Anatomy and Physiology II Week 1 Notes: Endocrine System PPT 1
Anatomy and Physiology II Week 1 Notes: Endocrine System PPT 1 Biol 2230-001
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This 12 page Class Notes was uploaded by Victoria Hills on Sunday January 17, 2016. The Class Notes belongs to Biol 2230-001 at Clemson University taught by Dr. John Cummings in Fall 2015. Since its upload, it has received 173 views. For similar materials see Human Anatomy & Physiology II in Biology at Clemson University.
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Date Created: 01/17/16
Clemson University Spring 2016 Human Anatomy and Physiology II Endocrine System PowerPoint 1/12/16 Notes Abbreviations: AA = Amino Acid; Ex = Example; FA = Fatty Acid Slide 1: Endocrine System Slide 2: Activity Controlling Mechanisms • Theme of homeostasis in the nervous and endocrine systems • Review: Nervous System -‐ The nervous system creates an electrical impulse to respond to stimuli -‐ Able to activate excitable tissue (Ex: Muscles-‐ Cardiac and skeletal and some glands) -‐ Responds very quickly to stimuli (Within milliseconds) -‐ Responses are generally short-‐lived • Endocrine system: -‐ Can activate a target cell using a chemical messenger (Ex: Hormone) -‐ Chemical messenger: Goes into blood stream and travels throughout the body until it reaches a target cell with the specific receptor for that hormone -‐ Target cell: Cell that possesses the receptor for the hormone -‐ Hormones are chemical secretions produced by glands that change cellular metabolic activity • Explicit Differences between the nervous sand endocrine systems: -‐ The nervous system responds almost immediately vs. the endocrine system having a lag time (Can take from a few seconds to days for a response) -‐ The nervous system lasts for a short amount of time while the endocrine system has a longer response • Nervous system and endocrine system due function together although they have different properties Slide 3: Glands-‐ Exocrine • Exocrine glands produce secretions that are not hormones (These secretions are not part of the endocrine system) • Example of exocrine glands: Sweat glands, salivary glands, digestive enzymes produced by exocrine glands • Exocrine glands have a duct for the most part where the secretions are secreted into in order to go to the site where its going to have its activity Slide 4: Glands-‐ Endocrine • Endocrine glands produce hormones and are ductless • Secrete on the surface and are picked up in circulation and transported through the body • Endocrine glands are therefore very vascularized in order to increase efficiency in circulation • Pancreas: Considered to be an exocrine and endocrine gland -‐ Part of the pancreas secretes digestive enzymes into a duct that carries into the small intestine -‐ The other part of the pancreas secretes hormones like insulin or glucagon that is transported in the blood stream in order to maintain blood glucose levels Slide 5: Neuroendocrine Link • There is a link between the nervous and endocrine systems • The nervous system can activate glands so that a nervous impulse could travel to an endocrine gland to cause it to secrete something • The presence of a hormone could turn on or off impulses • Specific example with a strong link: Hypothalamus -‐ Part of the midbrain (Neural tissue) -‐ Connected to the pituitary gland that has some strong endocrine functions -‐ Mechanism: Signal is sent from the hypothalamus to the pituitary gland to release hormones Slide 6: Chemical Messengers • Hormones: -‐ Chemical secretion produced in one part of the body but has an effect somewhere else in the body -‐ Long-‐distance chemical messenger • Autocrines: -‐ Chemical produced by a cell that changes the activity of that cell -‐ Short-‐distance chemical messenger -‐ “Self-‐regulator” -‐ Only affects the cell that produces the chemical • Paracrines: -‐ Chemical that is secreted by cells that affect the neighboring cells in that area -‐ Key to understand that they only affect the area where it was produced • Pheromones: -‐ Chemical secretion that alters behavior of another individual -‐ Ex. of non-‐human functions: Marking territory, mate attraction, etc. -‐ 1970’s: Research on mate attraction showed that humans due produce pheromones and was seen in perspiring women Slide 7: Hormone Classifications: 1) Amino Acid Based • Derivative of AA • Water soluble • Cannot diffuse across the plasma membrane because of its hydrophobic properties due to lipids (Chemical composition helps us understand where receptors are located for that cell) • Majority of the