"Microscopic Anatomy Endocrine Mira Krendel" 3/16 Flashcards
Endocrine glands consist mostly of what kind of tissue?
Epithelial tissue
Endocrine cells are in close contact with capillaries. What kinds of capillaries facilitate the most communication for hormones?
Many capillaries/sinusoids in endocrine glands have irregular shape and are fenestrated.
The prefix “adeno” means:
glandular
What are 3 characteristics of cells that secrete protein/polypeptide hormones?
Cells that secrete protein/polypeptide hormones:
- have abundant RER
- have prominent golgi
- Hormones are stored in secretory granules.
What are 3 characteristics of steroid-producing cells?
Steroid-producing cells:
- Have a central nucleus
- Lipid droplets can be seen in the cytoplasm
- Abundant smooth ER for cholesterol synthesis
- Mitochondria can be sphere-shaped with tubular or vesicular cristae
* *#4 is unique to steroid-producing cells.
The anterior pituitary gland is derived from what embryonic origin?
The anterior pituitary gland is derived from the oral ectoderm.
The AP consists of epithelial cells.
The posterior pituitary is derived from what embryonic origin?
The posterior pituitary is derived from the neuroectoderm. The PP consists of neurons and glia.
What is the function of a Rathke’s cyst?
Rathke’s cysts are colloid-filled circled between the AP and the PP. They are left over from the development of the pituitary, and have no known function.
Chromaphils of the AP consist of what cell types?
Chromaphils include Acidophils and Basophils.
Chromaphobes are either stem cells or degranulated chromaphils and do not pick up stain.
Explain the acronym for the anterior pituitary “GPA”
Growth hormone (somatotrophs) Prolactin (lactotrophs) Acidophils
What cell types stain as basophils in the AP?
Gonadotrophs - LH and FSH
Thyrotrophs - TSH
Corticotrophs - ACTH and beta-lipotropin
Thyrotropin is also known as:
TSH, thyroid stimulating hormone
Acidophils, basophils and chromophobes are best visualized using special stains such as:
Hematoxylin, phloxine and isomine blue
What part (“pars”) of the AP is inactive?
The pars intermedia is largely inactive in adults and contains colloid-filled follicles and Rathke’s cysts.
Hormones are produced in the pars distalis and the pars tuberalis sections of the AP.
What are Herring bodies?
Herring bodies are where peptide hormones, produced in the hypothalamic neurons, are stored after they are sent, via axons, to the PP.
PP stores ADH (vasopressin) and oxytocin.
Glial cells of the PP are also known as:
pituicytes
Disruption of the infundibulum of the pituitary gland, such as through trauma or neoplasm, causes lack of communication between the hypothalamus and the PP. What pathology can then ensue?
Diabetes insipidus from lack of ADH getting to the PP.
The adrenal cortex has an epithelial origin, and its cells produce steroid hormones. What three zones are seen in the adrenal cortex?
The three zones of the adrenal cortex are:
- Zona glomerulosa (furthest from medulla)
- Zona fasiculata
- Zona reticularis (closest to medulla)
Why do cells of the zona fasciculata appear foamy?
The cells of the zona fasciculata appear foamy due to their participation in steroid hormone synthesis, and contain lipid droplets.
Cells of the other two adrenal cortex zones also make steroid hormones, but in general do not appear as foamy.
Explain the study trick “Salt Sugar Sex” as it applies to the adrenal cortex.
- Zona glomerulosa - makes mineralcorticoids such as aldosterone - “salt”
- Zona fasciluata - makes glucocorticoids such as cortisol (with some androgen secretion) - “sugar”
- Zona reticularis - makes glucocorticoids and androgens such as DHEA - “sex”
Reticularis cells appear the most irregularly organized.
Glomerulosa cells frequently appear in bundles.
Why does silver or chromium stain cause the adrenal medulla to appear dark? How does the adrenal medulla appear in H&E staining?
The adrenal medulla appears dark because these stains react with the electron-dense secretory granules containing the catecholamines being produced in the cells, such as epi and norepi.
The adrenal medulla appears pale in H&E preparation.
What will happen to the adrenal cortex of an animal that lacks or loses its pituitary gland?
The adrenal cortex will atrophy if it is not stimulated to produce hormones.
What are the symptoms and possible causes of Cushing’s syndrome?
Symptoms of Cushing’s syndrome:
- Weight gain
- Hyperglycemia
- Easy bruising
Some Potential Causes of Cushin’s Syndrome:
- Adrenal tumor
- Excess ACTH secretion by AP
- Ectopic ACTH secretion
What are the functions of the islets of Langherhans of the pancreas?
The islets of Langherhans are compount masses of endocrine tissue. They produce polypeptide hormones, and stain lighter than surrounding exocrine tissue. The cells, as to be expected with poly-peptide hormone-producing cells, contain secretory granules.
What hormones are produced in the islets of Langherhans?
- Glucagon - raises blood glucose level
- Insulin - lowers blood glucose level
- Somatostatin - inhibits GH secretion and other hormones, is both endocrine and paracrine
- Pancreatic polypeptide - helps with digestion
Basal metabolic rate
Body growth and development
Heat production
These are all functions of what endocrine organ?
Thyroid gland
What is the shape of follicular epithelial cells?
Squamous to low columnar, but mostly cuboidal
Follicular cells produce:
Follicular cells produce thyroglobulin, which is iodinated in the colloid. Iodinated hormones are absorbed and processed by the follicular cells before release into the bloodstream.
What is another name for C cells? What is their function?
C cells are also known as parafollicular cells. In H&E preparation, they appear pale, and are located between thyroid follicles.
C cells produce calcitonin which inhibits bone resorption/promotes calcification. Calcitonin is fedback by serum calcium levels
How does PTH increase blood calcium levels?
PTH increases blood calcium levels by:
- promoting osteoclast activity
- regulating calcium absorption by the intestines and kidneys
- increasing vitamin D synthesis
Where are oxyphil cells found?
Oxyphil cells are found in the parathyroid gland. They stain brightly acidiphilic, and have no known function, though they may produce small amounts of PTH.
Chief cells are more abundant in the parathyroid gland
Many nonendocrine organs perform endocrine functions. Name two.
Heart secretes ANP - regulation of BP and electrolyte balance
Stomach/small intestine secrete enteric hormones - regulate digestive enzyme production, GI motility, modulation of growth hormone secretion
Adipose tissue
–Leptin - regulates apetite and metabolism
–Adiponectin - regulates FA and glucose metabolism, modulates sensitivity to insulin
–Secretes steroid hormones such as androgens and estrogens
