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OK, I think it's live now. So, hi, everyone. Today we'll be covering the first half of phase one A and all. So these topics are quite crucial throughout phase one and as you progress through medical school, so hopefully today will be useful. The way this session is run is we're gonna have our first lecturer give a few talks and then we'll have a short break and then we'll hand it over to the second lecturer. So if you have any questions, feel free to put in the chat and our first lecturer is Rachel. So I like to hand over to her. Cool, thanks, Alicia. So, hi everyone. My name is Rachel. And the three things I'm gonna be talking to you about today is the Pituitary Gland, Adrenal, Gland, and Thyroid gland. So there's gonna be a mentee as well, which I'll give you the code to later. But yeah, any other questions put in the chat, but let's get started. So we'll start with the Pituitary Gland. So first, how does your pituitary gland develop? So you know that you have your anterior pituitary and your posterior pituitary and they have two different origins. So, your anterior pituitary, which is also known as your adenohypophysis, that's derived from an outgrowth from the oral ectoderm of the primal oral cavity. And that's called Rathke's pouch. So your anti pituitary has epithelial origin, your posterior pituitary, on the other hand, has neural origin and it's continuous with the hypothalamus. This is because it is formed from a downgrowth of the diencephalon that forms from the floor of your third ventricle. So just remember, anterior and posterior pituitary, they've got two different origins. Anterior is epithelial, posterior is neural origin and it's continuous with your hypothalamus. And in terms of anatomy, this is where your pituitary gland sits important things to note, it sits in the sella turcica of your sphenoid bone, which is this here and note your anterior pituitary here is very, very close to your optic chiasm, which is this bit here. This is really important for a condition that we'll talk about in a bit. But I want you to remember that your optic chiasm is extremely close to your pituitary gland. So we said that our anterior pituitary over here, it's not continuous with the hypothalamus, like the posterior pituitary is. So how does it communicate with the hypothalamus? How does information get passed between the two? This is done via the hypothalamopituitary portal system, also known as the hypothalamohypophyseal portal system. And what does this involve? Let's go through it step by step. So, first, your hypothalamic parvocellular neuron here releases hormones into this space here, which is called the median eminence. These releasing or inhibiting hormones then travel via your portal circulation this bit to your anterior pituitary over here and these hormones because we said they are releasing or inhibiting hormones, they are going to either stimulate or inhibit the release of hormones from your anterior pituitary. And the hormones that are then produced are going to leave via the blood. Let's look at this, looking at an example. Now, so if we take thyroid hormone, so your hypothalamic parvocellular neurons release trh into the median eminence. Trh travels via your portal circulation into the anterior pituitary. Th is going to stimulate the release of TSH, thyroid stimulating hormone from thyrotroph, which are a type of cell in your anterior pituitary and TSH then leaves via the blood and it's going to travel to your thyroid gland to make T three and T four. This table neatly summarizes all the things you need to know in terms of the types of cells in the pituitary, what hormones they produce they're releasing and inhibiting factors and then where those hormones act in the body. So there's five types of cells in your anterior pituitary, somatotrophs, lactotrophs, thyrotroph, gonadotrophs and corticotrophs. So, somatotrophs produce growth hormone and growth hormone is released. Um when there's increased growth growth hormone releasing hormone and it's inhibiting by, it's inhibited, sorry, by somatostatin. And where does growth hormone work? It works directly on the body's tissues to cause growth. Lactotrophs produce prolactin and prolactin is inhibited by dopamine and prolactin acts on the breast and it's involved in lactation, which we'll talk about thyrotroph, produce TSH, thyroid stimulating hormone. And they're released by thyrotrophin releasing hormone. And TSH produces acts to produce thyroxine from the thyroid. Gland gonadotrophs produce your LH and your FS H and these are stimulated by gonadotrophin releasing hormones and they act in the testes in Maine and in, in men and in the ovaries in females to create more sex hormones and sexual characteristics as well. And then finally, we have corticotrophs, they produce ACTH and this ACTH is stimulated by a corticotrophin releasing hormone or crh. Um and ACTH acts in your adrenal cortex to make cortisol and aldosterone. So this is extremely, extremely high yield. Um And I'm sure you'll remember this name is bitemporal hemianopia. So what is this when you have a pituitary tumor or a pituitary adenoma? Because we said, remember the anterior pituitary is really close to optic chiasm, sitting just above it. When there's a tumor, you can get compression of your optic chiasm. And this is important because it would mean that there would be no transmission of sensory info from your lateral slash temporal visual fields to the occipital lobe. So you'll essentially lose half of your vision and you'll lose a temporal aspect of it. And this is called bitemporal hemianopia. Um Now let's look at growth hormone more specifically. So, we said growth hormone is produced in the anterior pituitary and it binds to growth hormone receptors and growth hormone does two things. It acts directly on body tissues to cause growth and development. But it also acts on the liver and it causes the liver to produce IGF one which is insulin like growth factor in adults. Igf one is the um more predominant one. IGF two is more relevant in terms of fetal development. Um So IGF one is the one to remember, um growth hormone causes the liver to produce insulin like growth factor, which will then act on body tissues and will also cause growth and development. So remember that growth hormone causes growth and development directly when it acts on body tissues, but also through this indirect way as well. What happens when you have too much growth hormone? So when you have excess growth hormone, it would result in a condition called acromegaly. The symptoms of this are coarsening of facial features. Macroglossia, which is when you have an enlarged tongue, a prominent nose, a large jaw, increased hand and feet size, sweatiness, and headaches as well can also cau be caused by that. So I have a few questions on mentee. So if you guys wanna type in the code up here, I'll give you a few seconds and then we'll go through the questions. And so the first question is, what is the name of the bony dish that the pituitary gland sits on good. We have a couple of responses which are so far. Correct. Excellent, good. So you guys have said the sella TSA, which is absolutely correct. So, yeah, the seller of your sphenoid bone, that's where it sits the next question, which hormone is an excess in acromegaly? And this is not something I mentioned, but you might remember it from your lectures. Does acromegaly occur before or after puberty? And if you're unsure about the second part of the question, you can just answer the first part. We'll go through it anyway. Good. So it looks like you guys are saying growth hormone, which is absolutely correct. And yes, acromegaly occurs after puberty if you have an excess of growth hormone, but it's before puberty, that's called gigantism. So, before puberty, your growth plates haven't fused.