Endocrine System Flashcards
what are the two main types of glands?
endocrine
exocrine
____ are ductless
endocrine
_____ have ducts
exocrine
which secrete hormones into surrounding tissue fluid
endocrine
give examples of endocrine glands?
pituitary thyroid parathyroid adrenal pineal thymus
which organs have discrete areas of endocrine tissue as well as exocrine tissue
pancreas
gonads
hypothalamus
nonhormonal products are…
directed to membrane surfaces
define hormones
chemical substances secreted by cells into extracellular fluids, that regulate metabolic function of other cells in the body
most hormones are..
amino acid based hormones
give examples of steroid hormones
gonadal and adrenocortical hormones
the main mechanism of action for hormones is
to increase or decrease rates of normal cellular activity
name some of the hormonal effects?
alter plasma membrane permeability alter protein or regulatory molecule synthesis activate or inactivate enzyme induction of secretory activity stimulate mitosis
what are some of the mechanisms that transduce hormonal signal into an intracellular change
G-protein linked receptor activation of intracellular second messengers
direct gene activation
G-protein linked receptor activation of intracellular is done by….
amino acid hormones
direct gene activation is done by…
steroid hormones
give an overview of cAMP
- signal molecule binds to cell-surface receptor protein
- this activates a G protein in intracellular fluid
- G protein GDP is replaced by GTP when that subunit is activated
- diffuses within plasma membrane until it reaches Adenylate cyclase
- it activates
- this produces cAMP from ATP
- the cAMP formed in inner surface of membrane diffuses into cytoplasm where it binds to and activates protein kinase
give an overview of PIP Calcium signal mechanism
Phospholipase is an enzyme that will cut a phospholipid
DAG remains in the membrane and this activates PKC
IP3 is soluble in cytoplasm
it works on a intracellular receptor on smooth E.R.
this causes the SER to release calcium into cytoplasm
the calcium activates PKC
direct gene activation mainly is for ________ hormones
steroid
steroid hormones are ____ solube
lipid
since steroid hormones are lipid soluble, they are able to pass through…
plasma membrane
once inside, what do the steroid hormones do?
bind to intracellular receptor
the binding of the steroid hormone to the intracellular receptor forms…
activated complex
what does the activated complex later do?
passes into nucleus and binds to specific DNA sequences
the association with the DNA sequence does what?
turns on gene
target cell specificity is mediated by…
specific protein receptors
where are the receptors localized?
to cells that are influenced by a given hormone
what do hormones act as?
molecular triggers
what are the factors affecting target cell activation?
hormonal levels
number of receptors on target cell
receptor affinty
define half-life
measure of hormonal persistence in blood stream
what affects the half-life?
depends on rate of synthesis and release
speed of removal or degradation
the onset of effect is dependent on…
hormonal type
steroid hormone has a slower onset and…
lower magnitude of effect and longer lifetime
what kind of feedback controls hormone release?
negative
hormone secretion is triggered in response to a
stimulus
as hormone level increases, what happens?
target organ is affected
name the 3 types of stimuli for hormone release
humoral
neural
hormonal
describe the humoral response
endocrine glands release hormones in direct response to changing levels of ions or nutrients
describe neural response
nerve fibers stimulate hormonal release
describe hormonal response
occurs when a hormone is secreted that in turn, stimulates the secretion of other hormones.
another name for the pituitary is the
hypophysis
where is the pituitary located?
rests in the sella turcica of the sphenoid bone
to what is the pituitary connected to?
the superiorly lying hypothalamus
what is the infundibulum?
its the stalk-like connection between the two
the hypothalamus is part of the
brain
what does the hypothalamus serve as?
connection between brain and endocrine system
what are the 2 main lobes?
posterior
anterior
Posterior lobe + infundibulum =
neurohypophysis
what is the anterior lobe comprised of?
glandular tissue
the two main lobes are highly….
vascular
posterior lobe is an…
outgrowth of the brain and maintains its neural connections
what do the neurons in the supraoptic and paraventricular nuclei of the hypothalamus give rise to?
the hypothalamic- hypophyseal tract
where are hormones synthesized?
in the secretory cells of the hypothalamus
when neurons fire, what happens?
hormones are released into capillary bed in posterior pituitary
the anterior lobe is derived from
epithelial tissue
the anterior lobe has no direct connection between…
posterior pituitary or hypothalamus
the anterior lobe has a vascular connection called
hypophyseal portal veins
_____ and ______ hormones secreted by hypothalamus are carried by portal system to anterior pituitary
releasing and inhibiting
what is the anterior pituitary referred to as?
