Endocrine System Histo Flashcards
secrete onto a surface, either directly or through a duct
exocrine gland
secrete internally; ductless glands; secrete hormones; primarily utilize cardiovascular system for distribution
endocrine gland
2 types of hormones
circulating and local hormones
local hormones are ___ or ____
paracrines; autocrines
main visceral control center for body; the autonomic control center; regulates body temperature, food intake, water balance/thirst, sleep-wake cycles, sexual behavior and endocrine system functioning; its influence on the body is vital for maintaining homeostasis
hypothalamus
hypothalamus is major link betw ____ and ____ systems; considered the command center for the endocrine system; its secretions can regulate other glands
endocrine; nervous
hypothalamus produces 9 hormones: 5 ____ hormones which impact/control the anterior pituitary; 2 ____ hormones which impact/control the ant. pituitary, and 2 other hormones released from the ____
releasing; inhibiting; posterior pituitary
the hypothalamus is connected to the pituitary gland by the ____; the pituitary gland is known as the ____
infundibulum; master gland of the endocrine system
together the hypothalamus and the pituitary gland regulate virtually all aspects of ____, ____, ____, and _____
growth; development; metabolism; homeostasis
pituitary gland also known as ____; it sits in the ____ within the ____ of the sphenoid bone
hypophysis; hypophyseal fossa; sella turcica
bulk of the anterior lobe of the pit. gland; cords of epithelial cells interspersed with fenestrated capillaries; develops from anterior wall of Rathke’s pouch
pars distalis
thin remnant of posterior wall of Rathke’s pouch; next to pars distalis; surrounds a series of colloid-filled follicles that represent the residual lumen of Rathke’s pouch
pars intermedia
from thickened lateral walls of Rathke’s pouch; forms a collar or sheath around the infundibulum; most cells here are basophilic gonadotropic cells
pars tuberalis
anterior pituitary/anterior lobe/adenohypophysis has 3 parts:
- pars distalis
- pars intermedia
- pars tuberalis
neurosecretory axons and their endings
pars nervosa
contains neurosecretory axons forming the hypothalamo-hypophyseal tracts
infundibulum
2 parts of the posterior lobe/posterior pituitary/neurohypophysis
- pars nervosa
- infundibulum
the hypophysis or pituitary gland is derived in part from an outpocketing of the ____ lining the roof of the mouth called the _____ and in part from an outpocketing of the _____ lining the floor of the hypothalamus called the _____
ectoderm; hypophyseal (Rathke’s pouch)
neuroectoderm; neurohypophyseal bud
the ____ of the pituitary gland develops from the roof of the mouth
anterior lobe
release of hormones from the anterior pituitary is stimulated by _____ (5) and suppressed by ____ (2) from the ____ as well as through _____
releasing hormones; inhibiting hormones; hypothalamus; negative feedback
the regulating hormones from the hypothalamus reach the anterior lobe of the pituitary gland by the _____
hypothalamo-hypophyseal portal system
cluster of specialized cells called ____ in the hypothalamus synthesize the hypothalamic releasing and inhibitory hormones in their cell body
neurosecretory neurons
these hypothalamic hormones travel down the axons of the neurosecretory cells to the axon terminals where they exit via ____
exocytosis
these hormones diffuse into the hypophyseal portal system at the ____
primary plexus of the hypophyseal portal system (fenestrated capillaries)
these hormones then pass from the primary plexus of the hypophyseal portal system to the ____ into the _____, bringing these hypothalamic hormones directly to the cells of the ____
hypophyseal portal veins; secondary plexus of the hypophyseal portal system; pars distalis
there are two groups of secretory cells in pars distalis based on staining affinity:
chromophils and chromophobes
chromophils are 50% of pars distalis; hormone stored in ____
cytoplasmic granules
chromophils are either ___ or ____
basophils (affinity for basic dyes, 10% of pars distalis)
acidophils (affinity for acidic dyes, 40% of pars distalis)
three types of basophils from most to least abundant
- corticotropes (ACTH cells)- 15-20% of anterior lobe
- gonadotropes (FSH and LH cells)- 10% of anterior lobe
- thyrotropes (TSH cells)- 5% of anterior lobe
two types of acidophils from most to least abundant
