Endocrine Flashcards
how does the endocrine system message a target tissue
by sending hormones through the blood and connective tissue spaces
how does the nervous system message a target tissue
by the release of neurotransmitters and by the transmission of neural impulses along nerve cell processes
what is the speed and affect of the endocrine system response as compared to the nervous system response
allow, prolonged affect
what traits do all endocrine glands have in common
they do not have excretory ducts
hormone secretions are carried through an extracellular matrix of connective tissue and blood vessels
endocrine glands typically are aggregates of epithelioid cells or cells that lack a free surface, which are embedded with the connective tissues
the secretory products of endocrine glands influence target organs or tissues at some distance from the gland
endocrine glands are well vascularized and surrounded by rich vascular networks
most endocrine cells are derived from what cell origin
epithelial cells
what endocrine cells are of mesenchymal origin
cortex cells of adrenal gland
leydig cells of testis
steroid-secreting cells of the developing follicles in the ovary
what type of cell signaling is associated with the release of hormones that act on adjacent or nearby target cells in the connective tissue matrix
paracrine signaling
what type of cell signaling is associated with a cell targeting itself, and the screwed hormone binding to a receptor on its own surface
autocrine signaling
what are the three major classes of hormones
peptides
steroids
amino acids
what is the largest class of hormones of the three major classes
peptides
by what method does a peptide hormone enter a cell
hormone has to bind to specific receptor proteins because they cannot pass the cell membrane
a second messenger is needed to activate an enzyme or protein synthesis
describe the effects of a peptide hormone
fast acting and transient
what type of protein within the cytoplasm protects a steroid hormone from degradation
carrier proteins
which hormones are examples of peptide hormones
insulin
glucagon
growth hormone
adrenocorticotropic hormone
follicle-stimulating hormone
luteinizing hormone
antidiuretic hormone
oxytocin
interleukins
various growth factors
what three endocrine organs secrete steroid hormones
ovaries
testes
adrenal cortex
what are the five examples of steroid hormones
cortisol
estrogen
progesterone
aldosterone
testosterone
what is the expected rate of onset and lasting effect of steroid hormones
they have a slower onset than other hormones but a lasting effect
what are the three examples of amino acid or amino acid derivative hormones
epinephrine and norepinephrine
thyroxin
triiodothyronine
what amino acid derivatives are fast acting and have transient effects
norepinephrine and epinephrine
what amino acid are the class of amino acid hormones derived from
tyrosine
what are the two ways amino acid derivative hormones interact with a target cell
by binding to receptors on plasma membrane which activates a second messenger
by binding to carrier proteins to pass through the cell membrane then bind to receptor sites on the nucleus
which of the two major hormones classes have storing mechanisms following synthesis
peptides and amino acid derivatives
what is the most typical way a hormone acts upon a target cell
by binding to a specific hormone receptor
where are target cell hormone receptors found
exposed on the surface of a target cell
intracellular receptors within the cytoplasm or nucleus
what two specific hormone classes require cell surface receptors
peptide hormones
catecholamines
what is the function of second messengers when a hormone binds to a cell surface receptor
they amplify the signal initiated by the hormone binding to the cell surface receptor
how are the second messengers produced when hormones are bound to cell surface receptors
the membrane associated G proteins are activated
what four hormones have specific intracellular receptors
steroid hormones
thyroid hormones
vitamin A
vitamin D
what two specific steroids use nuclear initiating signaling
estrogen and progesterone
what are the four ways hormone abnormalities may present as endocrine disease
hormone overproduction
hormone underproduction
altered target tissue response
tumors of an endocrine gland
when do hormone feedback mechanisms occur
when the response to a stimulus influences the original stimulus
when does a negative feedback hormone mechanism occur
when the hormone response diminishes the original stimulus
when does a positive feedback hormonal mechanism occur
when the hormone response enhances the original stimulus
what is the most common hormone feedback mechanism
negative feedback
what is the broad cellular composition of the anterior pituitary lobe
glandular epithelium
what is the broad cellular composition of the posterior pituitary lobe
neural secretory tissue
what are the three derivatives of Rathke’s pouch associated with the anterior pituitary gland
pars distalis
pars intermdia
pars tuberalis
what is the largest derivative of Rathke’s pouch present within the anterior pituitary fland
pars distalis
what derivative of the anterior pituitary is associated with cystic formation
pars intermedia
what derivative of the anterior pituitary is the most vascular
par tuberalis
what are the two embryonic derivatives of the posterior pituitary gland
pars nervosa and infundibulum
what anterior pituitary hormone promotes mammary gland development; initiates milk formation; stimulates and maintains secretion of casein, etc.
prolactin
what anterior pituitary hormone regulates the final maturation of ovarian follicle, ovulation, etc.
