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What is the primary function of the parafollicular cells in the thyroid gland?
What is the primary function of the parafollicular cells in the thyroid gland?
What is the result of iodine deficiency on the thyroid gland?
What is the result of iodine deficiency on the thyroid gland?
What is the characteristic of myxedema?
What is the characteristic of myxedema?
What is the primary feature of Graves' disease?
What is the primary feature of Graves' disease?
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What are the four small glands located behind the thyroid gland?
What are the four small glands located behind the thyroid gland?
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What is the function of chief cells in the parathyroid gland?
What is the function of chief cells in the parathyroid gland?
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What is the adrenal gland composed of?
What is the adrenal gland composed of?
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What is the function of the zona glomerulosa in the adrenal gland?
What is the function of the zona glomerulosa in the adrenal gland?
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What is the function of Somatotrophs in the pituitary gland?
What is the function of Somatotrophs in the pituitary gland?
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What is the characteristic feature of Basophils?
What is the characteristic feature of Basophils?
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What is the function of Thyrotrophs?
What is the function of Thyrotrophs?
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What is the role of Herring bodies in the pars nervosa?
What is the role of Herring bodies in the pars nervosa?
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What is the consequence of a tumor in the anterior pituitary gland?
What is the consequence of a tumor in the anterior pituitary gland?
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What is the structure composed of in the thyroid gland?
What is the structure composed of in the thyroid gland?
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What is the function of Pituicytes?
What is the function of Pituicytes?
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What is the primary function of the Zona Fasiculata?
What is the primary function of the Zona Fasiculata?
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What is the importance of iodine for the thyroid gland?
What is the importance of iodine for the thyroid gland?
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What is unique about the cells in the Zona Reticularis?
What is unique about the cells in the Zona Reticularis?
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What does the pineal gland secrete at night?
What does the pineal gland secrete at night?
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What is the function of chromaffin cells?
What is the function of chromaffin cells?
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What is the name of the second main component of the adrenal medulla?
What is the name of the second main component of the adrenal medulla?
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What is the name of the hormone precursor secreted by pinealocytes during the day?
What is the name of the hormone precursor secreted by pinealocytes during the day?
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What is the function of secretary cells in endocrine glands?
What is the function of secretary cells in endocrine glands?
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Which part of the pituitary gland originates from the brain?
Which part of the pituitary gland originates from the brain?
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What is the function of the pars distalis?
What is the function of the pars distalis?
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What is the composition of stroma in the pituitary gland?
What is the composition of stroma in the pituitary gland?
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What type of cells are acidophils?
What type of cells are acidophils?
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What is the percentage of chromophils in the adenohypophysis?
What is the percentage of chromophils in the adenohypophysis?
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Study Notes
Endocrine Glands
- Endocrine glands release hormones, which are signaling molecules, into the bloodstream through capillaries.
- The pituitary gland consists of two parts: neurohypophysis and adenohypophysis.
Pituitary Gland
- Pituitary gland is divided into two parts:
- Neurohypophysis (pars nervosa)
- Adenohypophysis (pars distalis, pars tuberalis, and pars intermedia)
- Adenohypophysis consists of:
- Stroma (capsule, reticular connective tissue, and septa containing sinusoidal capillaries)
- Parenchyma (chromophils, chromophobes, and acidophils)
Chromophils
- Chromophils are characterized by:
- Acidophilic granules in the cytoplasm
- Function: secrete growth hormone (somatotrophs) and prolactin hormone (mammotrophs)
- Basophils have:
- Basophilic granules in the cytoplasm
- Function: secrete thyroid-stimulating hormone (thyrotrophs), adrenocorticotropic hormone (corticotrophs), and follicle-stimulating hormone (gonadotrophs)
Chromophobes
- Chromophobes are:
- Poorly stained cells
- Function: partially degranulated chromophils and reserve or stem cells
Pars Nervosa
- Structure of pars nervosa:
- Unmyelinated nerve fibers
- Herring bodies
- Fenestrated blood capillaries
- Pituicytes
- Function: storage and release of oxytocin, which plays a role in sexual reproduction
Pituitary Tumors
- Tumor of the anterior pituitary may compress the optic nerve, leading to blindness
- Tumor composed mainly of somatotrophs leads to gigantism in children and acromegaly in adults
- Excessive prolactin in males causes breast enlargement and impotence
Thyroid Gland
- Thyroid gland consists of two lobes connected by a narrow isthmus
- Stroma: capsule, reticular connective tissue, and septa
- Parenchyma: secretory cells
- Thyroid gland produces thyroxine (T4) and triiodothyronine (T3)
Thyroid Hormones
- Thyroid hormones are produced by follicular cells
- Parafollicular cells (C cells) produce calcitonin, which decreases bone osteoclast activity and lowers blood calcium levels
Thyroid Disorders
- Thyrotoxicosis: increased follicular cells and thyroxine secretion
- Iodine deficiency goiter: occurs with a diet low in iodine and leads to hypothyroidism
- Myxedema: hypothyroidism leads to fatigue, sleeping, muscular, and mental sluggishness
- Graves' disease: autoimmune disease characterized by exophthalmic goiter and hyperthyroidism
Parathyroid Glands
- Four small glands located behind the thyroid gland
- Structure:
- Stroma: capsule, septa, and reticular connective tissue
- Parenchyma: chief cells, oxyphil cells, and some fat cells
- Chief cells secrete parathyroid hormone, which regulates calcium levels
Adrenal Glands
- Two glands, one above each kidney
- Structure:
- Stroma: capsule, septa, and reticular connective tissue
- Parenchyma: adrenal cortex and adrenal medulla
- Adrenal cortex is divided into three zones:
- Zona glomerulosa
- Zona fasiculata
- Zona reticularis
Adrenal Cortex Zones
- Zona glomerulosa: secretes mineral corticoids, mainly aldosterone
- Zona fasiculata: secretes glucocorticoids, mainly cortisone
- Zona reticularis: secretes androgens
Adrenal Medulla
- Has profuse blood supply in-between cell cords
- Structure: two types of cells
- Chromaffin cells
- Autonomic ganglion cells
- Chromaffin cells secrete epinephrine (80%) or norepinephrine (20%)
Pineal Gland
- Also known as the third eye
- Function is affected by light
- Structure:
- Stroma: capsule, septa, and reticular connective tissue
- Parenchyma: pinealocytes (secretory cells)
- Pinealocytes secrete melatonin (by night) and form serotonin (by day)
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Description
Learn about the structure and function of endocrine glands, including the pituitary gland, and how they release hormones into the bloodstream.
