Endocrine System 1 Flashcards
endocrine system is responsible for the production and secretion of
chemical messengers known as
hormones
secrete their products into
ducts that carry the secretions into body cavities, into the lumen of an organ, or to outer surface of the
body.
Exocrine glands
secrete their products into
the interstitial fluid surrounding the secretory cells.
Endocrine glands
Endocrine cells produce hormones based on amino acids, peptides and proteins often have characteristic _____ vacuoles with electron-dense central cores
membrane-bound secretory
It is called the “master” endocrine gland because it secretes several hormones that control other
endocrine glands
pituitary gland
pituitary gland is also called
hypophysis
the pituitary gland is controlled by the
hypothalamus
this small region of the brain below the thalamus is the major link between the nervous and endocrine systems
hypothalamus
Cells in the hypothalamus synthesize at least ___ different hormones, and the pituitary gland secretes ____
9; 7
a small bean-shaped gland, about 1 cm diameter and lies in the
hypophyseal fossa of the sella turcica of the sphenoid bone.
pituitary gland
Partly developing from the brain and partly from the oral cavity
Development (Dual Origin):
Neurohypophyseal bud growing down from the floor of the future
diencephalon as a stalk (or infundibulum) that remain attached to the brain
Neural component
the thyroid gland, adrenal cortex and gonads may be described as
pituitary-dependent
endocrine glands
The _______ bring blood into the
hypothalamus.
superior hypophyseal arteries,
arteries divide into a capillary network called the
primary plexus of the
hypophyseal portal system
blood drains into the _____ that pass down the outside of the infundibulum
hypophyseal portal system
in the anterior pituitary, the hypophyseal
portal veins divide again and form another capillary network called the .
secondary plexus of the
hypophyseal portal system
- also known as neurohypophysis is composed of neural tissue
- does not contain cells that synthesize hormones
Posterior Pituitary (Posterior Lobe)
The larger bulbar portion that consists of modified neural tissue
Pars nervosa
100,000 unmyelinated axons of large secretory neurons
Neural tissue
contain membrane-enclosed organelles with either antidiuretic
hormone (ADH) or oxytocin
Herring Bodies
Membrane-enclosed organellle with oxytocin is bound to carrier protein
neurophysin-I
Membrane-enclosed organellle with ADH is bound to carrier protein
neurophysin-II
- glial cells that resemble astrocytes
- most abundant cell type in the
posterior pituitary
Pituicytes
- glial cells that resemble astrocytes
- most abundant cell type in the
posterior pituitary
Pituicytes
hormones of posterior pituitary glands
- antidiuretic hormone/ vasopressin/ arginine vasopresin
- oxytocin
hormone that increases renal permeability of renal collecting ducts
Antidiuretic hormone/Vasopressin/Arginine vasopressin
hormone that stimulates contraction of mammary gland myoepithelial cells and uterine smooth muscle
oxytocin
- also known as adenohypophysis, accounts for about 75% of the total weight of the gland
- arises as an epithelial upgrowth from the roof of the primitive oral cavity known as Rathke’s
pouch
anterior pituitary
anterior pituitary arises as an epithelial upgrowth from the roof of the primitive oral cavity known as
Rathke’s pouch
part of the anterior pituitary that is:
- The larger portion (75%)
- Has two (2) broad group of cells
pars distalis
part of the anterior pituitary that is:
- smaller funnel-shaped region surrounding the infundibulum
- predominantly gonadotrophs
part of the anterior pituitary that is:
- Between pars distalis and pars nervosa of the neurohypophysis
- Thin zone of basophilic cells (<2%)
- Atrophies during fetal development and ceases to exist as a separate lobe in adults
- Stores hormone in cytoplasmic granules
- Stain with hematoxylin & eosin (H&E) and secrete hormones
Chromophils
stain pinkish-red with H&E:
stain bluish purple with H&E:
- acidophilic cells
- basophilic cells
- Stain poorly with H&E and do not secrete hormones
- Heterogenous group of stem cells and progenitor cells as well as any
degranulated cells present
Chromophobes
hormones in acidophilic cells:
- somatrotroph
- mammotrophs
hormones in basophilic cells:
Corticotrophs
Gonadotrophs
Thyrotrophs
associated hormones with anterior pituitary
- somatotrophin
- prolactin
- follicle-stimulating hormone (FSH)
- luteinizing hormone (LH)
- thyrotropin (TSH)
- adrenocorticotropic hormone (ACTH)
- lipotropin
The butterfly-shaped gland is located just inferior to the larynx (voice box).
thyroid gland
About 50% of thyroid glands have a small third lobe, known as
pyramidal lobe
Microscopic spherical sacs called ____ make up most of the thyroid gland.
