Endocrine System Quiz
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Questions and Answers

Which hormone is primarily responsible for regulating metabolism and is produced by the thyroid gland?

  • Prolactin
  • Calcitonin
  • Insulin
  • Thyroxine (correct)

    • What is the main target tissue for adrenocorticotropic hormone, and what is its primary function?

  • Digestive system; stimulates hunger
  • Muscle tissue; promotes growth
  • Heart; regulates heartbeat
  • Adrenal cortex; stimulates cortisol release (correct)

    • Which of the following hormones is NOT released during short-term stress?

  • Glucocorticoids (correct)
  • Norepinephrine
  • Epinephrine
  • Mineralocorticoids

    • Which hormone, produced by the pancreas, is primarily involved in lowering blood glucose levels?

    <p>Insulin</p> Signup and view all the answers

    What can be a possible consequence of the endocrine organs failing to maintain homeostasis?

    <p>Severe fatigue and metabolic disorders</p> Signup and view all the answers

    What hormone is primarily responsible for stimulating growth hormone release from the anterior pituitary?

    <p>GHRH</p> Signup and view all the answers

    How does GHIH affect growth hormone synthesis and release?

    <p>Inhibits GH synthesis and release</p> Signup and view all the answers

    Which of the following is a direct action of growth hormone?

    <p>Increased fat breakdown</p> Signup and view all the answers

    What effect do insulin-like growth factors (IGFs) have on the body?

    <p>Promotion of skeletal growth</p> Signup and view all the answers

    Which hormone is produced by the thyrotropic cells of the anterior pituitary?

    <p>Thyrotropin</p> Signup and view all the answers

    What triggers the release of thyroid-stimulating hormone (TSH)?

    <p>Thyrotropin-releasing hormone</p> Signup and view all the answers

    Which of the following statements about thyroid hormone regulation is true?

    <p>Thyroid hormones inhibit their own secretion by acting on the hypothalamus</p> Signup and view all the answers

    What forms DIT and MIT in the colloid?

    <p>Tyrosines that are oxidized</p> Signup and view all the answers

    What is the role of the Golgi apparatus in the process described?

    <p>To package and modify thyroglobulin</p> Signup and view all the answers

    What is the first step in the iodination process?

    <p>Iodide is actively transported in</p> Signup and view all the answers

    What is produced when iodinated tyrosines are linked together?

    <p>T3 and T4</p> Signup and view all the answers

    What process follows the endocytosis of thyroglobulin colloid?

    <p>It combines with a lysosome</p> Signup and view all the answers

    Which molecule is actively transported into the follicular cells?

    <p>Iodide</p> Signup and view all the answers

    What process occurs after T4 is formed from linked iodinated tyrosines?

    <p>Lysosomal enzymes degrade thyroglobulin</p> Signup and view all the answers

    What occurs to iodide before it attaches to tyrosine?

    <p>It is oxidized to iodine</p> Signup and view all the answers

    Which statement about thyroglobulin is true?

    <p>It serves as a precursor for T3 and T4</p> Signup and view all the answers

    What stimulates the release of thyroid hormones from the thyroid gland?

    <p>Thyroid-stimulating hormone (TSH)</p> Signup and view all the answers

    Which hormone is primarily responsible for regulating the secretion of prolactin?

    <p>Prolactin-inhibiting hormone (PIH)</p> Signup and view all the answers

    What triggers the release of both follicle-stimulating hormone (FSH) and luteinizing hormone (LH)?

    <p>Gonadotropin-releasing hormone (GnRH)</p> Signup and view all the answers

    Which factor does NOT directly influence the regulation of Adrenocorticotropic Hormone (ACTH) release?

    <p>Follicle-stimulating hormone (FSH)</p> Signup and view all the answers

    What occurs in males due to hypersecretion of prolactin?

    <p>Impotence</p> Signup and view all the answers

    Which hormone does NOT stimulate adrenal cortex to release corticosteroids?

    <p>Follicle-stimulating hormone (FSH)</p> Signup and view all the answers

    What physiological state primarily leads to a rise in prolactin levels?

