Endocrinology I Flashcards
define neurohormones
released from neuroendocrine cells, diffuse into the blood
e.g. in hypothalamus and adrenal medulla
define paracrine action
receiving receptors are located on neigboring cells
define autocrine action
the receiving receptors are located on the endocrine cell itself
Common to the digestive system
define „tropic“ hormones
tropic meaning ‘stimulating’
hormones that regulate secretion of another
hormone
Don ́t confuse with „trophic“ - nourishing
name 3 hormone mechanisms of action
alter permeability of cell membranes
activate or inhibit intracellular enzymes
regulate protein synthesis
Name 4 classes of hormones based on chemical structure
Amino acid derivatives
Fatty acid derivatives
Peptide and protein hormones
Steroid hormones
Amino acid derivatives are mainly synthesized from?
amino acid thyrosine
give 3 examples of amino acid derivative hormones
Thyroid hormones
Catecholamines
Dopamine
fatty acid derivative hormone precursor is?
arachidonic acid
Name what class of compound free arachidone acid is converted into
eicosanoids
name 3 types of eicosanoids
prostaglandins,
thromboxans,
leukotrienes
define prohormones
inactive peptide hormones
Most peptide and protein hormones signal via what type of receptors?
G-protein coupled receptors
name 3 sources for steroid hormones
gonads
adrenal cortex
placenta
name a ‘steroid-like’ hormone
d-vitamin hormone/calcitriol in kidneys
how do steroid hormones travel?
bound to plasma proteins such as specific globulins or non-specific albumin
how are hormones metabolized?
enzymatic dergadation
name 3 types of hormone interaction
permissiveness
synergism
antagonism
define permissiveness
first hormone enhances a target cell
responsiveness to another hormone
e.g. thyroxine increases the number of receptors for epinephrine
define hormone synergism
combined effect of two or several hormones is greater than the sum of their separate effects
e.g. FSH and testosterone in spermatogenesis
define hormone antagonism
one hormone causes the loss of another hormones’ receptors / one trumps the other
e.g. progesterone and estrogen,
progesterone keeps uterine smooth muscles inactive during the pregnancy
describe Primary hyposecretion
abnormality within a gland
describe Secondary hyposecretion
gland is normal but its tropic hormone is deficient
explain how an auto-immune disorder could be hypersecretion
irregular antibodys mimic tropic hormone
Corticotropin-releasing hormone (CRH) function
Stimulates release of Adrenocorticotropic hormone - ACTH
Gonadotropin releasing hormone (GnRH) function
Stimulates release of FSH & LH
Thyrotropin releasing hormone (TRH)
Stimulates release of thyrotropin (TSH) and prolactin
name 4 Hypothalamic hormones –hypophysiotropic hormones
CRH
GHRH
GnRH
TRH
name 3 Hypothalamic hormones
PRL-LH
PIH
dopamine
GHIH
another name for somatostatin
growth hormone inhibiting hormone (GHIH)
Somatostatin functions
Inhibits release of GH TSH insulin glycagon
hormones of anterior pituitary
ACTH GH FSH LH prolactin TSH
hormones of posterior pituitary
ADH, oxytocin
3 Corticosteroid types
mineralocorticoids
glycocorticoids
androgens
Adrenal medulla hormones
catecholamines:
epinephrine, norepinephrine
Thyroid gland hormones
T4, T3 and calcitonin
parathyroid hormone function
Release of calcium by bones into the bloodstream. Absorption of calcium from food by the intestines. Conservation of calcium by the kidneys.
