16 Questions
What is the main function of the endocrine system?
To secrete hormones directly to the blood
Which of the following glands is part of the endocrine system?
Suprarenal gland
What is the main difference between chromophobes and chromophils?
Chromophobes don't take histological stain, chromophils do
Which cells in the pars distalis produce growth hormone?
Somatotrophs
What is the function of the posterior lobe of the pituitary gland?
To store and release neurosecretory material
What is the characteristic of the cells in the pars nervosa?
They are lightly stained and composed of a few cells and nerve fibers
What is the name of the hormone produced by lactotrophs?
Prolactin
What is the characteristic of the cells in the pars intermedia?
They are arranged in follicles or cords and have blood vessels in between
What is the function of the cells in the zona glomerulosa of the adrenal cortex?
Secretion of mineralocorticoids
What type of cells are found in the pituitary gland?
All of the above
What is the function of the principal cells in the thyroid gland?
Secretion of thyroid hormones
What is the location of the Herring bodies in the pituitary gland?
Along the nerve fibers
What is the function of the C cells in the thyroid gland?
Secretion of thyrocalcitonin hormone
What is the characteristic of the cells in the zona fasciculata of the adrenal cortex?
Large polyhedral cells with acidophilic vacuolated cytoplasm
What is the location of the pituicytes in the pituitary gland?
Few in number and scattered throughout the gland
What is the characteristic of the zona reticularis of the adrenal cortex?
Small polyhedral cells with less vacuolated cytoplasm
Study Notes
The Endocrine System
- The endocrine system secretes hormones directly into the blood, including the pituitary gland, thyroid gland, and suprarenal gland.
The Pituitary Gland
- The pituitary gland has anterior and posterior lobes.
- The anterior lobe consists of:
- Pars distalis
- Pars intermedia
- Pars tuberalis
- The posterior lobe (neurohypophysis) consists of:
- Pars nervosa
- Pars distalis:
- Surrounded by a thin CT capsule
- Consists of irregular cords of cells with numerous fenestrated capillaries
- Cells of Pars distalis:
- Chromophobes (52%): smaller, non-granular cytoplasm, don't take histological stain
- Chromophils (48%): larger, granular cytoplasm, take histological stain
- Chromophils:
- Acidophil cells (37%): moderate in size, have acidophilic granules, secrete somatotrophs (Growth Hormone, GH)
- Basophil cells (11%): larger in size, have basophilic granules, secrete thyrotrophs (Thyroid Stimulating Hormone, TSH)
- Lactotrophs: secrete prolactin
- Gonadotrophs: secrete Follicle Stimulating Hormone (FSH) and Luteinizing Hormone (LH)
- Corticotrophs: secrete Adrenocorticotrophic Hormone (ACTH)
- Pars intermedia:
- Separated from Pars distalis by a thin, incomplete cleft
- Cells arranged in follicles or cords with blood vessels in between
- Pars nervosa:
- Lightly stained due to few cells and mainly nerve fibers
- Nerve fibers carry neurosecretory material from the hypothalamic nuclei
- Neurosecretions (vasopressin and oxytocin) are stored in Herring bodies
- Few cells, "pituicytes", are neuroglial cells
- Rich blood capillaries
The Thyroid Gland
- The thyroid gland is surrounded by a CT capsule, which sends septa to divide the gland into indistinct lobules
- The parenchyma is formed of follicles, which are filled with acidophilic colloid
- Lining epithelium varies from flat to columnar
- Two types of cells are present:
- Follicular cells (principal cells): main type of cells, secrete thyroid hormones (T3 & T4), cuboidal, columnar, or squamous
- Parafollicular cells (C cells): secrete thyrocalcitonin hormone, larger in size, don't reach the follicular cavity
- Blood capillaries are found between the follicles
The Suprarenal Gland
- Each gland has an outer cortex and an inner medulla
- The adrenal cortex:
- Zona glomerulosa: a narrow zone under the capsule, formed of columnar acidophilic cells, secretes mineralocorticoids (aldosterone)
- Zona fasciculata: the middle zone, formed of large polyhedral cells with acidophilic vacuolated cytoplasm, secretes glucocorticoid
- Zona reticularis: the inner zone, formed of small polyhedral cells with less vacuolated cytoplasm, secretes sex hormones and some glucocorticoids
Learn about the endocrine system, its functions, and the structure of the pituitary gland, including its anterior and posterior lobes.
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