by: ­Permissiveness­ one hormone is not fully effective without another      hormone being present  ­Synergism­ more than one hormone produces the same effects at the           target cell and their combined effects are amplified  ­Antagonism­ one hormone opposes the action of another hormone  Specific Hormone Examples  Hypothalamus and the Pituitary Gland ­Infundibulum­ connects the hypothalamus to the pituitary gland  ­Hypothalamus­ “master endocrine gland” ­Produces 8 hormones ­Pituitary Gland­ two separate structures ­Posterior Pituitary (neurohypophysis) ­Neurons and neuroglia ­Hypothalamo­Hypophyseal Tract ­2 neurohormones: ­Oxytocin ­Stimulated by: stretching of the cervix and uterus,  suckling of an infant at the breast ­Inhibited by: Lack of stimulus ­Target and Effects:      1. Stimulates smooth muscle contraction of the           uterus during labor and nursing       2. Stimulates milk ejection during nursing             (positive feedback)       3. Cuddle hormone  ­Antidiuretic hormone (ADH) ­Aka= Vasopressin ­Stimulated by: when blood­solute concentration  increases due to dehydration or fluid loss ­Inhibited by: Alcohol, caffeine, high water intake ­Target and effects:    1. Decrease urination to conserve water and         prevent dehydration    2. Minor role in stimulation of peripheral       vasoconstriction in order to increase systemic BP ­Diabetes Insipidus­ hyposecretion of ADH ­Output large amounts of dilute urine ­ADH­mediated water retention—hypersecretion  ­Associated with meningitis, anesthesia,  neurosurgery or hypothalamic surgery  ­Can lead to edema, headache, disorientation ­Anterior Pituitary (adenohypophysis)  ­Glandular tissue similar to other endocrine organs ­Hypophyseal­Portal System  ­6 neurohormones (FLAT PG) ­Follicle Stimulating Hormone (FSH) ­Gonadotropin ­Stimulated by: GnRH ­Inhibited by: increased levels of gonadal hormones  (negative feedback) ­Targets and Effects: ­Males­ testes to produce sperm  (spermatogenesis) ­Females­ ovaries to induce growth of  ovarian follicles and produce estrogens  ­Luteinizing Hormone (LH) ­Gonadotropin ­Stimulated by: GnRH ­Inhibited by: increased levels of gonadal hormones  (negative feedback) ­Targets and Effects: ­Males­ testes to produce testosterone  ­Females­ ovaries to trigger ovulation and  production of progesterone by the corpus  luteum  ­Adrenocorticotropic Hormone (ACTH) ­Stimulated by: CRH ­Inhibited by: increased levels of ACTH (negative  feedback) ­Target and Effects: 1.Stimulates the adrenal cortex to release     corticosteroid hormones (some reduce the     stress­response) 2. Part of the HPA axis ­Thyroid Stimulating Hormone (TSH) ­AKA= thyrotropin  ­Stimulated by: TRH ­Occurs when energy needs of the body  increase or when TH levels begin to drop  ­Inhibited by:  ­High blood­TSH levels (negative feedback) ­High glucocorticoid levels ­Target and Effect­ stimulates normal development  and secretory activity of thyroid gland  *Hypothyroid individuals often exhibit high levels  of TSH ­Growth Hormone (GH)  ­Stimulated by: GHRH ­Inhibited by: GHIH (Somatostatin), high blood  levels of GH (negative feedback) and  decreased GHRH ­Target and effects: ­Induces widespread tissue growth ­Indirectly promotes growth by  stimulating the release of Insulin­ Like Growth Factors (IGFs)  ­Targets cartilage, bone, muscle, fat ­Stimulates lipid breakdown for energy ­Prevents metabolism of proteins & glucose ­Increases levels of Na+, K+, Cl­, and Ca2+ *GH is highest during the first two hours of sleep  and following vigorous exercise; also following  trauma, stress, and hypoglycemia  ­Pituitary Gigantism­ hypersecretion of GH before          growth plates fuse; people are abnormally tall  ­Acromegaly­ hypersecretion of GH after the         growth plates fuse; overgrowth of cartilage and         bones ­Pituitary Dwarfism­ hyposecretion of GH in         children  ­Psychosocial Dwarfism­ stress and emotional         disorders suppress the hypothalamic release of         GHRH and GH ­Prolactin (PRL) ­Stimulated by: high estrogen levels ­Inhibited by: prolactin­ inhibiting hormone (PIH) ­Target and effect: ­Breast tenderness during menstrual cycle ­Milk production after birth ­In males, can increase sensitivity to LH ­Hypersecretion of PRL­ can cause inappropriate  lactation, lack of menses, infertility and impotence  (in males) Other Endocrine Organs  ­Thyroid Gland ­Follicles ­Site of TH production ­Follicle cells­ cuboidal or squamous epithelium, and produce the  glycoprotein thyroglobulin  ­Colloid ­stores thyroglobulin ­Parafollicular cells ­Epithelial cells embedded in the CT between follicles  ­Produce calcitonin  ­Thyroid Hormone (TH) ­Source­ follicle cells