up: Tags: # Hormones and Behavior ### What are hormones? Hormones are chemicals created in one area of the body and sent to another area of the body through the bloodstream. They are created by glands. ###### What are the main four systems through which hormones can communicate? Hormones can act on other parts of the body through endocrine systems or exocrine systems. Endocrine glands synthesize hormones that are released inside of the body where as exocrine glands excrete things from the body through ducts. However, hormones can act on themselves through paracrine systems which involves locally diffusing hormones to other parts of the same cell. ![[Pasted image 20220912105707.png]] While there are many similarities, there are quite a few [[The differences between neuronal and hormonal communication|differences between neuronal and hormonal communication.]] ### Main characteristics of hormones 1. Hormones levels are affected not only by our internal environment but also our external one. This means your behavior in the world can change hormone secretion. For example, if you see a donut on the countertop you will likely have increased levels of Ghrelin. 2. Multiple hormones can have an effect on a behavior or organ and one hormone can also affect a great number of different behaviors or responses. 3. Hormones are regulated primarily through your [[Circadian rhythms]]. ### Major classes of hormones 1. Peptide hormones 2. Amine hormones 3. Steroid hormones ### How do these hormone classes differ? Peptide and Amine hormones generally cause change through interaction with [[Neuropharmacology#^omiipv|Metabotropic]] receptors on target cells. Their actions are generally much faster and shorter lasting then Steroid hormones. Steroid hormones, however, can easily pass into cells and have effects there. Steroid hormones generally take much longer to take effect than peptide and amine hormones but can have effects that change DNA expression. They can't be stored in the body. ==Aromatase== is the enzyme that converts Testosterone into Estrogen. ![[Pasted image 20220906074549.png]] ## How does the body regulate hormone levels? The regulation of hormones happens through beautiful communication between the endocrine glands and the nervous system. This happens through four main communications: 1. Neuron to endocrine 2. Endocrine to neuron 3. Neuron to neuron 4. Endocrine to endocrine ![[Pasted image 20220913161601.png]] The body regulates most hormones on a negative feedback system. This means the output of the hormone synthesis comes back and causes less of that hormone to be secreted. ###### How does the hypothalamus regulate hormone levels? The main regulator from the brain on hormone levels is the hypothalamus. It regulates the tropic hormones from the anterior pituitary with releasing hormones, the thyroid hormones with TRH, and the gonads. ###### How is this hormone regulation system similar to neurons? This reminds me of the [[Autoreceptor system]] that neuron cells use to regulate their neurotransmitter levels. Autoreceptors are receptors located in neurons that monitor neurotransmitter synthesis and/or release. Then, in response they regulate how much more neurotransmitter is released or synthesized. Hormones are also regulated by monitoring the biological responses they cause in other cells. For example, the hypothalamus controls hormones released with feelings of fear like adrenaline. After release the brain monitors the effects of this adrenaline and determines if we need to release more or less. ## The Four Types of Endocrine Feedback Loops ### Autocrine Feedback In autocrine feedback a endocrine cell synthesizes a hormone that stops the production of the hormone in the endocrine cells but also affects a target cell. ### Target Cell Feedback In target cell feedback an endocrine cell produces hormones that affects target cells which cause a biological response that signal back to the endocrine cells to stop producing the endocrine cells. ![[Pasted image 20220913162605.png]] ### Neuroendocrine Cells The neuroendocrine system is made up of nerve and gland cells and makes hormones that release into the bloodstream. ### How does hormonal and neuronal communication differ? I explain this in my note, [[The differences between neuronal and hormonal communication]]. # Pituitary ^b5da7b The pituitary is known as the master gland as it impacts virtually all other hormone secretion in the rest of the body. ### Types of hormones in the brain 1. Tropic hormones 2. Releasing hormones Tropic hormones regulate hormone secretion by affecting other endocrine glands