    <p>Suckling</p> Signup and view all the answers

    Which of the following is released in a daily rhythm triggered by the hypothalamus?

    <p>Adrenocorticotropic hormone (ACTH)</p> Signup and view all the answers

    Which statement is true regarding gonadotropins in prepubertal individuals?

    <p>FSH is absent from the blood.</p> Signup and view all the answers

    What is the correct order of events in the cyclic AMP signaling mechanism after a hormone binds to its receptor?

    <p>Hormone binds receptor, receptor activates G protein, G protein activates adenylate cyclase.</p> Signup and view all the answers

    What role does phosphodiesterase play in the cyclic AMP second-messenger system?

    <p>It degrades cAMP, halting the signaling cascade.</p> Signup and view all the answers

    Which of the following best describes the nature of lipid-soluble hormones in relation to their cellular action?

    <p>They act on intracellular receptors and directly activate genes.</p> Signup and view all the answers

    What is the significance of the amplification effect seen in the cyclic AMP signaling cascade?

    <p>It allows a single hormone to elicit a much larger cellular response.</p> Signup and view all the answers

    What happens to proteins after they are phosphorylated by cAMP-activated protein kinases?

    <p>They can either be activated or inactivated depending on the function of the protein.</p> Signup and view all the answers

    What is the effect of prolactin-inhibiting hormone (PIH) on prolactin release?

    <p>It inhibits prolactin release</p> Signup and view all the answers

    Which factor does NOT influence the secretion of gonadotropins?

    <p>Circadian rhythms</p> Signup and view all the answers

    What physiological consequence can arise from hypersecretion of prolactin in females?

    <p>Inappropriate lactation</p> Signup and view all the answers

    What primarily triggers the release of adrenocorticotropic hormone (ACTH)?

    <p>Corticotropin-releasing hormone (CRH)</p> Signup and view all the answers

    Which function is NOT associated with adrenocorticotropic hormone (ACTH)?

    <p>Regulating gamete production</p> Signup and view all the answers

    Which hormone is associated with stimulating both egg and sperm production?

    <p>Follicle-stimulating hormone (FSH)</p> Signup and view all the answers

    Which of the following influences the release of corticosteroids from the adrenal cortex?

    <p>Adrenocorticotropic hormone (ACTH)</p> Signup and view all the answers

    During which physiological condition is the release of prolactin primarily heightened?

    <p>End of pregnancy</p> Signup and view all the answers

    What is the primary effect of luteinizing hormone (LH) in the body?

    <p>Increasing testosterone levels in males</p> Signup and view all the answers

    Which statement accurately reflects the activity of T3 and T4?

    <p>T4 is converted to T3 in peripheral tissues and is less active than T3.</p> Signup and view all the answers

    What physiological role does calcitonin play in calcium regulation?

    <p>At higher doses, it inhibits osteoclast activity and promotes calcium uptake into bone.</p> Signup and view all the answers

    What is the primary feedback mechanism regulating thyroid hormone release?

    <p>Negative feedback inhibition of TSH release by rising TH levels.</p> Signup and view all the answers

    Which condition is caused by hyposecretion of thyroid hormones in adults?

    <p>Myxedema, which can lead to serious metabolic issues.</p> Signup and view all the answers

    How does the hypothalamic thyrotropin-releasing hormone (TRH) influence thyroid hormone regulation during specific conditions?

    <p>It enhances TSH release, overcoming negative feedback during cold exposure.</p> Signup and view all the answers

    In the context of thyroid hormones, which of these statements correctly describes the relationship between T4 and T3?

    <p>T3 is derived from the conversion of T4 in peripheral tissues, making it more active.</p> Signup and view all the answers

    What is the primary cause of goiter formation in adults?

    <p>Hyposecretion of thyroid hormones caused by lack of iodine.</p> Signup and view all the answers

    Which of the following describes the primary role of thyroxine-binding globulins (TBGs) in relation to thyroid hormones?

    <p>They transport T3 and T4 in the bloodstream, facilitating their activity.</p> Signup and view all the answers

    Which structure is NOT a part of the pituitary gland?

