Endocrine Glands Flashcards
1
Q
Endocrine intro
A
- system of glands and cells that produce hormones
- singnaling molecules that are released into the bloodstream and regulate a variety of physiologic functions and metabolic processes
2
Q
Properties of the hormones produced by the endocrine glands
A
- act long-distance
- distributed by circulation
- released into the bloodstream or interstitial fluid
3
Q
Properties of the endocrine glands
A
- most endocrine glands consist of epithelial tissue
- some endocrine tissue/glands are derived from neural crest cells or neurons
- no ducts are present in the endocrine glands
- highly vascular
- hormones may be stored in intracellular secretory granules
4
Q
Membrane-impermeable hormones
A
- hydrophilic
- receptors for these hormones are located on the cell surface
- these hormones act through secondary messengers
- examples: peptides and proteins, glycoproteins, modified amino aicds
5
Q
Membrane permeable hormones
A
- receptors are intracellular DNA-binding proteins that affect transcription
- examples: steroid and thyroid hormones
6
Q
Cell producing protein hormone characteristics
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- abundant rough ER
- prominent Golgi
- hormones are often stored in secretory granules
7
Q
Cell producing steroid hormone characteristics
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- centrally located nucleus
- lipid droplets in the cytoplasm
- abundant smooth ER for cholesterol synthesis
- spherical mitochondria with characteristic tubular or vesicular cristae
8
Q
Hypophysis (pituitary gland)
A
- pea-sized gland that hangs by a stalk in the hypothalamus in the brain
- dual embryonic origin: anterior pituitary (adenohypophysis) is derived from the oral ectoderm and consists of epithelial tissue while posterior pituitary (neurohypophysis) is derived from the neural ectoderm
9
Q
Anterior pituitary
A
- produces a variety of hormones that regulate body growth, milk production and the functions of the other endocrine glands
- the three regions of the adenohypophysis are pars tuberalis, pars distalis, and pars intermedia
10
Q
Posterior pituitary
A
- contains no secretory cells
- it stores and releases hormones produced in the hypothalamus
11
Q
Cells of the anterior pituitart
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- Chromophils- cells containing secretory granules that can interact with the dyes used in histogy: basophils and acidophils
- Chromophobes (cells that do not contain brightly stained granules)- this group includes stem/pregenitory cells and cells that have released their granules or lost their granules during fixation
12
Q
Acidophils
A
-include cells that produce two types of protein hormones: somatotropic or growth hormone and mammotropic hormone (prolactin)
13
Q
Basophils
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-include cells that produce glycoprotein hormones (FSH, LH, TSH) and small polypeptide hormones (ACTH and Beta-LPH)
14
Q
Somatotropic cell of anterior pituitary
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- somatotropic cell
- acidophilic
- 50% of cells
- somatotropin (growth hormone) produced
- physiologic activity- growth of long bones and other growth-related processes
15
Q
Lactotropic or mammotropic cell of anterior pituitary
A
- acidophilic
- 15-20% of cells
- secretes prolactin
- stimultion of milk secretion
16
Q
Gonadotrophic cell of anterior pituitary
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- basophilic
- 10%
- FSH, LH (often produced by the same cell)
- FSH stimulation of gametogenesis
- LH: regulation of estrogen and androgen secretion; promotes ovulation in females
17
Q
Thyrotropic cell of anterior pituitary
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- basophilic
- 5% of cells
- secretes Thyrotropin (TSH)- stimulation of thyroid hormone secretion
18
Q
Corticotropic cell of anterior pituitary
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- basophilic
- 15-20% of cells
- secretes ACTH- stimulation of adrenal cortical hormone secretion; Beta-lipotropin- promotes utilization of fat
19
Q
Cells and hormones of the pars distalis and par distalis and pars tuberalis in the anterior pituitary
A
- each cell type in the anterior pituitary secretes only one hormone type, with two exceptions: gonadotropic cells produce two types of gonadotropic hormones (FSH and LH) and corticotropic cells produce ACTH and Beta- lipotropin
- different cell types can be distinguished by immunostaining for specific hormones or by electron microscopy because they contain granules of different sizes
20
Q
Cells and hormones of the pars intermedia
A
-in humans, pars intermedia is largely inactive in the adults and contains colloid-filled follicles and cysts (Rathke’s cysts) of unknown function
21
Q
Posterior pituitary (neurohypophysis)
A
- neurohypophysis contains no secretory cells
- contains two cell types: neurons (or more precisely, their axons) and glial cells called pituicytes
- cell bodies of the neurons are located in the hypothalamus
- hormones secreted include vasopressin (also called antidiuretic hormone or ADH) and oxytocin
- hormones are stored in dilated axons; these eosinophilic dilatations are called Herring bodies
22
Q
Vasopressin
A
- ADH
- from posterior pituitary
- regulation of blood osmolarity; increases water reabsorption in kidney collecting
23
Q
Oxytocin
A
- posterior pituitary
- stimulation of uterine contraction during childbirth and contraction during childbirth and contraction of myoepithelial cells of mammary glands during nursing
24
Q
Hypothalamo-hypophyseal portal system and control of hypophyseal secretion
A
- hypothalamus regulates the functions of the adenohypophysis via releasing and inhibiting hormones
- there are no direct neural connections between the hypothalamus and the adenohypophysis
- hypophysis-regulating hormones produced by the hypothalamus are carried to the adenohypophysis via specialized blood vessels (the portal systems)
25
Adrenal Cortex
- outer layer
- epithelial origin
- 3 concentric zones (zona glomerulosa, zona fasciculata, zona reticularis)
- cells have typical features of steroid-producing cells: central nucleus, adiophilic cytoplasm containing lipid droplets, abundant smooth ER for cholesterol synthesis, spherical mitochondria with characteristic tubular cristae contrain enzymes involved in synthesis of sterioid hormones from cholesterol.
