Endocrine System Introduction
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Questions and Answers

What is the primary difference between Type 1 and Type 2 diabetes mellitus?

  • Type 2 requires daily insulin injections, whereas Type 1 does not.
  • Type 1 usually develops later in life than Type 2.
  • Type 1 is insulin resistant, while Type 2 has inadequate insulin production.
  • Type 1 is characterized by inadequate insulin production, while Type 2 typically involves insulin resistance. (correct)

    • Which complication is NOT commonly associated with poorly managed diabetes mellitus?

  • Peripheral nerve problems
  • Increased risk of early heart attacks
  • Kidney degeneration
  • Increased insulin sensitivity (correct)

    • Which hormone is primarily produced by the testes and plays a key role in male sexual differentiation?

  • Inhibin
  • Thymosin
  • Estrogen
  • Testosterone (correct)

    • Which organ produces hormones that promote the development and maturation of lymphocytes?

    <p>Thymus (B)</p> Signup and view all the answers

    What is the function of the hormone leptin produced by adipose tissue?

    <p>Provides feedback control of appetite (A)</p> Signup and view all the answers

    Which of the following hormones is responsible for converting angiotensinogen to angiotensin I?

    <p>Renin (A)</p> Signup and view all the answers

    Which hormone produced by the heart acts to reduce blood volume and blood pressure?

    <p>Atrial natriuretic peptide (ANP) (B)</p> Signup and view all the answers

    What is the effect of down-regulation on hormone receptors?

    <p>Decrease the sensitivity of cells to the hormone (C)</p> Signup and view all the answers

    Which of the following best describes the action of intracellular receptors?

    <p>They initiate responses by altering genetic activity (A)</p> Signup and view all the answers

    What occurs during the process of amplification in hormone action?

    <p>A single hormone binding leads to the activation of multiple pathways (C)</p> Signup and view all the answers

    Which of the following statements about catecholamines is accurate?

    <p>They bind to extracellular receptor proteins (B)</p> Signup and view all the answers

    What is the role of G-proteins in the hormone signaling process?

    <p>They help transmit signals from the receptor to enzymes within the cell (D)</p> Signup and view all the answers

    How does the presence of a hormone influence the number of hormone receptors?

    <p>It decreases when hormone levels are high (D)</p> Signup and view all the answers

    Which type of hormones typically utilize second messengers for their action?

    <p>Peptide hormones and catecholamines (D)</p> Signup and view all the answers

    What is the primary outcome of a hormone acting as a first messenger?

    <p>Triggering the production of second messengers inside the cell (C)</p> Signup and view all the answers

    What percentage of T4 remains unbound and free to diffuse into tissues?

    <p>0.03 percent (A)</p> Signup and view all the answers

    What is one major function of thyroid-stimulating hormone (TSH)?

    <p>Activates key enzymes in thyroid hormone production (C)</p> Signup and view all the answers

    What effect does the absence of TSH have on thyroid follicles?

    <p>They remain inactive (D)</p> Signup and view all the answers

    What hormone is produced by the C cells in the thyroid gland?

    <p>Calcitonin (B)</p> Signup and view all the answers

    What process is activated by thyroid hormones that results in increased energy consumption?

    <p>Glycolysis (B)</p> Signup and view all the answers

    How does parathyroid hormone (PTH) primarily respond to low calcium ion levels?

    <p>Stimulates osteoclast activity (C)</p> Signup and view all the answers

    Which gland is responsible for secreting hormones that affect stress responses and electrolyte balance?

    <p>Adrenal glands (D)</p> Signup and view all the answers

    Which of the following effects is NOT caused by thyroid hormones?

    <p>Reduce oxygen consumption (D)</p> Signup and view all the answers

    What primary function does the zona glomerulosa of the adrenal cortex serve?

    <p>Produces mineralocorticoids (D)</p> Signup and view all the answers

    What is the role of calcitonin in the body?

    <p>Decreases calcium levels in blood (D)</p> Signup and view all the answers

    Which of the following hormones is primarily produced by the zona fasciculata?

    <p>Cortisol (C)</p> Signup and view all the answers

    What percentage of T3 remains free and available for tissue diffusion?

    <p>0.3 percent (C)</p> Signup and view all the answers

    What physiological effect results from the secretion of epinephrine by the adrenal medulla?

    <p>Enhanced glycogenolysis (A)</p> Signup and view all the answers

    How does the adrenal cortex respond to a rise in blood potassium concentration?

    <p>Secretion of aldosterone (C)</p> Signup and view all the answers

    Which zone of the adrenal cortex is responsible for producing small quantities of androgens?

    <p>Zona reticularis (C)</p> Signup and view all the answers

    What role does cortisol play in regulating hormonal feedback mechanisms?

    <p>Inhibits the production of CRH (D)</p> Signup and view all the answers

    What is the primary effect of norepinephrine secretion by the adrenal medulla?

    <p>Enhances cardiac output (B)</p> Signup and view all the answers

    What triggers the secretion of melatonin from the pineal gland?

