Endocrine System & Glands

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Questions and Answers

Which characteristic is NOT associated with the endocrine system?

  • Closely works with the nervous system to maintain homeostasis
  • Uses hormones for communication
  • Possesses ducts to transport secretions (correct)
  • Direct secretion into the bloodstream

The pituitary gland is located at the base of the brain within the sella turcica of the temporal bone.

False (B)

The anterior pituitary, also known as the ______, is one of the two major lobes of the pituitary gland.

adenohypophysis

Which hormone is NOT secreted by the adenohypophysis (anterior pituitary)?

<p>Oxytocin (B)</p> Signup and view all the answers

What is the main function of the hormone prolactin (PRL)?

<p>Stimulates milk production in mammary glands</p> Signup and view all the answers

The adrenal glands are located:

<p>On top of the kidneys (B)</p> Signup and view all the answers

The adrenal cortex produces catecholamines, while the adrenal medulla produces steroid hormones.

<p>False (B)</p> Signup and view all the answers

The zona glomerulosa of the adrenal cortex primarily produces ______, which regulates sodium and potassium balance.

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

Which hormone primarily increases blood sugar levels by breaking down fats and proteins?

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

What is the primary function of the Renin-Angiotensin-Aldosterone System (RAAS)?

<p>Regulates blood pressure and fluid balance</p> Signup and view all the answers

What is the main function of chromaffin cells in the adrenal medulla?

<p>Produce catecholamines (B)</p> Signup and view all the answers

Epinephrine primarily focuses on maintaining blood pressure and alertness, while norepinephrine prepares the body for the 'fight-or-flight' response.

<p>False (B)</p> Signup and view all the answers

The thyroid gland is located in the ______, below the larynx and in front of the trachea.

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

Which structure is NOT a part of the thyroid gland?

<p>Cortex (B)</p> Signup and view all the answers

What two hormones does the thyroid gland produce?

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

Match the following pituitary gland parts with their associated hormones:

<p>Adenohypophysis = Adrenocorticotropic hormone (ACTH) Neurohypophysis = Antidiuretic Hormone (ADH)</p> Signup and view all the answers

If an individual has low body temperature, the hypothalamus:

<p>Secretes thyrotropin-releasing hormone (TRH) (D)</p> Signup and view all the answers

Increased body temperature causes the hypothalamus to secrete TRH.

<p>False (B)</p> Signup and view all the answers

TSH stimulates ______ cells of the thyroid gland to release thyroid hormone (TH).

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

What is the effect of thyroid hormone (TH) on metabolic activities?

<p>Increases metabolic activities</p> Signup and view all the answers

The adrenal medulla directly responds to:

<p>Nerve impulses (B)</p> Signup and view all the answers

The adrenal cortex contains chromaffin cells.

<p>False (B)</p> Signup and view all the answers

The zona ______ produces weak male sex hormones that convert into testosterone and estrogen.

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

In the RAAS system, what does ACE stand for?

<p>Angiotensin converting enzyme</p> Signup and view all the answers

Match the hormones with their primary functions:

<p>Cortisol = Manages stress, regulates metabolism Aldosterone = Regulates sodium and potassium balance Epinephrine = Prepares the body for fight-or-flight response Norepinephrine = Maintains blood pressure and alertness</p> Signup and view all the answers

In the adrenal gland, which hormone increases blood sugar by breaking down fats and proteins?

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

Parafollicular cells of the thyroid follicles produce thyroid hormones T3 and T4.

<p>False (B)</p> Signup and view all the answers

Within the thyroid gland, ______ ensures rapid hormone transport into circulation.

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

What substance is essential for the thyroid to create hormones?

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

Match the anatomical structures with their primary functions:

<p>Thyroid Follicles = Produce thyroid hormones Colloid = Stores thyroid hormone precursors Parafollicular Cells = Secrete calcitonin Capillaries = Rapid hormone transport into circulation</p> Signup and view all the answers

Flashcards

Endocrine System

Glands that secrete hormones directly into the bloodstream without using ducts.

Pituitary Gland

Base of brain within the sella turcica of the sphenoid bone, weighing approximately 0.5g in adults.

Adenohypophysis

The anterior pituitary lobe, derived from the developing oral cavity.

Neurohypophysis

The posterior pituitary lobe, derived from the developing brain.

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Growth Hormone (GH)

Hormone that stimulates growth and cell reproduction.

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Adrenocorticotropic hormone (ACTH)

Hormone that stimulates the adrenal cortex to release corticosteroids.

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Thyroid-stimulating hormone (TSH)

Hormone that stimulates the thyroid gland to release thyroid hormones.

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Prolactin (PRL)

Hormone that promotes milk production in mammary glands.

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Luteinizing hormone (LH) & Follicle-stimulating hormone (FSH)

Hormones that act on the gonads to stimulate development of gametes and release hormones.

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Oxytocin

Hormone that stimulates uterine contractions during childbirth and milk ejection during breastfeeding.

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Antidiuretic hormone (ADH)

Hormone that reduces water loss by increasing water reabsorption in the kidneys.

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Adrenal Gland

Located on top of the kidneys that produce steroid hormones and catecholamines.

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Adrenal Cortex

Outer region of the adrenal gland that produces steroid hormones.

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Aldosterone

Regulates sodium and potassium balance, maintaining blood pressure.

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Cortisol

Manages stress, regulates metabolism, suppresses inflammation.

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Androgens (e.g., DHEA)

Produces weak male sec hormones that convert into testosterone and estrogen.