luteinizing hormone
what anterior pituitary hormone maintains structure and stimulates secretion of glucocorticoids
adrenocorticotropic hormone (ACTH)
what anterior pituitary hormone stimulates growth of thyroid epithelial cells
thyroid stimulating hormone (TSH)
what anterior pituitary hormone stimulates liver and other organs to make insulin-like growth factor
growth hormone
what anterior pituitary hormone stimulates spermatogenesis in the testis
follicle stimulating hormone (FSH)
what posterior pituitary hormone decreases urine volume
antidiuretic hormone (ADH)
what posterior pituitary hormone stimulates activity of mammary glands to eject milk
oxytocin
what pituitary artery supplies hypothalamus and infundibular stalk
superior hypophyseal arteries
what pituitary arteries supply the pars nervosa of the posterior lobe
inferior hypophyseal arteries
what is unique about the arterial supply of most of the anterior pituitary gland
it does not have a direct arterial blood supply
what is the main function of the hypothalamohypophyseal portal system
provides mechanism for the hypothalamic neuroendocrine to regulate pituitary function
what is the main function of hypophyseal veins
to quickly transport and exchange hormones between the hypothalamus arcuate nucleus and anterior pituitary gland
how would anterior pituitary gland cells that secrete GH and prolactin stain with H&E
they stain red with acidic dyes
how would anterior pituitary gland cells that secrete TSH, ACTH, FH, and LH stain with H&E
stain blue
which anterior pituitary cells have high carbohydrate content and stain positively for PAS
acidophils
what anterior pituitary cells stain poorly with routine H&E
chromophobes
what are the functional cell types of the par distills of the anterior pituitary gland and associated hormone secretion based on IHC
somatotrope
lactotrope
corticotrope
gonadotrope
thyrotrope
is the posterior pituitary gland an endocrine gland
no, it is considered a storage site for the neurosecretions of the hypothalamus
what is the composition of the pars nervosa of the posterior pituitary
contains unmyelinated axons
what modified glial cells can be identified on routine H&E of the posterior pituitary gland
pituicytes
what is the name for neurosecretory terminals of the posterior pituitary glands that store ADH or Oxytocin seen on routine H&E
herring bodies
what 5 bodily functions are regulated by the hypothalamus
blood pressure
body temperature
fluid and electrolyte balance
body weight
appetite
what are the three neurosecretory products produced by the hypothalamus
oxytocin
ADH
polypeptides
what are the regulating hormones of the hypothalamus
GHRH
somatostatin
dopamine
CRH
CnRH
TRH
what hypothalamus hormone stimulates secretion of LH and FSH by gonadotropes
GnRH
what hypothalamus hormone inhibits secretion of GH by somatotropes and TSH by thyrotropes
somatostatin
What hypothalamus hormone stimulates secretion and gene expression of TSH by thyrotropes, and stimulates synthesis and secretion of PRL?
thyrotropin-releasing hormone (TRH)
What hypothalamus hormone inhibits secretion of prolactin (PRL) by lactotropes?
dopamine
What hypothalamus hormone stimulates secretion of adrenal corticotropic hormone (ACTH) by corticotropes and stimulates gene expression for proopiomelanocortin (POMC) in corticotropes?
corticotropin releasing hormone (CRH)
What hypothalamus hormone stimulates secretion and gene expression of GH by somatotropes?
GHRH
What cell sites do the hormones of the target organ go to in the feedback regulation system?
hypothalamus cells and pituitary gland cells
What is the primary hormone mechanism by which changes in emotional state are translated into changes in the physiologic homeostatic state?
The secretion of hypothalamic regulatory peptides
What function does the hypothalamohypophyseal feedback loop have?
It provides a regulatory pathway of general information from the CNS to anterior pituitary gland
What hormone is activated by the hypothalamus if there is continuous stress or the brain perceives a situation as continuously dangerous?
CRH
What are three names associated with the pineal gland?
pineal body
epiphysis cerebri
third eye
What is the major function of the pineal gland
Regulation of daily body rhythm and melatonin production
What tissue does the pineal gland embryologically develop from
neuroectoderm
Where is the location of the pineal gland?
posterior wall of third ventricle
What neurotransmitter is melatonin derived from?
serotonin
What are the 3 main functions of melatonin?
a. Maintains circadian rhythms
b. Improves onset, duration, and quality of sleep
c. Plays a role in adjusting core temperature
What type of light has the worst impact on the production of melatonin?
blue light
What effects do melatonin have on gonadotropin releasing hormone (GnRH)?
