Endocrinology Chapter Overview
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Questions and Answers

The medulla is composed of closely associated glands.

False (B)

The pituitary gland is an example of a pure endocrine entity.

True (A)

Hormones are secreted directly into the lymphatic system only.

False (B)

Only a large quantity of hormones is necessary to influence target organs.

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

Endocrine components of the body can form part of any of the three primary germ layers.

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

Basophils contain more numerous granules than acidophils.

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

Chromophobes are best identified by the Periodic Acid-Schiff (PAS) technique.

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

Methylene blue stains the granules of chromophobes poorly.

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

Basophils can be identified by the aniline blue stain.

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

There are at least 6 confirmed cell types in the pars distalis identified by immunohistochemistry.

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

Parathormone production is controlled by other endocrine glands.

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

Oxyphil cells have a known secretory role in the body.

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

Only about two-thirds of chief cells are actively synthesizing parathormone in a normal adult.

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

The adrenal glands are located at the upper poles of the kidneys.

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

Active chief cells stain lighter than less active chief cells in light microscopy.

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

Thyrotropes stain with aldehyde fuchsin and secrete thyrotropic hormone (TSH).

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

Gonadotropes stain positively with aldehyde fuchsin and secrete gonadotropins.

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

Corticotropes are included in the group of cells that secrete thyroid-stimulating hormones.

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

The cell boundaries of thyrotropes are easily visible in ordinary preparations.

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

The cytoplasm of thyrotropes contains specific granules that are located in the peripheral cytoplasm.

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

Neurons in the adrenal medulla can convert norepinephrine (NE) to epinephrine (EPI).

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

The adrenal medulla secretes hormones into the blood that help an individual respond to emergency situations.

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

Epinephrine primarily acts as a vasodilator with significant effects on metabolism.

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

Cells of the adrenal cortex have a greater capacity for regeneration than those of the adrenal medulla.

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

The adrenal cortex is responsible for maintaining the body's fluid and electrolyte balance.

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

The adrenal glands receive blood supply from two arteries only.

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

The medulla of the adrenal glands has a dual blood supply.

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

The zona reticularis is known to have a well-developed Golgi complex.

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

There is no venous system in the cortex of the adrenal glands.

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

The adrenal medulla contains a high amount of glycogen particles.

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

Catecholamine primarily includes epinephrine in the adrenal medulla.

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

The cortical sinusoids do not anastomose with the medulla's capillary bed.

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

The adrenal glands have a highly vascular structure.

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

Flashcards

Endocrine System

A group of glands that produce hormones and release them directly into the bloodstream.

Hormones

Chemical messengers produced by endocrine glands that regulate various bodily functions.

Target Organs

Organs or tissues that respond to a specific hormone.

Pure Endocrine Glands

Glands that are solely dedicated to producing hormones, like the pituitary gland or thyroid gland.

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Endocrine Components

These glands are derived from various tissues, like the skin, digestive system, or nervous system.

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Thyrotrope

A type of cell in the anterior pituitary gland responsible for producing thyroid-stimulating hormone (TSH).

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Thyrotrope Staining

Thyrotropes stain with aldehyde fuchsin and respond to thyroidectomy. This means their number increases after the thyroid gland is removed.

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Thyrotrope Size

Thyrotropes have a larger size compared to other pituitary cells due to the presence of granules within the peripheral cytoplasm.

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Thyrotrope Function

Thyrotropes secrete thyroid-stimulating hormone (TSH), which controls the thyroid gland. TSH regulates the production of thyroid hormones.

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Thyrotrope Boundaries

The cell boundaries of thyrotropes are not easily visible in typical preparations due to their lack of distinctive granules.

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Basophils (beta cells)

A type of cell found in the anterior pituitary gland (pars distalis) that stains well with aniline blue in Mallory's or Masson's trichrome stains. These cells contain less numerous and smaller granules than acidophils.

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Chromophobes

Cells in the anterior pituitary gland that are not readily stained by standard dyes, also known as reserve cells. They are important for maintaining the hormonal balance of the gland.

