what is going on its medicosis perfectionist where medicine makes perfect sense let's continue our biology playlist today we'll talk about the basics of the endocrine system what does endocrine mean well it's a gland that secretes its secretions known as hormones directly into the bloodstream such as your pituitary gland your thyroid gland your adrenal gland etc this video is in the biology playlist if you want more details check out my endocrinology playlist let's compare between nervous stimulation and hormonal stimulation nervous stimulation is fast hormone is slow it takes time nervous look at this look at a neuron boom muscle that's very fast but hormone the gland has to make the secretion and then secrete that hormone and then the hormone goes to the bloodstream and then the bloodstream will take it to the heart the heart will pump it and the upper heart will bump it all over your body oh it takes a lot of time nervous system somatic or autonomic in other words voluntary or involuntary hormonal is always involuntary the nervous system is always firing neurons are always firing but hormones are secreted only when you need them it's like netflix on demand hormones secreted when needed in very small amount they are measured in micrograms or even nanograms highly active could be steroidal fat or not fat lipid soluble water soluble and the act via secondary messenger system all right where's the primary messenger the hormone is the primary messenger the second messenger is something like the g protein if you want to know more about the g protein i have a separate video just on this topic autocrine paracrine endocrine what's the difference autocrine is a cell that secretes something to act on the same freaking cell paracrine is a cell that secretes something to act on the neighboring cell keep it in the neighborhood keep it local endocrine however is a cell that secretes its hormone into the bloodstream which will take it into distant locations not in the neighborhood no far away international exocrine glands like your salivary glands or sweat glands have a duct but endocrine glands are duct less they don't have a duct they just dump their secretions into the bloodstream big companies have a ceo and then general managers and then employees and independent contractors same thing here hypothalamus pituitary and then glands that obey the pituitary these are the employees and they include thyroid gland adrenal cortex go nuts how about those who don't care about the pituitary parathyroid adrenal medulla and pancreas let's talk about the glands that obey in order for the pituitary to talk to the thyroid gland the pituitary will secrete thyroid stimulating hormone and now you stimulate the thyroid when the pituitary wants to talk to the adrenal cortex it will secrete the adrenal adrenal cortico cortex tropic growth hormone if i want to talk to the gonads lh and fsh also known as gonadotropins ceo general manager remember you have antipituitary and posterior pituitary most of the hormones come from the anti-pituitary with two famous exceptions that come straight from the hypothalamus hypothalamus will give them the distributivity posterior pituitary will give them the blood these two are adh and oxytocin antidiuretic hormone oxytocin the blood pressure hormone the love and bonding hormone if i was distracted by crossing the street and i got hit by a car lost all kinds of blood developed hypovolemia and my blood pressure decreased adh will make sure that the blood pressure does not drop even more adh will try to raise the blood pressure that's the adh oxytocin love and bonding hormone love making hormone it also binds mommy with her baby why do these come from the pasture pituitary because they come from the hypothalamus but she pituitary does not make anything it just stores what the hypothalamus gave her so why do these have to come from the hypothalamus because the hypothalamus is part of the limbic system which is related to memory if he was distracted like this do you think you should remember this to learn from your mistakes of course i should remember this therefore hypothalamus memory but mommy should mummy remember the pain of child birth well if mommy remembered the pain of child birth so bad by the way mommy will never repeat this mommy will never get pregnant again and humanity will go extinct because for human beings just to break even and to maintain the current number of people each lady should give birth to 2.1 children so oxytocin is from the hypothalamus and it helps your brain forget the pain that's why these two come from the hypothalamus everything else and jupiter is hairy let's talk about the thyroid gland all right the thyroid gland secretes thyroid hormone t3 and t4 who's going to simulate the thyroid gland tsh from the anterior pituitary okay who's going to simulate the anterior pituitary to stimulate the thyroid hypothalamus hypothalamus will release trh which goes to the pituitary and tells the pituitary to secrete tsh tsh will go to the thyroid and tell the thyroid to secrete thyroid hormone trh stands for thyroid releasing hormone and tsa stands for thyroid stimulating hormone t3 is triodo thyronine t4s tetra iodo thyronine let's say that we have a patient and the patient is secreting less t3 and t4 than normal where's the problem well the problem could be in the thyroid we call this primary hypothyroidism or the problem could be the inability of the anterior pituitary to make tsh and we call the secondary hypothyroidism or the