hormones produced in the body are AA derivatives (Non-‐ steroids) and almost all the hormones produced are water soluble Slide 8: Hormone Classifications: 2) Steroid • Steroid: A derivative of cholesterol which is fat soluble • Can diffuse across the plasma membrane by itself • Steroid hormones are only produced by the gonads (Testes and ovaries) or cortex of the adrenal gland; Otherwise, the hormone is AA based if it is not produced by these Slide 9: Hormone Classifications: Eicosanoid (Not truly considered to be hormones) • Eicosanoid: Biologically active lipid that is a chemical secretion that has a localized effect – What makes it not a true hormone (Similar to a paracrine but is not exactly the same) • The 2 most common types of eicosanoids: a) Prostaglandins: -‐ Biologically active lipids -‐ Ex: When there is damage to a tissue, the tissue releases prostaglandins that cause other cells to migrate to the site and can disrupt the action of the action potential in the nervous system so that won’t have a pain signal -‐ Ex: One ovulating ovary secretes prostaglandins so that the sperm know which one to go to b) Leukotrines Slide 10: Hormone Actions-‐ Target Cells • Target Cell: Anything that has a receptor • Figure on the slide: Hormone producing structure -‐ Blue dot is a hormone and is secreted on the surface of the structure and the moves into the blood stream to be transported throughout the body -‐ The hormone will only have an affect on cells with the receptor specific to that hormone • Cells can respond to different hormones with different kinds of specific receptors Slide 11: Hormone Actions-‐ Open or close ion channels • Actions of hormones when they act on target cells: When the hormone binds to its specific receptor of a cell, it changes the permeability which is what allows the changes in ion flow Slide 12: Hormone Actions-‐ Stimulates protein synthesis • Hormones can cause the cell to start producing proteins (Structural or functional) • Ex: -‐ Could cause the cell to produce actin or myosin to increase muscle mass -‐ Enzyme produced to catalyze a reaction -‐ Protein packaged for export to have an effect somewhere else -‐ Others Slide 13 Hormone Actions-‐ Activate or deactivate enzymes • Hormones can activate or deactivate enzymes within a cell • Can cause the production of new proteins or change the activity of existing proteins already in a cell Slide 14: Hormone Actions-‐ Promote secretion • Hormone binds to specific receptor on target cells to cause them to start secreting thing (Ex: Mucous, a different enzyme, etc.) Slide 15: Hormone Actions-‐ Stimulate mitosis • Hormones can cause cells to start dividing with the stimulation of mitosis for growth to occur Slide 16 Hormonal Mechanisms • Steroid Hormones: -‐ Produced in the gonads and cortex of the adrenal gland -‐ Made up of cholesterol derivatives making this group fat soluble so they can pass across the plasma membrane unaided -‐ Therefore, receptors for steroids are located inside of the cell (Often times in the nucleus) -‐ Purpose: Produce new proteins via direct activation • AA Based Hormones: -‐ Water soluble so cannot pass through the plasma membrane of the cell without help -‐ Therefore, the receptors are located on the exterior surface of the plasma membrane (Receptors can be in the form of glycoproteins, glycolipids, etc.) -‐ When the AA based hormone binds to the receptor, it requires the use of a G protein to activate secondary messengers -‐ More specifically: The AA based hormone binds to the receptor on the surface of a cell (Usually an integral protein) and it has a secondary peripheral protein on the inside of the cell à So when the AA based hormone binds to the receptor it activates the G protein that activates something inside the cell to cause some activity (Via secondary messenger) à This means that AA based hormones do NOT provided direct activation Slide 17: Steroid Action Video Slide 18: Steroid Action • When stress (or another type of stimuli) is applied to the body, an endocrine gland (In this case, a gonad or adrenal gland) produces a secretion that goes into the blood stream where it encounters a cell with its specific receptor and then diffuses across the membrane • With steroid hormone activity, the hormone diffuses across the plasma membrane and binds with the intracellular receptor • (If there isn’t a receptor inside the cell, the steroid hormone crosses back out of the cell and won’t have any effect on it) • When the steroid hormone binds to the receptor, the complex is now activated which will then bind to a second receptor that is located on