Endocrine System Overview
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Questions and Answers

Which of the following hormones directly stimulates smooth muscle contractions?

  • Thyroid stimulating hormone (TSH)
  • Antidiuretic hormone (ADH)
  • Luteinizing hormone (LH)
  • Oxytocin (OXY) (correct)

    • What is the correct order of events in the release of a tropic hormone from the anterior pituitary?

  • Hypothalamus releases a releaser, target tissue produces hormones, anterior pituitary cell secretes a tropic hormone
  • Anterior pituitary cell secretes a tropic hormone, hypothalamus releases a releaser, target tissue produces hormones
  • Target tissue produces hormones, hypothalamus releases a releaser, anterior pituitary cell secretes a tropic hormone
  • Hypothalamus releases a releaser, anterior pituitary cell secretes a tropic hormone, target tissue produces hormones (correct)

    • Which of the following is NOT a characteristic of the neurohypophysis?

  • Releases hormones that use the PIP mechanism of action
  • Secretes hormones but does not produce them
  • Composed of neural tissue
  • Stimulated by the hypothalamus through releaser hormones (correct)

    • What is the primary function of antidiuretic hormone (ADH)?

    <p>Regulates water balance and prevents urine formation (B)</p> Signup and view all the answers

    Which of the following is an example of a tropic hormone released by the anterior pituitary?

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

    Which of the following is NOT a factor that controls hormone action?

    <p>The type of G protein involved (D)</p> Signup and view all the answers

    What is the primary role of adenylate cyclase in the cAMP mechanism?

    <p>To convert ATP into cAMP (C)</p> Signup and view all the answers

    What is the role of phospholipase in the PIP-calcium mechanism?

    <p>To split PIP2 into DAG and IP3 (C)</p> Signup and view all the answers

    Which of the following is an example of permissiveness in hormone interaction?

    <p>Thyroid hormone allowing for normal growth and development in response to growth hormone (B)</p> Signup and view all the answers

    Which of the following is an example of synergism in hormone interaction?

    <p>Epinephrine and norepinephrine both increasing heart rate and blood pressure (A)</p> Signup and view all the answers

    Which of the following is an example of antagonism in hormone interaction?

    <p>Insulin and glucagon working together to regulate blood glucose levels (A)</p> Signup and view all the answers

    What is the primary mechanism by which the nervous system regulates hormone release?

    <p>By directly stimulating the release of hormones from endocrine glands (B)</p> Signup and view all the answers

    What is the function of phosphodiesterase in the cAMP mechanism?

    <p>To degrade cAMP (B)</p> Signup and view all the answers

    What is the effect of increased levels of glucocorticoids on the ACTH cascade?

    <p>Increased levels of glucocorticoids inhibit the release of CRH from the hypothalamus. (D)</p> Signup and view all the answers

    Which hormone stimulates the production of testosterone in males?

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

    What is the primary function of Growth Hormone Inhibiting Hormone (GHIH)?

    <p>Inhibits the production of growth hormone by the anterior pituitary. (C)</p> Signup and view all the answers

    What is the primary function of Prolactin Inhibiting Hormone (PIH)?

    <p>Inhibits the release of prolactin from the anterior pituitary. (A)</p> Signup and view all the answers

    Which of the following is NOT a direct action of growth hormone?

    <p>Stimulates uptake of amino acids from blood into cellular proteins (A)</p> Signup and view all the answers

    What is the primary function of Thyroid Releasing Hormone (TRH)?

    <p>Stimulates the release of thyroid stimulating hormone (TSH) from the anterior pituitary. (A)</p> Signup and view all the answers

    In the gonadotropin cascade, what is the role of GnRH (Gonadotropin-releasing hormone)?

    <p>Stimulates the release of FSH and LH from the anterior pituitary. (A)</p> Signup and view all the answers

    What is the effect of increased levels of gonadotropins on the gonadotropin cascade?

    <p>Increased levels of gonadotropins inhibit the release of GnRH from the hypothalamus. (B)</p> Signup and view all the answers

    What is the primary function of prolactin?

    <p>Stimulates milk production and enhances testosterone production in males. (B)</p> Signup and view all the answers

    What is the relationship between PIH and prolactin during pregnancy?

    <p>PIH levels remain constant during pregnancy. (C)</p> Signup and view all the answers

    Which of the following statements accurately describes the difference between steroid and amino acid-based hormone actions?

    <p>Steroid hormones act directly on genes, while amino acid-based hormones indirectly influence cellular processes. (B), Steroid hormones typically have a slower onset of action due to gene activation, while amino acid-based hormones act more rapidly through secondary messengers. (C)</p> Signup and view all the answers

    Which of the following is NOT a characteristic of steroid hormones?

    <p>Bind to extracellular receptors on the cell membrane. (D)</p> Signup and view all the answers

    Which of the following is a key role played by G proteins in the action of amino-acid based hormones?

    <p>Binding to the hormone receptor to initiate signal transduction. (A)</p> Signup and view all the answers

    Which of the following is TRUE about the cyclic AMP (cAMP) mechanism in amino acid-based hormone action?

    <p>cAMP activation leads to the phosphorylation of proteins, altering their activity. (B)</p> Signup and view all the answers

    What is the primary difference between the cyclic AMP and the PIP-calcium mechanisms in amino acid-based hormone action?

    <p>The cyclic AMP mechanism involves phosphorylation, while the PIP-calcium mechanism relies on calcium release. (B)</p> Signup and view all the answers

    Which of the following is NOT a characteristic of endocrine glands?

    <p>They secrete their products into ducts. (C)</p> Signup and view all the answers

    Which type of chemical messenger affects only the cell that secreted it?

