Histology Endocrine System Flashcards
What type of glands secrete onto a surface, either directly or via a duct
exocrine glands
What type of glands secrete internally, are ductless, secrete hormones, and primarily utilize the cardiovascular system for distribution?
endocrine glands
There are two types of hormones. They are:
circulating hormones and local hormones (local include paracrine and autocrine)
What types of body parts does the hypothalamus control?
visceral functions
What types of functions does the hypothalamus include?
regulation of body temp, food intake, water balance/thirst, sleep-wake cycles, sexual behavior, and endocrine system function
the hypothalamus is the major link between what two systems?
endocrine and nervous
What is considered the “command center for the endocrine system”
hypothalamus
How many hormones are produced by the hypothalamus?
9
Briefly describe the number of hormones that go to each part of the pituitary, where they come from, and what about them is unique?
All of the hormones to the pituitary are coming from the hypothalamus. There are 5 RELEASING hormones going to the anterior pituitary, 2 INHIBITING hormones going to the anterior pituitary, and 2 OTHER hormones going to the posterior pituitary
What connects the hypothalamus to the pituitary gland?
infundibulum
The pituitary gland is also known as what?
hypophysis
What sits in the hypophyseal fossa within the sella turcia of the sphenoid bone?
pituitary gland
Name the three divisions of the anterior pituitary gland
1) pars distalis (bulk of anteior lobe… epithelial cells interspersed with fenestrated capillaries)
2) pars intermedia (thin remnant)
3) pars tuberalis (forms a collar or sheath around infundibulum, most cells here are basophilic gonadotropic cells)
Name the two divisions of the posterior pituitary gland
1) pars nerosa (neurosecretory axons and their endings)
2) infundibulum (neurosecretory axons forming hypothalamo-hypophyseal tracts)
Of the anterior and posterior pituitary lobes, which is the larger and more well defined of the two?
posterior
What is the embryological name for the future posterior pituitary? anterior?
posterior: neurohypophyseal bud
anterior: hypophyseal pouch
At what week in embryological development do the hypophyseal pouch and neurohypophyseal bud form?
week 3
During what period of pregnancy have the anterior and posterior pituitary fully formed?
fetal period
The pituitary gland (hypophysis) is derived in part from an outpocketing of the _____ lining the roof of the mouth called the _____ pouch and in part from an outpocketing of the _____ lining the floor of the hypothalamus called the neurohypophyseal bud
ectoderm
hypophyseal
neuroectoderm
Which lobe of the pituitary develops from the roof of the mouth?
anterior lobe
Hypothalmic hormones travel down the axons of _____ neurons to the axon terminals where they exit into the pituitary via exocytosis
neurosecretory
The hormones of the hypothalamus diffuse into the hypophyseal portal system via what?
primary plexus of the hypophyseal portal system (fenestrated capillaries)
Which structure brings hormones from the primary plexus of the hypophyseal portal system to the pars distalis of the pituitary gland?
secondary plexus of the hypophyseal portal system
What are the two large groupings of secretory cells stored in the pars distalis based on staining affinity?
1) chromophils
2) chromophobes
What are the two divisions of the chromophilic secretory cells in the pituitary gland?
1) basophils (gonadotropic, corticotropic, & thyrotropic)
2) acidophils (somatotropic, mammotropic)
Name the 7 hormones of the anterior pituitary
1) HGH
2) TSH (thyroid stim)
3) FSH (follicle stim)
4) LH
5) Prolactin
6) ACTH (adrenocorticotrophic)
7) MSH (melanocyte-stimulating)
What percent of the pars distalis cells are chromophobes?
50%
HGH is secreted by _____ and is an _____
somatotrophs, acidophil
TSH is secreted by _____ and is an _____
thyrotrophs, basophil
FSH is secreted by _____ and is an _____
gonadotrophs, basophil
LH is secreted by _____ and is an _____
gonadotrophs, basophil
Prolactin is secreted by _____ and is an _____
lactotrophs, basophil
ACTH is secreted by _____ and is an _____
corticotrophs, basophil
MSH is secreted by _____ and is an _____
corticotrophs, basophil
acidophils stain _____ and basophils stain ____
light pink
purple/blue
What is the main role of HGH and what does it stimulate the secretion of?
it stimulates the liver, muscle, cartilage, bone, and other tissues to synthesize and secrete IGFs which promote growth of body cells, tissue repair, etc
What is the main role of TSH?
it stimulates synthesis and secretion of thyroid hormone by the thyroid gland
What is the main role of FSH?
in femalse, it initiates development of oocytes and induces ovarian secretion of estrogens. In males, it stimulates testes to produce sperm
What is the main action of LH?
in females, it stimulates secretion of estrogens and progesterone, ovulation, and formation of corpus luteum. In males, it stimulates testes to produce testosterone
What is the main role of PRL (prolactin)?