the DNA inside the nucleus • When the activated complex binds to the DNA, it acts as a promoter and starts transcription (Taking gene and using genetic code to produce mRNA to then be translated and go out of the nucleus and find the ribosome to begin producing the protein) à Demonstrates direct activation of protein production by steroid hormones • Note: the receptor for the steroid hormone could also be located in the cytoplasm which then can cross into the nucleus and bind to the DNA activator which then causes the cascade of the production of a protein (Transcription and translation processes, more specifically) Slide 19: Non-‐Steroid Action (Include AA based hormones) Video • AA based hormones attach to specific receptors on the surface of the cell that use secondary messenger mechanisms to change the activity of the cell • Note: Most of the hormones produced in our body are non-‐steroid Slide 20: Non-‐Steroid Action (2 Mechanisms) • Cyclic AMP Mechanism: Cyclic AMP is the secondary messenger to cause something to happen in the cell • PIP-‐Calcium Mechanism: PIP causes something to happen in the cell and then calcium follows with its effect • The benefit of second messenger signaling is the amplification that occurs inside of the cells; small amounts of signal create a large response— Secondary messengers do not have to do with conducting a rapid response with communication Slide 21: Cyclic AMP Mechanism • Hormone binds to a receptor located on the exterior surface of the plasma membrane, which modifies the receptor • A second protein associated with the now modified receptor known as a G protein is activated • The activated G protein is used to activate adenylate cyclase, which is an enzyme that causes the production of cyclic AMP (cAMP) from ATP • cAMP then stimulates the protein kinases enzymes, which phosphorylate proteins (Addition of a phosphate group to a protein) • Phosphorylation by protein kinases to already existing proteins inside the cells either 1) Activates the protein or 2) Deactivates the protein • At some point, it will be necessary to have a way to break down cAMP à Occurs through phosphodiesterase (Hormone response has a duration time) • Overall idea: This mechanism demonstrates that only one hormone affected the cell but it causes hundreds of different responses due to the effect of changing the proteins inside the cell to be either turned on or off Slide 22: PIP-‐Calcium Mechanism • Hormone binds to the membrane bound receptor, which becomes the modified receptor and activates the G protein • The activated G protein causes the activation of phospholipase (PLP) inside the cell, which splits PIP2 into DAG and IP3 • DAG activates protein kinases, which phosphorylate proteins • IP3 causes calcium to be released from the ER in the cell, which can act as another secondary messenger to be released to promote other changes in cellular activity Slide 23: Factors Affecting Hormone Action • Hormonal activity is affected by the amount of hormones circulating in the blood stream à The higher the concentration, the higher the response to the hormones • The human body is capable of adapting to stress (For example) through: 1) Up regulation in the number of receptors as a result so that there will be a greater hormonal response with continued stress à More receptors allows for more binding of the specific hormones that produce the necessary proteins 2) High levels of stress can also cause the number of receptors on target cells to be reduced if that particular hormone’s response is not needed à Decreased numbers of receptors leads to decreased response to that hormone 3) Receptor Affinity: Can change the way the receptor binds to the hormone—Ex: May be necessary for an increase in speed in the response of a hormone on a cell and body can accompany this need • Hormone producing structures can be working at the same time so hormones are able to interact amongst themselves as a result Slide 24: Hormone Interactions • Permissiveness: -‐ A hormone, such as FSH (Follicle-‐Stimulating Hormone), will affect reproductive development so that as it is secreted it will cause development of the reproductive organisms but if there are higher levels of thyroid hormone present, for example, FSH will have a greater effect -‐ In this example, thyroid hormone isn’t necessary for FSH to work properly, but it enhances FSH’s effect • Synergism: -‐ When more than one hormone produces the same effect so when that when these multiple hormones are present together, a greater effect is experienced -‐ Ex: Glucagon and epinephrine both increase blood glucose levels