Endocrinology - Overview

I Ramona Singer in biology medicine videos please make sure to subscribe join the firm a group of ladies videos places a Facebook camera so you're on a place like here in this video we're going to talk about the endocrine system now the endocrine system main purpose is to maintain a homeostatic environment through the use of hormones so when we think of the endocrine system we should think of hormones hormones are essentially signaling molecules now the endocrine system works in close proximity with the nervous system in that both the endocrine system and the nervous system tries to maintain a homeostatic environment by sending out signals the main difference between the two is that the nervous system is a quick response so when a stimulus arrives at a neuron the neuron can pass on these signals these commands as neurotransmitters that will then target a particular cell the neurotransmitter will bind onto a specific receptor that will cause the target cell to initiate a short-term quick response now the endocrine system on the other hand will send signals not to get to neurotransmitters but through hormones and these hormones will travel via the bloodstream where it will then target a cell and it's specific receptors so what happens is with an endocrine cell is that what a stimulus or command comes this will stimulate the endocrine cell to secrete hormones into the bloodstream like so these hormones will then target and bind onto a specific receptor on a target cell this will cause a target cell to initiate a long-term slow response so that is a major difference in that the nervous system is a short term quick response whereas the endocrine system is a long term slow response the endocrine cell typically secrete hormones into the bloodstream this is normal this type of signalling is called endocrine signaling hence the name endocrine system however hormones does not always have to be secreted into the bloodstream to target a cell the endocrine cell can also secrete hormones that target cell directly close to it like this cell for example and so when it does this this type of secretion is known as paracrine signaling para as an across and this will initiate a long-term slow response when the endocrine cell is secreted when the endocrine cell sorry secretes hormones into the bloodstream which is the basics for the endocrine system we have hormones in the bloodstream the hormones can travel in the bloodstream as a free form which can be cleared quickly by the body free form as in it's just a hormone traveling in the blood or the hormone can actually travel bound to a protein these hormones that are bound to a protein and trouble through the blood are typically lipid hormones because lipids hate water they need to travel bound to proteins we call these protein bound hormones so now let's talk a little bit more about hormones hormones as I mentioned our signaling molecules hormones can be grouped into three types amino acid derivatives peptide hormones or lipid derivatives lipid derivatives for example are steroid hormones or thyroid hormones if you know a little bit about your hormones and so these hormones they will bind onto a target cell onto the specific receptor that will initiate a desired response a long-term response here I'm drawing these hormones binding on to target receptors on this plasma membrane of the target cell to initiate response well peptide hormones and most hormones derived from amino acid they bind to receptors on the play asthma membrane whereas the lipid derived hormones they cross the cell membrane and bind to receptors in the cytoplasm as shown siren hormones and steroid hormones they cross the plasma membrane and bind to receptors in the cytoplasm to initiate a response and this is because the thyroid and steroid hormones are lipid derived okay now that we know a bit more about hormones these signaling molecules let's look and look at an example of an endocrine response a good example is to look at blood glucose so here in the blood stream we have low glucose levels and this is not very good because we need glucose glucose is a source of energy for tissues in our body so low blood glucose is a stimulus and the body will have will have to try to fix this to maintain homeostasis so it will try to increase blood glucose levels and this is when the endocrine system kicks in the stimulus which is low blood glucose levels will stimulate an endocrine cell known as the pancreas cell actually it's called the alpha cell but let's call it pancreas cells for simplicity the pecker cell will then secrete a hormone called glucagon into the bloodstream glucagon will travel through the bloodstream to the liver which is the target cell glucagon is not a lipid hormone because one it is not bound to a protein when it travels through the blood and two it binds to receptors on the cell membrane when glucagon binds to the receptors on the liver cell glucagon will stimulate the liver to break down glycogen to secrete glucose in the blood and so the response by this liver cell is that it will secrete more glucose in the blood we to increase blood glucose levels like so all these glucose is being secreted out when blood glucose level is increasing this will send a net this will sent a feedback back it will send a feedback it will send a negative feedback signal to stop stimulating the pancreas cell because when you have normal to high blood glucose levels you don't need any you don't have low blood glucose stimulation and you don't need any more glucose to be secreted I hope you