    <p>Circadian rhythm changes (A)</p> Signup and view all the answers

    How does aldosterone affect the body's electrolyte balance?

    <p>Promotes sodium conservation (A)</p> Signup and view all the answers

    What is the main function of catecholamines produced in the adrenal medulla?

    <p>Mediate stress responses (C)</p> Signup and view all the answers

    What is the role of adenylate cyclase in the cAMP signaling pathway?

    <p>It converts ATP to cyclic AMP. (A)</p> Signup and view all the answers

    Which molecule acts as a second messenger in the signaling pathway involving cAMP?

    <p>Cyclic AMP (B)</p> Signup and view all the answers

    What is the function of phosphodiesterase (PDE) in relation to cAMP?

    <p>To convert cAMP into AMP. (B)</p> Signup and view all the answers

    Which of the following triggers the release of calcium ions from intracellular reserves?

    <p>Inositol triphosphate (D)</p> Signup and view all the answers

    How do steroid hormones affect target cells?

    <p>By altering DNA transcription rate in the nucleus. (C)</p> Signup and view all the answers

    What primarily controls hormone secretion within the body?

    <p>Negative feedback mechanisms. (B)</p> Signup and view all the answers

    Which structure connects the pituitary gland to the hypothalamus?

    <p>Infundibulum (C)</p> Signup and view all the answers

    Which hormone secretion mechanism involves neurotransmitters?

    <p>Neural stimuli (D)</p> Signup and view all the answers

    Which hormone regulatory mechanism might only involve a single hormone?

    <p>Humoral stimuli (B)</p> Signup and view all the answers

    What is the primary action of calcium ions in the signaling process?

    <p>Binding to calmodulin to activate enzymes. (B)</p> Signup and view all the answers

    Flashcards

    Type 1 Diabetes Mellitus

    A form of diabetes characterized by inadequate insulin production requiring insulin injections.

    Type 2 Diabetes Mellitus

    The most common form of diabetes; initially produces normal insulin but shows insulin resistance, often related to obesity.

    Complications of Diabetes

    Untreated diabetes can lead to kidney damage, retinal damage, heart issues, nerve problems, and possible amputations.

    Endocrine Functions of Kidneys

    Kidneys release hormones like calcitriol and erythropoietin, and the enzyme renin.

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    Natriuretic Peptides

    Hormones produced by the heart to reduce blood volume and pressure when it becomes excessive.

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    Role of Thymus

    Produces thymosin, which promotes the development and maturation of lymphocytes.

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    Leptin from Adipose Tissue

    A hormone produced by fat tissue that regulates appetite.

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    Adenylate Cyclase

    An enzyme activated by G proteins that converts ATP to cAMP.

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    Cyclic AMP (cAMP)

    A second messenger involved in signaling pathways that activates kinases.

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    Phosphodiesterase (PDE)

    An enzyme that converts cAMP to AMP, terminating its action.

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    G-proteins

    Molecular switches that activate second messenger pathways in cells.

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    Phospholipase C (PLC)

    An enzyme activated by G-proteins that produces DAG and IP3 from phospholipids.

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    Diacylglycerol (DAG)

    A second messenger that remains in the membrane and activates protein kinase C.

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    Inositol Triphosphate (IP3)

    A second messenger that triggers the release of Ca2+ ions from storage.

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    Hormonal Stimuli

    Hormone secretion response to the presence or absence of hormones.

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    Humoral Stimuli

    The change in the composition of bodily fluids that regulates hormone secretion.

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    Negative Feedback

    A mechanism that reduces the intensity of a stimulus to control hormone levels.

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    Equilibrium State

    The balance between free and bound hormone forms in the bloodstream.

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    Hormone Action Mechanisms

    Hormones alter genetic activity, protein synthesis, or membrane permeability.

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    Hormone Receptor

    Protein molecule where a hormone attaches to exert its effects.

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    Down-regulation

    Process where high hormone levels decrease receptor numbers.

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    Up-regulation

    Process where low hormone levels increase receptor numbers.

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    Extracellular Receptors

    Receptors on the plasma membrane for non-lipid soluble hormones.

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    Second Messenger

    Intermediary molecule activated by first messenger hormone that modifies cellular reactions.

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    Thyroid-stimulating hormone (TSH)

    A hormone that activates thyroid hormone production by binding to receptors on thyroid follicles.

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    Free T3 and T4

    Small percentages of thyroid hormones unbound and able to diffuse into tissues.

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    Calorigenic effect

    Increased energy consumption and heat generation in cells due to thyroid hormones.

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    Thyroid hormones and development

    Essential for normal skeletal, muscular, and nervous system development in children.

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    C cells and calcitonin (CT)

    C cells produce calcitonin, regulating calcium concentration and promoting its excretion.

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    Parathyroid hormone (PTH)

    Hormone that increases blood calcium levels, antagonizing calcitonin.

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    Effects of thyroid hormones

    Elevate oxygen consumption, increase heart rate, and stimulate RBC formation.

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    Parathyroid glands location

    Four glands located on the posterior surface of the thyroid gland.