and together, this is experienced even more • Antagonism: -‐ Hormones that have opposite effects -‐ Ex: Insulin vs. glucagon Slide 25: Modes of Endocrine Gland Stimulation • Humoral: (Humors are liquids) -‐ Concentrations of something in the blood stream can stimulate endocrine secretions -‐ Ex: Increase in blood sugar level can cause the pancreas to produce insulin in order for cells to take up glucose and reduce the concentrations in the blood stream • Neural: -‐ Nervous impulses directly stimulate glands to start producing hormones -‐ Ex: Sympathetic nervous stimulation of the adrenal gland causes the production of epinephrine • Hormonal: -‐ Hormones in the blood stream bind to target cell to cause it to produce another hormone • Modified by Nervous System: -‐ The previously discussed modes of endocrine gland stimulation can be fine tuned by nervous system activity because the endocrine and nervous system work together • Inhibited by negative feedback: -‐ Most hormones will function through negative feedback mechanisms -‐ Ex: Stress causes the hormone to be released to reduce stress and once the stress is successfully reduced, the hormone will be shut off • Both "turn on" factors (hormonal, humoral, and neural stimuli) and "turn off" factors (feedback inhibition and others) may be modulated by the activity of the nervous system Slide 26: Endocrine Glands • Pituitary • Thyroid • Parathyroids • Adrenals • Pancreas • Gonads • Pineal • Thymus Slide 27: Pituitary Gland (Hypophysis) • The pituitary gland (hypophysis) is divided into the anterior and posterior pituitary • The pituitary gland extends off of the hypothalamus via what is called the infundibulum = pituitary gland’s funnel-‐shaped stalk • The posterior pituitary gland (neurohypophysis) is comprised of nervous tissue -‐ Does NOT produce hormones but instead is responsible for storing hormones made originally in the hypothalamus -‐ Releases the hormones into circulation when signaled to do so by the hypothalamus • The anterior pituitary gland (adenohypophysis) is not directly part of the nervous brain but it is fused to neural tissue of the posterior pituitary gland -‐ Made up of glandular tissue, which is secretory tissue -‐ Starts out as out-‐pouching (Rathke’s pouch) of the oral cavity and this piece breaks off the oral cavity and travels until it comes in contact with neural tissue and fuses together -‐ Produces many hormones • Both the hypothalamus and anterior pituitary gland produce hormones à -‐ The hypothalamus sends the produced hormones to the posterior pituitary to be stored -‐ In terms of regulation of the anterior pituitary gland, the hypothalamus sends releasing or inhibiting hormone that tell the anterior pituitary to release or not to release the hormones it has produced • The connection between the anterior and posterior pituitary = blood vessels Slide 28: Neurohypophyseal (Posterior Pituitary Gland) Hormones • Oxytocin • Antidiuretic Hormone (ADH) • Both are AA based hormones and use the PIP-‐calcium mechanism à Activate proteins that are already inside cells Slide 29: Oxytocin (Posterior Pituitary Gland) • Stimulates smooth muscle contraction à Childbirth, milk ejection • Promotes the ejection of milk (NOT production but the release itself) • Example of its involvement in a positive feedback mechanism: Giving birth to an infant à Stimulation of the contraction of muscles in labor, increase in pressure, baby pushed out and released • Involved with sexual arousal and satisfaction à Associated with climax response • High levels of oxytocin promote nurturing behavior; This is seen especially immediately after the mother finishes giving birth (“Cuddle hormone”) • NOT produced by the posterior pituitary gland itself Slide 30: Anti-‐Diuretic Hormone (Posterior Pituitary Gland) • Regulates water balance by affecting the kidney tubules and prevent urine formation • The kidneys are caused by ADH to absorb water so that it goes back into circulation to reduce urine production • Important to monitor tonicity of blood as a result of this • Alcohol suppresses ADH à Leads to release of lot of fluids that cause dehydration • NOT produced by the posterior pituitary gland itself Slide 31: Adenohypophyseal (Anterior Pituitary Gland) Hormones • Growthy Hormone (GH) • Thyroid-‐Stimulating Hormone (TSH) • Adenocorticotropic Hormone (ACTH) • Gonadotropins: FSH (Follicle-‐Stimulating Hormone) and LH (Luteinizing Hormone) • Prolactin • Pro-‐opiomelanocortin (POMC): -‐ A “pro-‐hormone,” meaning it is a precursor to become a hormone -‐ “Opio” = Opiate that is involved with pleasure