and colloid  ­Stimulated by: TSH from the anterior pituitary  ­Inhibited by: decreased TSH levels (negative feedback) ­Target and Effects: ­Development of multiple body systems (nervous, reproductive,  musculoskeletal) ­Promote alertness and quicken reflexes ­Stimulates protein synthesis in hair, skin, nails and teeth  ­Increases respiratory rate, heart rate, and contractility  ­Calorigenic effect­ increased metabolism stimulates hunger and  nutrient catabolism, increases the catabolism of fats and glucose  ­Synthesis: 1. Iodide from the bloodstream is oxidized to Iodine 2. Iodine and thyroglobulin are assembled into both forms of TH 3. Colloid releases some T3 and mostly T4 in response to TSH 4. T4 and T3 are transported through the blood bound to      Thyroxine­binding globulins (TBGs) and produced by the liver  5. T4 an T3 reach target cells­ most cells will use T3, and then      convert T4 to T3 ­Imbalances  ­Myxedema (mucous swelling) ­Prolonged hyposecretion of TH ­Low metabolic rate, lethargy, chills, constipation, thick  dry skin, puffy eyes, edema  ­Endemic Goiter  ­Enlargement of the thyroid gland due to iodide deficiency ­Associated with hyposecretion of TH ­Cretinism ­Extreme hypothyroidism in infants ­Results in short stature, mental retardation, thick tongue  and neck; may be caused by insufficient thyroid gland or  maternal dietary deficiencies  ­Grave’s Disease (Toxic Goiter) ­Abnormal antibody production mimics TSH and  stimulates TH release from the thyroid gland  ­Elevated metabolic rate, sweating, rapid irregular  heartbeat, nervousness, weight loss  ­Exophthalmos­ protrusion of eyeballs due to edema in the                            eye socket, which eventually causes the                             tissue to become fibrous ­Calcitonin ­Source: Parafollicular cells ­Stimulated by: excessive blood­calcium levels ­Inhibited by: declining blood­calcium levels ­Target and Effect: ­Stimulates calcium uptake and storage into bone matrix ­Osteoclast activity is inhibited ­Parathyroid Hormone ­Source: Parathyroid gland ­Stimulated by: decreased blood­calcium levels ­Inhibited by: rising blood­calcium levels ­Targets and effects: ­Stimulates bone resorption (osteoclasts) and inhibits bone deposit ­Increases reabsorption of Ca2+ from the kidneys ­Increases activation of Vitamin D (calcitriol) to increase  absorption of Calcium from the intestines  ­Hyperparathyroidism  ­Often from a parathyroid tumor ­Bones soften, kidney stone formation ­Metastatic calcification of soft organs ­Hypoparathyroidism  ­Often due to trauma ­Leads to fatal tetany within 3­4 days  ­Adrenal Cortex ­Regions: ­Zona Glomerulosa ­Thin, superficial; cluster of cells ­Produce mineralocorticoids   ­Zona Fasciculata  ­Cells arranged in parallel cords separated by capillaries  ­Secretes glucocorticoids and androgens  ­Zona Reticularis ­Thin, deep layer ­Cells form branching network ­Secretes glucocorticoids and androgens   ­Aldosterone ­Source: Zona Glomerulosa  ­Accounts for 95% of mineralocorticoids  ­Stimulated by: decreasing blood volume and pressure, and by rising  levels of K+ ­Inhibited by: increasing blood volume/pressure ­Target and effects: 1. Promotes Na+ reabsorption (water retention) and K+ elimination     by the kidneys  2. Maintains blood volume, blood pressure and pH ­Cortisol and Corticosterone  ­Source: Zona Fasciculata   ­Stimulated by: Rhythmic release of ACTH from the Anterior Pituitary ­Inhibited by: Rising cortisol levels “shut off” CRH release at the  hypothalamus (negative feedback) ­Target and Effects: 1. Regulate daily glucose levels 2. Increase catabolism of lipids, proteins and promote      hyperglycemia  3. Helps the body respond to stress and repair damaged tissue 4. Can inhibit inflammatory and immune response 5. Long­term secretion can disrupt normal activity of the      cardiovascular and GI systems and can deplete protein stores,       and cause retention of water and electrolytes ­Gonadocorticoids ­Source: Zona Reticularis  ­Produces Androgens ­DHEA is most abundant  ­Triggers and release are unclear ­Target and effects: 1.   