Master gland
what are the anterior pituitary tropic hormones?
they regulate secretory activity of other endocrine glands
name the anterior pituitary tropic hormones
TSH: thyroid stimulating hormone
ACTH: adrenocorticotropic hormone
FSH:follicle-stimulating hormone
LH: luteinizing hormone
what are the other 2 hormones that are not tropic?
PRL: Prolactin
GH:growth hormone
the other 2 hormones have…
neuroendocrine targets
the growth hormone is controlled by the…
anterior pituitary gland
the growth hormone is produced by
somatotropic cells
what does the growth hormone do?
stimulates most cells in the body to grow and divide
what are the major targets of the growth hormone?
bones and muscles
the growth hormone can also be called the ____ hormone
anabolic
what does it do?
promotes metabolism
growth-promoting effects are mediated….
indirectly
what are IGF’s
insulin-like growth factors
what produces IGF’s
liver and other tissues
name all the effects of the growth hormone
stimulates uptake of amino acids from blood and their incorporation into proteins
stimulates sulfur uptake
mobilizes fats from fat deposits
decreases rate of glucose uptake and metabolism
name the 2 regulations of the the GH by the hypothalamic hormone
GHRH
GHIH
name the GHRH (growth hormone releasing hormone)
somatocrinin (positive effect)
name the GHIH (growth hormone inhibiting hormone)
somatostatin (negative effect)
IGF (insulin-like growth factors) has what kind of effect on GH
negative
IGF has what kind of effect on somatostatin
positive
gigantism results from…
adolescent hypersecretion
acromegaly results from…
adult hypersecretion
progeria occurs when __________ is severe
adult hyposecretion
adolescent hyposcretion can be related to…
pituitary dwarfism
TSH stands for
thyroid-stimulating hormone
what does TSH do?
stimulates normal growth and activity of the thyroid gland
TSH can be considered what type of hormone?
tropic hormone
what controls the TSH?
hypothalamus
how does the hypothalamus control the TSH?
By releasing thyroid releasing hormone (TRH)
what can inhibit the release of TSH?
GHIH
What does ACTH stand for?
Adrenocorticotropic hormone
what does ACTH do?
stimulates adrenal cortex to release corticosteroid hormones
what can it help release?
glucocorticoids
what do glucocorticoids do?
offset effects of stress
ACTH release is controlled by ______
Corticotropin-releasing hormone (CRH)
what kind of hormone is CRH?
a hypothalamic hormone
CRH has a _____ rhythm
diurnal (24 hr)
name the feedback inhibition of ACTH
rising glucocorticoids
name the 2 gonadotropins
FSH and LH
what do gonadotropins do exactly?
regulate gonads
what does FSH stand for?
follicle stimulating hormone
what does FSH stimulate?
gamete production
what does LH stand for?
Lutenizing hormone
what does LLH promote?
production of gonadal hormones
FSH and LH work in concert to cause what?
follicle to mature
____ causes egg to be extruded from follicle
LH
In males, what does LH stimulate?
interstitial cells of the testes to produce testosterone
what controls the release of LH and FSH?
hypothalamus
how does the hypothalamus regulate the release of LH and FSH?
through the use of gonadotropin-releasing hormone (GnRH)
Prolactin stimulates what?
milk production
Prolactin is controlled by what 2 hormones?
prolactin releasing hormone (PRH) and prolactin inhibiting hormone (PIH)
T/F estrogen has a + effect on PRH
True
ADH and oxytocin are comprised of what?
9 amino acids
ADH and oxytocin are released as a result of what?
neural signals from hypothalamus
oxytocin is stored where?
posterior pituitary gland
what does oxytocin do?
stimulates smooth muscle contraction
____________depends on number of oxytocin receptors
muscle response
name some places where muscle responses from oxytocin could occur.
uterus
breast
pregnancy
oxytocin is a hormonal trigger for…
milk ejection
what does ADH stand for?
antidiuretic hormone
what does ADH do?
inhibits or prevents urine production
why does the hypothalamus release ADH?
in response to increases in solute concentration
what does ADH cause the kidneys to do?
reabsorb more water
At high doses, what does ADH cause?
vasoconstriction
diabetes insipidus is caused by a
deficiency in ADH secretion
one of the main symptoms of diabetes insipidus is…
output of huge amounts of urine and thirst
describe the structure of the thyroid gland
2 lobes containing follicles connected by isthmus
the center of each thyroid follicle is filled with _______-
colloid
what is colloid composed of?
