ENDO 1- General endocrinology Flashcards
what does the endocrine system do
provides broadcast regulation of many tissues
what is the specificity of the endocrine system due to
receptors
what are the 3 things hormones regulate
-maintenance of homeostasis
-growth and differentiation
-reproduction
what hormones maintain homeostasis
thyroid hormone, insulin, PTH, vasopressin, aldosterone
what hormones participate in growth and differentation
growth hormone, thyroid hormone
what hormones participate in reproduction
-LH
-FSH
-Estrogen
- progesterone
-testosterone
what are the specialized endocrine glands
-pituitary gland
-thyroid gland
- parathyroid gland
- adrenal gland
- pineal gland
what endocrine cells are in the hypothalamus
TRH,CRH
what endocrine cells are in the skin
vitamin D
what endocrine cells are in the liver
iGF-1
what endocrine cells are in the pancreas
insulin and glucagon
what endocrine cells are in the kidney
renin, epo, and vitamin D
what are the classes of hormones
-proteins and polypeptides
-steroids
- derivatives of tyrosine
where are protein and polypeptide hormones found
hypothalamus
-anterior pituitary
-posterior pituitary
-pancreas
what is the process of synthesis in protein and polypeptide hormones
synthesized first as a preprohormone
-converted to prohormone
-prohormone is cleaved into the active hormone and inactive fragments
are protein and polypeptide hormones made on demand
no they are made early then stored
what steroid hormones are synthesized from cholesterol
-cholesterol
- DHEA
-androstenedione
-aldosterone
-cortisol
- testoterone
-estradiol
where are steroid hormones from
adrenal cortex, ovaries and testes
what type of steroid hormone is cortisol
glucocorticoid
what type of steroid hormone is aldosterone
mineralocorticoid
are steroid hormones made on demand
yes
what are amine hormones derived from
amino acid tyrosine
what are examples of amine hormones
thyroid hormone and adrenal medullary neurohormones such as epinephrine and norepinephrine
are amine hormones produced on demand
no they are made early
how are amine hormones stored
thyroid hormones bind to the protein thyroglobulin
-epinephrine and norepinephrine are stored in vesicles and released by exocytosis
what makes thyroid hormones an exception to transport across a membrane
the carbon rings make it slightly hydrophobic which allows it to diffuse across the membrane freely and bind to intracellular receptors
what do binding proteins do
serve as a reservoir for the hormone and prolong the hormone’s half life
what type of the hormone is the active form of the hormone
the free or unbound hormone
how do the majority of amines peptides, and protein hormones circulate
in their free form
how do steroid and thyroid hormones circulate
bound to specific transport proteins
what do globulin and albumin bind to
hormones
what does thyroid hormone travel in plasma bound to
thyroxine binding globulin (TBG) and transthyretin (TTR) and albumin
where are most binding proteins synthesized
in the liver
what could changes in liver function do to binding protein levels
could alter them and indirectly affect plasma hormone levels
do binding proteins cross the membrane and enter the target cell
no they stay in the blood vessel and it unbinds the hormone which crosses the membrane alone
what is the fluctuation in plasma hormone levels due to
hormonal, neural, nutritional and environmental factors
what type of hormone is cortisol
tonic
when is cortisol the highest
in the early morning
what is pulsatile secretion
secreted in pulses
what is an example of a hormone that has pulsatile secretion
growth hormone
the location of the hormone receptor depends on ___
the chemical properties of the hormone (lipophilic/lipophobic)
what does ligand/receptor binding demonstrate
specificity, affinity, and saturation
what types of hormones use plasma membrane receptors
polypeptide, protein and amine hormones
what are the peptide and protein hormones that use plasma membrane receptors
glucagon, angiotensin, GnRH, SS, GHRH, FSH,LH,TSH,ACTH
what are the amino acid hormones that use plasma membrane receptors
epi and NE
which type of hormones use nuclear receptors
thyroid and steroid hormones
what do hormones that bind to nuclear receptors cause
changes in gene expression, biological response, and protein synthesis
which type of receptors elicit a faster response
plasma membrane receptors
what are the plasma membrane hormone receptors
-GPCRs
- tyrosine kinase: insulin
-serine kinase
-cytokine: leptin
what hormones use Gs coupled receptors
beta adrenergic, calcitonin, ACTH, glucagon, TSH, vasopressin
what second messenger do plasma membrane hormone Gs coupled receptors use
cAMP
what hormones use Gq coupled receptors
alpha adrenergic, angiotensin II, TRH
what second messengers do Gq coupled receptors use
IP3, DAG and Ca2+
where are nuclear hormone receptors found
either in cytoplasm or nucleus
how do nuclear hormone receptors work (mechanism)
the hormone receptor complex binds to a hormone responsive element in the promoter region of a gene which leads to either activation or repression of transcription and forms new proteins
what are the effects of combined actions of hormones
-antagonism
-additive
-synergistic
-permissiveness
what is permissiveness
presence of one hormone required to see the max effect of another hormone
explain the 5 steps in regulation of thyroid hormone secretion
-stimulus causes the hypothalamus to secrete TRH which acts on the anterior pituitary
- thyrotropic cells in the anterior pituitary release TSH
- TSH stimulates follicular cells of the thyroid gland to release thyroid hormone
- TH stimulates target cells to increase metabolic activities resulting in an increase in basal body temperature
- increased body temperature is detected by the hypothalamus and secretion of TRH by the hypothalamus is inhibited. TH also blocks TRH receptors on the thyrotropic cells inhibiting synthesis and release of TSH. both effects indirectly dampen TH production in the thyroid
how do endocrine orders occur
when negative feedback loops dont function properly
what is a primary disorder
abnormality in the last endocrine organ secreting the hormone leading to either hypo or hyper secretion
what are the causes of primary hyposecretion
-partial destruction of the gland
- dietary deficiency
- enzyme deficiency required for hormone synthesis
what is the cause of primary hypersecretion
a tumor in the endocrine gland
what are secondary disorders caused by
an abnormality in tropic hormone leading to either hypo or hyper secretion
what causes secondary hyposecretion
a lack of sufficient tropic hormone
what causes secondary hypersecretion
a tumor either in an endocrine gland that secretes tropic hormone or in non-endocrine tissues that secretes hormones
what is another name for secondary hypersecretion
paraneoplastic endocrine syndrome
what happens with cortisol in primary hypersecretion
-the adrenal gland is abnormal and secreting excess cortisol. it acts back on the hypothalamus and anterior pituitary and results in decrease CRH from hypothalamus and decrease ACTH from the anterior pituitary
what happens with cortisol in secondary hypersecretion
the problem starts with the anterior pituitary that secretes excess ACTH resulting in excess cortisol secretion from the adrenal gland. this acts back on the hypothalamus and anterior pituitary but regulation is inadequate in anterior pituitary but decreases CRH in the hypothalamus
what are the diagnostic tests of endocrine function
-plasma hormone levels
- autoantibodies
-urine hormone or hormone metabolite levels
- stimulation tests by administrating of a tropic or stimulating hormone
- suppression tests when hyperfunction of an endocrine organ is suspected
- measurement of hormone receptor presence, number and affinity
- imaging