understand this concept of negative feedback so in the example we just saw we looked at the hormone called glucagon which is - created by the alpha cells of the pancreas now let's look at some other major hormones such as glucagon and where they come from we will not look at what they do or I'll try to mention them but we'll just look at what they are before we continue we should know that we have many hormones in the body that perform different functions or have different responses another terminology to learn is also what's called what's called endocrine glands endocrine glands are essentially groups of endocrine cells that are dedicated to perform a specific function so let's look at the first two or three most important endocrine glands I think the first is situated in the brain here this is known this the first one is known as the hypothalamus and this is an endocrine us endocrine tissue and the hypothalamus is responsible for the production of antidiuretic hormone and oxytocin it is also responsible for the production of the regulatory hormones and we will look at what these do probably the most important endocrine glands are the pituitary glands which are located right below the hypothalamus here and there are two lobes of the pituitary glands there is the anterior lobe and the posterior lobe the posterior lobe secretes oxytocin and antidiuretic hormone that were produced by the hypothalamus so the hypothalamus produces these hormones and sends them to the pitcher posterior posterior lobe which then the posterior lobe will secrete into the blood the anterior lobe of the pituitary glands actually secrete many hormones including ACTH which stands for adrenocorticotropic hormone TSH thyroid stimulating hormone obviously stimulates the thyroid the GH growth hormone for growth PRL prolactin for milk production in the breast and then FSH which is follicle stimulating hormone and LH luteinizing hormone which are responsible for the reproductive system so these hormones that are secreted by the anterior lobe they are regulated by the hormones from the hypothalamus so if you remember the hypothalamus secretes regulatory hormones that regulates the secretion of the anterior hormones if that makes any sense there's another are endocrine gland in the brain known as a pioneer gland which is around this area and it secretes melatonin melatonin is actually responsible for the body clock now let's make our way down in the trachea or throat area we have wrapping around the trick here we have the thyroid gland now the thyroid gland secretes few hormones thyroxine which is which is abbreviated t4 and trudeau thyromine which is t3 it also that's responsible for metabolism essentially then you have calcitonin now the thyroid glad it it also has another other endocrine glands on it so if we zoom into this area here we're looking at this person from pasti point of view from from the back so we have the thyroid gland and then we have these four sort of lobes on the thyroid gland these are known as the parathyroid gland para is enough cause but it's just on it so there are four parathyroid glands and these are behind the thyroid gland and they secrete the hormone parathyroid hormone simple enough parathyroid hormone is important in the regulation of calcium and phosphate enamel in our blood in our body now right below the thyroid gland we have another endocrine gland you can say known as the thymus now the thymus is not really a big deal in the inner crisis but it is a big deal in the immune system world but in endocrine world the thymus actually undergoes atrophy during adulthood and it begins secreting thymosin of course this person we have in this person we have the lungs connected to trachea and the heart between the levels now if you didn't know the hot is also classified as an endocrine gland because it secretes hormones the hutt secretes the hormone naturally peptide which is responsible in blood pressure regulation it's actually decreases blood pressure when there is an increase in blood pressure then we have the digestive tract now the digestive tract they secrete a lot of variety of hormones and what I mean by the digestive tract I mean the stomach the duodenum the small intestines etc and they produced many hormones such as gastrin somatostatin Coley cytokinins etc another important well another very important endocrine gland or tissue is the pancreas and it secretes two main hormones insulin and glucagon now we talked about glucagon in that it increases blood glucose levels well insulin works opposite it decreases blood glucose levels and you might know diabetes diabetes people they have very low insulin levels or type-2 diabetes they have low into the levels or type 1 they're depleted insulin levels and so you have a lot you know very high blood glucose levels and you can't decrease this because you have no insulin and if you wait until the end of the video I will provide links to some of these hormones so you can watch them in more detail and to see what they do the kidneys also secrete hormones they secrete erythropoietin which stimulates red blood blood cell production in the bone marrow and also secretes calcitriol which I don't know what it does above the kidneys we also have the very important adrenal glands if we take a cross-section of the adrenal glands we have two adrenal glands of course because we have two kidneys if we cut across section of the adrenal glands we have the adrenal cortex the outer part of the adrenal glands and then we have the adrenal medulla the middle of the adrenal glands and this