thyroglobulin
_______ stores colloid
lumen
thyroglobulin is associated with?
iodine
the thyroid hormone is derived from what?
iodinated thyroglobulin
_____________ cells produce calcitonin
parafollicular
where do parafollicular cells lie?
in-between the follicles and make up the walls of the follicle
what kind of role does calcitonin play?
in reducing the concentration of calcium in body fluids
what does TH stand for?
thyroid hormone
TH is made up of these 2 things:
Thyroxine (T4) AND Triiodothyronine (T3)
another name for Thyroxine is…
T4
another name for Triiodothyronine is…
T3
T4 is produced by _____________
thyroid gland
T3 is formed at ___________-
target tissue
__ is converted into T3
T4
the thyroid hormone increases what?
metabolism in most tissues by stimulating glucose oxidation
the thyroid hormone can increase __________ in blood vessels
adrenergic receptors
the thyroid hormone can regulate what?
tissue growth and development
What is T4 bound to when it is transported to target tissues?
plasma proteins called thyroxine-binding globulin (TBG)
falling levels of thyroxine triggers…
TSH release
rising levels of thyroxine inhibits…
TSH release
conditions in which there is _______________ requirements causes TRH release from hypothalamus
increased energy
name the 3 examples of metabolic disturbances associated with thyroid gland activity
Myxedema
Cretinism
Grave’s disease
Myxedema is a ______ disorder
hypothyroid
If Myxedema is caused by a lack of iodine, what is the condition called?
endemic (colloidal) goiter
what is Myxedema?
condition where colloid can be made by follicles but end up accumulating because the colloid cannot be iodinated to make functional hormone
cretinism is _______ in infants
hypothyroidism
Grave’s disease is ________________ pathology
hyperthyroid
what kind of disease is Grave’s disease?
autoimmune disease
Grave’s disease is associated with what?
abnormal antibodies that mimic TSH
what is the main function of calcitonin?
lowers blood calcium levels
calcitonin is ___________ to the effect of parathyroid hormone
antagonist
calcitonin inhibits calcium release from bones by
osteoblast activity
calcitonin can stimulate…
calcium uptake and incorporation
calcium acts as a _______ signal for calcitonin release
humoral
describe the structures of the parathyroid glands
2 pairs of glands in the posterior aspect of the thyroid gland
______ screte PTH
chief cells
what does PTH stand for?
parathyroid hormone
the parathyroid hormone can control
calcium balance
the parathyroid hormone is released in response to what?
falling blood calcium levels
PTH stimulates _____ activity
osteoclast
the osteoclast activity caused by PTH allows
digest bone matrix and releases calcium
the parathyroid hormone enhances…
reabsorption by kidney tubules
the parathyroid hormone increases calcium absorption by…
intestine
the increased calcium absorption by the intestines stimulates….
conversion of vitamin D into active form
T/F hyperparathyroidism is not rare
false
what happens in hyperparathyroidism?
calcium is leached from bones and replaced by connective tissue
hypoparathyroidism is a PTH _______
deficiency that increases NS excitability
name the 2 endocrine adrenal glands
adrenal medulla
adrenal cortx
the adrenal medulla acts part of the…
sympathetic NS
the adrenal cortex is involved in responses to….
stressful conditions
name the 3 zones of the adrenal cortex from closest to the medulla, out
zona reticularis
zona fasciculata
zona glomerulosa
the zona reticularis releases…
gonadocorticoids which are involved in estrogen, progesterone, and testosterone
the zona fasciculata releases…
glucocorticoids which is involved with cortisol
the zona glomerulosa releases…
mineralocorticoids which is involved with aldosterone
the adrenal cortex releases….
corticosteroids
the corticosteroids are synthesized from…
cholesterol
what does mineralocorticoids regulate?
electrolyte concentrations in extracellular fluid
in mineralocorticoids, ______ is most abundant
aldosterone
what does aldosterone do?
reduced excretion of sodium from the body and thus increases ADH levels
mineralocorticoids stimulates reabsorption of sodium in the _________________
distal tubule of kidney
there are ___ mechanisms controlling aldosterone secretion
4
what happens during Renin-angiotensin mechanism?