reception, pain, etc. -‐ Melanocortin affects melanocytes that produce melanin and involved in UV radiation • All of these hormones are AA based and use the cyclic AMP mechanism Slide 32: Tropic Hormones • Tropic comes from the Greek word “trephein” = “to nourish” • Tropic hormone is a hormone whose target cells are other endocrine glands so that it causes the production of another hormone 1/14/16 Notes (Endocrine System continued) Slide 33: GH (Growth Hormone) • GH is an anabolic hormone that builds tissue (Seen with muscle and bone tissue for example) • GH stimulates cell growth and division, protein synthesis, fat metabolism and glucose conservation • GH’s target cell could be skeletal muscle, for example, and when it binds to the receptor it stimulates the production of myosin/actin, which make the muscle larger • With increasing glucose concentrations and storing glucose, the cells get bigger inclusions as a result • GH Malfunctions: -‐ Pituitary Dwarfism: Insufficient concentrations of GH lead to smaller and maintain younger looking features -‐ Giantism: Excess concentrations of GH lead to bigger and older looking features -‐ Acromegaly: Where GH levels are normal until adulthood where an excess amount is produced and there are effects of enlargement of hands, feet, longer face etc.; Simple diagnostic test: Taking had and putting around wrist to see if the thumb overlaps the fingers by a great extent Slide 34: GH Cascade • Cascade: What causes the anterior pituitary gland to start producing hormones and also includes what shuts it back off -‐ The anterior pituitary is generally stimulated by the hypothalamus (But not always) = Chemical hormonal stimulus to cause anterior pituitary cells to start to produce the wanted hormone (Example of the hormonal mechanism) -‐ Many kinds of cells are in the anterior pituitary with each cell having different receptors and responding to different signals from the hypothalamus • GH Cascade: • The hypothalamus secretes growth hormone releasing hormone (GHRH) that signals the somatotrope cells in the anterior pituitary gland which causes the production of GH (On switch) • GH is released then by the anterior pituitary and travels in the blood stream to affect any cells with the GH receptor • GH is AA based so it binds on the surface of the cell with its specific receptor and then causes a 1) Direct effect on the cell or 2) Indirect effect on the cell through use of a secondary component • This is a negative feedback system so as GH levels increase in circulation, growth hormone inhibiting hormone (GHIH) is triggered which shuts off GHRH which stops GH production • GHIH is also known as somatostatin and this hormone can shut off other hormones too, such as digestive enzyme production Slide 35: Direct Actions of GH • GH that is released from the anterior pituitary gland travels in the blood stream until it reaches a cell with its specific receptor that it binds to and causes an increase in blood levels of fatty acids (FA) à This means that fat is being taken out of storage and is going to be made available for energy • GH decreases cellular uptake of glucose so that it is kept in circulation to be used for energy elsewhere instead of glucose coming out of the blood stream to be stored in a cell • Glucose and FA function as energy sources à By taking fat out of storage and preventing glucose from being stored, energy is being provided for the body • GH encourages the breakdown and release of glucose from glycogen in the liver = diabetogenic effect (Releasing glucose from the storage of glycogen) • GH demonstrates the changing of membrane permeability where it closes off the in-‐flow of glucose into cells and opens up the out-‐flow of glucose out of cells so that more energy is available and is in circulation Slide 36: Indirect Actions of GH • Indirect actions of GH function through IGF (Insulin-‐like Growth Factors) • IGFs are produced by the liver and require GH presence for activity • GH stimulates an increase in IGFs by the liver • GH binds to IGFs and stimulates the uptake of AA from the blood into cells that stimulates protein synthesis • GH stimulates uptake of sulfur through IGF binding which is important for making the matrix of cartilage à In an embryo, when cartilage matrix is being made, this is the foundation for where bone comes from and in order to do this, the GH has to interact with IGF Slide 37: TSH (Thyroid Stimulating Hormone) • TSH is produced by the anterior pituitary gland • Stimulates the development of the thyroid gland and secretion from the thyroid gland Slide 38: TSH Cascade • The hypothalamus