EX 2; Endocrinology Flashcards
What is the main route of communication in the endocrine system
chemical signals (hormones) released into blood
What are two factors affecting onset and duration of signal effects
the response can be delayed; time for the blood to travel
the duration is prolonged; some hormones stay in blood
This part of the endocrine system releases hormones directly into the blood of ECF
endocrine glands
The endocrine glands for an organ system without what
physical links; hormone connection
What are the three steps in hormone travel
release
in the blood
reaching the target
The specificity of target cells is due to what
receptors on the target cells
This is any organ or tissue that secretes something; ducts (exocrine)
gland
Most hormones are made of this structure
peptides
True or False
Only very small peptides are hormones
False; thy can vary in size, from small to very larg
These are sugar residues attached to backbone, helping to protect the hormone from degradation, and to enhance specificity
glycosylations
Some peptide hormones function as neurotransmitters, what is the main difference between them
where it is released; the blood or a synapse
This is the first thing synthesized in peptide hormone synthesis it comes off of ribosomes
preprohormone
contains lots of aa’s and gets folded
This step in peptide hormone synthesis is to the RER, then off to golgi, then to secretary vesicles
prohormone
Cleavage of he pro-part (aa’s) of a pro-hormone, leads to this, that is stored in vesicles
hormones
What two things are released from the vesicles
pro fragments and hormones
the pro-hormone is cleaved to the pro fragments and hormone in the secretory vesicles
What three things are important in the packaging and storing of peptide hormones
allows a cell to store until its needed
helps regulate cell itself
prevents degradation
What are some of the glandular source of lipid hormones (steroids)
gonads
outer adrenal cortex
placenta
some brain cells
All steroids are derived from what by a series of enzymatic reactions
cholesterol
Some cholesterol needed for the membrane is produced via which method
de novo synthesis
Most cholesterol is derived from what
low density lipoproteins; LDL is up-taken by a cell via LDL receptor to an endosome where it is broken down to a cholesterol ester
This type of cell stores cholesterol esters; looks like an adipocyte
steridogenic cells
These determines which stereoid is produced
enzymes
Steroid hormone synthesis is typical stimulated by what
peptide hormones from other glands
This frees cholesterol from stores
cholesterol esterases; PKA phosphorylates cholesterol esterases to free cholesterol
This protein facilitates intracellular transport of cholesterol (to mitochondria)
steroid acute regulatory protein (StAR)
Steroids are not stored why?
they are lipid soluble; they will diffuse out of the membrane to intracellular fluid
What three things regulate steroids
enzymes
regulate peptide hormone stimulating steroidogenesis
increases cell division of steroid producing cells
Most steroid biosynthesis enzymatic reactions are what
uni-directional
What are the five different molecules along the steroid biosynthesis pathway
cholesterol –> progestagens –> corticosteroids or androgens –> estrogens
Amine hormones are all derived from which amino acid
tyrosine
What are the two hormones that are synthesized in the thyroid
thriiodothyronine (T3)
thyroxine (T4)
Thyroid hormones are steroid-like with respect to what two things
solubility and receptors
Catecholamines are synthesized in which two areas
adrenal gland
hypothalamus
What are three examples of catecholamines
norepinephrine
epinephrine
dopamine
catecholamines are common what
neurotransmitters
Catecholamines are similar to what in respect to solubility and receptors
peptide-like
What is the 4t class of hormones
eicosanoids
Lipids are derived from what
arachindonic acid
Most hormones are secreted in which way
in short burst; timing based on upstream signals
Secretion of GH and cortisol is what type of pattern
circadian
GH secretion high when sleeping and cortisol is high during the day
What are the three factors that hormone secretion may be controlled by
plasma concentration of a nutrient
neuronal control
hormone control
This type of hormone dissolves in the blood
hydrophilic hormones
This type of protein requires a carrier protein
lipophilic hormones
The use of these will affect hormone availability
carriers; only free hormones can react, therefore it must be released by the carrier protein
