Endocrine system overview Flashcards
what is an hormone?
regulatory chemical secreted into blood by ductless endocrine glands ( DUCTLESS = GLAND DIRECTLY SECRETES INTO THE BLOOD )
Produce effect in the target organs having ( HORMONES ARE HIGHY SPECIFIC THEY ONLY WORK ON SPECIFIC TISSUE WITH THE RECEPTOR FOR IT ) so it doesnt js run around in the blood affecting everything
what are the essential needs for hormones ?
Hormones are maintaining homeostasis :
1- metabolism ( thyroid + corticosteroid )
2- Growth and development ( Growth hormone )
3- Water and electrolyte balance ( ADH and aldosterone )
4- Reproduction and behaviour ( gonads horomones )
describe the hormone - receptor interaction?
hormones produced in the endocrine gland Is gonna get released directly into the blood
2- The hormones binds to a specific receptor on a target cell –> producing an effect
3- Receptor could be inside the cell in the cytoplasm and nucleus OR on the cell membrane
what is endocrine communication?
hormone gland cell will release the hormone ——> and then it will travel in the blood — > Hormone will bind to the receptor on target cell
THE HORMONE WILL AFFECT ANOTHER Organ not the same organ
example : growth hormone, thyroid hormone, etcs
what is an neuroendocrine communication?
neuros will release the hormone —> IT WILL GET RELEASED IN THE BLOOD —> travel to the target tissue and bind to the receptor –> effect
IT will travel to different organ, BUT IT IS RELEASED FROM NEURONS
example : epinephrine, norephrine , ADH ( vassopressin ) , Oxytoxin
describe paracrine communication?
Hormone gland cell will release hormone –> IT WILL TRAVEL VIA INTERSTITIAL FLUID –> reach target cell –> Effect
HERE THE EFFECT IS GONNA BE IN THE SAME ORGAN BECAUSE IT IS NOT RELEASED IN THE BLOOD
for example : estrogen , serotonin
describe autocrine communication
hormone gland cell will release hormone —> IN INTERSITTIAL FLUID -> IT WILL WORK ON THE CELL THAT RELEASED IT
the same cell will have receptors for the hormone it releases
what are major endocrine glands in the body?
Hypothalamus
pituitary gland ——-> master gland
pineal gland
thyroid gland
parathyroid gland
adrenal gland
GI tract
Gonads
what hormones are secreted by the hypothalamus?
Thyroptin releasing hormone
Corticotropin releasing hormone
Gonadotropin releasing hormone
Growth hormone releasing hormone
Growth hormone inhibiting hormone ( SOMATOSTATIN )
prolactin releasing hormone
Prolactin inhibiting hormone -> dopamine
Oxytocin
adh ( vasopressin )
what is the function hypothalamus gland?
control and release of anterior pituitary hormones
what hormones are released by post - pituitary gland?
it doesnt synthesize hormones they are js stored in it
Oxytocin
ADH
what is the function of post - pituitary ?
ADH/Vasopressin : increases water and sodium reabsorption / VASOCONSTRICTION
Oxytocin : Increase contractility during labor , Causes milk ejection
what are the hormones released by anterior - pituitary?
Thyroid releasing hormones
Adrenocorticotropic hormone
Growth hormone
Follicle stimulating hormone
Luteinizing Hormone
Prolactin
what is the function of anterior pituitary glands ?
TSH : Stimulates T3 and T4 secretion
ACTH : Stimulates cortisol secretion
GH : body growth
FSH : follicular growth and sperm production
LH : Ovulation and testesterone secretion
Prolactin : Breast development and milk production
what hormones does pineal gland release?
Melatonin
what is the function of melatonin?
Body biological rhythm
reduction of melatonin leads to puberty initiation
what hormones are released by thyroid gland?
T3-T4
calcitonin
what is the function of thyroid gland?
T3-T4 : increase metabolic rate , normal growth and nerve development
Calcitonin : Decrease Calcium level in blood
what are the hormones released by adrenal cortex?
aldosterone
cortisol
androgens
what is the function of adrenal cortex?
aldosterone : Increases water and sodium retention and potassium secretion
Cortisol : increases blood glucose
Androgens : axillary and pubic hair growth
what are the hormones released by pancreas?
insulin
glucagon
somatostatin
what is the function of pancreas?
insulin : promotes cellular uptake , use , storage of absorbed nutrients
Glucagon : maintain nutrients level
somatostatin : inhibit digestion and absorption of nutrients
what is the hormone released by parathyroid gland?
parathyroid gland
what is the function of Para thyroid gland?
paratyhroid hormone : Increase blood level of calcium
what are the hormones released by ovaries?
estrogen
progesterone
what is the function of ovaries?
