Endocrine physiology and Anterior Pituitary Flashcards
what major processes are under control of hormones
reproduction
growth and development
maintenance of homeostasis
regulation of metabolism
hormones make it to pretty much every cell in the body, why are only specific ones activated by specific hormones
because those specific cells have receptors specific to certain hormones. those are called TARGET CELLS
what do hormones actually do to target cells
they increase or decrease the rate of synthesis of enzymes or structural proteins, and/or they turn enzyme or membrane channels on or off.
What are the three classes of hormones
amino acid derivatives
peptide hormones
lipid derivatives
how do hormones travel in the blood
some freely, some bound to special carrier proteins
thyroid hormones and catecholectamines are derivatives of what
the amino acid tyrosine
Melatonin and seratonin are derivatives of what
the amino acid tryptophan
What are the two types of peptide hormones
glycoproteins and short polypeptides and small proteins
What is unique about the synthesis of peptide hormones
they are synthesized and pro-hormones. meaning they have no function or role until they are converted into active forms of the peptide hormone
what is the structure of glycoproteins
proteins of 200 or more amino acids that have a carb side chain
which hormones are the three glycoproteins
TSH
FSH
LH
which hormones are short chain peptides
ADH
OXT
which hormones are small proteins
GH
PRL
what type of hormones are all of the hormones secreted by the hypothalamus, heart, thymus, digestive tract, pancreas, and posterior lobe of the pituitary gland
peptide hormones (small proteins/short polypeptides)
What are the two types of lipid derived hormones
eiconasoids and steroid hormones
what is the molecule from which eiconasoids are derived,
they are derived from arachadonic acid
what are the main eiconasoids
leukotrienes
prostaglandins
thromboxanes
prostacyclins
What are steroid hormones derived from
cholesterol
which steroid hormones are secreted from where
androgens/estrogens/progestins are secreted by the gonads
corticosteroids are secreted by the adrenal cortex
calcitrol is secreted by the kidney
why do steroid hormones and thyroid hormones remain in circulation longer than other hormones
because they are bound to specific transport proteins
how long do free hormones remain in circulation, and why
less than an hour. because they are either used up, or broken down by the liver, and kidneys, or enzymes in the plasma and interstitial fluids
which types of proteins aren’t lipid soluble, and why does that matter
catecholamines and peptide hormones, it matters because they can’t cross plasma membranes of cells meaning they bind extracellular receptors
which type of receptor do lipid soluble hormones bind
intracellular proteins (because they can cross the plasma membrane)
What are first messengers, and what do they do
they are often hormones, and they lead to second messengers
what are important second messengers
cAMP
cGMP
Calcium ions
what is amplification (hormones)
the binding of a small number of hormones to membrane receptors leading to thousands of secondary messengers and magnification of the hormones effect on the target cell
What is down regulation with hormones
an increase in concentration of hormones leads to a decrease in number of hormone receptors (cells are less sensitive when hormones are high)
what is up regulation with hormones
the lower the concentration of hormones the higher the number of receptors. (cells are more sensitive when hormones are low)
what is the importance of G-proteins in the endocrine system
they are the link between first messengers (hormones) and second messengers
what is the enzyme that is activated when a hormone binds its receptor and then increases cAMP in the cell
adenylate cyclase
what does increased cAMP do in the cells
increase the metabolic activity (activates enzymes and opens channels)
what does an activated G protein cause
- opening of calcium ion channels in the membrane
- release of calcium from intracellular stores
- activate phospholipase C (PLC)
- triggers receptor cascade
what is the receptor cascade triggered by an activated G protein
- DAG (diacylglycerol) and IP3 (inositol triphosphate) are produced
- DAG and IP3 activate calcium ion channels through protein kinase C (PKC)
- activation of calmodulin by calcium ions
how do steroid and thyroid hormones affect cells
they alter the rate of DNA transcription in the nucleus
what are the functional counterparts of neural reflexes
endocrine reflexes
what are most endocrine reflexes controlled by
negative feedback
what are the three ways that endocrine reflexes can be triggered
- humoral stimuli (changes in composition of the extracellular fluid)
- harmonial stimuli (arrival or removal of specific hormone)
- neural stimuli (arrival of neurotransmitters at neuroglandular junctions)
what are the four types of hormone interactions
antagonistic (work against each other)
synergistic (enhance each others effects)
permissive (one hormone is required for the other to work)
integrative (hormone action differs with differing target tissues)
how are hormone levels in the blood usually maintained
negative feedback (when hormone levels are low, it causes more to be secreted, when there is enough, the hormone stops being secreted)
what is the hypophysis
the pituitary gland
where is the pituitary gland found
in the sella turcica
what holds the pituitary gland in the sella turcica
the sellar diaphragm
what connects the pituitary gland to the hypothalamus
the infundibulum
how do the pituitary hormones act on target cells
via membrane receptors and cAMP as secondary messengers
what is the adenophysis
the anterior pituitary
what are the three regions of the anterior pituitary
pars distalis (main body) pars tuberalis (top part) Pars intermedia (part between ant. and post. pit)
What are the anterior pituitary hormones
GH TSH ACTH PRL LH FSH
what are the posterior pituitary hormones
ADH
Oxytocin
what is the hypophyseal portal system
the fenestrated capillary system that allows hypothalamic hormones to reach the anterior pituitary gland, and which gets hormones from the posterior pituitary gland
what is the median eminence
the swelling near the infundibulum where the hypothalamus releases its hormones into the interstitial fluids
what are portal systems
blook vessels that link two capillary networks
what are the two types of hormones released by the hypothalamus to the hypophyseal portal system
releasing hormones and inhibiting hormones
what is the function of FSH, what are problems with incorrect FSH levels
regulation of maturation of follicular cells, and production of estrogen in women.
regulation of maturation of spermatocytes in men
problems with FSH levels can lead to irregular menstrual cycles, infertility and impotence
what is the function of LH, and what are the problems with incorrect LH levels
regulation of ovulation and production of progesterone in women
regulation of production of testosterone
problems with LH levels can cause irregular menstrual cycles, amenorrhea, and impotence
What is the function of ACTH, and what are the problems with low ACTH levels
stimulation of the adrenal cortex to produce and secrete corticosteroids. when we don’t have ACTH we become stressed out
what is cushing’s syndrome
when the body is exposed to cortisol for long periods of time. leads to fat gain, muscle loss, anxiety
What is the function of TSH, and what are problems associated with incorrect TSH levels
it regulates the release of thyroid hormones from the thyroid. it can cause loss of the optic nerve
What is the function of PRL, and what are the problems associated with incorrect PRL levels
it females it regulates mammary gland growth, and breast milk production.
in males it influences interstitial cell’s sensitivity
wrong levels can lead to too low or too high breastmilk production, and can lead to fertility problems
What is the function of GH (somatotropin)
it stimulates growth and cell division, and stimulates the liver to secrete somatomedin
What affects GH levels
stress, sleep, exercise, blood glucose levels
what are the problems associated with GH levels
deficiency = dwarfism
too much whole life = gigantism
to much later in life = acromegaly
What usually causes acromegaly
tumor of the pituitary gland or tumor of the pancreas, lung, or adrenal gland
what causes gigantism
tumor in somatotropes in young kids or teenagers