- somatotropes (GH cells)- 50% of anterior lobe
2. lactotropes (mammotropes, PRL cells)- 15-20% of anterior lobe
50% of pars distalis; with few or no secretory granules; stain weakly; clear cells; reserve/primitive cells; undifferentiated cells; can become chromophils
chromophobes
7 hormones of the anterior pituitary
- Human growth hormone (hGH)
- thyroid stimulating hormone (TSH)
- follicle-stim hormone (FSH)
- luteinizing hormone (LH)
- prolactin (PRL)
- adrenocorticotrophic hormone (ACTH)
- melanocyte-stim hormone (MSH)
human growth hormone (hGH) secreted by _____
somatotropes (acidophils)
thyroid-stimulating hormone (TSH) secreted by ____
thyrotropes (basophils)
follicle-stim hormone (FSH) secreted by ____
gonadotropes (basophils)
luteinizing hormone (LH) secreted by _____
gonadotropes (basophils)
Prolactin (PRL) secreted by _____
lactotropes (acidophils)
adrenocorticotrophic hormone (ACTH) secreted by ____
corticotropes (basophils)
melanocyte-stim hormone (MSH) secreted by ____
corticotropes (basophils)
human growth hormone also called ____
somatotropin
the posterior pituitary (posterior lobe/neurohypophysis) does not ____ hormones (i.e. no secretory cells here), but instead ____ and _____ two hormones
synthesize; stores; releases
posterior pituitary (pars nervosa) contains the ___ and ___ of hypothalamic neurosecretory neurons, along with ____, ____ and ____
axons; axon terminals
along with fibroblasts, mast cells, and pituicytes
a type of glial cells, resembling the astrocyte, that associates fenestrated capillaries; cell has many branches; pigment vesicles in cytoplasm; nuclei round or oval; most common cell type in the posterior pituitary
pituicytes
the two hormones released from the posterior pituitary are:
- oxytocin (OT)
2. antidiuretic hormone (ADH or vasopressin)
these two hormones are synthesized within the cell bodies of the _____ in the ____
neurosecretory neurons; hypothalamus
the axons of the neurosecretory neurons form the _____ in the _____
hypothalamo-hypophyseal tract; infundibulum
the hormones, once formed in the hypothalamus, are transported down the axons in the hypothalamo-hypophyseal tract to the posterior pituitary where they are stored in ____ in dilated portions of the axons near the terminals called _____
secretory vesicles; Herring bodies (aka neurosecretory bodies)
neuroendocrine gland that regulates daily body rhythm; day/night cycle (circadian rhythm)
pineal gland/body
major hormone production of the pineal gland
melatonin
two cell types of the pineal gland
- pinealocytes (parenchymal cells) 95% of cells
2. interstitial (glial) cells - 5% of cells
characteristic presence of ____ in the pineal gland
corpora arenacea (brain sand)
adrenal glands or suprarenal glands have a ___ around the gland
capsule
the cortex of the adrenal gland is a large, peripheral area just below the capsule that makes up 80-90% of the gland; contains ____ cells
steroid-secreting
the medulla of the adrenal gland is a smaller, centrally located area that contains _____ cells
catecholamine-secreting
3 regions of the adrenal cortex
- zona glomerulosa
- zona fasciculata
- zona reticularis
the thickest of the 3 adrenal cortex regions; contains cells that are arranged in long rows/cords
zona fasciculata
zona glomerulosa (outermost layer) secretes _____, mainly _____
mineralocorticoid hormones; aldosterone
zona fasciculata (middle layer) secretes _____, mainly ____
glucocorticoid hormones; cortisol
zona reticularis (deepest layer) secretes _____, mainly ____
androgen hormones; DHEA
adrenal medulla chromaffin cells secrete 3 catecholamine hormones:
epinephrine, norepinephrine, and a small amount of dopamine
Regulates Na+, K+, and water; Control of blood pressure
mineralocorticoid hormones such as aldosterone
Regulate glucose and fatty acid metabolism; Suppresses the immune system; Provides resistance to stress
glucocorticoid hormones like cortisol
Assists in early growth of axillary and pubic hair in both sexes
androgen hormones like DHEA
Intensify sympathetic responses in other parts of the body
catecholamines like epinephrine (adrenaline) and norepinephrine (noradrenaline)
a modified sympathetic ganglion of the autonomic NS (ANS)
adrenal medulla
the adrenal medulla develops from the same embryonic tissues as all other ____ in the body (i.e. neural crest cells), but the cells found in the medulla lack ____ and do not release ____