It inhibits effects, decreasing gonadal steroid production
What is the name of the common calcified concretions found in the pineal gland
corpora arenacea (brain sand)
What are the two types of pineal parenchymal cells?
pinealcytes and interstitial gland cells
What cell in the pineal gland is the most prevalent?
pinealcytes
What cell in CNS do interstitial cells of the pineal gland most resemble?
astrocytes
What is the average weight of a normal thyroid gland
20-30 g
How often is the pyramidal lobe of the thyroid present
40% of population
What are the two cells of the follicular epithelium of the thyroid gland?
follicular cells (principle cells)
parafollicular cells (C cells)
What cells in thyroid follicular epithelium produce T3 and T4?
follicular cells (principle cells)
What cells in thyroid follicular epithelium produce calcitonin?
parafollicular cells (C cells)
Where are parafollicular cells located in the thyroid parenchyma
at the periphery of the epithelium and lie within the follicle basal lamina
What is the chemical name of T4?
tetraiodothyronine
What is the chemical name of T3?
triiodothyronine
What hormone is produced at a greater rate by follicular cells of the thyroid?
T4
What hormone produced by follicular cells of the thyroid is more potent and fast acting
T3
What impact does calcitonin have on blood calcium
decrease blood calcium levels
The secretion of calcitonin is an antagonist to PTH but is unaffected by what endocrine glands?
hypothalamus and pituitary
What endocrine tumor secreted calcitonin
medullary carcinoma
Calcitonin is used treat patients with what bone diseases?
osteoporosis and Paget’s disease
What is the main glycoprotein in colloid of the thyroid follicle?
thyroglobulin
What are the major steps in thyroid hormone synthesis?
a. The synthesis of thyroglobulin
b. The reabsorption, diffusion, and oxidation of iodide
c. The iodination of thyroglobulin
d. The formation of T3 and T4
e. The resorption of colloid
f. The release of T3 and T4 from follicular cells to the circulation
Why are T3 and T4 critical in fetal development?
Low levels of T3 and T4 can result in irreversible damage to CNS (Reduced numbers of neurons, defective myelination, intellectual disability)
What week of gestation does the thyroid develop in a fetus?
14 weeks
The lack of thyroid hormone interferes with gene expression for growth hormone, which can result in what childhood abnormality?
stunted growth
Where can parathyroid glands be found besides the posterior aspect of the thyroid
in the thymus
Parathyroid glands are derived from embryologic structure?
endodermal cells from 3rd and 4th pharyngeal pouch
What are the two epithelial cells of the parathyroid?
principle (chief) cells and oxyphil cells
What cell is most prevalent in the parathyroid?
principle (chief) cells
What hormone is produced by chief cells of the parathyroid gland?
PTH
What cells are the largest cells of the epithelial cells of the parathyroid gland?
oxyphil cells
How does PTH cause calcium levels to increase in the blood?
a. Promotes calcium release from bone increasing the relative number of osteoclasts
b. Acts on the kidneys to stimulate calcium reabsorption by the distal tubules while inhibiting phosphate reabsorption by the proximal tubules
c. Increase levels of hormonally active Vitamin D3 in the kidney, which promotes tubular reabsorption of calcium
d. Activation of Vitamin D3 also stimulates intestinal absorption of calcium
What 4 types of bone cells have parathyroid hormone (PTH) receptors?
a. Osteoprogenitor cells
b. Osteoblasts
c. Osteocytes
d. Bone lining cells
What cell of the bone do not have PTH receptors and indirectly activated by the RANK-RANKLE signaling system?
osteoclasts
What organ converts Vitamin D3 to become hormonally active?
kidney
How does parathyroid hormone (PTH) impact phosphate?
decreases phosphate by increasing urination
In what part of the renal tubule does parathyroid hormone (PTH) decrease the excretion of calcium?
distal tubule
How can you anatomically differentiate the right and left adrenal glands by shape?
a. The right is slightly flattened and triangular
b. The left is semilunar shaped
What region of the adrenal gland is larger by weight?
the cortex
Where does the cortex of the adrenal gland originate from?
mesoderm
Where does the medulla of the adrenal gland originate from?
neural crest
What is the primary secretory product of the cortex of the adrenal gland?
steroids
What is the primary secretory product of the adrenal gland?
catecholamines
What are the three hormone classes secreted by the adrenal cortex?
a. Mineralocorticoids – regulate minerals
b. Glucocorticoids – regulate glucose metabolism
c. Androgens- stimulate masculinization
What is a mineralocorticoid produced by the zona glomerulosa
aldosterone
What is the main function of aldosterone?
a. Aids in controlling electrolyte homeostasis
b. Functions to maintain osmotic balance in the urine to prevent serum acidosis
What are glucocorticoids produced by the zona fasciculata and zona reticularis of the adrenal cortex?