release of hormones. The ==hypothalamus== releases releasing hormones to control the anterior pituitary glands release of ==tropic== hormones. ## Hormones of the Pituitary The pituitary is split up into the ==anterior pituitary== and the ==posterior pituitary==. ### Posterior Pituitary The posterior pituitary is largely responsible for secreting the hormones ==oxytocin and Vasopressin==. High levels of oxytocin and vasopressin receptors have been shown to have a significant impact on [[Emotion in Social Psychology#^f3f7de|relationships]]. ###### What is vasopressin responsible for? It controls blood pressure, osmotic pressure, kidney function, and sodium homeostasis. ##### How does it communicate? The posterior pituitary communicates through neuroendocrine cells in the hypothalamus which have action potentials that travel down into the posterior pituitary and cause hormonal release into the bloodstream. ![[Pasted image 20220914103339.png]] One example of a behavior causing hormone release using the posterior pituitary is a baby sucking on a mothers breast. ![[Pasted image 20220914103134.png]] ### Anterior Pituitary ^e4a7b1 ##### How does it communicate? In contrast to the posterior pituitary, the anterior pituitary communicates through neuroendocrine cells in the hypothalamus that produce releasing hormone which travel down a narrow blood region into the anterior pituitary that causes the release of tropic hormones. ![[Pasted image 20220914103832.png]] The anterior pituitary is responsible for the release of the tropic hormones ACTH, TSH, FSH, LH, Prolactin (which creates milk), and growth hormone which have effects on a variety of endocrine glands and organs throughout the body. # Organs Controlling Hormone Secretion ## Adrenal Glands The Adrenal is best thought of as two glands. The ==cortex== which is controlled by hormones and the ==medulla== which is controlled by nerves. Resting atop both of the kidneys are the adrenal glands. ### Adrenocorticoids: Hormones of the Adrenal Glands The hormones that the Kidneys produce are collectively called ==adrenocorticoids==. The kidneys are largely responsible for secreting the fight or flight hormones norepinephrine and epinephrine. Another subgroup of adrenocorticoids are glucocorticoids which have a large effect on glucose metabolism. Cortisol is a big one. ##### What does the Adrenal Medula do under conditions of stress. Under conditions of stress the anterior pituitary releases ACTH which signals for the adrenal medulla to release adrenaline and noradrenaline, the same molecules as epineprhine and norepinephrine. They are also responsible for producing mineralocorticoids so called because of their effect on various minerals like sodium and potassium. Aldosterone is a big mineralocorticoids which acts on the kidneys to retain sodium and thus decrease urine production. Interestingly, neurotransmitters used in the brain can act as hormones in the body. For example, the neurotransmitters norepinephrine and epinephrine act as adrenaline in the body. For some reason, during the [[Evolution of The Brain and Behavior|evolution of our brain]], these specific molecules proved to be helpful in both the brain and the body. This is seen even among other animals. ## The Thyroid The thyroid is another major producer of hormones right around your Adam's apple. Similar to steroids the hormones it produces enter cells directly and have effects on receptors in their rather than acting as ligands at metabotropics. The release of these thyroid hormones is regulated largely by the hypothalamus with TRH. The thyroid stores about a 100s days worth of hormones making it unique compared to other endocrine glands. ![[Pasted image 20220906081759.png]] ### The Pineal Gland The pineal gland is in your brain and plays a massive role in regulating biological systems as part of your bodies [[Circadian rhythms]]. It's largely responsible for secreting Melatonin. ![[Pasted image 20220906081734.png]] ## Hormones influence social behavior According to [[Evolutionary Biology]] we are simply "beings meant to reproduce" and all of our actions and behaviors reflect that. I don't agree wholehardily with this statement but there is an element of truth to it. The regulation of sex hormones in your body has a large influence on how you act socially. ### Hypothalamus regulates gonads The hypothalamus is the major regulator of gonad hormone secretion through releasing gonadotropin-releasing hormone (GnRH) and gonadotropin-inhibiting hormone (GnRH) each effecting the pituitary gland in different ways and leading to different effects on the gonads.