thyroid follicles
thyroid follicles are lined with simple epithelium and have a central lumen densely filled with ____
gelatinous acidophilic colloid
Simple flat or cuboidal cell type of glands:
Active glands
Tall columnar epithelium cell type of glands:
Inactive glands
Range in shape depending on activity:
Follicular cells
Larger that follicular cells and stain less intensely
Parafollicular
• More abundant (90%)
• Less active
• Half-life: 1 week
Thyroxine (T4) (Tetraiodothyronine)
• 2- to 10-fold more
active
• Half-life: 1.5 days
Triiodothyronine (T3)
are small, oval endocrine glands which are closely associated with the thyroid gland.
parathyroid gland
parathyroid glands regulate serum calcium, and phosphate levels via _____
parathyroid hormone (PTH) or parathyrin
- enclosed by a thin layer of connective tissue
Capsule
- connective tissue extends inwards from the capsule to partially outline
irregular lobes and lobules
Trabeculae
- Small cells (5 to 8um in diameter) with dark nuclei and thin rim of LIGHTLY STAINED cytoplasm
- Secrete PTH
Chief cells/ Principal cells
- Larger cells (8 to 12um in diameter) with dark nuclei and STRONGLY EOSINOPHILIC cytoplasm
because of numerous mitochondria - Appear after the first decade of life and are thought to be non-secretory cells
Oxyphil cell
Larger cells (8 to 12um) in diameter with dark nuclei and a watery, CLEAR cytoplasm
Clear cells
Accumulate after puberty and makes up 25% to 40% of the total tissue in normal adults
Adipose cells
are small, flattened endocrine glands which are closely applied to the upper pole of each kidney.
adrenal glands or suprarenal glands
The two (2) components of the adrenal gland are
- adrenal cortex
- adrenal medulla.
penetrate the capsule and branch into sinusoids that supply the cortex and medulla
Afferent blood vessels
- Outer part which arises form the mesoderm
- Produces and secretes steroid hormones
Cortex
Closely packed, funded or ARCHED cords of columnar or pyramidal cells
ZonaGlomerulosa (15%)
Hormone in Zona Gromerulasa:
Aldosterone
- LONG cords of large polyhedral cells, one or to cells thick separated by fenestrate sinusoidal capillaries
- Cells are filled with lipid droplets and appear vacuolated
Zone Fasciculata (80%)
- IRREGULAR cords containing smaller cells
- More heavily stained than the other zones (contain fewer lipid droplets and
more lipofuscin pigment)
Zona Reticularis (10%)
- Arises from the neural crest
- Large, pale staining polyhedral cells arranged in cords or clumps
Medulla
- Modified postganglionic sympathetic neurons (lacking axons and dendrites)
- Contain electron-dense granules for storage and secretion of
catecholamines
Chromaffincells
- Infrequent sympathetic ganglion cells
Ganglioncells
Stimulation of sympathetic nervous system which facilitate the fight-or-flight response (vasoconstriction, increased blood pressure, changes in heart rate, elevated blood glucose levels)
Together with norepinephrine:
- Glycogenolysis and lipolysis
Epinephrine alone
- about 99% of the exocrine cells of the pancreas are arranged in clusters known as
- produce digestive enzymes that flow into the GIT through a network of ducts
acini
Scattered among the exocrine acini are 1 - 2 million tiny clusters of endocrine tissue called
pancreatic islets or islets of Langerhans
cell type that constitute about 17% of pancreatic islet cells and secrete glucagon that raises blood glucose level
Alpha or A cells
cell type that constitute about 17% of pancreatic islet cells and secrete glucagon that raises blood glucose level
Alpha or A cells
______ constitute about 70% of pancreatic islet cells and secrete insulin that counteracts the effect of glucagon
beta or B cells
constitute about 7% of pancreatic islet cells and secrete somatostatin acts in a paracrine manner to inhibit both insulin and glucagon release from neighboring beta and
alpha cells;
delta or d cells
constitute the remainder of pancreatic islet cells and secrete pancreatic polypeptide
that inhibits somatostatin secretion, gallbladder contraction, and secretion of digestive enzymes by the pancreas.
f cells
- Specific cells in the digestive tract, respiratory mucosa, and other organs such as the
pancreas - Highly important due to their role in regulating motility and secretions of all types within the
digestive system
Diffuse neuroendocrine system (DNES)
______: Stained by solutions of chromium
Enterochromaffin cells
Stained with silver nitrate
Argentaffin cells
Demonstrate amine precursor uptake and decarboxylation; Secrete
serotonin or certain amine derivatives
APUD cells
a small, roughly spherical gland 6 to 10mm in diameter
attached to the roof of the third ventricle of the brain at the midline
pineal gland
pineal gland also known as
Epiphysis Cerebri