a. Cortisol
b. Corticosterone
What function do the glucocorticoids have
a. Promote normal metabolism, particularly carbohydrate metabolism
i. Promote removal of protein from skeletal muscle and its transport to liver
ii. Reduce rate of glucose metabolism by cells and stimulate glycogen synthesis by liver
iii. Stimulate mobilization of fats from storage deposits for energy use
b. Provide resistance to stress
c. Suppress inflammatory response
d. Suppress some allergic reactions
What gonadocorticoid is produced by the zona reticularis and zona fasciculata cells?
androgens
What hormones are produced by the chromaffin cells of the adrenal medulla?
a. Norepinephrine
b. Epinephrine
What are effects does the catecholamines have on the sympathetic division of the autonomic nervous system?
a. increase heart rate
b. increase blood pressure
c. reduce blood flow to viscera and skin
d. stimulate conversion of glycogen to glucose
e. increase sweating
f. induce dilation of bronchioles
g. increase rate of respiration
h. decrease digestion
i. decrease enzyme production by digestive system glands
j. decrease urine production
What are the major arteries that supply the adrenal gland?
a. Superior suprarenal artery
b. Middle suprarenal artery
c. Inferior suprarenal artery
What blood supply is shared in the medulla of the adrenal gland?
a. Arterial blood from the medulla arterioles
b. Venous blood from the cortical sinusoidal capillaries that already supplied the cortex
Where are the lymphatics of the adrenal gland located?
a. Capsule
b. Connective tissue surrounding vessels in the gland
What is the main cell type in the medulla of the adrenal gland?
chromaffin cells
What is the mechanism by which the sympathetic nervous system stimulates secretion of hormones in the chromaffin cells?
a. Myelinated, presynaptic sympathetic nerve fibers pass directly to the chromaffin cells
b. Nervous impulses reach the chromaffin cells, and they release their secretory products into blood stream
What product from the cortex of the adrenal gland converts norepinephrine to epinephrine in the chromaffin cells?
glucocorticoids
What physiologic changes occur when there is a sudden release of catecholamines?
a. Stimulate glycogenolysis (release of glucose into the blood)
b. Provides maximum strength and maximum energy
c. Increase rate of breathing
d. Increases blood pressure, heart rate and heart output
e. Dilates the coronary arteries and skeletal muscle
f. Vasoconstriction to the skin and gut
What cells in the medulla of the adrenal gland have axons that extend to the cortex to modulate secretory activity and innervate vessels and axons that extend outside the adrenal gland to abdominal organs?
ganglion cells
What are the three zones of the adrenal cortex and percentage of each?
a. Zona glomerulosa 15%
b. Zona fasciculata 80%
c. Zona reticularis 5%
What product is aldosterone produced from?
cholesterol
What sites does aldosterone cause reabsorption of sodium?
a. Principle cells of the distal tubules of the kidneys
b. Gastric mucosa
c. Salivary
d. Sweat glands
What cells in the kidney are responsible for releasing renin?
juxtaglomerular cells
What are the steps in the renin-angiotensin aldosterone feedback mechanism?
a. Juxtaglomerular cells in the kidney release renin in response to decreased blood pressure or low sodium
b. Circulating renin converts angiotensin 1 to angiotensin 2
c. Angiotensin 2 stimulates the cells of zona glomerulosa to produce and secrete aldosterone
d. As the blood pressure, sodium, and blood volume increase, the juxtaglomerular cells are inhibited
What common medication is used to treat essential hypertension?
ACE inhibitors
What are the main effects of cortisol
It acts on many cells to increase metabolic activity of glucose and fatty acid, which are immediate sources of energy
What different effects do glucocorticoids have on different organs?
a. Stimulate conversion of amino acids to glucose, polymerization of glucose to glycogen, and promotes the uptake of amino acids and fatty acids in the liver
b. Stimulate the breakdown of lipids to glycerol and free fatty acids in adipose tissue
c. Reduces the rate of glycose use and promote oxidation of fatty acids in other tissues
What impact does glucocorticoids have on inflammation and the immune system?
Depress the immune system and inflammatory response by depressing IL-1 and IL-2 production by lymphocytes and macrophages, and inhibits the mitosis in transformed lymphoblasts
How does the corticotropin releasing hormone - adrenocorticotropin hormone (CRH-ACTH) feedback mechanism impact glucocorticoids and sex steroids?
It controls their secretion and production mainly by exerting feedback to the hypothalamus
What physical changes in males and females are related to androgen production in the adrenal gland?
a. In men the effect is minimal because testosterone is a much more potent androgen
b. In women, these androgens stimulate the growth of axillary hair and pubic hair during puberty and adolescence
What is the major differentiation between a fetal adrenal gland and an adult adrenal gland?
The fetal adrenal gland consists of an outer narrow permanent cortex and an inner thick fetal cortex or fetal zone