JGA releases renin in response to blood pressure decrease, initiates cascade forming angiotensin II formation, angiotensin II stimulates aldosterone release from adrenal cortex
aldosterone can be secreted through direct stimulation by….
plasma sodium and potassium ions
aldosterone can be secreted due to high levels of…
ACTH
describe importance of ANP (atrial natriuretic peptide)
when blood pressure is high, heart release ANP to inhibit renin and aldosterone secretion
what do glucocorticoids influence?
metabolism and mediate response to stress
name 3 glucocorticoids.
cortisol
cortisone
corticosterone
only the _____ glucocorticoid is secreted in significant amounts
cortisol
what is gluconeogenesis?
the primary effect of cortisol; conversion of fats into glucose
Cushing’s disease results from…
excess cortisone
what is Cushing’s disease characterized by?
persistent hyperglycemia
name the symptoms of Cushing’s disease
loss of muscle and bone protein
water and salt retention
“moon” face
redistribution of body fat
Addison’s disease is ______ disorder of adrenal cortex
hyposecretory
name some of the symptoms of Addison’s disease
weight loss
reduced plasma glucose and sodium levels
severe dehydration and hypotension
gonadocorticoids are primarily _________
androgens
___________________ is only a fraction of gonadal sources
adrenal cortex secretion of sex hormones
gonadocorticoids have a possible role in what?
puberty
androstenedione is converted to
testosterone and dihydrotestosterone
the adrenal medulla contain ____cells
chromaffin cells
what are chromaffin cells?
modified postganglionic sympathetic neurons
what do chromaffin cells secrete?
epinephrine and norepinephrine
initial response to stress is mediated by
sympathetic NS
activation of adrenal medulla and associated release of EPI and NE prolong what?
sympathetic response
activation of adrenal medulla and associated release of EPI and NE can cause…
elevated BP and heart rate
mobilization of glucose
shunt blood from GI
_______ contains both exocrine (GI enzymes) and endocrine cells
pancreas
name the 2 populations that can be found in the pancreatic islets
alpha cells
beta cells
what do alpha cells produce?
glucagons
what do beta cells produce?
insulin
insulin is a ______ hormone
hypoglycemic
glucagon is a ________ hormone
hyperglycemic
name the 3 effects of glucagon
breakdown of glycogen to glucose
synthesis of glucose from lactic acid, fatty acids, and amino acids
release of glucose from liver
what can regulate glycogen?
humoral response to decreased circulating glucose
name the 4 effects insulin has
lower blood glucose
alter protein and fat metabolism
inhibits breakdown of glycogen
triggers enzymatic activity
insulin is able enhance __________ of glucose into body cell
membrane transport
oxidation of glucose is able to produce…
ATP
what can regulate insulin?
humoral response to increased circulating glucose
what is diabetes mellitus?
hyposecretion or hypoactivity of insulin
in diabetes mellitus, excessive hyperglycemia triggers what?
sympathetic response
in lipidemia, why are fats mobilized?
to use as cellular food
fatty acid metabolites accumulate as _______________
ketone bodies
what is ketoacidosis?
accumulating of ketones and a drop in blood pH
name the 3 signs of diabetes mellitis
polyuria
polydipsia
polyphagia
in polyuria, excessive glucose in kidney filtrate acts as a what?
diuretic which inhibits water reabsorption
in polyuria, increased urine output causes what?
dehydration and decreased blood volume
in polyuria, electrolyte loss is associated with…
excretion of excess ketones
describe polydipsia
dehydration stimulates thirst centers in brain
describe polyfagia
glucose cannot be used because it cannot be absorbed by cells and this results in hunger
Type I DM is named…
insulin dependent diabetes mellitus
Type II DM is named….
non-insulin dependent diabetes mellitus
which diabetes mellitus is related with autoimmune destruction of beta cells
Type 1 IDDM
which diabetes mellitus starts usually after age of 40
Type II NIDDM
Type 1 IDDM usually has what kind onset?
juvenile onset
which diabetes mellitus is related with lack of insulin activity?
Type 1 IDDM
which type of diabetes mellitus is most common in 90% of cases?
Type 2 NIDDM
what is the main characteristic of Type II NIDDM?
insulin is produced in inadequate quantities or with faulty receptors
ovaries produce…
estrogens and progesterone
the ovaries help regulate….
sexual maturation and menstrual cycle
the testes produce….
testosterone
the testes hep regulate….
sexual maturation and sex drive
release of gonadal hormones is regulated by what?
gonadotropins
the pineal gland can be found where?
floor of third ventricle within diencephalons
the pineal gland’s primary secretory product is?
melatonin
the pineal gland receives indirect inputs from?
visual system
______ is large in children but decreases with age
thymus
name the 2 hormonal products from the thymus that is important for T cell maturation
thymopoietin
thymosins