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Adrenal Medulla

Inner region of the adrenal gland that produces catecholamines.

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Epinephrine (Adrenaline)

Prepares the body for "fight-or-flight" response; increases heart rate, blood pressure, and energy availability.

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Norepinephrine (Noradrenaline)

Works alongside epinephrine but focuses more on maintaining blood pressure and alertness.

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Thyroid Gland

In the neck, below the larynx, in front of the trachea, producing T3 and T4.

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Thyroid Follicles

Spherical structures filled with a gel-like substance called colloid.

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Follicular cells

Absorb iodine to make thyroid hormones.

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Colloid

Protein-rich substance inside follicles containing thyroglobulin.

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Parafollicular Cells

Secrete calcitonin to lower blood calcium levels.

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Study Notes

  • Endocrine glands are discussed

Endocrine System

  • Consists of glands secreting hormones directly into the bloodstream
  • It has no ducts
  • Works closely with the nervous system to maintain homeostasis
  • Provides long-lasting effects via hormones
  • Hormones include insulin, cortisol, and thyroid hormones

Major Endocrine Glands

  • Pituitary
  • Adrenal
  • Thyroid
  • Pineal
  • Pancreatic Islets
  • Parathyroid

Pituitary Gland/Hypophysis

  • Located at the base of the brain within the sella turcica of the sphenoid bone
  • Weighs 0.5g in adults
  • Measures 10 X 13 X 6 mm
  • Forms in the embryo partly from the developing brain and partly from the developing oral cavity
  • Has 2 major lobes
    • Adenohypophysis (Anterior Pituitary)
      • Pars tuberalis
      • Pars intermedia
      • Pars distalis
    • Neurohypophysis (Posterior Pituitary)
      • Infundibular stalk
      • Pars nervosa
  • Adenohypophysis hormones
    • Growth hormone (GH)
    • Adrenocorticotropic hormone (ACTH)
    • Thyroid-stimulating hormone (TSH)
    • Prolactin (PRL)
    • Luteinizing hormone (LH)
    • Follicle-stimulating hormone (FSH)
  • Neurohypophysis hormones
    • Oxytocin
    • Antidiuretic hormone (ADH)
  • Reminder: The Big Red Parrot Takes Everything: Trigger, Brain (Hypothalamus), Releasing Hormones, Pituitary Gland, Target Organs, Effect on the Body

Adrenal Gland

  • Located on top of the kidney
  • Flattened, half-moon shape
  • Measures 4-6 cm in length, 1-2 cm in width, and 4-6 mm in thickness in adults
  • Combined weight is 8g
  • Has 2 regions
    • Cortex: Produces steroid hormones
    • Medulla: Produces catecholamines
  • Adrenal Cortex hormones
    • Zona Glomerulosa: Aldosterone (Mineralocorticoid)
      • Regulates sodium (Na+) and potassium (K+) balance, maintaining blood pressure
      • Triggered by low sodium or high potassium levels, or low blood pressure (activates Renin- Angiotensin-Aldosterone System or RAAS)
      • Increases Na+ reabsorption and water retention in kidneys, increases K+ excretion, and raises blood pressure
    • Zona Fasciculata: Cortisol (Glucocorticoid)
      • Manages stress, regulates metabolism, and suppresses inflammation
      • Triggered by ACTH from the pituitary gland, physical/emotional stress, or low blood glucose
      • Increases blood sugar by breaking down fats and proteins (gluconeogenesis), suppresses immune function, and helps the body cope with long-term stress
    • Zona Reticularis: Androgens (e.g., DHEA)
      • Produces weak male sex hormones that convert into testosterone and estrogen
      • Triggered by ACTH stimulation from the pituitary gland
      • Contributes to secondary sex characteristics, maintains libido, and supports estrogen production (especially in postmenopausal women)
  • Adrenal Medulla hormones
    • Epinephrine (Adrenaline)
      • Prepares the body for "fight-or-flight" response, increases heart rate/blood pressure, and energy availability
      • Triggered by physical/emotional stress, low blood sugar, or signals from the sympathetic nervous system
      • Increases heart rate and blood pressure, dilates airways, increases glucose release, and boosts blood flow to muscles
    • Norepinephrine (Noradrenaline)
      • Works alongside epinephrine and focuses more on maintaining blood pressure and alertness
      • Triggered by sympathetic nervous system activation (stress, low blood pressure, danger)
      • Constricts blood vessels to maintain blood pressure, increases alertness/focus, and enhances blood flow to essential organs

Thyroid Gland

  • Located in the neck, below the larynx, in front of the trachea
  • Butterfly-shaped and reddish-brown
  • Produces thyroid hormones T3 and T4
  • Parts include
    • Right lobe
    • Left lobe
    • Isthmus
    • Pyramidal lobe
  • Main components
    • Thyroid follicles
      • Spherical structures filled with colloid
      • Function is to produce and store thyroid hormones (T3 & T4)
    • Follicular cells/thyrocytes
      • A simple epithelium lining that surrounds the follicles
      • Function is to absorb iodine and synthesize thyroid hormones
    • Colloid
      • A protein-rich substance inside follicles containing thyroglobulin
      • Stores thyroid hormone precursors until needed
    • Parafollicular cells/C cells
      • Scattered between follicles, larger and paler than follicular cells
      • Function is to secrete calcitonin to lower blood calcium levels
    • Capillaries
      • surround the follicles
      • Ensure rapid hormone transport into circulation

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