secretes TRH (Thyrotropin Releasing Hormone) which stimulates the thyrotrope cells of the anterior pituitary gland which produces TSH (Thyrotropin) and secretes it into the blood stream to bind to specific receptors • High levels of TSH inhibit the pituitary gland and hypothalamuas and it also stimulates the production of GHIH which blocks the production of TRH and therefore the production of TSH Slide 39: ACTH (Adrenocorticotropic Hormone) • ACTH is an AA based hormone that stimulates the adrenal cortex to secrete its steroid based hormones (corticosteroids) using the cyclic AMP mechanism • The adrenal gland produces 3 classes of steroid hormones and of these 3, ACTH primarily causes the production of mostly glucocorticoids • All of the steroids that are secreted by the adrenal cortex help the body relieve stresses (Ex: Fever, blood pressure, external stresses, etc.) Slide 40: ACTH Cascade • The hypothalamus secretes CRH (Corticotropin Releasing Hormone) which stimulates the corticotrope cells of the anterior pituitary gland to release/produce ACTH which binds to receptors on cells of the adrenal cortex where the production of glucocorticoids primarily occurs • Increased levels of glucocorticoids shut off CRH which stops the production of ACTH which stops the production of glucocorticoids • Fever, hypoglycemia, and other stressors cause CRH to be produced in the hypothalamus Slide 41: Gonadotropins • Gonadotropins are anterior pituitary gland secretions that help regulate and develop the functioning of the gonads (Ovaries/testes) • 2 types of gonadotropins: a) FSH (Follicle-‐Stimulating Hormone): Stimulates the production of gametes (Sex cells-‐ sperm/eggs) b) LH (Luteinizing Hormone): Stimulates the production of gonadal hormones (Testosterone, estrogen, progesterone) Slide 42: Male • FSH: Stimulates sperm production • LH: Stimulates production of testosterone, which is produced in the tests by the interstitial cells • Testes: Produce gametes (sperm) and testosterone Slide 43: Female • FSH: Stimulates production of ova (eggs) = gametes -‐ Women are born with all the gametes that are going to be produced in the ovaries which means that FSH is producing the ova prior to birth and the ova are then maintained in the follicles -‐ Normally 3-‐5 follicles develop each month with normally one finishing development in making it into a mature egg • LH: Triggers ovulation and development of the female sex hormones (estrogen and progesterone) • After puberty, the FSH and LH work together to cause maturation of some of the ova in the follicles, cyclically Slide 44: Gonadotropin Cascade • At puberty, the hypothalamus secretes GnRH (Gonadotropin Releasing Hormone) that stimulate the gonadotrope cells of the anterior pituitary gland to secrete FSH and LH • FSH and LH cause the gonads to mature and produce their own hormones • The production of these hormones by the gonads are then what shut off the production of LH and FSH when there are increased levels Slide 45: Prolactin (PRL) • Prolactin stimulates the breasts to produce milk • Oxytocin and prolactin are associated with lactation • Prolactin may enhance testosterone production in males (But they don’t produce much) Slide 46: Prolactin Cascade (Cycling) • During a woman’s cycle, an ovum begins to develop in the ovary and as the follicle where the ovum is located in matures, this causes an increase in estrogen and this causes prolactin to be released form the lactotrope cells of the anterior pituitary gland • Key to understand that a chemical is NOT being released from the hypothalamus to stimulate prolactin release from the lactotropes—It is high estrogen levels that stimulate the lactotropes to secrete prolactin by suppressing PIH (Prolactin Inhibiting Hormone) production • Decreased estrogen levels stimulate PIH production from the hypothalamus • Prolactin production then stops from the lactotropes Slide 47: Prolactin Cascade (Pregnant) • PIH is produced by the hypothalamus and high estrogen levels causes suppression of PIH in order to start the production of prolactin from the lactotropes in the anterior pituitary gland • Estrogen levels don’t get very high until the end of pregnancy so then the production of milk begins at this point • Oxytocin then kicks in to deliver the baby and milk is released here • Suckling is what maintains the production of prolactin so as long as breast feeding is occurring, prolactin is being produced • When the mother weans the baby and the suckling stops, the PIH is produced by hypothalamus and prolactin production stops
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