Estrogen : follicular development , secondary sex characters , uterine and breast growth, closure of epiphyseal plate
progesterone : prepare for pregnancy
what is the hormone released by testes?
testosterone
what is the function testes?
testosterone : Sperm production, male sex organs , closure of epiphyseal plate
what are the hormones released by the placenta?
Estrogen
progesterone
human chorionic gonadotropin
what is the function of placenta?
estrogen and progesterone : pregnancy , preparation of breasts
hCG : maintain corpus luteum of pregnancy
what are the hormones released by kidney?
renin
erythropoietin
what is the function of kidney hormones?
Renin : stimulate aldosterone , ang 2 , potent stimulant of thirst
Erythropoietin : RBC production
what are the hormones released by the stomach?
Ghrelin
Gastrin
whats the function of stomach hormones?
Ghrelin : stimulate appetite
gastrin : control mobility and secretion
what are the hormones released by small intestines?
Cholecystokinin
Gastric inhibitory polypeptide
Peptide YY3-36
what is the function of small intestine hormones?
CCK : Control mobility and secretions ( like gastrin )
GIP : Stimulates insulin
Peptide yy3-36 : Suppresses appetite ( opposite to ghrelin )
what are the hormones released by liver?
IGF-1
HEPCIDIN
Thrombopoietin
what is the function of liver hormones?
IGF-1 : Promotes growth
Hepcidin : inhibit iron absorption into blood
thrombopoietin : increases platelet production
what is the hormone released by skin?
vitamind D
what is the function of skin?
vitamin D: increases absorption of ingested calcium and PO4
what hormone released by thymus?
thymosin
what is the function of thymosin?
enhances of T lymphocyte proliferation and function
what is the hormone released by heart?
ANP
what is the function of ANP?
inhibit NA reabsorption –> water and sodium are excreted
what hormone is released by adipose tissue?
leptin
what is the function leptin?
suppresses appetite –> like peptide yy3-36
what is the difference between peptides and proteins ?
peptides : less than 100 peptides –> TRH
Protein : more than 100 peptides —> Growth hormone
what are examples of peptidal/ protein hormones?
TRH, Gnrh, CRH , GHRH, Somatostatin ( GHIH )
ACTH, TSH, FSH, LH , Prolactin , Growth hormone
Oxytocin, ADH
Calcitonin
Insulin, glucagon, somatostatin
somatomedin C ( IGF-1 )
pth
hcg, HCS, hpl
Renin
Anp
Gastrin, CCK, Secretin, GIP , somatostatin
Leptin
how are the peptide / protein hormones synthesized?
they are synthesized as prohormones or prehormones –> INACTIVE and require activation
ACTIVATED by cleavage steps
produced in rough ER
modified and stored in golgi apparatus
where are they stored and how are they are released?
they are water SOLUBLES so they can be stored and they are stored in the membrane bound to granules and released by EXOCYTOSIS
how do they circulate in the blood?
Since they are water soluble AND POLAR–> CAN TRAVEL UNBOUND IN THE BLOOD
how are they administered in case of diseases?
INJECTION ONLY because IF GIVEN ORALLY THEY WILL BE DIGESTED BY GI
our body can easily digest proteins and peptides
Also since they are in blood alone EASILLY DISSOLVED AND BROKEN DOWN
where are their receptors found?
they cant pass the membrane because water soluble –> the receptor is on the cell membrane
what are steroid hormones?
cortisol
aldosterone
androgens
Testosterone
estrogen
progesterone
VITAMIN D
how are steroid hormones produced ?
from cholesterol
either from blood
from cholesterol stored in the cell
cell synthesize cholesterol
how is it stored?
steroids hormones are FAT SOLUBLE –> cannot be stored it is synthesized and secreted imme EXCEPT THYROID HORMONE IS STORED
how do they travel from tissue to to tissue?
THEY ARE fat soluble cannot travel alone in blood, HAS TO BE BOUND TO A PROTEIN
When theres low level of the hormone it gets unbound from the protein to increase the level
where are their receptors found ?
since they are lipid soluble they can cross the membrane –> THE RECEPTOR IS INSIDE the cell
how do we administer steroid hormones?
they can be given orally
or IV
cannot be destroyed by GIT because they are cholesterol –> easily aborbed
describe the half life of steroid hormones?
they have long half life because they are bound to proteins so they are not degraded easily
also they cannot produce effect unless released from the carrier
what are the amine hormones? why are they are called amine hormones?
T3 , T4
catecholamines ( NE, EPI)
they are both derived from tyrosine but have different properties
which one of the amine hormones is lipid soluble and which is water soluble?
