Reading...
Play button
Play button
Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
69 Cards in this Set
- Front
- Back
|
What is the DNES?
|
Diffuse neuroendocrine system. Hormone-secreting cells that occur singly.
|
|
|
Do endocrine cells show polarity or are they organized into discrete units like acini?
|
No. Unlike exocrine cells they don't release product into a duct, but into the bloodstream. They usually form plates or cords interspersed with capillaries.
|
|
|
Peptide-releasing endocrine cells appear _________ when viewed under microscope due to secretory granules, golgi, and RER
|
grainy, stain intensely
|
|
|
How are peptide hormones released into the blood?
|
They're stored in secretory granules and released via the merocrine mode of secretion.
|
|
|
Where are steroid secreting cells common?
|
Adrenal gland, testis, ovary
|
|
|
What do steroid secreting cells look like under microscope?
|
Frothy due to lipid droplets because steroid hormones are derived from cholesterol
|
|
|
Enteroendocrine cells are an example of what type of endocrine tissue? Where are their secretory granules located?
|
DNES. They release hormone into lamina propria, so secretory granules are facing lamina propria
|
|
|
What cells in testicle secrete androgens?
|
Leydig cells in seminiferous tubules
|
|
|
Glucagon is produced by _________ cells of pancreas; insulin by ___________ cells; somatostatin by ____________ cells.
|
alpha; beta; delta
|
|
|
What is the anlagen (initial clustering of embryonic cells) of the thyroid?
|
Thyroid diverticulum
|
|
|
What does the thyroid gland secrete and what do these products do?
|
A. Synthesizes thyroxine (tetraiodothyronine T4) and triiodothyronine (T3) for metabolic regulation
B. Synthesizes calcitonin, lowers blood calcium levels |
|
|
What is thyroid gland composed of?
|
two lobes separated by an isthmus. spherical follicles with a simple epithelium containing a colloid (thyroglobulin)-filled lumen.
A 2nd cell type secretes calcitonin |
|
|
What is the cell type that secretes calcitonin? Where is it located?
|
parafollicular/C cells; located between the follicular epithelial cells in the basal lamina. Appears paler.
|
|
|
What is thyroglobulin? Where is it secreted?
|
Glycoprotein found in center of follicle secreted by follicle cells. It's a modified storage form of the hormones that will become T3 and T4
|
|
|
What is calcitonin?
|
Secreted by parafollicular cells.
-Inhibits bone resorption, lowers blood Ca++ levels -Secretion stimulated by high blood Ca++ levels |
|
|
How is thyroid unusual?
|
It stores precursor to its hormones in the form of thyroglobulin
|
|
|
How does the shape of follicular thyroid cells vary in active vs inactive?
|
Active: more columnar (due to more organelles)
Inactive: squamous |
|
|
What chemical reaction occurs to convert thyroglobulin to T3 and T4?
|
Iodination and rearrangement of tyrosines
|
|
|
Embryonic origin of the pituitary gland
|
Two origins!
A) Stomodeal ectoderm – aka Rathke’s pouch: Adenohypophysis - Anterior pituitary 2) Evagination of diencephalon - Neuroectoderm: Neurohypophysis (posterior pituitary) |
|
|
Anterior lobe of pituitary embryonic origin
|
Rathke's pouch. Stomodeal Ectoderm. Goes thru developing sphenoid bone.
Adenohypophysis |
|
|
Posterior lobe of pituitary embryonic origin
|
Formed from a blebbing/evagination of diencephalon. Neurohypophysis.
|
|
|
Where does pituitary sit?
|
Sella tursica of sphenoid bone. Directly below hypothalamus.
|
|
|
What separates pituitary from hypothalamus?
|
Diaphragm sella. This is where pituitary stalk, the infundibulum, passes.
|
|
|
Subdivisions of Anterior Pituitary
|
Pars Distalis: Largest portion
Pars Tuberalis: Tube encircling infundibulum Pars Intermedia |
|
|
Subdivisions of Posterior Pituitary
|
Pars nervosa
Infundibulum |
|
|
Characteristics of structure of pars distalis
|
Forms majority of pituitary gland
Glandular, with cells in cords, protein secreting: RER/Golgi Reticular fiber framework <b>Fenestrated capillaries</b> |
|
|
What are cell types (and their characteristics) of the pars distalis?
|
1) <b>Chromophobes</b>: smallest cells; pale staining,
No secretory granules, Reserve/Degranulated chromophil cells 2.)<b> Chromophils</b>: Secretory granules with protein hormone Acidophils (eosin affinity granules):stained pink/orange Basophils (hematoxylin affinity granules): stained purple/blue |
|
|
What are the subdivisions of Acidophils in pars distalis?
|
Somatotropes (75%)
Mammotropes (25%) |
|
|
What cells secrete somatotropin (growth hormone GH) that indirectly stimulates the epiphyseal plate?
|
Somatotropes
|
|
|
What cells secrete prolactin that stimulates milk secretion?
|
Mammotropes (they increase when bearing children)
|
|
|
What are the causes of
A) Agromegaly B) Galactorrhea |
A) Continued and excessive secretion of GH after epiphyseal plates fuse. Causes appositional growth (deposits on bone), making bone thicker. (somatotropes)
B) Continuous milk production from a prolactin-secreting tumor (mammotropes) |
|
|
Basophils are (larger, smaller) than acidophils and (fewer, greater) in number.
|
Larger; Fewer
|
|
|
What are the subdivisions of Basophils in pars distalis?
|
All types are indistinguishable histologically.