    <p>Corpus callosum</p> Signup and view all the answers

    What role does the hypothalamus play in relation to the pituitary gland?

    <p>It synthesizes and releases hormones that regulate the pituitary.</p> Signup and view all the answers

    What is the function of hypophyseal portal veins?

    <p>To deliver hypothalamic hormones to the anterior pituitary.</p> Signup and view all the answers

    Which hormone does NOT directly influence the secretion process of the pituitary gland?

    <p>Adrenaline</p> Signup and view all the answers

    What type of cells primarily make up the posterior lobe of the pituitary gland?

    <p>Pituicytes</p> Signup and view all the answers

    Which part of the pituitary gland receives the hypothalamic hormones via the portal circulation?

    <p>Pars distalis</p> Signup and view all the answers

    Which hormone synthesis is controlled by hypothalamic neurons?

    <p>Prolactin Inhibiting Hormone (PIH)</p> Signup and view all the answers

    Which of the following terms refers to a chemical messenger produced by an endocrine gland that travels in the bloodstream to target cells?

    <p>Hormone</p> Signup and view all the answers

    The nervous system communicates with body functions through electrical signals, while the endocrine system uses chemical signals.

    <p>True</p> Signup and view all the answers

    What are the two types of feedback mechanisms that control hormone release?

    <p>Negative feedback and positive feedback</p> Signup and view all the answers

    The ___ plays a crucial role in the release of hormones from the anterior and posterior pituitary glands.

    <p>hypothalamus</p> Signup and view all the answers

    Match the following types of hormones with their primary characteristics:

    <p>Peptide hormones = Water-soluble and bind to cell membrane receptors Steroid hormones = Lipid-soluble and often bind to intracellular receptors Amino acid-derived hormones = Can be either water-soluble or lipid-soluble Eicosanoids = Derived from fatty acids and involved in local signaling</p> Signup and view all the answers

    Which hormone is primarily responsible for stimulating uterine contractions during childbirth?

    <p>Oxytocin</p> Signup and view all the answers

    Glucocorticoids are a type of hormone released by the adrenal gland during long-term stress.

    <p>True</p> Signup and view all the answers

    What hormone produced by the pancreas is involved in raising blood glucose levels?

    <p>Glucagon</p> Signup and view all the answers

    The hormone predominantly responsible for regulating calcium levels in the blood is __________.

    <p>parathyroid hormone</p> Signup and view all the answers

    Match the following hormones with their target tissues:

    <p>Insulin = Liver Testosterone = Skeletal Muscle Thyroxine = All Body Cells Epinephrine = Heart</p> Signup and view all the answers

    Which of the following functions is primarily associated with the hormone cortisol during stress?

    <p>Reduces inflammation</p> Signup and view all the answers

    Erythropoietin is produced by the kidneys and helps to lower red blood cell production.

    <p>False</p> Signup and view all the answers

    What is the first step in the cyclic AMP signaling mechanism?

    <p>Hormone binds to its receptor</p> Signup and view all the answers

    Lipid-soluble hormones cannot enter the cell.

    <p>False</p> Signup and view all the answers

    What enzyme is responsible for converting ATP to cAMP?

    <p>Adenylate cyclase</p> Signup and view all the answers

    CAMP acts as a ______ messenger in the signaling pathway.

    <p>second</p> Signup and view all the answers

    Match each component to its function in the cyclic AMP signaling process:

    <p>Hormone = First messenger that binds to the receptor G protein = Relays signals from the receptor to adenylate cyclase cAMP = Activates protein kinases Phosphodiesterase = Degrades cAMP to stop the cascade</p> Signup and view all the answers

    What is the role of protein kinases activated by cAMP?

    <p>To phosphorylate other proteins</p> Signup and view all the answers

    Phosphorylation always activates proteins.

    <p>False</p> Signup and view all the answers

    What effect does the degradation of cAMP by phosphodiesterase have on the signaling cascade?

    <p>It stops the cascade.</p> Signup and view all the answers

    What is the role of diacylglycerol (DAG) in the signaling mechanism?

