exam 1 lecture notes Flashcards
what is endocrinology
the study of endocrine glands and their secretions (hormones)
what is the difference between endocrine glands and exocrine glands
endocrine: secrete inside body
exocrine: secrete outside body
what is extirpation
removal of an endocrine gland
what is hormone replacement
treating an individual who lacks a particular hormone with that hormone or a drug substitute for that hormone
what are the three classes of evidence for determining hormone-behavior interactions
- hormonally dependent behavior should be altered/disappear when the source of the hormone is removed or blocked
- restoration of the hormone should reinstate or normalize the behavior
- hormone concentrations and the behavior should be covariant
does pharmacological treatment with a hormone mimic the normal secretion pattern of the endogenous hormone? why?
usually no because of different doses and different temporal considerations
what are organizational effects of hormones
relatively permanent effects of hormones on structure and function of the body
when do organizational effects usually take place
during a critical period of development
what are activational effects of hormones
relatively immediate (temporary) effects of hormones that come and go with the presence or absence of the hormone
when transplanted testis were autopsied, what was discovered to be reestablished and what was not reestablished
they had reestablished a blood supply but not a neural supply
what was determined about the size of the transplanted testis
2x larger than normal
-compensatory hypertrophy of the single testis
what is a bioassay
using a physiological or behavioral measure to indirectly assess hormone activity/levels
what are direct hormone assays
hormones are measured directly in the blood or saliva samples
what is a hormone
intercellular signal that is delivered via blood vessel
what is the main difference between a hormone and a neurotransmitter
NT diffuse through a synapse to a nearby cell
hormones travel via blood vessels
if a hormone travels a short distance through the pituitary stalk is it a systemic hormone
no
if the hormone travels a long distance throughout the body is it a systemic hormone
yes
what determines which cells are a target for a systemic hormone
whether or not a particular cell expresses receptors for the specific hormone
what are receptors
specialized protein molecules produced by a cell and located either inside or on that cells surface
does hormonal signaling or NT signaling have better temporal and spatial resolution
NT signaling
what are the four chemical structures of hormones
steroid
lipid
monoamine
peptide/protein
how do endocrine glands usually produce effects on targets
by clumping together into a gland
can glands secrete more than one type of hormone
yes
what is a neurohormone
a hormone that is produced by a neuron
what is a neurosecretory neuron
a neuron that produces a neurohormone
what are the two main functional classes of hormones
release control hormone (releasing factor)
effector hormone
what is a releasing factor (release control hormone)
hormone that acts on endocrine cells to regulate the release of other hormones
(can be stimulatory or inhibitory)
what is an effector hormone
non-releasing factors
hormones that produce a regulatory effect on physiological/psychological function
what is the master gland
pituitary
what is the master of the master gland
hypothalamus
what do hypothalamic neurons innervate
the posterior pituitary
how does the hypothalamus communicate with the anterior pituitary
through hormones
do any neurons innervate the anterior pituitary
no
what is a first order hormone
the neurohormone itself is an effector hormone
where is a first order hormone released
in the posterior pituitary through axon terminals
what order hormone is oxytocin
first
what are the two main physiological effects of oxytocin
milk ejection and contraction in the uterus
what is a second order hormone
neurohormone is a releasing factor for an anterior pituitary hormone that is an effector hormone
in a second order hormone where are the two hormones released
the releasing factor is released by hypothalamic neurons
the effector hormone is released in the anterior pituitary
what is a third order hormone
neurohormone is a releasing factor for an anterior pituitary hormone which is a releasing factor for an effector hormone
what order hormone is growth hormone
second
GHRH released by hypothalamus
growth hormone released by anterior pituitary
what does growth hormone do
stimulates growth of various target tissues
what order hormone hormone is testosterone
third order
where and by what are neurohormones produced
produced by neurosecretory neurons in the hypothalamus
what is the “home” of a neuron designated as