A) Thyrotropes B) Gonadotropes C) Corticotropes |
|
|
Secrete thyroid stimulating hormone (TSH)
|
thyrotropes of pars distalis of anterior pituitary
|
|
|
Secrete luteinizing hormone (LH:ovulation,corpus luteum/maintains interstitial cells of Leydig) and follicle stimulating hormone (FSH:produces ovarian follicles/stimulates spermatogenesis)
|
gonadotropes of pars distalis of anterior pituitary
|
|
|
Secrete adrenocorticotropic hormone (ACTH), lipotropin, melanocyte stimulating hormone (MSH) and endorphin
|
Corticotropes of pars distalis of anterior pituitary
|
|
|
A Smart Move By The Clever Girls
|
A: Acidophils
S: Somatotropes M: Mammotropes B: Basophils T: Thyrotropes C: Corticotropes G: Gonadotropes |
|
|
What is a collar of cells surrounding the infundibulum?
|
Pars Tuberalis
|
|
|
What cell type does Pars Tuberalis have?
|
Gonadotropes ONLY
|
|
|
What is Composed of
Cells surrounding cystic remnants of Rathke’s pouch, making up only 2% of adenohypophysis? |
Pars Intermedia
|
|
|
What cell type does Pars Intermedia have?
|
Corticotropes ONLY
|
|
|
Explain Control of adenohypophysis secretion
|
1) Hormones that are inhibitory OR excitatory are synthesized by hypothalamus neurons and transported down their axons.
2) Axons end at the median eminence, a capillary bed located in a brain region just above the infundibulum. Hypothalamic factors released into the median eminence. 3) Capillary bed drains into hypophyseal portal vessels, which travel down the infundibulum carrying hypothalamic factors; portal vessels connect/end in capillaries within pars distalis. 4) Hypothalamic factors exit capillaries in pars distalis and stimulate or inhibit release of hormones from acidophils and basophils in pars distalis. There is negative feedback at multiple levels for control. |
|
|
What connects the hypophysis (aka pituitary gland) with hypothalamus?
What is it made of? |
infundibulum.
It's made of axons from hypothalamus forming the hypothalamus hypophyseal tract. It terminated in the pars nervosa. |
|
|
What are the Herring bodies?
|
Structures found in the posterior pituitary. They represent the terminal end of the axons from the hypothalamus, and hormones are temporarily stored in these locations.
|
|
|
What are highly polymorphic glial cells that are dark purple when stained, found in pars nervosa?
|
Pituicytes
|
|
|
What cells SYNTHESIS oxytocin and vasopressin and transport them to Herring bodies (axon terminals?
***** |
Supraoptic nucleus and paraventricular nucleus of hypothalamus
|
|
|
What hormone:
Synthesized in paraventricular nucleus Stimulates smooth muscle contraction: uterus during childbirth, expression of milk |
oxytocin
|
|
|
Embryonic origin of thyroid gland
|
Develops during the 4th week of gestation
Forms in the floor of the primitive pharynx Thyroid diverticulum is the anlagen Foramen cecum of the tongue is the site of its origin |
|
|
What hormone:
Synthesized in the supraoptic nucleus Increases water retention |
ADH/vasopressin
|
|
|
What does calcitonin do?
|
Lowers blood calcium levels
|
|
|
Origin of parafollicular cells of thyroid
|
Neural crest
|
|
|
Do parafollicular and follicular cells have polarity?
|
parafollicular : NO
follicular : YES |
|
|
Where does synthesis, secretion, and storage of thyroglobulin occur?
|
Rough ER; secreted into Follicle lumen
|
|
|
How do tyrosines get iodinated on thyroglobulin in the follicle lumen?
|
1) Iodide pump in basal cell membrane takes up iodide from the intercellular fluid --> transported to apical surface
2) Enzyme converts iodide --> iodine (I2) 3) Iodine released into lumen, followed by spontaneous iodination of phenyl rings of tyrosines in thyroglobulin |
|
|
Tyrosines iodinated with one iodine = _______________; Tyrosines iodinated with two iodines __________
|
monoiodotyrosine (MIT); diiodotyrosine (DIT)
|
|
|
DIT + DIT =
|
T4
|
|
|
DIT + MIT =
|
T3
|
|
|
What is the cause of an iodine-deficiency goiter?
|
Thyroid still makes thyroglobulin that can't get iodinated but is still produced and stored. (Can't release it as TH)
|
|
|
On what surface of the thyroid are the parathyroid glands?
|
Posterior
|
|
|
What does parathyroid hormone do?
|
Increase blood Calcium (exact opposite of calcitonin released by C cells of thyroid)
|
|
|
Which cells secrete PTH?
|
Chief/principal cells
|
|
|
What are the other types of cells in the thyroid?
|
Oxyphil cells. Function is unclear
|
|
|
How does PTH regulate blood Ca2+ levels?
|
Negative feedback.
When there is high Ca2+, there is decreased PTH, resulting in calcium deposition in bone. When there is low Ca2+, there is high PTH, causing resorptiono f bone. |
|
|
Adrenal cortex release _________while medulla releases _____________.
|
steroid hormones; catecholamines
|
|
|
What are the three divisions of the adrenal cortex, from outermost to innermost?
|
1) Zona glomerulosa
2) Zona fasciculata 3) Zone reticularis (G-F-R) |
|
|
Characteristics of zona glomerulosa
|
Outermost region of adrenal cortex; thinnest section, mineralocorticoids are made here
|
|
|
Characteristics of zona fasciculata
|
Middle region of adrenal cortex, widest region, cells are most vaculoated, arranged in fascicles
|
|
|
Characteristics of zona reticularis
|
Innermost region, many mitochondria, stain darker, more eosinophilic, lots of fenestrated capillaries present
|
|
|
What is the emryonic origin of adrenal medulla cell?
|
Neural crest
|