    <p>Activates protein kinases</p> Signup and view all the answers

    Calcium ions serve as a second messenger in cell signaling.

    <p>True</p> Signup and view all the answers

    After the hormone binds to the receptor, the receptor activates a ______.

    <p>G protein</p> Signup and view all the answers

    What enzyme is activated by the hormone-activated G protein in the PIP2-calcium signaling mechanism?

    <p>Phospholipase C</p> Signup and view all the answers

    The activated ____ activates adenylate cyclase, which converts ATP to cAMP.

    <p>G protein (Gs)</p> Signup and view all the answers

    Match the following components with their functions in cellular signaling:

    <p>G protein = Activates adenylyl cyclase cAMP = Second messenger IP3 = Releases Ca2+ from storage Calmodulin = Binds calcium ions and activates enzymes</p> Signup and view all the answers

    Which molecule is split by phospholipase C to form second messengers?

    <p>PIP2</p> Signup and view all the answers

    Inactive G protein binds directly to adenylate cyclase.

    <p>False</p> Signup and view all the answers

    What triggers the activation of protein kinases in the signaling pathway?

    <p>DAG and Ca2+</p> Signup and view all the answers

    Activated adenylate cyclase converts ATP to ____.

    <p>cAMP</p> Signup and view all the answers

    Study Notes

    Endocrine Physiology Overview

    • Endocrinology is the study of hormones and endocrine organs.
    • The endocrine system acts with the nervous system to coordinate and integrate body cell activities
    • Endocrine system responses are slower but longer lasting than nervous system responses.
    • Endocrine system influences metabolic activities
    • The endocrine system controls and integrates reproduction, growth, development and maintenance of electrolyte, water, and nutrient balance of blood; regulation of cellular metabolism and energy balance; and mobilization of body defenses.

    Chemical Messengers

    • Hormones are long-distance chemical signals that travel in blood or lymph.
    • Autocrines are chemicals that exert effects on the same cells that secrete them.
    • Paracrines are locally acting chemicals that affect cells other than the ones that secrete them.
    • Autocrines and paracrines are considered local chemical messengers and aren't part of the endocrine system.

    Mechanisms of Hormone Action

    • Hormones circulate systemically, but only cells with receptors for a specific hormone are affected.
    • Hormones alter target cell activity in several ways.
    • Some hormones alter plasma membrane permeability and/or membrane potential.
    • Other hormones stimulate the synthesis of enzymes or other proteins; activate or deactivate enzymes; or induce secretory activity.
    • Some hormones stimulate mitosis.

    Mechanisms of Hormone Action - Receptor Location

    • Water-soluble hormones (all amino-acid-based hormones, except thyroid hormone) act on plasma membrane receptors and use G protein second messengers.
    • Water-soluble hormones include Cyclic AMP, PIP2-Calcium
    • Lipid-soluble hormones (steroid and thyroid hormones) act on intracellular receptors, directly activating genes to enter cells.

    Plasma Membrane Receptors and Second-Messenger Systems

    • Hormone (first messenger) binds to the receptor.
    • Receptor activates a G protein.
    • G protein activates or inhibits an effector enzyme.
    • Effector enzyme generates a second messenger.
    • Second messenger activates protein kinases.
    • Protein kinases phosphorylate proteins.
    • Phosphorylated proteins cause the cell's response and amplification cascade.
    • Some second messenger systems use cyclic AMP (cAMP), or PIP2-calcium signal for different cell responses

    PIP2-calcium signaling mechanism

    • Hormone-activated G proteins activate phospholipase C.
    • Activated enzyme cleaves phospholipids, forming diacylglycerol (DAG) and inositol trisphosphate (IP3).
    • DAG activates protein kinases.
    • IP3 causes Ca2+ release from intracellular storage sites.
    • Calcium acts as a messenger, altering enzyme activity.

    Intracellular Receptors

    • Steroid hormones and thyroid hormones diffuse into target cells.
    • They bind to intracellular receptors within the target cells.
    • The receptor-hormone complex travels to the nucleus.
    • The hormone-receptor complex binds to specific DNA regions, promoting/inhibiting DNA transcription.
    • This process results in new proteins or changes affecting metabolic actions.