the location of that neuron’s cell body
where is the hypothalamus located
below thalamus
base of forebrain
surrounding the third ventricle
what is the median eminence
part of the hypothalamus immediately above the pituitary stalk
what are two examples of effector hormones
oxytocin
vasopressin
what is the size of the cell body that produces effector hormones
magnocellular neurons
large
where is the location of the cell body that produces effector hormones
lateral paraventricular neuron (PVN)
supraoptic nucleus (SON)
where is the location of the axon terminal of the cell that releases effector hormones
posterior pituitary
what is the size of the cell body that produces releasing hormones
parvocellular neurons
small
where is the location of the cell body that produces releasing hormones
various hypothalamic nuclei
where is the location of the axon terminal of the cell that releases releasing hormones
median eminence (part of hypothalamus)
why is there a difference in neuronal cell body size
differ in the quantity of hormone
the axon terminals of hypothalamic neurosecretory neurons that secrete effector hormones are located in the
posterior pituitary
the axon terminals of hypothalamic neurosecretory neurons that secrete releasing hormones are located in the
median eminence
(hormones are released from anterior pituitary but the neurons do not extend to there)
why is it important that there are more effector hormones produced (larger cell body) than releasing hormone
releasing hormones only need to travel a small distance to the pituitary but effector hormones are released into systemic circulation
why are hormones secreted in the median eminence not systemic hormone
they are not secreted in a large enough quantity to circulate throughout the entire body
where is the pituitary located
in the sella tursica indentation in the sphenoid bone
what are the three subdivisions (lobes) of the pituitary
anterior
posterior
intermediate
where does the anterior pituitary originate from
the roof of the mouth
where does the posterior pituitary originate from
the brain
what is the intermediate pituitary
the distinct junction between anterior and posterior pituitary in non-human mammals
how is the pituitary attached to the hypothalamus
by the infundibulum or pituitary stalk
what is the portal blood system
blood vessel system that carries neurohormones from the median eminence to the anterior pituitary
what are the three components of the portal blood system
primary plexus
secondary plexus
portal vein
where is the primary plexus located
in the median eminence
where is the secondary plexus located
in the anterior pituitary
what is the portal vein
connects the primary and secondary plexus
located in pituitary stalk
one way blood flow from hypothalamus
oxytocin and vasopressin are neurohormones secreted by neurosecretory neuron axon terminals in the
posterior pituitary
how can the milk letdown reflex be classically conditioned
suckling can be associated with cues that become conditioned stimuli for milk letdown
what are the two main functions of vasopressin (ADH)
mediates vasoconstriction
mediates water retention at kidney
what is the affect of alcohol on vasopressin secretion
alcohol inhibits vasopressin
how many AA do the peptides of oxytocin and vasopressin contain
nine
9
what is the difference between a peptide and a protein
peptide: short chain of amino acids
protein: long chain of amino acids
what are the two variants of vasopressin
arginine vasopressin: found in most mammals
lysine vasopressin: found in other animals
what is a prohormone
precursor molecule that may have some other hormonal function of its own but can be converted into another hormone
when the cell cleaves the large proteins, what are the proteins that are left over besides oxytocin and vasopressin
oxytocin - neurophysin I
vasopressin - neurophysin II
what do neurophysin I and II function as
secreted into circulation with oxytocin and vasopressin to act as carrier proteins
what is a carrier protein
protein that binds to hormone molecule and escorts it around in the blood stream
- often protects the hormone from degradation
what is the half-life
time for 50% degradation/clearance
does the half life increase or decrease with a carrier protein
increases
what kind of signals are oxytocin and vasopressin
neuropeptide/neurotransmitter intercellular signals
what is the difference between hormone vasopressin and oxytocin and NT vasopressin and oxytocin
the hormones are peptide hormones that cannot cross the BBB so it is unclear if they are involved in brain processes
releasing factor neurohormones are secreted by neurosecretory neuron axon terminals located in the
median eminence
what inhibits prolactin secretion
dopamine
what do tropic and trophic mean
tropic: causing a change
