Endocrine Glands Part 2 Flashcards
describe the parathyroid glands
small endocrine glands associated with thyroid
where are the parathyroid glands located
posterior surface of thyroid gland, one superior and one inferior
what are the parathyroid glands embryologically derived from
third and fourth branchial (pharyngeal) pouches
what do parathyroid glands secrete and what does it do
parathyroid hormone- regulates serum calcium and phosphate
what are the reciprocal effects of calcitonin and PTH
PTH slowly increases serum calcium, calcitonin rapidly decreases serum calcium
what are the 3 ways in which PTH increases serum calcium
-increases osteoclast activity (inhibits osteoblasts)
- increases renal tubular absorption of Ca in kidneys (and inhibits resorption of phosphate)
- increases calcium absorption from gut via Vit D
what is PTH stimulated by
decrease in blood calcium
what happens if parathyroid is damaged in surgery
hypoparathyroidism
what is hyperparathyroidism
excesss PTH production
what it the result of hyperparathyroidism
bony erosion and lysis
what are the 2 types of secretory cells in the parathyroid gland
chief cells and oxyphil cells
what cell is more abundant in the parathyroid gland
chief cells
what do chief cells secrete
PTH
what do oxyphils contain
large numbers of mitochondria
what is the function of oxyphils
unknown function
what happens to the parathyroid gland in older individuals
fatty infiltration
where are the adrenal glands located
superior to the kidneys
what are the adrenal glands covered by
thin CT capsule
what is the embryological origin of the adrenal cortex
mesoderm
what is the adrenal cortex regulated by
ACTH secreted by the anterior pituitary
what does the adrenal cortex secrete
steroid hormones structurally similar to cholesterol precursor
what are the 3 functional classes of adrenal hormones
-mineralocorticoids
- glucocorticoids
- sex hormones
what is the most common mineralocorticoid
aldosterone
what does aldosterone do
control electrolyte and fluid balance
what do mineralocorticoids do
-regulate Na and K levels via Na pumps especially in renal tubules
- regulate BP via JGA
what is the most common glucocorticoid
cortisol
what do glucocorticoids do
stimulate gluconeogenesis and glycogenolysis which increase blood glucose
- increase metabolism and breakdown of proteins, carbohydrates, and lipids
what do sex hormones do
supplement gonadal production
what are the 3 layers of the adrenal cortex from superficial to deep
zona glomerulosa, zons fasciculata, zona reticularis
what does the zona glomerulosa secrete
mineralocorticoids
what is the largest region in the adrenal cortex
zona glomerulosa
what cell is in the zona fasciculata
spongicytes
what does the zona fasciculata secrete
glucocorticoids and small amounts of androgens
what affect does cortisol have on the immune system
decreases immune response
what causes cortisol release
stress
what does the zona reticularis secrete
small quantities of andorgens and glucocorticoids
what is another term for hypoadrenocorticism
addison’s disease
what happens in addison’s disease
failure of the adrenal cortex to produce mineralo and glucocorticoids
what is addison’s disease usually caused by
atrophy of the gland often caused by autoimmune disease
what is the result of decreased aldosterone
decreased ECF volume, hyponatremia, hyperkalemia, mild acidosis -> shock, death
-AKA Addisonian crisis
what is the result of decreased cortisol in glucose
decreased blood glucose
what is the treatment for addisons disease
exogenous administration of meralocorticoids and glucocorticoids
what is another term for hyperadrenocorticism
cushings disease
what is the name for primary hyperadrenocorticism? secondary?