    Target Cell Activation

    • Target cell specificity depends on the blood level of hormone.
    • Relative number of receptors or in the target cell.
    • The affinity of receptor binding between receptor and hormone.
    • Hormones influence receptor numbers.
    • Up-regulation occurs in low hormone levels which increase receptor numbers.
    • Down-regulation occurs in high hormone levels which reduces receptor numbers,

    Control of Hormone Release

    • Endocrine gland stimuli include hormonal, neural, and humoral stimuli.

    Hormones in the Blood

    • Hormones circulate freely or bound to plasma proteins.
    • Steroid and thyroid hormones travel bound.
    • Others circulate freely.
    • Hormone concentration reflects the rates of hormone release.
    • Hormone half-life is the time needed for the hormone's blood level to reduce by half.

    Interaction of Hormones at Target Cells

    • Multiple hormones may act on the same target cell.
    • Permissiveness is when one hormone is needed for the action of another hormone.
    • Synergism is when the actions of multiple hormones enhance each other.
    • Antagonism occurs when multiple hormones oppose each other's actions.

    Comparison of Lipid- and Water-Soluble Hormones

    • Lipid-soluble hormones are usually steroids or thyroid hormones.
    • Lipid-soluble hormones have longer half-lives in blood.
    • Lipid-soluble hormones act on intracellular receptors.
    • Water-soluble hormones are most amino acid based hormones.
    • Water-soluble hormones have shorter half-lives in blood.
    • Water-soluble hormones act on membrane receptors.

    Hypothalamus & Pituitary

    • The hypothalamus and pituitary glands are essential for regulating many body functions.
    • The hypothalamus controls pituitary hormone release through neural or hormonal pathways.
    • The anterior pituitary is controlled by hormonal pathways of releasing and inhibiting hormones from the hypothalamus.
    • The posterior pituitary releases hormones synthesized in the hypothalamus via neural pathways.

    Posterior Pituitary and Hypothalamic Hormones

    • Oxytocin is associated with uterine contractions and milk ejection.
    • ADH (vasopressin) regulates water balance.
    • ADH deficiency/excess can cause many health problems.

    Anterior Pituitary Hormones

    • The main anterior pituitary hormones include growth hormone (GH), thyroid-stimulating hormone (TSH), adrenocorticotropic hormone (ACTH), follicle-stimulating hormone (FSH), luteinizing hormone (LH), and prolactin (PRL).
    • Most are proteins.
    • TSH and ACTH, FSH and LH are tropic hormones.

    Growth Hormone (GH)

    • GH has metabolic and growth effects on the body
    • Direct actions affect metabolism, including increase blood fatty acids, decrease glucose uptake, and glycogen breakdown to release glucose into the blood.
    • Indirect actions involve growth via growth hormone like factors promoting growth of cartilage, bone and skeletal muscle.
    • Imbalances include gigantism in children and acromegaly in adults.

    Thyroid-stimulating Hormone (Thyrotropin)

    • Produced by thyrotropic cells of the anterior pituitary.
    • Stimulates normal development and secretory activity of the thyroid.

    Adrenocorticotropic Hormone (ACTH)

    • Produced by corticotropic cells of the anterior pituitary.
    • Stimulates adrenal cortex to release corticosteroids.
    • Daily rhythm triggered by hypothalamic CRH.

    Gonadotropins

    • Follicle-stimulating hormone (FSH) and luteinizing hormone (LH) stimulate gamete production.
    • FSH stimulates gamete products.
    • LH promotes production of gonadal hormones.
    • Regulation of release triggered by gonadotropin-releasing hormone (GnRH).
    • Release is suppressed by gonadal hormones.

    Prolactin (PRL)

    • PRL is produced by prolactin cells of the anterior pituitary.
    • Stimulates milk production.
    • Role in males not well understood.
    • Release regulated by prolactin-inhibiting hormone and suckling reflexes.
    • Hypersecretion leads to inappropriate lactation.

