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Anatomy & Physiology: Endocrine System Key Concepts

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Terms in this set (31)

  • What is the primary function of endocrine glands?

    Endocrine glands secrete hormones into the bloodstream to maintain homeostasis through negative feedback loops.

  • How do endocrine hormones reach their target cells?

    Hormones are secreted into interstitial spaces and bloodstream, then bind to receptors on target cells located far from the secretory cell.

  • What distinguishes endocrine from exocrine secretion?

    Endocrine secretion releases hormones into the bloodstream; exocrine secretion releases substances through ducts to body surfaces.

  • Name the four types of intercellular communication.

    Direct (gap junctions), paracrine (local factors), endocrine (hormones via blood), and synaptic (neurotransmitters across synapses).

  • List the major endocrine glands.

    Hypothalamus, pituitary, pineal, thyroid, parathyroid, adrenal glands, pancreas, plus heart, digestive tract, kidneys, and gonads with secondary endocrine functions.

  • What are the three chemical classes of hormones?

    Amino acid derivatives, peptide hormones, and lipid derivatives.

  • Give examples of amino acid derivative hormones.

    Thyroid hormones (thyroxine), catecholamines (epinephrine, norepinephrine, dopamine), and melatonin.

  • What are peptide hormones and examples?

    Short polypeptides like antidiuretic hormone, oxytocin, insulin, growth hormone, and glycoproteins like thyroid stimulating hormone.

  • Describe lipid derivative hormones.

    Eicosanoids (leukotrienes, prostaglandins) and steroid hormones (estrogen, testosterone, corticosteroids, calcitriol) derived from cholesterol.

  • How do cells respond to hormones?

    Cells must have specific protein receptors; different receptors on different cells cause varied effects from the same hormone.

  • Explain the role of secondary messengers in hormone action.

    Catecholamines bind membrane receptors activating G-proteins, producing cAMP or releasing Ca2+, which act as secondary messengers to open ion channels or activate enzymes.

  • How do steroid hormones affect target cells?

    Steroid hormones diffuse through membranes, bind receptors in cytoplasm or nucleus, then the complex binds DNA to regulate gene transcription.

  • How do thyroid hormones enter and act within cells?

    Carried across membranes by proteins, thyroid hormones bind receptors on mitochondria to increase ATP or in nucleus to increase gene transcription.

  • What is a negative feedback loop in the endocrine system?

    The process outcome inhibits its own production, e.g., hormone action signals hypothalamus to reduce hormone release.

  • What hormones are synthesized by hypothalamic neurons and stored in the posterior pituitary?

    Antidiuretic hormone (ADH) and oxytocin.

  • How does the hypothalamus regulate the anterior pituitary?

    It secretes releasing and inhibiting hormones transported via the hypophyseal portal system to control anterior pituitary hormone secretion.

  • Name the major hormones secreted by the anterior pituitary.

    Growth hormone, prolactin, thyroid-stimulating hormone, adrenocorticotropic hormone, follicle-stimulating hormone, and luteinizing hormone.

  • What are the functions of posterior pituitary hormones?

    ADH promotes water retention in kidneys and regulates blood pressure; oxytocin stimulates childbirth and milk ejection.

  • Describe the structure of the thyroid gland.

    Located anterior to the trachea, it has two lobes connected by an isthmus and contains thyroid follicles lined by cuboidal epithelium.

  • What are thyroid hormones and their iodine content?

    Triiodothyronine (T3) contains 3 iodine atoms; thyroxine (T4) contains 4 iodine atoms, both derived from thyroglobulin.

  • How is iodide processed in thyroid hormone synthesis?

    Iodide is absorbed, oxidized by thyroid peroxidase, attached to tyrosine in thyroglobulin, then processed to release T3 and T4 into the bloodstream.

  • What is the role of calcitonin?

    Produced by C cells in the thyroid, it lowers blood calcium by increasing bone uptake and reducing bone resorption.

  • How does parathyroid hormone (PTH) regulate calcium levels?

    PTH increases blood calcium by stimulating bone release, kidney reabsorption, and calcitriol production to enhance intestinal absorption.

  • What are the two main parts of the adrenal gland and their hormone types?

    Medulla produces catecholamines (epinephrine, norepinephrine); cortex produces steroid hormones like aldosterone, cortisol, and androgens.

  • What is the function of aldosterone?

    Aldosterone promotes sodium retention in kidneys, leading to water retention and increased blood volume.

  • What is the role of cortisol?

    Cortisol is a glucocorticoid that inhibits protein synthesis and stimulates glucose production in the liver.

  • What cells produce insulin and glucagon in the pancreas?

    Beta cells produce insulin to lower blood glucose; alpha cells produce glucagon to raise blood glucose.

  • What is diabetes mellitus and its two main types?

    A disorder of high blood glucose: Type 1 is insulin deficiency (autoimmune), Type 2 is insulin resistance (common in adults).

  • What are complications of untreated diabetes mellitus?

    Energy crisis in cells, increased blood pressure, damage to heart, kidneys, eyes, nerves, and extremities.

  • What is the function of the pineal gland?

    Produces melatonin, which regulates circadian rhythms based on light and dark cycles.

  • What is the role of the thymus gland?

    Supports maturation of T cells in the immune system and shrinks with age.