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Periodic Acid-Schiff (PAS) stain

A technique used to identify basophils, which stains glycoproteins in the secretory granules of these cells bright magenta.

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Basophils: type 1

A type of basophil characterized by its staining properties.

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Basophils: type 2

A type of basophil characterized by its staining properties.

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Adrenal Medulla: Function

The adrenal medulla is responsible for the body's 'fight or flight' response by releasing hormones like epinephrine and norepinephrine.

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Hormone Release: Adrenal Medulla

The adrenal medulla's neurons release epinephrine and norepinephrine directly into the bloodstream, allowing for a rapid response to stressful situations.

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Adrenal Medulla: Neuron Limitations

Unlike other neurons, the adrenal medulla's neurons cannot convert norepinephrine to epinephrine. This means that the adrenal medulla is not essential for life.

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Adrenal Cortex: Regeneration

Cells in the adrenal cortex can regenerate, suggesting a greater capacity for renewal compared to the adrenal medulla.

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Adrenal Cortex: Functions

The adrenal cortex is vital for regulating fluid & electrolyte balance, managing carbohydrate metabolism, and other critical body functions.

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What are chief cells?

Chief cells are responsible for producing and secreting parathyroid hormone (PTH). PTH is critical for regulating calcium levels in the blood.

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What is parathyroid hormone (PTH)?

Parathyroid hormone (PTH) is a hormone that regulates calcium levels in the blood. It increases calcium levels by promoting its release from bones, increasing its absorption from the intestines, and promoting its reabsorption from the kidneys.

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What are oxyphil cells?

Oxyphil cells are found in the parathyroid glands but their function is unknown. They do not seem to secrete anything.

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How does parathyroid activity affect phosphate levels?

Low parathyroid activity leads to an increase in phosphate levels in the blood.

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How are parathyroid glands regulated?

Parathyroid glands are directly responsive to calcium levels in the blood and are not controlled by other endocrine glands or the nervous system.

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Adrenal Gland Blood Supply

The adrenal glands are highly vascular, receiving blood supply from three arteries: superior, middle, and inferior suprarenal.

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Adrenal Artery Branching

These arteries enter the capsule of the adrenal gland at various points and branch out within the gland.

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Adrenal Cortex Vascularization

Some branches of the adrenal arteries extend into the cortex, forming a network of capillaries and sinusoids.

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Cortical Venous System

These capillaries and sinusoids in the cortex eventually merge into a collecting vein, which marks the boundary with the medulla.

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Dual Medulla Blood Supply

The medulla of the adrenal gland also has a dual blood supply, receiving blood from two sources.

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Cortical Sinusoids to Medulla

One source is the cortical sinusoids that connect with the capillaries in the medulla.

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Medulla's Own Vascular Network

The second source of blood supply for the medulla is a separate network of capillaries and sinusoids within the medulla itself.

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Medullary Vascular Significance

The adrenal medulla is characterized by its dual blood supply, ensuring its vascularity and ability to quickly release hormones into the bloodstream.

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Study Notes

Endocrine System Outline

  • Composed mainly of ductless glands releasing hormones directly into the blood or lymph.
  • Three primary germ layers (ectoderm, mesoderm, endoderm) give rise to different endocrine components.
  • Endocrine components can be separate glands, scattered masses within exocrine glands, or isolated endocrine cells within other organs.

Primary Germ Layers

  • Ectoderm: Hypophysis, adrenal medulla, Chromaffin bodies
  • Mesoderm: Adrenal cortex, testes, ovaries
  • Endoderm: Thyroid, parathyroid, pancreatic islets of Langerhans

Hormone Classes

  • Steroid hormones: Adrenocortical hormones (adrenal cortex), testosterone (testes), estrogen and progesterone (ovaries)
  • Protein hormones; prolactin, insulin (hypophysis, pancreas, thyroid, parathyroid)
  • Amino acid analogues and derivatives; thyroxine, norepinephrine (thyroid, adrenal medulla)

Endocrine System Functions

  • Hormones have a specific effect on target organs, often stimulating or activating or sometimes inhibiting.
  • Target cells contain receptors affecting specific physiological responses.
  • Neuro-Endocrine System: overlapping control involving both endocrine and nervous systems.
  • Endocrine cells are regulated by neural mechanisms.