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    Role of osteoclasts

    Cells stimulated by PTH that break down bone tissue and release calcium.

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    Adrenal glands function

    Secrete hormones affecting electrolyte balance and stress responses.

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    Superficial adrenal cortex

    Outer layer of the adrenal gland that stores lipids and produces corticosteroids.

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    Corticosteroids

    Steroid hormones manufactured by the adrenal cortex, involved in stress responses.

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    Zona glomerulosa

    The outer layer of the adrenal cortex producing mineralocorticoids like aldosterone.

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    Aldosterone

    A mineralocorticoid hormone that conserves sodium ions and eliminates potassium.

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    Zona fasciculata

    Middle layer of the adrenal cortex that produces glucocorticoids like cortisol.

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    Glucocorticoids

    Hormones that regulate glucose metabolism and have anti-inflammatory effects.

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    Zona reticularis

    Inner layer of the adrenal cortex that produces small amounts of androgens.

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    Adrenal medulla

    Inner part of the adrenal gland that produces catecholamines: epinephrine and norepinephrine.

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    Epinephrine

    A catecholamine produced in the adrenal medulla that triggers fight-or-flight response.

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    Melatonin

    Hormone secreted by the pineal gland that regulates circadian rhythms.

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    Study Notes

    Endocrine System Introduction

    • Endocrine cells and tissues produce about 30 different hormones (chemical messengers)
    • Hormones control and coordinate bodily processes
    • Homeostasis is preserved through intercellular communication by the nervous and endocrine systems

    Mechanisms of Intercellular Communication

    • Direct communication: Specialized exchange of ions and molecules between adjacent cells via gap junctions
    • Paracrine communication: Chemical signals transfer information from cell to cell within a single tissue
    • Autocrine communication: Messages affect the same cells that secrete them. Example: prostaglandins secreted by smooth muscle cells cause the same cells to contract.
    • Endocrine communication: Cells release hormones transported in the bloodstream, altering the metabolic activities of many organs. Target cells have receptors to bind and "read" hormonal messages.

    Hormone Function

    • Hormones alter the quantity/type/activity of enzymes and proteins in target cells (affecting multiple tissues/organs at the same time)
    • They also affect long-term processes such as growth and development
    • Hormones can lead to action potentials propagated along axons

    Hormone Classes

    • Amino acid derivatives (Biogenic amines): Small molecules related to amino acids
      • Derivatives of tyrosine: thyroid hormones, catecholamines (epinephrine, norepinephrine, dopamine)
      • Derivative of tryptophan: serotonin, melatonin
    • Peptide hormones: Chains of amino acids
      • Most synthesized as prohormones- inactive molecules converted into active hormones before or after secretion
      • Divided into glycoproteins (proteins >200 amino acids long with carbohydrate side chains) and short polypeptides/small proteins (e.g., ADH, OXT, insulin, GH, PRL)
    • Lipid derivatives (Steroid hormones): Derived from cholesterol
      • Bound to specific plasma transport proteins – remaining longer in circulation compared to peptide hormones
      • Includes androgens from testes, estrogens/progesterone from ovaries, corticoids from adrenal cortex, calcitriol from kidneys

    Transport and Inactivation of Hormones

    • Hormones may circulate freely or travel bound to carrier proteins
    • Free hormones have a limited lifespan (typically <1 hour); deactivated by diffusion, absorption by liver/kidneys, or breakdown by enzymes in blood/interstitial fluid.
    • Thyroid and steroid hormones remain functional much longer because most circulate bound to transport proteins in the bloodstream.

    Hormone Action

    • Hormone binding can alter genetic activity
    • Extracellular Receptors: Bind to receptors on the cell surface (e.g., catecholamines/peptides) triggering intracellular events through second messengers
    • Intracellular Receptors: Lipid-soluble hormones (e.g., steroid/thyroid hormones) bind inside the cell triggering changes in gene expression

    Hormone Regulation

    • Hormone secretion is mainly controlled by negative feedback
    • A stimulus triggers the production of a hormone that decreases the intensity of the initial stimulus.

    Hypothalamus and Pituitary Glands

    • Hypothalamus: Regulates functions of the pituitary gland. Synthesizes and releases ADH and OXT to posterior pituitary; releases regulatory hormones that control the anterior pituitary
    • Posterior Pituitary (Neurohypophysis): Secretes ADH and oxytocin
    • Anterior Pituitary (Adenohypophysis): Secretes multiple hormones under hypothalamic control (e.g., TSH, ACTH, PRL, GH, FSH, LH)

    Other Endocrine Organs

    • Various organs, such as the intestines, kidneys, heart, thymus, gonads, and adipose tissues, have secondary endocrine functions; produce hormones that regulate specific processes.

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    Related Documents

    Chapter 18: Endocrine System PDF

    Description

    This quiz covers the fundamental concepts of the endocrine system, including hormone production, intercellular communication mechanisms, and the overall function of hormones in regulating bodily processes. Explore how hormones maintain homeostasis and their impact on cellular activities.

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