Endocrine System Overview
32 Questions
0 Views

Choose a study mode

Play Quiz
Study Flashcards
Spaced Repetition
Chat to lesson

Podcast

Play an AI-generated podcast conversation about this lesson

Questions and Answers

What physiological response is triggered by Trousseau's sign?

  • Extension of fingers
  • Contraction of facial muscles
  • Increased blood circulation
  • Flexion of wrist and thumb (correct)

    • Which hormone is primarily responsible for increasing calcium levels in the blood?

  • Parathyroid hormone (PTH) (correct)
  • Calcitonin
  • Insulin
  • Testosterone

    • What effect does calcitonin have on serum calcium and phosphate levels?

  • Elevates both calcium and phosphate levels
  • Has no effect on calcium levels
  • Increases calcium while lowering phosphate
  • Lowers serum calcium and phosphate levels (correct)

    • What dietary sources can provide Vitamin D3?

    <p>Fat fish and egg yolk</p> Signup and view all the answers

    Where is cholecalciferol activated in the body?

    <p>Liver and kidney</p> Signup and view all the answers

    What condition is caused by hyperparathyroidism?

    <p>Hypercalcemia leading to tetany</p> Signup and view all the answers

    Which of the following actions does parathyroid hormone NOT perform?

    <p>Lowers calcium levels in the blood</p> Signup and view all the answers

    What is the relationship between calcitonin and parathyroid hormone regarding calcium and phosphate?

    <p>Calcitonin antagonizes PTH in calcium but acts similarly in phosphate</p> Signup and view all the answers

    What primarily regulates the secretion of parathyroid hormone (PTH)?

    <p>Blood calcium levels</p> Signup and view all the answers

    What happens to calcium levels in the plasma when PTH secretion is inhibited?

    <p>Calcium is deposited in bones</p> Signup and view all the answers

    In primary hyperparathyroidism, which of the following is NOT typically a manifestation?

    <p>Increased bone density</p> Signup and view all the answers

    What condition results from the hyperfunction of parathyroid hormone secretion?

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

    What is the solubility product involving calcium and phosphorus meant to maintain?

    <p>An inverse relationship between calcium and phosphorus</p> Signup and view all the answers

    What can excessive calcium salts filtered through kidneys lead to?

    <p>Renal failure</p> Signup and view all the answers

    Which of the following best describes a manifestation of primary hyperparathyroidism related to the skeletal system?

    <p>Multiple bone cysts</p> Signup and view all the answers

    Which factor is NOT associated with the increase in PTH secretion?

    <p>High plasma magnesium levels</p> Signup and view all the answers

    What is the main role of Parathyroid Hormone (PTH) in the body?

    <p>Regulating calcium and phosphate concentrations in the extracellular fluid</p> Signup and view all the answers

    How does PTH affect the skeleton in the short term?

    <p>It increases bone resorption and mobilizes calcium to the blood</p> Signup and view all the answers

    What is the delayed effect of PTH on bone?

    <p>Increased activity of osteoclasts leading to bone dissolution</p> Signup and view all the answers

    Which organ does PTH stimulate to reabsorb calcium and magnesium?

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

    How does PTH indirectly increase calcium absorption in the intestine?

    <p>By promoting the production of calcium binding proteins through vitamin D3</p> Signup and view all the answers

    What is the impact of PTH on phosphate levels in the plasma?

    <p>Decreases phosphate levels by enhancing its excretion</p> Signup and view all the answers

    What triggers the direct action of PTH on bone tissue?

    <p>Low calcium concentration in the plasma</p> Signup and view all the answers

    What role does calcitriol play in the actions of PTH?

    <p>It helps increase intestinal calcium absorption stimulated by PTH</p> Signup and view all the answers

    What is an effect of hypercalcemia on neuromuscular excitability?

    <p>Decreased neuromuscular excitability</p> Signup and view all the answers

    Which gastrointestinal disorder is associated with prolonged hypercalcemia?

    <p>Peptic ulcer</p> Signup and view all the answers

    Hypoparathyroidism most commonly results from what surgical complication?

    <p>Injury to multiple parathyroid glands during thyroidectomy</p> Signup and view all the answers

    What is the key manifestation of hypocalcemic tetany?

    <p>Spastic contraction of skeletal muscles</p> Signup and view all the answers

    What condition can lead to latent tetany?

    <p>Blood calcium level between 7–8.5 mg%</p> Signup and view all the answers

    What causes acute pancreatitis in the context of hyperparathyroidism?

    <p>Prolonged hypercalcemia</p> Signup and view all the answers

    Which of the following is NOT a cause of hypocalcemia?

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

    What could potentially trigger latent tetany to become manifest?

    <p>Stress or hyperventilation</p> Signup and view all the answers

    Study Notes

    Endocrine System

    • The endocrine system is responsible for regulating bodily functions.
    • Dr. Yasmine Gamal Sabry presented this information.

    Parathyroid Gland

    • The parathyroid glands are typically four small glands located on the posterior aspect of the thyroid gland.
    • These glands contain chief cells that secrete parathyroid hormone (PTH).
    • PTH's primary function is regulating calcium concentration in extracellular fluid (ECF).
    • PTH is essential for life.