DHEA is the precursor to Testosterone in males and females 2. Indirectly responsible for male secondary sex characteristics  (bone growth, pubic and axillary hair growth, apocrine gland  activation) and libido 3. In adult females, it contributes to libido and estrogen  production following menopause ­Adrenal Disorders ­Aldosteronism ­Hypersecretion of aldosterone ­Typically results from adrenal tumors ­Can result in hypertension and edema (due to increased Na+  reabsorption) ­Accelerated excretion of K+ can result in hypokalemia  ­Addison’s Disease ­Hyposecretion of mineralocorticoids and glucocorticoids  ­Causes hypoglycemia, hypotension, and electrolyte imbalances ­Weight loss and muscle weakness ­Corticosteroid replacement therapy is successful  ­Cushing’s Syndrome ­Usually caused by a pituitary tumor (increased ACTH release) ­Results in hypersecretion of glucocorticoids ­Prolonged hyperglycemia, hypertension, depletion of muscle and  bone proteins, water and salt retention, and edema  ­Abnormal fat deposition between shoulders or in the face  ­Androgenital Syndrome  ­Congenital adrenal hyperplasia­ hypersecretion of  Gonadocorticoids  ­Obscured by testosterone production of gonads in adult males ­Can result in precocious puberty in young males  ­Masculinization of features in females—hirsutism, ambiguous  genitalia, and failure to menstruate  ­Stress Management  ­Short Term Stress ­Autonomic nervous system—sympathetic neurons target the  adrenal medulla  ­Triggers release of epinephrine and norepinephrine into the  body’s bloodstream—fight or flight response ­Long Term Stress ­Sympathetic neurons and the HPA axis (Hypothalamic­pituitary­ adrenal cortex) ­Surges in ACTH target the adrenal cortex ­Induces cortisol release and causes aldosterone release  ­Effects: 1. Heart palpitations and Hypertension (and      atherosclerosis) 2. Susceptibility to infection and cancer formation 3.  Suppressed secretion of sex hormones       4.  Severe tissue wasting and organ failure ­Pineal Gland  ­Melatonin ­Stimulated by: absence of light ­Inhibited by: presence of bright light  ­Target and Effects:       1. Linked to activities like sleep, appetite and body temperature      2. Powerful antioxidant      3. Inhibits Gonadotropin release  Thymic Hormones  ­Functions of the Thymus:  ­Associated with the endocrine, lymphatic and immune systems ­Site of maturation of T Cell Lymphocytes ­Grows until the age of 5­6, then undergoes atrophy into adulthood ­Hormones: Thymopoietin, Thymosin and Thymulin ­Functions of Thymic Hormones: 1. Stimulate the development of lymphatic organs 2. Regulate the development and activity of T Cell Lymphocytes The Pancreas  ­Capable of both exocrine and endocrine functions ­Exocrine Secretions are digestive enzymes from Acinar Cells  ­Endocrine Secretions are Insulin from Beta (β) Cells, and Glucagon from  Alpha (α) Cells– both amino acid­based hormones ­Pancreatic Islets contain clusters of α and β cells Insulin ­Source: Pancreatic β Cells ­Stimulated by: High blood levels of glucose, amino acids and fatty acids during and         immediately following a meal       ­Parasympathetic Activity        ­Inhibited by: decreased levels of Glucose in the blood (hypoglycemia)      ­Increased Sympathetic Activity        ­Targets and Effects:  1. Lowers circulating amounts of glucose, amino acids and fat by promoting  cellular uptake of them 2. Some of these molecules are immediately used for cellular activities 3. Some of these molecules are stored for later use as glycogen, protein and fat        ­Diabetes Mellitus ­Hyposecretion or hypoactivity of insulin  ­Type I DM ­Insulin Dependent Diabetes Mellitus (IDDM) ­More than 1 million Americans ­Beta cells are destroyed by the immune system  ­Type II DM ­Non­Insulin Dependent Diabetes Mellitus (NIDDM) ­approx. 12 million Americans ­Insulin resistant­ insulin receptors are unable to respond  ­Most are overweight and sedentary Glucagon ­Source: Pancreatic α Cells ­Stimulated by: Blood­glucose levels drop       ­Sympathetic Nervous System can induce glucagon release        ­Inhibited by: Rising blood­glucose levels (hyperglycemia)     ­Insulin and GHIH can inhibit glucagon release        ­Targets and Effects:  1. Promotes Glycogen breakdown (glycogenolysis) and the formation of glucose       from amino acids (gluconeogenesis) 2. Increases circulating blood­glucose 3. Promotes release of fat from Adipose cells (lipolysis) 4. Promotes amino acid absorption following a high­protein meal Endocrine Functions of Other Tissues  -The Skin produces: cholecalciferol, the precursor for calcitriol -The Liver produces: -Calcidiol, another precursor to calcitriol -Angiotensin to regulate blood volume and pressure -Erythropoietin to stimulate erythrocyte production -Hepcidin to stimulate iron homeostasis -Insulin-Like Growth Factors -The Kidneys produce: calcitriol and Renin to regulate angiotensin production -The Heart produces: Natriuretic Peptides to regulate blood pressure -The Stomach and Small intestine produce: -Cholecystokinin -Gastrin -Ghrelin -Peptide YY -Adipose Tissue produces: Leptin to regulate appetite and puberty -Osseous Tissue produces Osteocalcin to regulate pancreatic production of insulin -The Placenta secretes estrogens to maintain pregnancy and fetal development


