34 Questions
What is the primary function of the follicular cells in the thyroid gland?
Produce T3 and T4 hormones to regulate basal metabolism
Where are the parafollicular cells located within the thyroid gland?
Surrounding a central cavity
From which embryonic germ layer is the thyroid gland derived?
Endoderm
What is the shape of the thyroid gland?
Butterfly-shaped
What is the main reason chromaffin cells in the adrenal medulla are called chromaffin cells?
They have a basophilic cytoplasm with granules that stain brown with chromium salts
Which type of glandular cells in the adrenal medulla contain large, spherical nuclei and numerous secretory granules with an electrodense nucleus?
Norepinephrine (noradrenaline) producing cells
What stimulates the chromaffin cells of the adrenal medulla to secrete adrenaline and norepinephrine to capillaries?
Acetylcholine released by sympathetic endings of the splanchnic nerves
What are the main actions of adrenaline and norepinephrine when secreted by the adrenal medulla?
Increase heart rate and tissue irrigation, and release of glucose
Which organ regulates the activity of the adrenal medulla through sympathetic endings of the splanchnic nerves?
Hypothalamus
What is the role of sympathetic ganglion cells in the adrenal medulla?
Found between the strands of chromaffin cells
What characteristic differentiates cells that produce epinephrine (adrenaline) from norepinephrine (noradrenaline) producing cells in the adrenal medulla?
Size and electron density of secretory granules
What is the function of numerous sinusoid capillaries in the adrenal glands?
Lead to postcapillary venules communicating with larger venules
Which cells in the thyroid gland produce calcitonin in response to high calcium levels?
Parafollicular cells
What do the parathyroid glands produce to increase calcium levels in the blood?
Parathormone
Where is the location of the adrenal glands?
Near the kidneys
What do the chief cells in the parathyroid glands produce?
Parathormone
What is the name of the glycoprotein that stores thyroid hormones T3 and T4 in the thyroid follicles?
Thyroglobulin
Which hormone is produced by the adrenal glands in response to stress and low blood glucose levels?
Cortisol
What is the function of thyroid peroxidase in the synthesis of thyroid hormones?
Producing thyroxine (T4)
What are the two thyroid hormones secreted into the blood by follicular cells?
Thyroxine (T4) and triiodothyronine (T3)
What is the role of oxyphil cells in some species of parathyroid glands?
Their role is unclear
What is the function of parathormone produced by the parathyroid glands?
Increasing calcium levels in the blood
What are the morphological differences in thyroid follicles based on?
Their size and shape
Which part of the adrenal gland is of mesodermal origin?
Cortex
Which zone of the cortex is the site of mineralocorticoid production?
Glomerular zone
Which hormone is primarily produced in the fascicular zone of the adrenal cortex?
Glucocorticoids
What type of cells is predominant in the reticular zone of the adrenal cortex?
Smaller polyhedral cells with pyknotic nucleus
What is the primary function of the adrenal medulla?
Produce catecholamines
Which layer in the adrenal cortex is the largest?
Fascicular zone
What is the composition of the stroma in the adrenal gland?
Thin capsule of dense connective tissue
Where are reserve cells located in the adrenal gland?
Stroma
Which type of tissue produces sex hormones in the adrenal cortex?
Smaller polyhedral cells with pyknotic nucleus
What is the color description of the cortex and medulla in the adrenal gland?
Brownish-reddish and greyish respectively
What physiological functions are regulated by the adrenal gland?
Blood volume and electrolyte balance
Study Notes
- The adrenal gland is composed of a cortex (70-80% of the volume) and a medulla (20-30% of the volume).
- The cortex is brownish-reddish in color and of mesodermal origin, while the medulla is greyish and neuroectodermal.
- The stroma is a thin capsule of dense connective tissue that occasionally emits fine trabeculae, with reserve cells in the capsule.
- The cortex is divided into three zones: glomerular, fascicular, and reticular.
- The glomerular zone (arcuate or zona glomerulosa) consists of irregular cords of cells with a columnar morphology, abundant SER, and is the site of mineralocorticoid production (aldosterone).
- The fascicular zone (zona fasciculata) is the largest of the three layers, with cuboidal cells that form spongy tissue and produce glucocorticoids (cortisol, cortisone, and corticosterone).
- The reticular zone (zona reticularis) consists of irregular cords of smaller polyhedral cells with a more pyknotic nucleus and less lipid vacuoles, which produce sex hormones (androgens, estrogens, and progesterone).
- The adrenal medulla is located in the central portion of the gland, is smaller than the cortex, and produces catecholamines (epinephrine and norepinephrine).
- The adrenal gland is essential for life, producing steroid hormones through cholesterol and regulating various physiological functions, such as blood volume and electrolyte balance, metabolism, and inflammation.
Test your knowledge of the anatomical structure of endocrine glands in the human body, including the division of parenchyma into cortex and medulla, the composition of stroma, and other related concepts.
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