Hormones of pancreas
insulin, glucagon
2 Male sex hormones
testosterone
dihydrotestosterone
3 Female sex hormones
estrogens,
progesterone,
prostaglandin F2α
three major naturally occurring estrogens
estrone (E1)
estradiol (E2)
estriol (E3)
Pineal gland produces
melatonin
Kidneys produce what hormones
erythropoietin
renin-angiotensin
vitamiin-D3-hormone/calcitriol
Adipose tissue hormones
leptin
adiponectin
Digestive tract
cholecystokinin (CCK) gastric inhibitory polypeptide (GIP) gastrin secretin Somatostatin vasoactive intestinal peptide (VIP)
adiponectin function
helps with insulin sensitivity and inflammation
regulates lipid metabolism, and insulin sensitivity and is anti-inflammatory
gastrin function
secretion of hydrochloric acid (HCl) into the stomach
enhances gastric mucosal growth
gastric motility
Cholecystokinin (CCK) function
stimulates the release of bile
also stimulates the secretion of pancreatic juice
secretin function
stimulates the secretion of a bicarbonate-rich pancreatic fluid
secretin function
stimulates the secretion of a bicarbonate-rich pancreatic fluid
Vasoactive intestinal peptide (VIP) function
stimulate secretion of water and electrolytes
relaxation of enteric smooth muscle
etc.
Gastric inhibitory polypeptide (GIP) function
inhibitor of gastric acid secretion,
stimulates insulin secretion.
Posterior pituitary consists of
nerve fibers, glia cells and blood vessels
the neuronal bodies are actually in the hypothalamus
Anterior pituitary contains
endocrine cells, blood vessels,
few nerve fibers
Antidiuretic hormone (ADH), vasopressin main function
increases water reabsorption in distal tubules and the collecting ducts by regulating the density of aquaporins
ADH secretion is controlled via?
regulated by osmolarity-sensitive cells in the hypothalamus, and pressure sensitive cells in
the circulatory system (sense volume of fluids)
A reduction in blood volume and blood pressure of 5-10% or more induces secretion of ADH.
GH growth-stimulating effects are mediated by
insulin-like growth factor 1, IGF-1
is synthesized in many tissues, particularly in
the liver.
another name for growth hormone
Somatotropin
a disorder that occurs when your body makes too much growth hormone
Acromegaly
define gonadotropins
any of a group of hormones secreted by the pituitary which stimulate the activity of the gonads.
3 examples of gonadotropins that affect females
Human and equine chorionic gonadotropin hCG/eCG
FSH
LH
Follicle stimulating hormone, FSH - stimulates
growth of ovarian follicles in females and spermatogenesis in males
Luteinizing hormone, LH - stimulates
ovulation and corpus luteum development in females
synthesis of androgens in males
PRL effects In birds
contributes to the onset of brooding and changes of metabolism during brooding.
PRL regulated by?
hypothalamic hormones PRL-RH and PRL-IH (dopamine)
Adrenocorticotropic hormone function
stimulates production of steroid hormones in the
adrenal cortex
thyrotropin function
stimulates production of thyroid hormones in thyroid gland
Regulation of ACTH and TSH?
via hypothalamic ACTH-releasing
hormone (secretion is stimulated in stress situation) and
via TSH-releasing hormone (low body temperature
stimulates, high thyroid hormone concentration inhibits)
Intermediate lobe of pituitary produces?
melanocyte stimulating hormone (MSH)
most important glucocorticoids are
cortisol and corticosterone
Mineralocorticoid function
regulate water, Na, K and Cl balance and blood pressure
primary mineralocorticoid is
aldosterone
aldosterone function
supports active reabsorption of sodium with associated passive reabsorption of water and active secretion of potassium.
the effect of Catecholamines depends on
type of receptors, α and β-receptors
where is calcitonin produced
by C-cells located in the connective tissue between thyroid follicles
main 3 endocrine cell types of pancreas
alfa-, beta- and delta- cells
alfa-cell function
produce glucagon
beta- cell function
produce insulin
delta- cell function
produce somatostatin, inhibitor hormone (paracrine action).
the most important estrogen in the body
17-beta-estradiol
calcitriol stimulates
reabsorption of calcium in the intestines etc
increases blood calcium levels
Renin function
induces cascade of changes resulting in
the secretion of aldosterone in adrenal cortex