primary- adrenal hyperadrenocorticism
secondary- pituitary hyperadrenocorticism “classical form”
what is primary hyperadrenocorticism caused by
general adrenal hyperplasia or functional tumor of adrenal cortex -> excess cortisol secretion
what is secondary hyperadrenocorticism caused by
increased ACTH from anterior pituitary or other cortisol producing tumor
what does increased ACTH secretion lead to
adrenal hyperplasia and excess cortisol secretion
what is the adrenal medulla embryologically derived from
neuroectoderm
what cells does the adrenal medulla contain
chromaffin cells
what are chromaffin cells
modified, post ganglionic neuronal cells with secretory function
what is the adrenal medulla controlled by
preganglionic, sympathetic nerve fibers
what do chromaffin cells secrete
catecholamines such as adrenaline and noradrenaline
what are catecholamines in the adrenal medulla stored in
dense core granules
what does catecholamine release have a systemic effect on
adrenergic receptors throughout the body - especially skeletal, cardiac, and smooth muscle
what do catecholamines work in concert with glucocorticoids to do
prepare body for fight or flight response
what does adrenaline promote in the liver
glycogenolysis for energy
what is adrenaline responsible for the production of and what are they
enkephalins- endogenous opiates responsible for pain relief
what is a pheochromocytoma
generally benign, functional tumor of chromaffin cells of adrenal medulla
what are the symptoms of pheochromocytoms due to
increased epinephrine and norepinephrine secretion
what are the symptoms of pheochromocytomas
hypertension, headache, cardiac arrhythmias, chest pain, anxiety, panic attacks, nausea
what is the treatment for pheochromocytomas
surgical removal of tumor
what does the bulk of the pancreas contain and what does it do
exocrine acini- secrete digestive products into the gut
where do endocrine cells migrate in development and what do they form
migrate from duct system and aggregate around capillaries of pancreas to form islets of langerhand
where are islets of langerhans located
distributed throughout exocrine pancreatic tissue
what are the 3 main types of islet cells
alpha, beta, and delta
what islet cells are most abundant to least
beta> alpha > delta
what do alpha cells secrete and what does it do
secrete glucagon, increases blood glucose, stimulates glucogenesis and glycogenolysis
what do beta cells secrete and what does it do
secrete insulin- decreases blood glucose and stimulates intracellular glycogen synthesis
what do delta cells secrete and what does it do
secretes somatostatin- inhibits both insulin and glucagon production
what do other miscellaneous cell types in the pancreas secrete
vasoactive intestinal peptide (VIP) and pancreatic polypeptide (PP)
what is diabetes characterized by
hyperglycemia and glucosuria
what happens in type 1 diabetes
decreased insulin production
what happens in type 2 diabetes
decreased number of insulin receptors or decreased responsiveness
where is the pineal gland/body located
anterodorsal to cerebullem
what does the pineal gland develop from
neuroectodeerm as evagination of posterior portion of third ventricle from roof of diencephalon
what does the pineal gland do
communicates with hypothalamus; acts as photoreceptor in lower vertebrates
how does the pineal gland act as a photoreceptor
translates light intensity and duration into endocrine activity- important in circadian rhythms and seasonal reproductive cycles
what hormones does the pineal gland secrete
melatonin and serotonin
what does melatonin do
stimulates melanopores, chromatophores -> change in color intensity with reproductive cycle
what does serotonin do
vasoconstrictor and neurotransmitter
what affect does melatonin have in mammals
anti-gonadal effect, decrease sex activity
how does melatonin affect other hormones
-decreased GNRH from hypothalamus
- decreased sex hormone secretion from gonads
what are the two main cell types in the pineal gland
pinealocytes and neuroglial cells
what are pinealocytes and what do they secrete
highly modified neurons
- secrete melatonin and serotonin
what are neuroglial cells
support cells such as astrocytes, microglial cells
what might the pineal gland also contain
corpora arenacea
what is corpora arenacea
calcified accretions of Ca and Mg phosphate in aging individuals, “brain sand”
how do you identify the parathyroid
contains pale staining chief cells with clusters of larger, brighter pink oxyphil cells scattered throughout
how do you identify adrenal gland
cortex contains three alternating bands of dark and light pink cells
- central medulla contains chromaffin cells
what does the GI and respiratory endocrine system look like
a variety of endocrine cells scattered in the mucosa of GI, respiratory tract and other organs
what do the cells of the GI and respiratory endocrine system do
secrete peptide and amine hormones such as gastrin, secretin, CCK, and serotonin with neurosecretory granules and hormone like activity
what are the cells of the GI and respiratory endocrine system called
APUD cells - amine precursor uptake and decarboxylation
how are APUD cells similar
similar ultrastructure and metabolic pathways, however not common ancestors because different embryological origins
what are most APUD cells embryologically derived from
neural crest- aka neuroendocrine cells
what are other APUD cells in the gut embryologically derived from
endoderm- enteroendocrine cells
what are the best known examples of APUD cells
chromaffin cells, thyroid C cells, and pancreatic islets
what do enteroendocrine cells in GI and respiratory tracts secrete
gastrin, CCK, VIP, substance P, serotonin and bombesin