sympathetic ganglia; axons; neurotransmitter
instead, these modified neurons (called _____) cluster around ____ and release hormones
chromaffin cells; blood vessels
the chromaffin cells are controlled by ____, which allows for quick signalling to the chromaffin cells to release hormones via _____
sympathetic preganglionic neurons; exocytosis
the ____ component of the pancreas synthesizes and secretes hormones
endocrine
the endocrine portion seen in the pancreas as _____, found throughout the pancreas but most numerous in the tail
islets of Langerhans (aka pancreatic islets, 100-200 micrometers in diameter)
endocrine portion of pancreas stains ___ compared to the exocrine portion (i.e. pancreatic acini)
pale
3 principle cells of the islets of langerhans
- beta or B cells
- alpha or A cells
- delta or D cells
beta cells are 70% of the islets; they synthesize and secrete ____; cells found toward ___ of islet
insulin; center
alpha or A cells are 17% of the islets; they synthesize and secrete ____; cells found toward ____ of islet
glucagon; periphery
delta or D cells are 7% of islets; they synthesize and secrete ____ (which is identical to _____); cells are found toward ____ of islet
somatostatin; growth hormone inhibiting hormone (GHIH) from the hypothalamus
periphery
lowers blood glucose level as it signals for an acceleration of glucose transport into cells and the conversion of the glucose into glycogen (glycogenesis).
insulin
raises blood glucose level as it signals for the acceleration of the breakdown of glycogen into glucose in the liver (glycogenolysis); this glucose is released into the blood.
glucagon
inhibits insulin and glucagon secretion
somatostatin
the thyroid gland has a ___ and ____, creating lobules
fibrous capsule; septa
the thyroid gland contains ____
thyroid follicles
the walls of the thyroid follicles are made up by follicular cells (____ to ____) that are responsible for the production of _____
simple squamous; low columnar; thyroid hormones
the thyroid hormones are ____ and ____
- thyroxine (aka tetra-iodothyronine or T4)- 4 atoms of iodine
- tri-iodothyronine (T3)- 3 atoms of iodine
T3 and T4 are important for ____, ____, and control of ____ and ____ of body cells
growth; cell differentiation; basal metabolic rate; oxygen consumption
the follicles contain ____ which is a gel-like mass; the main component of this substance is _____, a large iodinated glycoprotein which is an inactive form of the thyroid hormones
colloid; main comp of colloid is thyroglobulin
when thyroid hormones need to be released, thyroglobulin is brought back into the ____, modified, and then released as the thyroid hormones into ____ that surround the follicles
follicular cells; fenestrated blood capillaries
_____ or ____ are also found in the thyroid gland; they are larger than follicular cells and stain less intensely
parafollicular cells; C cells
parafollicular cells are responsible for the production of _____
calcitonin (CT)
parafollicular cells may be part of the ____ or found between the follicles
follicular epithelium
calcitonin decreases the level of ____ in the blood by encouraging ____ to be deposited in bone matrix (i.e. building of bone) and responsible for inhibiting the action of ____ (cells that normally resorb or breakdown bone’s extracellular matrix).
calcium; calcium salts; osteoclasts
_____ system controls the secretion of calcitonin ; ____ stimulate the secretion of CT, and ____ inhibit the secretion of CT
negative feedback; high blood Ca levels; low blood Ca levels
the parathyroid glands have a surrounding ____ with ___ that enter gland
capsule; septa
two types of cells located in the parathyroid glands
- chief cells
2. oxyphil cells
chief cells produce ____; they are the most numerous of cells; small cell, round centrally located nucleus ; ____ staining and slightly ____ cytoplasm
parathyroid hormone (RTH); pale; acidophilic
larger cell with very acidophilic cytoplasm; more common in older individuals; unknown function
oxyphil cells
PTH ____ the level of Ca in the blood by stimulating ____ to resorb bone which releases Ca into the blood; PTH additionally acts on the ____ to slow the rate of Ca loss from the blood to the urine
increases; osteoclast; kidneys
____ system controls the secretion of PTH; ____ stimulate secretion of PTH and ____inhibit PTH secretion
negative feedback; low blood Ca levels; high blood Ca levels