trophic: nourishing, promoting growth
what are trophic/tropic factors
all hormones produced by the anterior pituitary
what are the three general classes of endocrine cells
basophils
acidophils
chromatophobes
what kind of dye stains the three kinds of endocrine cells
basophils: stain with basic dyes
acidophils: stains with acidic dye
chromatophobes: stains weakly (color phobic)
can anterior pituitary hormones be effector hormones
yes
what is the structural relationship between ACTH, beta endorphin, and MSH
they are all peptide fragments of the POMC prohormone
what does a second order neuroendocrine arrangement mean
the neurohormone is a releasing factor for an anterior pituitary hormone that is an effector hormone
what does a third order neuroendocrine arrangement mean
neurohormone is a releasing factor for an anterior pituitary hormone, which is a releasing factor for an effector hormone
what is the effect of LH
tropic effect on leydig cells in testes which stimulates the production and secretion of testosterone
also has trophic effect on leydig cells, promoting growth
what is the effect of FSH
tropic effect on sertoli cells in testes, stimulating spermatogenesis
trophic effect on sertoli cells, promoting growth
what is receptor downregulation
phenomenon when cells decrease the number of receptors for a given hormone that they produce
- often caused by exposure of cells to greater than normal levels of the receptor ligand
what is a gene
sequence of DNA that contains the code for a particular protein
where does transcription occur for proteins/peptide hormones
nucleus
where does translation occur for proteins/peptide hormones
cytoplasm
are proteins/peptide hormones water solubles
yes
and bulky
do proteins/peptide hormones require a carrier protein
no can circulate through blood without carrier
can proteins/peptide hormones pass through the phospholipid bilayer
no
-receptors on cell membranes
what is the BBB
tight junction between endothelial cells forming the walls of the blood vessels in the brain that prevents most molecules from being able to leak out of the blood vessels into brain tissue
can proteins/peptide hormones cross the BBB
no
how are proteins/peptide hormones stored
in vesicles
is there a gene that encodes for steroid hormones
no, they are synthesized by a series of enzyme mediated chemical reactions
what is a common precursor for steroids
cholesterol
what is a common precursor for thyroid hormones
tyrosine
what are steroid hormones soluble in
soluble in lipids/fats but not soluble in water
do steroid hormones need a carrier protein
yes, need to be escorted by carrier protein to circulate through bloodstream
are steroid hormones able to pass through cell membranes
yes
are steroid hormones able to penetrate the BBB
yes because they are lipid soluble
where are receptors for steroid hormones located
inside the cell since steroids can pass through the membrane
are steroid and thyroid hormones packaged into vesicles
no
what is the carrier protein for oxytocin
neurophysin I
what is the carrier protein for vasopressin
neurophysin II
what is the carrier protein for glucocorticoids (cortisol)
corticosteroid binding globulin (CBG)
what is the carrier protein for androgens
sex hormone binding globulin (SHBG)
what is the carrier protein for estrogens
sex hormone binding globulin (SHBG)
alpha fetal protein
what is the carrier protein for progesterone
CBG
what is the carrier protein for thyroid hormones
thyroid binding globulin (TBG)
where are metabotropic receptors located
in the outer cell membrane
how do metabotropic receptors mediate change
by triggering a series of intracellular chemical reactions (metabolism)
- activation of G protein and increase second messenger concentration
what are intracellular steroid and thyroid hormone receptors also called
hormone dependent transcription factors
what happens after steroid/thyroid hormone receptors are bound (activated)
the activated receptor binds to DNA to modulate the transcription of genes and therefore modulate protein synthesis
what happens to the glucocorticoid receptor protein when cortisol binds
the activated receptor:
-translocates to the nucleus
-dimerizes
-binds to specific sequence of DNA
what is gene expression largely determined by
transcription factors
what are transcription factors
proteins that bind to specific sequences of DNA and increase or decrease transcription of specific genes
why is protein synthesis a continuous process
most proteins live a short life and are continuously breaking down and being replaced by new proteins
why is there a time lag in the release of the hormone into the blood stream
it takes time to:
- release RF into median eminence
- RF traveling to anterior pituitary
- tropic factor release in anterior pituitary