line I'm drawing for the adrenal medulla it's meant to be in the in the middle of the adrenal glands not on the outside it's a mistake anyway the adrenal cortex secretes cortisol and aldosterone cortisol is essentially for stress and aldosterone is to promote sodium reabsorption as well as potassium secretion in the kidneys and then we have the adrenal medulla which secretes adrenaline and noradrenaline also known as epinephrine or norepinephrine in America these hormones are important in the fight-or-flight response as well as the rest and digest response adipose tissue which is essentially fat also stupid hormones it secrete leptin which is important fat metabolism the far endocrine tissue or endocrine glands I want to talk about other gonads now because we have a male and female version of humans we have two types of gonads we have the testes for the male and the ovaries for females so the testes in the testes we have cells that secrete androgens such as testosterone which is important a for promoting male characteristics as well as sperm production and then we have for the gonads the ovaries for the female we have important hormones being secreted such as estrogen and progesterone which is important in female characteristics and egg production okay so those were the main hormones that were secreted by the main endocrine tissue or endocrine glands but I'd like to concentrate and look into more detail on the pituitary glands which is very important in the crying gland because it for one secretes a lot of hormones and two it secretes hormones that regulate or stimulate the secretion of other hormones from other endocrine tissue if that make any sense so let's have a closer look at the pituitary glands the pituitary gland is located within the brain and easy way to remember this is it's located sort of below the hypothalamus the pituitary glands consists of two lobes one is called the posterior pituitary which is at the back it's also known as a neural hypotheses and then we have the anterior pituitary also known as a Edina hypotheses I hope I'm pronouncing that foursie's right anyway let's first look at the posterior pituitary and what its decrees well actually the hypothalamus it produces it synthesizes antidiuretic hormone and oxytocin these hormones that are synthesized in the hypothalamus they are synthesized in these neurons and these new neurons will then pass on these hormones to the steerer pituitary and so from here when a stimulus arrives stimulating the secretion of these hormones the posterior pituitary can then secrete it so the posterior pituitary can secrete the antidiuretic hormone the antidiuretic hormone main function is to is for water retention so it targets the kidneys particularly the kidney tubules the posterior pituitary can also secrete the hormone oxytocin oxytocin essentially targets the breast and it's important so it's important for a lactation and also is important for the contraction of the uterus during childbirth so remember for the posterior pituitary the hormones itself are actually synthesized or made within the hypothalamus the posterior pituitary only secretes them now let's look at the anterior pituitary now the anterior charger is different than the posterior pituitary in that the anterior pituitary makes its own hormones however these hormones they can only so most of them can only be secreted when there is some form of confirmation from the hypothalamus so the hypothalamus actually will secrete a hormones that will regulate the secretion of the anterior pituitary hormones the hormone secreted by the hypothalamus are known as regulatory hormones and these regulatory hormones they once it once they are secreted they will cause either stimulation or inhibition of the anterior pituitary hormones being secreted anyway whatever the case if it's if it's all okay the anterior pituitary can secrete prolactin abbreviated P RL which will target that member the breast essentially for a milk production and to your Petrucci can also secrete growth hormone which targets many tissues such as the bone for growth the anterior pituitary can't secrete gonadotropic hormones such as follicle stimulating hormone and luteinizing hormone which will target the testes or ovaries depending if it's male or female anterior pituitary can also secrete thyroid stimulating hormone which will stimulate stimulate the thyroid gland to secrete its own hormones and finally the anterior pituitary can also secrete a dino corticotropin or moan which will target the adrenal glands and it will stimulate the release of cortisol etc for example so as you can see the poster Petrucci glands to create a variety of hormones and they're controlled in a very confusing manner and I'll provide actually a video that will look more into detail on the pituitary glands actually I'll provide links hopefully to many of these hormones so you can click on the link on the screen and they'll take you to this video so you can watch it in a bit more detail thank you

Channel: Armando Hasudungan

Views: 1,920,944

Keywords: Endocrinology (Medical Specialty), endocrine system, anatomy and physiology, lecture, tutorial, hormones, function of hormone, pituitary gland, endocrine glands, tissue, hypothalamus, animation, simple, armandohasudungan, difference between the anterior and posterior pituitary, example, Medicine (Field Of Study), different types of hormones, signals, stimulus, negative feedback, the hypotalumus pituitary axis, response, quick fast

Id: YcPicFL5Jnw

Length: 21min 16sec (1276 seconds)

Published: Tue Oct 01 2013