Pituitary Gland

  • Also known as Hypophysis Cerebri
  • Pea-shaped endocrine gland connected to the hypothalamus.
  • Composed of anterior and posterior lobes.
  • Master control gland for hormone production in other endocrine glands.
  • 0.5-1.5g in weight

Pituitary Gland - Anterior Lobe (Adenohypophysis)

  • Composed of different cell types: acidophils (somatotropes and mammotropes), basophils (thyrotropes, corticotropes, gonadotropes) and chromophobes (reserve cells)
  • Secretes hormones regulating diverse bodily functions.

Hormones Secreted by Pars Distalis

  • STH/GH- Growth hormone, affects body growth.
  • Prolactin- Stimulates milk production
  • ACTH- Adrenocorticotropic hormone, targets the suprarenal glands.
  • FSH/LH- Follicle-stimulating and luteinizing hormones, involved in reproduction.
  • TSH- Stimulates thyroid function.

Thyroid Gland

  • Located in the neck, composed of follicles.
  • Thyroid hormones (T3, T4) increase metabolic rate.
  • Thyroid hormones are involved in growth and development
  • Contains follicular epithelial cells secreting hormones into the follicle lumen.

Parathyroid Glands

  • Small glands embedded on the posterior surface of the thyroid.
  • Chief cells are the most abundant cells secreting Parathyroid hormone (PTH) involved in calcium homeostasis, regulating blood calcium levels
  • Oxyphil cells: uncertain function, but present in larger quantities in older individuals.

Adrenal Glands

  • Located superior to the kidneys. Composed of adrenal cortex and adrenal medulla.
  • Adrenal cortex: secretes steroid hormones (mineralocorticoids, glucocorticoids, androgens).
  • Adrenal medulla: secretes catecholamines (epinephrine, norepinephrine).

Pineal Gland

  • Small gland in the brain
  • Secretes melatonin regulating circadian rhythms and influencing reproductive function.
  • Contains pinealocytes and glial cells.

Pancreatic Islets

  • Scattered in the exocrine tissue of the pancreas.
  • Alpha cells secrete glucagon.
  • Beta cells secrete insulin
  • Delta cells secrete somatostatin.

Other Endocrine Glands

  • Includes other glands with endocrine functions like testes, ovaries, gastrointestinal tract, and kidneys.

Female Reproductive System

  • Ovarian cycle: series of changes in the ovaries affecting follicle and oocyte development as well as hormonal variations.
  • Primordial follicle: contains a primary oocyte and a single layer of flattened follicle cells.
  • Primary follicle: contains a primary oocyte inside a cuboidal epithelium.
  • Secondary follicle: Contains a primary oocyte in a stratified follicle cells.
  • Mature-graafian follicle: Contains secondary oocyte.
  • Ovulation: the release of an ovum
  • Corpus luteum: structure formed during ovulation to produce hormones like estrogen and progesterone.
  • Corpus albicans: scar tissue formed after the corpus luteum degenerates.

Male Reproductive System

  • Spermatogenesis: process of sperm formation, starts at puberty.
  • Seminiferous tubules: where sperm development takes place surrounded by Sertoli cells which provide support and nutrition.
  • Interstitial cells of Leydig: secrete testosterone crucial for male characteristics.
  • Accessory glands; include seminal vesicles, prostate, and bulbourethral glands, they produce fluids nourishing and transporting sperm.

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Test your knowledge on the structure and function of the endocrine system with this quiz. Explore topics like the pituitary gland, hormone production, and cell types within the endocrine components. Ideal for students studying human anatomy and physiology.

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