26
Adrenal Medulla
- neuronal origin
- cells contain electron-dense secretory granules that react with chromium and silver salts (therefore cells of the medulla are referred to as chromaffin or argentaffin)
- produces catecholamines (epinephrine and norepinephrine)
27
Zona glomerulosa
- in adrenal cortex
- rounded cords of cells
- steroid-producing cells (appear foamy, especially in the zona fasciculata)
- mineralocorticoids (primarily aldoesterone)
- regulation of salt balance
- regulated by Angiotensin II
28
Zona fasciculata
- in adrenal cortex
- long cords
- steroid-producing cells (appears foamy, especially in the zona fasciculata)
- produce glucocorticoids (primarily cortisol), some DHEA
- regulation of glucose metabolism
- regulated by ACTH
29
Zona reticularis
- in adrenal cortex
- irregular meshwork
- steriod-producing cells (appear foamy, especially in the zona fasciculata)
- produce cortisol and a weak androgen (DHEA)
- glucose regulation and testosterone production
- regulated by ACTH
30
Cells in adrenal medulla
- cords or clumps
- cells react with chrome or silver salts
- catecholamines: epinephrine, norephineprine
- fight or flight response
- regulated by sympathetic nervous system
31
Pancreas (islets of Langerhans)
- compact masses of endocrine tissue embedded within the exocrine tissue of the pancreas
- polygonal or round cells arranged in cords
- typical protein-secreting cells (abundant RER, Golgi)
- cells contain secretory granules
- produce polypeptide hormones
32
Alpha cells
- 20%
- located on the periphery of the islets
- glucagon
- increases blood glucose by promoting conversion of glycogen into glucose
33
Beta cells
- 70%
- centrally located of islets
- insulin
- lowers blood glucose by promoting glucose storage
34
Delta cells
- 5-10%
- somatostatin
- inhibits release of other islet cell hormones (local paracrine effect), inhibits release of GH and TSH by the pituitary and HCl secretion by the gastric parietal cells
35
F or PP
- rare
- pancreatic polypeptide
- stimulates the activity of gastric chief cells
- inhibits bile and pancreatic enzyme secretion
36
Thyroid
- located anterior to the trachea
- consists of follicles, spherical structures lined by simple epithelium and filled with colloid
- colloid consists of the storage form of the thyroid hormones, called thyroglobulin
37
Follicular cells
- vary inshape from cuboidal to low columnar
- have features characteristic of protein-secreting cells (abundant RER and Golgi)
- activity is regulated by the TSH produced by the anterior pituitary
- thyroid hormones (t3 and t4) regulate basal metabolic rate, body growth and development, heat production
38
Parafollicular cells or C cells
- larger in size than follicular cells
- appear pate in H and E preparations
- located within the basal lamina of the follicles or between follicles
- produce hormone calcitonin that inhibits bone resorption and promotes calcification of bone (opposite of the PTH)
- regulated by the blood calcium levels
39
Parathyroid glands
- four small oval glands located on the back of thyroid
| - has chief cells and oxyphil cells
40
Chief cells
- small polygonal cells
- pale-staining, slightly acidophilic cytoplasm
- produce parathyroid hormone (PTH), a polypeptide hormone that increases blood calcium level by regulating osteoclast activity, kidney excretion of calcium, vitamin D synthesis, and intestinal absorption of calcium
- abundant
- regulated by the calcium level in the blood
41
Oxyphil cells
- large cells
- highly acidophilic (=oxyphilic)
- less abundant
- unknown function (may produce a small amount of PTH)
42
Endocrine functions of non-endocrine organs
- many non-endocrine organs contain endocrine cells that secrete hormones
- heart: atrial natriuretic peptide (regulation of blood pressure and electrolyte balance)
- kidney: erythropoietin (red blood cell production), renin
- stomach and small intestine: enteric hormones
- adipose tissue: leptin- regulates appetite and metabolism, adiponectin- regulates fatty acid and glucose metabolism and modulates sensitivity to insulin
- steroid hormones (androgens and estrogens)
43
B-FLat
-basophilic cells of the anterior pituitary secrete FSH, LH, ACTH, TSH
44
GPA
-growth hormone and prolactin are secreted by the acidophilic cells of the anterior pituitary
45
Salt, sugar, sex hormones
-the order of the products of the adrenal cortex: mineralcorticoids, glucocorticoids, androgens