Metabolism and excretion of hormones does what to the signal
inactivates it
Which two organs are important in the metabolism and excretion of hormones
liver and kidney
True or False
Some hormone degradation occurs in the blood
True
These hormones and water soluble and can be activated by proteolytic degradation
catecholmines and peptides
These hormones are protected via attachment of carrier proteins from degradation
steroids
Circulating concentrations are a function of what
synthesis va removal or clearance
Receptors for hydrophilic hormones are where
on the cell surface or in plasma membrane
Receptor activation triggers what
a signal transduction pathway; activates the 2nd messenger system
This response involves ions; opening the ion channels in plasma membrane or cell itself; rapid response
ionotropic responses
This response is more delayed and involves metabolism within the cell; transport around the cell via secretory vesicles
metabotropic responses
A response involving ions and phosphorylation is what type of response
rapid response
A response involving the alteration of protein translation/transcription mechanism is what type of response
delayed response
Receptors for lipophilic hormones are located where
intracellular and/or nuclear
These two things form a DNA-binding protein that regulates transcription
receptor + ligand
Where is the location of the hypothalamus and pituitary gland
hypothalamus is on the floor of the diencephalon
pituitary gland lies just below the hypothalamus in the sella turcica
What are the three components of the pituitary gland
anterior = adenohypophysis
posterior = neurohypophysis
infundibulum connecting the two structures
This part of the pituitary gland is derived from oral ectoderm; not neural
anteriorhypophysis
This part of the pituitary gland is from the neural area; hypothalamus
neurohypophysis; posterior
The hormones are synthesized where
in the neuronal cell bodies in the supraoptic and paraventicular nuclei
hormones are released in response to what
an action potential; axon terminals are in the posterior pituitary; the hormones are released into capillaries of the systemic circulation
This hormone from the posterior pituitary has actions on the smooth muscle
oxytocin; labor
This hormone from the posterior pituitary has actions in the kidney and blood
vasopressin (ADH)
This is NOT an extension of the hypothalamus, but it is regulated by hormones secreted by hypothalamic neurons
adenohypophysis
This secretes hypophysiotropic (or releasing) hormones; stimulates ant. pituitary
hypothalamic neurons
Axon terminals lie where
in the median eminence
Hypothalamic hormones are transported in the in the blood within what
the portal vessels to the anterior pituitary
This is composed of 5 different cell types that produce 6 primary hormones in response to different hypophysiotropic hormones
anterior pituitary
Hypophysiotropic or releasing hormones are typically named for what
the pituitary hormones they regulate; both stimulatory and inhibitory
Hypophysiotropic hormones all do what
regulate the release of hormones from the anterior pituitary
What are 6 of the 8 hormones the anterior pituitary secretes
FSH LH GH thyrotropin prolactin ACTH
This is a precursor polypeptide synthesized in corticotrophs
pro-opiomenalocortin (POMC)
POMC is cleaved to yield multiple peptides with varied actions and target tissues like what
ACTH
ɣ-MSH (melanocyte)
β-LPH (lipotropic)
True or False
hypophysiotropic hormones are often found elsewhere in the nervous system
True
True or False
Hypophysiotropic hormones are all peptides
False; they are not all peptides
The hypo-thalmo-pituitary portion of the endocrine stem is often referred to as what
neuroendocrine system
The hypothalamus + pituitary + target = what
an axis
The complexicity of the neuroendocrine system provides what two thins
multiple control sites, and permits and amplification of the initial signal
The release of the hypophysiotropic horses is controlled by what
neural signals; both stimulatory and inhibitory inputs
involving specific neural pathways
Release of hypophysiotropic hormones is also controlled by feedback mechanisms like what
loop feedbacks
This system is self-regulation by product/hormone of the ultimate target tissue
long-loop negative feedback
This system occurs when the hormone from the 2nd gland in the axis affects the action of the 1st land
short-loop negative feedback
Feedback mechanisms return hormone concentrations to what
normal; i.e maintain homeostasis