    PTH Actions on Target Organs

    • PTH increases blood calcium and decreases blood phosphate levels by acting on three target organs:
      • Skeleton: Directly increases bone resorption and mobilizes ionic calcium and phosphate into the bloodstream. This includes immediate effects that begin within minutes and continue for hours, stimulating calcium pumps to move calcium from bone fluid to plasma. There are also delayed effects that take days to weeks, causing osteoclasts to break down calcium crystals.
      • Kidneys: directly stimulates calcium reabsorption and phosphate excretion in the kidneys. It also increases the formation of the active form of vitamin D3 (calcitriol).
      • Intestine: PTH indirectly increases calcium absorption via the formation of calcitriol by the kidneys, in turn increasing calcium absorption throughout the small intestine through increased calcium binding protein (calbindin D).

    Regulation of PTH Levels

    • PTH levels are primarily regulated by blood calcium levels, not by other hormones.
    • A calcium sensing receptor on parathyroid cells and other tissues receives feedback on blood calcium
    • High blood calcium inhibits PTH secretion.
    • Low blood calcium increases PTH secretion.

    Relationship between Calcium and Phosphorus

    • Plasma phosphorus concentration is inversely related to calcium concentration. Their product is constant (solubility product)
    • Maintaining a constant product of calcium and phosphorus is important.

    Hyperparathyroidism

    • Cause: Typically due to a parathyroid gland tumor (adenoma) or compensatory hypertrophy (e.g., vitamin D deficiency, renal failure).
    • Manifestations: bone disease (bone softening and deforming due to demineralization and the presence of bone cysts), kidney stones due to excess calcium in the urine, neuromuscular effects including weakness, reduced alertness, and short-term memory problems. Also, possible digestive issues including abdominal pain, nausea, vomiting and constipation.

    Hypoparathyroidism

    • Cause: Accidental removal or injury to the parathyroid glands during thyroid surgery (thyroidectomy).
    • Characteristics: Low calcium and high phosphate levels.
    • Tetany: A state of muscle spasms due to increased neuromuscular excitability arising from low plasma calcium levels. Can be latent or manifest depending on severity.

    Hypocalcemia Causes

    • Hypoparathyroidism
    • Renal failure
    • Alkalemia (decreased ionized calcium)
    • Vitamin D deficiency

    Hypocalcemic Tetany Symptoms

    • Manifest: Symptoms appear when blood calcium levels fall below 7 mg%, characterized by muscle twitching, tonic-clonic seizures, and generalized convulsions.
    • Latent: Symptoms are minimal and absent at rest, but can be elicited with specific tests (e.g., Trousseau's sign, Chvostek's sign). These tests may induce mild symptoms when blood calcium is still slightly within the range of normal.

    Hypocalcemic Tetany Treatment

    • Manifest tetany (acute): Calcium gluconate administered intravenously.
    • Latent tetany (chronic): Dietary supplements that are rich in calcium and possibly active vitamin D (1,25-dihydroxycholecalciferol/calcitriol).

    Calcium Homeostasis

    • Key organs involved in calcium metabolism: Bone, small intestine, and kidneys.
    • Calcium is absorbed through the small intestine, taken up by blood, and incorporated into bone via calcium deposition and release.
    • Calcium can be lost in urine or stool in excretion.

    Role of Calcium in Physiology

    • Bone and teeth formation:
    • Neuromuscular excitability:
    • Muscle contraction:
    • Synaptic transmission:
    • Hormone secretion:
    • Intracellular communication:
    • Blood clotting mechanism:
    • Maintenance of tight junctions between cells.

    Hormonal Control of Calcium

    • PTH: Increases blood calcium levels.
    • Calcitonin: Decreases blood calcium levels.
    • Vitamin D(active): Increases calcium absorption and promotes bone mineralization.

    Vitamin D3

    • Vitamin D3 can be obtained from dietary sources (e.g., fatty fish, egg yolks) or produced in the skin through exposure to sunlight.
    • Cholecalciferol is activated in the liver into 25-hydroxyvitamin D3 then in the kidneys into 1,25-dihydroxyvitamin D3 (calcitriol).
    • Vitamin D3 primarily increases calcium levels in blood throughout the intestinal tract, kidney, and bone.

    Calcitonin

    • A polypeptide hormone released from parafollicular cells in the thyroid gland.
    • It's antagonistic to PTH in its effect on calcium but similar in its effect on phosphate.
    • It lowers blood calcium levels by inhibiting bone resorption, increasing calcium excretion in the kidneys and inhibiting calcium absorption in the intestines.

    Test Your Knowledge (True/False)

    • This section presents true/false questions regarding the information learned about calcium homeostasis and related hormones.

    Studying That Suits You

    Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

    Quiz Team

    Related Documents

    Endocrine- Parathyroid PDF

    Description

    Explore the functions of the endocrine system, focusing on the parathyroid gland and its crucial role in calcium regulation. This quiz covers the actions of parathyroid hormone (PTH) on various target organs, highlighting its importance for maintaining bodily functions and overall health.

    More Like This

    Use Quizgecko on...
    Browser
    Open
    Browser
    Browser