- travel of tropic factors to steroid producing cells
- synthesis of new steroid
- diffusion of new steroid into blood stream
what happens in between the hormone being released into the blood stream and the hormone modulating gene transcription
the hormone reaches the target cell
the receptor is activated
gene transcription is modulated
why is there a time lag in the onset of a change in gene transcription and a change in cell function
there is delay before an increase/decrease in newly synthesized proteins will significantly alter the concentration of that protein
there is a delay before the change in protein concentration actually produces a change in cellular function
how long will a steroid hormone induced change in cellular function last
hours-days
as long as the levels of the regulated proteins remain altered
is the effect of steroid hormones fast or slow to develop
slow to develop
are the effects of steroid hormones long or short lasting
long lasting
what are the female accessory sex organs
fallopian tubes
uterus
cervix
what are the male accessory sex organs
epididymis
vas deferens
seminal vesicle
what is the female external genitalia
vagina
clitoris
labia major
labia minor
what is the male external genitalia
penis
scrotum
what is the sex determining region on the Y chromosome
SRY gene
what is the TDF protein
a protein product of the SRY gene
- testis determination factor
what is differentiation
anatomical development
- process by which cells develop (differentiate) into specific cell types
what is an anlagen
the first accumulation of cells in an embryo which constitutes the beginning of a future tissue or organ
what does the germinal ridge develop into
can develop into either an ovary or testis
what does DHT act as
a super testosterone that is a more potent agonist for androgen receptors than testosterone
what is testicular feminization mutation
individual has testosterone but no functioning testosterone receptors
in a genetically male individual (XY), what gonads develop when there is a lack of TDF
ovary
in a genetically male individual (XY), what gonads develop when there is testicular feminization mutation (absence of androgen receptors)
testis
in a genetically male individual (XY), what gonads develop when there is lack of MIH or defective MIH receptors
testis
in a genetically male individual (XY), what gonads develop when there is a 5-alpha reductase deficiency
testis
in a genetically male individual (XY), what accessory sexual organs develop when there is a lack of TDF
female
in a genetically male individual (XY), what accessory sexual organs develop when there is testicular feminization mutation (absence of androgen receptors)
neither male or female
in a genetically male individual (XY), what accessory sexual organs develop when there is a lack of MIH or defective MIH receptors
both female and male
in a genetically male individual (XY), what accessory sexual organs develop when there is a 5-alpha reductase deficiency
male
in a genetically male individual (XY), what external genitalia develops with a lack of TDF
female
in a genetically male individual (XY), what external genitalia develops with testicular feminization mutation (absence of androgen receptors)
female
in a genetically male individual (XY), what external genitalia develops when there is a lack of MIH or defective MIH receptors
male
in a genetically male individual (XY), what external genitalia develops when there is a 5-alpha reductase deficiency
female
in a genetically male individual (XY), what secondary sex characteristics develop with a lack of TDF
female
in a genetically male individual (XY), what secondary sex characteristics develop with testicular feminization mutation (absence of androgen receptors)
female; no pubic hair and full breast development
in a genetically male individual (XY), what secondary sex characteristics develop with lack of MIH or defective MIH receptors
male; may experience abdominal cramps
in a genetically male individual (XY), what secondary sex characteristics develop with a 5-alpha reductase deficiency
male; hole at the base of the penis
is TDF a hormone
no it is a protein - transcription factor and only has an effect in the cell that it is produced in
which chromosome is the androgen receptor on
X
what are LH, FSH, and testosterone levels in someone with testicular feminization mutation
LH and FSH are high because there is no negative feedback because testosterone has no receptors to bind to
testosterone levels are high because of high LH levels
what is hypospadias
birth defect of the urethra that results in an abnormally placed urinary hole
what is the gender assignment at birth and usual gender identity of someone born with 5-alpha reductase deficiency
gender assignment at birth: female
gender identity: in most cases male after puberty