Together with other hormones, it promotes milk secretion by the mammary glands
What is the role of ACTH?
it stimulates secretion of glucocorticoids by the adrenal cortex
What is the main role of MSH?
the exact role is unknown but it can influence brain activity and can cause darkness of skin in high doses
be able to distinguish between the pars nervosa and pars distalis on a stained tissue section (remember that the pars distalis stains darker and more densel than the pars nervosa)
What hormones does the posterior pituitary synthesize?
none
What two hormones does the posterior pituitary gland store and secrete
Oxytocin and ADH
What is the most common cell type in the posterior pituitary?
pituicytes (a type of glial cell with many branches resembling an astrocyte that associates with the fenestrated capillaries)
Where are hormones stored in the posterior pituitary?
the axon terminal as well as the dilated portions of the axons near the terminals called HERRING BODIES
What stimulates the secretion of oxytocin?
uterine distension and stimulation of nipples
What is the principal action of oxytocin?
to stimulate smooth muscle contraction of uterus and cells in mammary glands
What controls the secretion of ADH?
elevated blood osmotic pressure, dehydration, loss of blood volume, pain, or stress
What is the principal action of ADH
to conserve body water by decreasing uring volume, lowering perpiration, and raising blood pressure by constricting arterioles
What are the two major divisions of the adrenal glands?
cortex and medulla
The the cortex or the medulla the larger of the two areas within the adrenal gland?
the cortex is larger
Is the cortex or the medulla the part of the adrenal gland that secretes steroids?
the cortex secretes steroids
Does the cortex or the medulla of the adrenal gland secrete catecholamine?
the medulla secretes catecholamine
label the layers of the adrenal gland
name the bottom 4 adrenal layers and their respective secretions
be able to distinguish histological sections of the glomerular zone, the fascicular zone, and the retiular zone of the adrenal gland
What is the main role of aldosterone?
to regulate Na+and K+ and water in order to control blood pressure
What is the main role of cortisol?
to regulate glucose and fatty acid metabolism as well as suppress the immune system in response to stress
What is the main role of DHEA?
to assist in early growth of axillary and pubic hair in both sexes
What is the main role of epinephrine and norepinephrine?
to intensify sympathetic responses in various parts of the body
The adrenal medulla is a modified _____ ganglion of the ____ nervous system
sympathetic, autonomic
The adrenal medulla develops from _____ cells
neural crest!
Do the cells in the adrenal medulla have axons?
No. Instead of releasing neurotransmitters via neural axons, they use modified neurons called CHROMAFFIN CELLS which cluster around blood vessels and release hormones directly into the blood stream. These chromaffin cells are controlled by sympathetic PREGANGLIONIC neurons which allow quick signaling
From which part of the adrenal gland are epinephrine and norepinephrine secreted?
adrenal MEDULLA
What cells within the pancreas are endocrine?
Islets of langerhan
What is characteristic about the staining of the islets of langerhan within the pancreas?
they tend to stain pale compared to the exocrine portion (the pancreatic acini)
What cells of the pancreas are exocrine?
pancreatic acinar cells
What are the three principle cells of the islets of langerhans?
1) Beta (B) cells. Make up 70% of the islet, synthesize and secrete insulin
2) Alpha (A) cells. Make up 17% of the islet, synthesize and secrete glucagon
3) Delta (D) cells. Make up 7% of islet, synthesize and secrete somatostatin (identical to growth hormone-inhibiting hormone from hypothalamus)
Insulin _____ blood glucose levels as it signals for an acceleration of _____ transport into cells and the conversion of glucose into _____
lowers
glucose
glycogen (aka glycogenesis)
What chemical synthesized and released in the pancreas raises blood sugar levels?
glucagon (from alpha cells)
What chemical synthesized and released from the pancreas inhibits glucagon and insulin secretion?
somatostatin (from delta cells)
know the approximate appearance of pancreatic islet cells
The walls of the thyroid gland are made up of follicular cells. What cell type are these?
simple squamous to low columnar
What are the two thyroid hormones?
1) T4 (4 atoms of iodione)
2) T3 (3 atoms of iodine)
The gel-like mass found within thyroid follicles is called what?
colloid
Parafollicular cells (C cells) within the thyroid are responsible for the production of what?
calcitonin
be able to identify and label the types of cells and membranes within a histological section of thyroid tissue
_____ feedback mechanism control the release of calcitonin from parafollicular (C) cells within the thyroid gland
negative feedback
High blood Ca levels _____ the release of calcitonin
stimulate
Low blood Ca levels ____ the secretion of calcitonin
inhibit
What two cell types are located within parathyroid glands?
1) chief cells (most numerous, pale-staining)
2) oxyphil cells (larger, very acidophilic, unknown function)
What cells produce parathyroid hormone?
chief cells in the parathyroid gland
What is the role of parathyroid hormone
parathyroid hormone increases the level of Ca in the blood by stimulating bones to release Ca. PTH also prevents Ca loss from blood into urine
