Endocrine System: Posterior Pituitary Gland
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Questions and Answers

What are the two main hormones secreted by the posterior pituitary gland?

Antidiuretic Hormone (ADH) and Oxytocin.

How does Antidiuretic Hormone (ADH) help maintain the body's water balance?

ADH increases water reabsorption in the kidneys, reducing urine output and conserving water.

What triggers the release of Antidiuretic Hormone (ADH)?

Increased blood osmolarity or decreased blood volume.

In what way does Oxytocin play a role during childbirth?

<p>Oxytocin stimulates uterine contractions during labor.</p> Signup and view all the answers

What condition results from a deficiency in growth hormone secretion during childhood?

<p>Dwarfism.</p> Signup and view all the answers

What are the symptoms of Gigantism?

<p>Excessive growth and height, poor blood flow, and increased muscle mass but weaker muscles.</p> Signup and view all the answers

Describe the primary characteristic of Acromegaly.

<p>Increased growth hormone secretion in adults leading to thickening of bones.</p> Signup and view all the answers

What is the main hormone produced by the thyroid gland, and what is its main function?

<p>The main hormone is thyroxine (T4), which regulates metabolism.</p> Signup and view all the answers

How many iodine atoms are contained in the main thyroid hormone, thyroxine?

<p>Four iodine atoms.</p> Signup and view all the answers

What is the role of thyroxine (T4) in the body?

<p>Thyroxine (T4) increases metabolic rate, glucose metabolism, and protein synthesis.</p> Signup and view all the answers

Describe the primary difference between Type 1 and Type 2 diabetes mellitus.

<p>Type 1 diabetes is characterized by insulin deficiency due to immune attack on insulin-producing cells, while Type 2 diabetes involves insulin resistance and decreased responsiveness of cells to insulin.</p> Signup and view all the answers

How does the hypothalamus respond to a decreased metabolic rate?

<p>The hypothalamus releases thyroid-releasing hormone (TRH), which stimulates the anterior pituitary to release thyroid-stimulating hormone (TSH).</p> Signup and view all the answers

What are common symptoms of hyperthyroidism, particularly in Graves' Disease?

<p>Common symptoms include high glucose metabolism, weight loss with increased appetite, heat intolerance, and eye irritations such as double vision.</p> Signup and view all the answers

Outline the blood pathway through the kidney starting from the renal artery.

<p>The blood pathway is: renal artery → afferent arteriole → glomerulus → efferent arteriole → peritubular capillaries → renal vein.</p> Signup and view all the answers

What is the importance of the 'undershoot' phase in the action potential of a neuron?

<p>The 'undershoot' phase helps re-establish resting potential and prevents immediate re-firing of the neuron.</p> Signup and view all the answers

Define resting membrane potential and its typical value.

<p>Resting membrane potential is the electrical charge difference across a cell's membrane, typically around -70 mV.</p> Signup and view all the answers

What happens during the depolarization phase of an action potential?

<p>During depolarization, sodium (Na+) channels fully open, allowing Na+ to rush into the neuron, leading to a rapid increase in membrane potential.</p> Signup and view all the answers

Identify the role of the collecting duct in the water filtrate pathway of the kidney.

<p>The collecting duct collects filtrate from several nephrons and directs it to the ureter for excretion.</p> Signup and view all the answers

What physiological changes occur in the body due to hyperthyroidism?

<p>Hyperthyroidism leads to increased glucose metabolism, elevated heart rate, weight loss, and heat intolerance.</p> Signup and view all the answers

Study Notes

Posterior Pituitary Gland

  • Extension of the hypothalamus
  • Stores and releases hormones synthesized in the hypothalamus
  • Two main hormones: Antidiuretic Hormone (ADH) and Oxytocin

Antidiuretic Hormone (ADH)

  • Regulates water balance
  • Increases water reabsorption in the kidneys, preventing dehydration
  • Concentrates urine and retains water in the body
  • Reduces urine output and maintains blood volume
  • Released when blood osmolarity increases (dehydration) or blood volume decreases
  • Can cause vasoconstriction (increase blood pressure)

Oxytocin

  • "Love hormone"
  • Involved in social bonding, reproduction, and childbirth
  • Stimulates uterine contractions during labor
  • Synthesized in the hypothalamus, stored and released by the posterior pituitary

Endocrine Diagnosis (Case Study)

Disorders

Dwarfism

  • Deficiency in growth hormone during childhood
  • Adult height typically 4'10" or shorter

Gigantism

  • Overproduction of growth hormone during childhood
  • Symptoms include excessive growth, poor blood flow, increased muscle mass (weaker muscles), and pituitary gland tumor formation

Acromegaly

  • Increased growth hormone secretion in adulthood
  • Bone thickening, leading to:
    • Enlarged forehead
    • Bulging eyebrow ridges
    • Prominent cheekbones
    • Enlarged lower jaw and outward-pushed lower teeth

Thyroid Gland

  • Located at the base of the neck
  • Main hormone is thyroxine (T4), also contains T3
  • Contains four iodine atoms
  • Regulates metabolism, impacting:
    • Glucose metabolism
    • Protein synthesis
    • Oxygen consumption (blood pressure and heart rate)
    • Growth and tissue differentiation

Thyroid Hormone Release

  • Stimulus: Decreased metabolic rate detected by the hypothalamus
  • Effect:
    1. Hypothalamus releases thyroid-releasing hormone (TRH)
    2. Anterior pituitary releases thyroid-stimulating hormone (TSH)
    3. Thyroid releases thyroxine (T4)
    4. T4 increases metabolic rate

Hyperthyroidism

  • Overactive thyroid gland, increasing thyroxine levels
  • Effects include high glucose metabolism, weight loss with increased appetite, heat intolerance, and increased heart rate

Graves' Disease

  • A type of hyperthyroidism
  • Symptoms: eye irritation, double vision, and protruding eyes ("bug eyes")
  • Antibodies target TSH receptors, stimulating TSH secretion

Diabetes Mellitus

  • Frequent urination is a common symptom
  • Type 1: Insulin deficiency (immune system attacks insulin-producing cells)
  • Type 2: Insulin resistance (cells don't respond to insulin efficiently)

Blood Pathway in the Kidney

  • Renal artery → afferent arteriole → glomerulus → efferent arteriole → peritubular capillaries → renal vein

Water Filtrate Pathway in the Kidney

  • Bowman's capsule → proximal convoluted tubule → descending loop of Henle → ascending loop of Henle → distal convoluted tubule → collecting duct → ureter → bladder → urethra

Action Potential

  • Resting State (-70 mV): Na+ channels closed, K+ channels closed
  • Threshold: Stimulus opens some Na+ channels, graded potential
  • Depolarization: Na+ channels fully open, Na+ rushes in (positive feedback loop)
  • Repolarizing Phase: Na+ channels close, K+ channels open, K+ exits
  • Undershoot: K+ channels close slowly, membrane potential becomes more negative, helps re-establish resting potential

Membrane Potential

  • Difference in electrical charge across a cell's membrane
  • Resting membrane potential: Typically around -70 mV (inside negative)

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Description

Explore the functions of the posterior pituitary gland, focusing on the two key hormones it stores: Antidiuretic Hormone (ADH) and Oxytocin. This quiz covers their roles in water balance, social bonding, and related disorders such as dwarfism and gigantism. Test your knowledge on how these hormones influence the endocrine system.

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