problem could be lack of the hypothalamus ability to secrete trh we call this tertiary hypothyroidism because of the hypothalamus doesn't make trh the antiquity will not make tsh and the thyroid will not make t3 and t4 the patient will suffer the symptoms of hypothyroidism now this is the most important slide in the entire lecture it's going to help you answer lots of questions let's go hypothalamus secretes ghrh growth hormone releasing hormone which goes to the anterior pituitary to tell her to secrete growth hormone growth hormone is also an astomatotropin growth hormone goes to the liver to secrete igf-1 what's the function of growth hormone growth it helps you build up protein bones cartilages muscles all kinds of good stuff the hypothalamus can also secrete somatostatin which inhibits everything including the growth hormone hypothalamus secretes gonadotropin releasing hormone it goes to the anterior pituitary telling her to secrete lh and fsh also known as gonadotropin gonadotropin will go to the gonads in males to tell them to secrete testosterone dihydroestosterone and inhibin in females to tell her to secrete estrogen progesterone and inhibin what's the gonad in male's testicles females ovaries hypothalamus secretes trh goes to the anterior pituitary to secrete tsh goes to the thyroid to secrete t3 and t4 hypothalamus secretes crh goes to the anterior pituitary to tell her to secrete acth which goes to the adrenal cortex not medulla cortex the cortex will secrete cortisol and androgen hypothalamus with the same trh the same one like this one yep say mtrh will secrete prolactin prolactin's pro-lactation it's pro-breastfeeding milk secretion if you want to inhibit prolactin dopamine is your men all of this was interior pituitary how about posture pituitary first of all the passive does not create anything it just stores whatever the hypothalamus gave her and these include adh and oxytocin we have two types of hormones lipid soluble and water soluble don't forget your blood has plasma which is made of water but the cell membrane is made of lip head called a phospholipid bilayer if you are lipid soluble well we cannot let you float inside the plasma because the plasma is water therefore someone has to carry you in the plasma and this is the plasma protein but once we get you close to the cell membrane you will just diffuse through the cell membrane because you are lipid and the cell membrane is lipid lipid can diffuse through lipid on the other hand of your water soluble can you float in the blood which is made of plasma which is made of water absolutely do you need a plasma protein shut up no but once you go to the membrane you will not be able to enter access denied why because your water but the cell membrane is lipid by layer therefore we have to put a receptor on the outside and this receptor will carry your signal and the second messenger is the middle man which will connect the receptor on the outside with the enzymes on the inside if you are lipid soluble you will cross through the membrane but this takes a lot of time because lipid diffusing through lipid takes it's a very slow process usually it ends up by entering into the nucleus and then gene transcription translation you make proteins we call this the genomic action because it's related to genes on the other hand water soluble usually the receptors on the outside and usually just flip a switch it's a very fast process and you sometimes secrete previously made proteins they are ready there is no need to make from scratch and that's why we call it non-genomic pause and review where should i put the receptor well if the hormone is water soluble it will not be able to diffuse through the membrane put the receptor on the outside but if the hormone is lipid soluble put the receptor on the inside because it will be able to diffuse it could be cytoplasmic receptor or nuclear receptor what are these lipid soluble hormones all right whatever is decreased by the thyroid whatever is secreted by the superior cortex whatever is secreted by the sex glands or the gonads what is degree by the thyroid thyroxin how about suprarenal cortex you have your corticosteroids and sex hormones estrogen progesterone testosterone dihydrotestosterone etc how about polar well polar are the proteins and the peptides such as pth which comes from the parathyroid epinephrine from the adrenal medulla not cortex medulla insulin glucagon from the pancreas so lipid soluble includes steroids and thyroid hormone the receptor is internal water soluble polar you have protein peptides pituitary pancreas parathyroid secretions receptor is external there is a rule in biology if you're bound you're not active if you're free you're active what does that mean if the hormone is bound to plasma protein it cannot exert any physiological function but if the hormone is freely floating in the bloodstream well it can exert physiological functions now i want you to read my 10 foundational rules of endocrinology if you want to understand this stuff better check out my endocrinology playlist here on youtube and we shall continue in the next video in the meantime pause and review i have premium courses on my website like the otakoids pharmacology course and the beloved endocrine pharmacology course thank you for watching please subscribe hit the bell and click on the join button you can support me here or here go to my website download my courses be safe stay happy study hard this is miracles per fictionalist where medicine makes perfect sense