T3, T4 —> lipid soluble -> has lipid soluble properties
Catecholamines –> Water soluble –> has water soluble properties
how are the thyroid hormones stored? and transported?
stored as Thyroglobulin
transported via thyroxine binding globulin ( NEEDTO BE BOUND BECAUSE LIPID SOLUBLE )
how are catechoalimes stored and transported?
stored in vesicles and excreted in exocytosis
Transport free in blood because water soluble
how do steroids and thyroid hormone circulate in the blood?
since they are fat soluble they cant transport free must be bound to protein
less than 10% exist free - cannot easily diffuse out of capillaries –> IN ACTIVE UNLESS DISSOCIATE FROM PLASMA PROTEINS
what is the function of bound hormones?
1- Serve as reservoirs –> WHEN LEVEL DROP THESE GET UNBOUND TO INCREASE THE LVL BACK UP
2- slow clearance –> stay for longer half life because it wont be dissolved unless its unbound
how is metabolic clearance rate determined ?
2 factors increase or decrease the concentration of hormone in the blood
1- Rate of hormone SECRETION into blood
2- rate of REMOVAL of hormone from blood
what is the equation of metabolic clearance rate?
Rate of disapperance of hormone from the plasma / concentration of hormone
usually expressed in terms of the number of mililiters of plasma cleared of the hormone per minute
what are the ways of clearing hormoneS?
metabolic destruction by tissue
binding with tissues
excreted by liver in bile
excreted by kidneys in urine
what is infundibulum?
hypothalamus is connected to the pituitry gland via infundibulum
infundibulum = infundibulum stem ( nervous tissue ) covered by glandular tissue ( pars tuberalis)
which pituitary gland is continuation of hypothalamus ?
posterior pituitary
it is neurohypophysis –> DIFFERENT EMBRYOLOGICAL ORIGIN : neural tissue –> Extension of hypothalamus
describe anterior pituitary ?
adenohypophysis ( glandular )
originate from pharyngeal epithelium —> Rathkes pouch
describe the neurohypophysis ? ( posterior pituitary )
doesnt synthesize hromones
Stores 2 hormones which are produced in hypothalamus
which nucleus in the hypothalamus produce Oxytocin ?
paraventricular nucleus
which nucleus in the hypothalamus produces ADH?
supraoptic nuclei
how does the anterior pituitary communicates with the hypothalamus?
through blood system –> hypothalamic hypophyseal portal system
the hypothalamus will produce the hormones which will reach the connection and then from there it will be released in the blood
what is median eminence?
connection between the base of hypothalamus and anterior pituitary
under normal condition the how will the hypothalamus inhibitory and releasing hormones control the level of anterior pit hormones?
the hypothalamus will stimulate all of the hormones will be RELEASED
EXCEPT prolactin which has stronger INHIBITORY SIGNAL compared to the others
what is the other name of Prolactin inhibitory hormone?
Dopamine
thyroid hormone also stimulates the prolactin release with PRH
which cells produce testesterone
leydig cells under the effect of FSH ( LH = secretion )
FSH - production ( follicular growth and sperm production )
LH ( secretion : ovulation , teste secretion )
what is the other name of growth hormone?
somatotropin
which cells of the anterior pit , release TSH?
Thyrotropes
which cells from the anterior pit releases ACTH?
Corticotropes
which cells from the anterior pit releases Growth hormones?
Somatotropes
which cells of anterior pit releases FSH and LH ?
Gonadotropes
which cells of anterior pit releases prolactin?
lactotropes
what are the 2 regulations methods of hormones?
1- neural mechanism –> neural signals ( Stress for example ) —->catacheloamines , cortisol
2- feedback ( negative / positive ) –> most common
3- humoral –> via blood
describe negative feed back?
the action of the hormone of the result/effect of it will inhibit the release of the hormone : SELF LIMITED
long loop feedback -> example : Hormones from adrenal cortex will go all the way back to inhibit the pituitary or hypothalamus
short loop feedback :- example : pituitary will inhbit the hypothalamus
ultrashort loop feedback :- Hypothalamus inhibit itself
describe positive feedback?
the action or the results/effect of the hormone will result in the hormone secretion MORE
self augmenting effect –> not very common
Oxytocin is an example in labor –> the contractions will cause more oxytocin release
what are the 2 types of pattern of secreiton?
Continuous
Example : T3, T4 –> levels in the blood show little variation
Intermittent secretion : level different according to the time of measurement
Example :
GLUCOCORTICOID
GONADOTROPHIN
LH, FSH
GNRH is pulsatile release –> lh and fsh is also pulsatile –> continuous administration of GNRH doesnt increase production of FSH AND LH because pulsatile
