Pituitary Gland Overview

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Questions and Answers

What is the name of the gland that is being discussed throughout the lecture?

Pituitary gland

What are the two main parts of the pituitary gland?

  • Pars tuberalis and Pars intermedia
  • Pars distalis and Pars tuberalis
  • Pars nervosa and Pars intermedia
  • Anterior pituitary and Posterior pituitary (correct)

What is the function of the acidophils and basophils in the pituitary gland?

Hormone secretion

Which part of the pituitary gland contains the infundibular stalk?

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

The pars tuberalis is poorly vascularized.

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

The pars intermedia is known for being the location of Rathke's cysts.

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

Which of these cells are found in the pars nervosa?

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

What is the function of the hormone oxytocin?

<p>Stimulates uterine contractions during childbirth and milk ejection from mammary glands</p> Signup and view all the answers

What is the other name for vasopressin?

<p>Antidiuretic hormone (ADH)</p> Signup and view all the answers

The superior hypophyseal artery supplies blood to the anterior pituitary.

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

Flashcards

Pars Distalis

The anterior lobe of the pituitary gland, composed of cords of cells and fenestrated capillaries.

Chromophils

Pituitary cells that contain granules and secrete hormones.

Chromophobes

Pituitary cells that lack granules and are considered undifferentiated or reserve cells.

Acidophils

A type of chromophil cell in the pars distalis that stains with orange G and secretes growth hormone (GH) and prolactin.

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Basophils

A type of chromophil cell in the pars distalis that stains with PAS and secretes various hormones like TSH, ACTH, and gonadotropins.

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Somatotrophs

Acidophil cells that produce growth hormone.

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Mammotrophs

Acidophil cells that produce prolactin.

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Thyrotrophs

Basophil cells that produce thyroid-stimulating hormone (TSH).

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Corticotrophs

Basophil cells that produce adrenocorticotropic hormone (ACTH).

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Gonadotrophs

Basophil cells that produce follicle-stimulating hormone (FSH) and luteinizing hormone (LH).

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Pars Tuberalis

Part of the pituitary gland, highly vascularized and with cords of basophilic cells, might contain some acidophils and basophils, involved in gonadotrophin regulation.

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Pars Intermedia

Small region between pars distalis and pars nervosa.

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Pars Nervosa

Posterior lobe of the pituitary, comprised of nerve fibers and pituicytes ,which stores hormones.

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Oxytocin

Hormone released from the pars nervosa, stimulating uterine contractions and milk ejection.

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Vasopressin (ADH)

Hormone released from the pars nervosa, regulating water reabsorption in kidneys.

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Study Notes

Pituitary Gland Overview

  • The pituitary gland is a small endocrine gland located in the sella turcica of the sphenoid bone.
  • It plays a crucial role in regulating various bodily functions.

Intended Learning Outcomes (ILOs)

  • Students will learn to recognize the histological organization of the pituitary gland.
  • Students will identify cells forming pars distalis.
  • Students will discuss the structure and function of acidophils and basophils.
  • The histological structure of pars tuberalis, pars intermedia, and pars nervosa will be described.
  • Students will describe the blood supply of the pituitary gland.

Pituitary Gland Anatomy

  • The pituitary gland has two main lobes: anterior and posterior.
  • The anterior pituitary (adenohypophysis) develops from Rathke's pouch.
  • The posterior pituitary (neurohypophysis) develops from the hypothalamus.

Pars Distalis

  • This is the anterior pituitary lobe.
  • It contains parenchyma (functional cells) and stroma (supporting tissue).
  • Parenchyma includes chromophils (hormone-producing cells) and chromophobes (non-hormone producing cells).
  • Acidophils (somatotrophs and mammotrophs) and basophils (thyrotrophs, corticotrophs, gonadotrophs) are further subdivisions of the chromophils.

Pars Tuberalis

  • This region encircles the infundibulum.
  • It has a highly vascular structure.
  • Predominantly contains basophils and undifferentiated cells.

Pars Intermedia

  • This region is poorly vascularized.
  • Contains Rathke's cysts.
  • Primary cells are corticotrophs (MSH producing cells).

Pars Nervosa

  • This part of the posterior pituitary is rich in nerve fibers, lack myelination.
  • Contains nerve fibers from the hypothalamus, Herring bodies and pituicytes.
  • Functions: Oxytocin (paraventricular nucleus) targets the uterus and mammary gland. Vasopressin/ADH (supraoptic nucleus) regulates water reabsorption in the kidneys.

Blood Supply

  • Pituitary blood supply is unique, featuring a hypothalamic-hypophyseal portal system. This system allows for direct delivery of hypothalamic hormones to the anterior pituitary.

Cell Types and Characteristics in Pars Distalis

Cell Type Percentage Size Granules Function Specific Stain
Acidophils 48% Larger Present Hormone secretion (e.g., growth hormone) Orange G
Chromophobes 52% Smaller Absent Undifferentiated or exhausted chromophils N/A
Basophils Hormone secretion (e.g., TSH, ACTH) PAS

Acidophils Subtypes

Cell Type Percentage of Chromophils Size Function
Somatotrophs 50% Medium-sized Growth hormone secretion
Mammotrophs 15-20% Large Prolactin secretion (milk formation)

Basophils Subtypes

Cell Type Percentage of Chromophils Size Function
Thyrotrophs 5% Large TSH (thyroid-stimulating hormone) secretion
Corticotrophs 15-20% Medium-sized ACTH (adrenocorticotropic hormone) secretion
Gonadotrophs 10% Small FSH (follicle-stimulating hormone) / LH (male/female) secretion

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