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

    Which of the following is a characteristic of the nervous system that distinguishes it from the endocrine system?

    <p>Responds very quickly to stimuli (D)</p> Signup and view all the answers

    What is the primary function of the neuroendocrine link?

    <p>To regulate the activity of the endocrine system (B)</p> Signup and view all the answers

    Which of the following actions can hormones NOT produce in target cells?

    <p>Promote the production of red blood cells (A)</p> Signup and view all the answers

    Which of the following is NOT a type of chemical messenger?

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

    Which of the following statements about target cells is TRUE?

    <p>A single hormone can have different effects on different target cells. (D)</p> Signup and view all the answers

    Which of the following best describes the relationship between the hypothalamus and the pituitary gland?

    <p>The hypothalamus secretes hormones that directly act on the pituitary gland. (A)</p> Signup and view all the answers

    Study Notes

    Endocrine System

    • The endocrine system uses chemical messengers (hormones) that affect any tissue with a receptor for that specific chemical.
    • Response is slower compared to the nervous system, taking days for action to occur.
    • The nervous system uses neurons to send electrical signals (action potentials).
    • This system stimulates muscles and glands, responding to stimuli very quickly, and has a short-lived effect.

    Exocrine and Endocrine Glands

    • Exocrine glands secrete hormones into ducts.
    • Endocrine glands are ductless, secreting hormones directly into the bloodstream.
    • Some organs have both endocrine and exocrine functions.
    • The neuroendocrine link involves stimulation by the hypothalamus, the major regulator for endocrine activity.
    • The hypothalamus sends nervous and precursor signals to activate other endocrine glands.

    Chemical Messengers

    • Hormones are chemical messengers that affect another part of the body.
    • Autocrines are chemicals produced by a cell to change the activity of that same cell.
    • Paracrines affect neighboring cells.
    • Local regulators act on nearby cells or tissues (e.g., prostaglandins, leukotrienes).
    • Pheromones are produced by one individual, affecting another's behavior (sexual or repulsive).

    Hormone Actions- Cellular Effects

    • Hormones target cells with specific receptors on their cell surface.
    • Hormones can have various effects, including opening or closing ion channels, changing membrane potentials, stimulating protein synthesis, and activating/deactivating enzymes.
    • Hormones can also promote secretion of other substances.

    Hormone Chemical Classifications

    • Amino acid-based hormones are derived from proteins, usually water-soluble and cannot cross plasma membranes.
    • Steroid hormones are lipid-soluble, derived from cholesterol, with receptors inside the cell.
    • Sources of steroid hormones are the adrenal cortex and gonads.
    • Eicosanoids are biologically active lipids that function locally but indirectly.

    Mechanisms of Hormone Action

    • Steroid hormones directly activate genes.
    • Non-steroid hormones (amino acid-based) use an indirect mechanism involving secondary messengers like cyclic AMP (cAMP) and calcium ions (PIP-Calcium mechanism).

    Hormone Action Regulation

    • Hormone levels in the bloodstream, receptor quantity, and receptor affinity affect hormone action.
    • Upregulation increases the number of receptors, while downregulation decreases them, often in response to stress.
    • Three types of hormone interactions:
      • Permissiveness: one hormone enhances the effect of another.
      • Synergism: two or more hormones have a combined effect.
      • Antagonism: two hormones have opposite effects.
    • Hormone release is regulated by humoral (blood concentration), neural (nervous stimulation), and hormonal stimuli (hormones produced from another gland).

    Major Endocrine Organs and Locations

    • Pituitary gland- brain extension.
    • Thyroid gland- surrounds the trachea.
    • Parathyroid glands- embedded in the thyroid.
    • Adrenal glands- on top of the kidneys.
    • Pancreas (endocrine portion)- abdominal cavity.
    • Gonads (testes/ovaries)- male/female reproductive organs.
    • Pineal gland- brain.
    • Thymus- active in young individuals.

    Posterior Pituitary (Neurohypophysis)

    • Composed of neural tissue, does not synthesize hormones but secretes them.
    • Releases oxytocin (stimulates uterine contractions and milk ejection) and antidiuretic hormone (ADH) (regulates water balance).

    Anterior Pituitary (Adenohypophysis)

    • Composed of glandular tissue, secretes tropic hormones that stimulate other endocrine glands.

    Growth Hormone (GH)

    • Stimulates growth, cell division, protein synthesis, fat metabolism, and glucose conservation.
    • Overactive GH leads to gigantism in children and acromegaly in adults.
    • Insufficient GH causes pituitary dwarfism.

    Thyroid Stimulating Hormone (TSH) Cascade

    • Involved in thyroid hormone production and its regulation.

    Adrenocorticotropic Hormone (ACTH) Cascade

    • Involved in the production of corticosteroids by the adrenal cortex and the body's response to stress.

    Gonadotropins

    • Stimulate the function of gonads (testes & ovaries).
    • Include follicle-stimulating hormone (FSH) and luteinizing hormone (LH), affecting sperm and egg production, and sex hormone production.

    Prolactin

    • Stimulates milk production and enhances testosterone production in males.
    • High estrogen levels stimulate prolactin release, and prolactin production is brief due to ovarian hormone cycling.
    • Suckling promotes sustained prolactin production.

    Pro-opiomelanocortin (POMC)

    • A precursor hormone involved in creating other hormones.

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    Endocrine System PDF

    Description

    Explore the intricacies of the endocrine system, including the functions of endocrine and exocrine glands, the role of hormones as chemical messengers, and the neuroendocrine link. This quiz will test your understanding of how these components interact and regulate bodily functions effectively.

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