    Thyroid Gland

    • The thyroid gland produces thyroid hormones (T4 and T3).
    • T4 and T3 have major metabolic and developmental effects regulating virtually every cell in the body.
    • They increase metabolic rate and heat production, influencing skeletal growth, nervous system development, reproduction, and blood pressure.
    • Control of release is through negative feedback regulation.
    • Homeostatic imbalances can cause myxedema in adults and cretinism in infants.

    Calcitonin

    • Calcitonin is produced by parafollicular cells.
    • It is the antagonist of parathyroid hormone.
    • It has lower than normal doses.
    • It regulates calcium levels.

    Parathyroid Glands

    • Parathyroid glands regulate calcium levels via actions through the body.
    • PTH is the main hormone produced in the parathyroid.
    • PTH increases calcium levels through the bone, kidneys and intestines.
    • Imbalances in PTH can cause bones to soften, deform, kidney stones or tetany

    Adrenal Glands

    • Adrenal glands consist of cortex and medulla regions.
    • Corticosteroid hormones (mineralocorticoids, glucocorticoids, and gonadocorticoids) are secreted in the cortex.
    • The adrenal medulla releases epinephrine and norepinephrine, leading to short-term stress response.
    • Imbalances can lead to several health issues.

    Mineralocorticoids

    • Mineralocorticoids like Aldosterone regulate electrolytes like sodium and potassium, vitally important for fluid balance, blood volume and pressure.
    • Aldosterone increases sodium reabsorption and water retention in the kidneys.
    • It also promotes the excretion of potassium.
    • Its release is triggered by decreasing blood volume, blood pressure, and rising potassium levels.
    • Imbalances may result in serious health problems.

    Glucocorticoids

    • Glucocorticoids like Cortisol are important in regulating blood glucose and pressure.
    • They help maintain constant blood glucose levels in the body during stress, while promoting glucose production and utilization.
    • Cortisol enhances metabolism in many tissues and affects immune function.
    • Homeostatic imbalances can lead to Cushing's syndrome or Addison's disease.

    Gonadocorticoids

    • Gonadocorticoids are weak androgens (male hormones).
    • They convert to androgens and estrogens.
    • They play a role in the onset of puberty, appearance of secondary sex characteristics, sex drive in women (estrogen in postmenopausal women).

    Adrenal Medulla

    • Adrenal medulla releases epinephrine, norepinephrine and are part of the body's stress response affecting metabolic activity, dilation of the bronchi, heart and skeletal muscle blood flow.
    • Imbalance results in several physiological conditions.

    Pancreas

    • Pancreas produces hormones regulating blood glucose levels.
    • Glucagon increases blood sugar levels.
    • Insulin lowers blood sugar levels, increasing glucose uptake.
    • Imbalances in these hormones lead to many conditions including hypo and hyperglycemia.
    • Imbalances may lead to diabetes.

    Factors Influencing Insulin Release

    • Blood glucose, amino acids and fatty acids are primary factors that trigger insulin release.
    • Parasympathetic neurons and hormones like glucagon lead to insulin release.

    Homeostatic Imbalances of Insulin

    • Diabetes mellitus is a common result from insulin imbalances and has several types.

    Diabetes Mellitus: Signs

    • Polyuria, polydipsia and polyphagia collectively form the three cardinal signs of diabetes mellitus (DM) indicating issues with blood glucose regulation.

    Gonads

    • Gonads are reproductive organs producing steroid sex hormones that influence reproductive organs.

    Ovaries and Placenta

    • Ovaries produce estrogen and progesterone.
    • These hormones are essential for reproductive development.
    • The placenta also produces estrogen, progesterone and human chorionic gonadtropin (hCG) to support pregnancy.

    Testes

    • Testes produce testosterone, which is essential for male reproductive function.
    • It triggers male reproductive organ maturation and secondary sexual characteristics.

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    Test your knowledge of the endocrine system with this quiz! Explore the hormones produced by various glands, their functions, and how they regulate metabolism and growth. Perfect for students studying human biology and physiology.

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