Buy Material

Are you sure you want to buy this material for

50 Karma

Buy Material

BOOM! Enjoy Your Free Notes!

We've added these Notes to your profile, click here to view them now.


You're already Subscribed!

Looks like you've already subscribed to StudySoup, you won't need to purchase another subscription to get this material. To access this material simply click 'View Full Document'

Why people love StudySoup

Bentley McCaw University of Florida

"I was shooting for a perfect 4.0 GPA this semester. Having StudySoup as a study aid was critical to helping me achieve my goal...and I nailed it!"

Jennifer McGill UCSF Med School

"Selling my MCAT study guides and notes has been a great source of side revenue while I'm in school. Some months I'm making over $500! Plus, it makes me happy knowing that I'm helping future med students with their MCAT."

Steve Martinelli UC Los Angeles

"There's no way I would have passed my Organic Chemistry class this semester without the notes and study guides I got from StudySoup."


"Their 'Elite Notetakers' are making over $1,200/month in sales by creating high quality content that helps their classmates in a time of need."

Become an Elite Notetaker and start selling your notes online!

Refund Policy


All subscriptions to StudySoup are paid in full at the time of subscribing. To change your credit card information or to cancel your subscription, go to "Edit Settings". All credit card information will be available there. If you should decide to cancel your subscription, it will continue to be valid until the next payment period, as all payments for the current period were made in advance. For special circumstances, please email


StudySoup has more than 1 million course-specific study resources to help students study smarter. If you’re having trouble finding what you’re looking for, our customer support team can help you find what you need! Feel free to contact them here:

Recurring Subscriptions: If you have canceled your recurring subscription on the day of renewal and have not downloaded any documents, you may request a refund by submitting an email to

Satisfaction Guarantee: If you’re not satisfied with your subscription, you can contact us for further help. Contact must be made within 3 business days of your subscription purchase and your refund request will be subject for review.

Please Note: Refunds can never be provided more than 30 days after the initial purchase date regardless of your activity on the site.