COMPLETE Unit 1 Exam Study Guide for Human Anatomy and Physiology II on Endocrine and Reproductive Systems
COMPLETE Unit 1 Exam Study Guide for Human Anatomy and Physiology II on Endocrine and Reproductive Systems Biol 2230-001
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Clemson University Spring 2016 Human Anatomy and Physiology II Unit 1 Exam Study Guide Endocrine System 1. Discuss the differences between neural and endocrine mechanisms of control of body functioning. • Both the nervous and endocrine systems function in maintaining homeostasis in the body • 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 - Has a lag time in a response to a stimulus (Can take from a few seconds to days) 2. Differentiate exocrine and endocrine glands. • Exocrine Glands: - Produce secretions that are not hormones (These secretions are not part of the endocrine system) - Have a duct for the most part where the secretions are secreted into in order for them to go to the appropriate site where its going to execute its activity - Examples: Sweat glands, salivary glands, digestive enzymes • Endocrine Glands: - Endocrine glands produce hormones and are ductless - The hormones are secreted on the surface and are picked up in circulation and transported throughout the body until they reach a target cell with the specific cell receptor - Endocrine glands are highly vascularized to increase efficiency in circulation 3. Identify the neuroendocrine link, and discuss its functioning. • Neuroendocrine link refers to the conjunction of the nervous and endocrine systems working together to function in the body • The nervous system is able to activate endocrine glands via a nervous impulse that travels to the endocrine gland to stimulate it to start secreting its corresponding secretions • The presence of a hormone also has the ability to turn on or off nervous impulses • Specific example of a strong neuroendocrine 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 4. List and differentiate the types of 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 5. Identify the cells at which hormones exert their effects, and discuss the generalized effects hormones can produce. • Hormones affect target cells, which are defined as anything that has a receptor • Hormone action: - When a hormone is secreted on the surface of the endocrine structure, it moves into circulation in the blood stream so that is transported throughout the body and will only have an effect on cells with the receptor specific to that hormone • Different effects of hormone action: a) Open or close ion channels: When the hormone binds to its specific receptor of a cell, it changes the permeability of the cell membrane, which is what allows the changes in ion flow b) Stimulates protein synthesis: o Hormones can stimulate the cell to start producing proteins (Structural or functional) o Ex: Hormone could stimulate the muscle cell to produce actin or myosin to increase muscle mass; an enzyme could be produced to catalyze a reaction; protein could be packaged for export to have an effect elsewhere, etc. c) Activate or deactivate enzymes: Hormones are able to stimulate the production of new proteins or change the activity of an existing protein within a cell d) Promote secretion: (Ex: Mucous, a different enzyme, etc.) e) Stimulate mitosis: Hormones can cause cells to start dividing with the stimulation of mitosis for growth to occur 6. Describe the chemical classifications of hormones. • 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 • 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 • Eicosanoid (NOT a real hormone): - 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: o Biologically active lipids o 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 o Ex: One ovulating ovary secretes prostaglandins so that the sperm know which one to go to b) Leukotrines 7. Describe the two major mechanisms by which these two classes of hormones bring about their effects. • 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) • Amino-Acid Hormones: - 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 - 2 Mechanisms (General Introduction): a) Cyclic AMP Mechanism: Cyclic AMP is the secondary messenger to cause something to happen in the cell b) PIP-Calcium Mechanism: PIP causes something to happen in the cell and then calcium follows with its effect 8. Discuss the two models of amino acid-based action. • 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 • 2 Mechanisms involving Secondary Messengers: a) Cyclic AMP Mechanism: o Hormone binds to a receptor located on the exterior surface of the plasma membrane, which modifies the receptor o A second protein associated with the now modified receptor known as a G protein is activated o The activated G protein is used to activate adenylate cyclase, which is an enzyme that causes the production of cyclic AMP (cAMP) from ATP o cAMP then stimulates the protein kinases enzymes, which phosphorylate proteins (Addition of a phosphate group to a protein) o Phosphorylation by protein kinases to already existing proteins inside the cells either 1) Activates the protein or 2) Deactivates the protein o 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) b) PIP-Calcium Mechanism: o Hormone binds to the membrane bound receptor, which becomes the modified receptor and activates the G protein o The activated G protein causes the activation of phospholipase (PLP) inside the cell, which splits PIP2 into DAG and IP3 o DAG activates protein kinases, which phosphorylate proteins o 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 • Overall idea: These mechanisms 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 • 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 9. Identify the factors that control 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 10. List three kinds of interaction that different hormones acting on the same target cell can have. • 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 11. Explain how hormone release is regulated. • 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 12. List the major endocrine organs, and describe their body locations. • Pituitary: Extends off of the hypothalamus via what is called the infundibulum = pituitary gland’s funnel-shaped stalk + it is divided into 2 parts à posterior (neurohypophysis) and anterior (adenohypophyseal) pituitary glands • Thyroid: Located around the trachea by the isthmus across the front • Parathyroid Glands: Embedded in the posterior portion of the thyroid gland • Adrenal Glands: Paired glands located on top of the kidneys • Pancreas: Located in the abdominal cavity behind the stomach • Gonads: Ovaries and testes • Pineal: Extends from roof of third ventricle in diencephalon of the brain • Thymus: Located beneath the sternum and on top of the heart (Deep to sternum in thorax) 13. Discuss the structure of the neurohypophysis, and describe the effects of its two hormones. • Neurohypophysis (Posterior Pituitary Gland): - Part of the pituitary gland, which extends off the hypothalamus via what is called the infundibulum (Pituitary gland’s funnel-shaped stalk) - The posterior pituitary gland is comprised of nervous tissue - It does NOT produce hormone structures but is instead responsible for storing hormones made originally in the hypothalamus - Releases the hormones into circulation when signaled to do so by the hypothalamus • Hormones: a) ADH (Anti-Diuretic Hormone): - AA based hormone that uses the PIP-calcium mechanism (Activates proteins that are already inside the cell) - 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 b) Oxytocin: - AA based hormone that uses the PIP-calcium mechanism (Activates proteins that are already inside the cell) - Regulates water balance by affecting the kidney tubules and prevent urine formation - The kidneys are stimulated by ADH to reabsorb 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 14. List and describe the adenohypophyseal hormones and their effects. • Adenohypophyseal (Anterior Pituitary Gland): - Part of the pituitary gland, which extends off the hypothalamus via what is called the infundibulum (Pituitary gland’s funnel-shaped stalk) - Anterior pituitary gland is not directly part of the nervous brain, but it is fused to the 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 that are all AA based and use the cyclic AMP mechanism - The hormones the anterior pituitary gland produces are tropic hormones à A hormone whose target cells are other endocrine glands so that it causes the production of another hormone • Hormones: a) 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: o Pituitary Dwarfism: Insufficient concentrations of GH lead to smaller and maintain younger looking features o Giantism: Excess concentrations of GH lead to bigger and older looking features o 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 - GH Cascade: o Cascade: What causes the anterior pituitary gland to start producing hormones and also includes what shuts it back off o 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) o Many kinds of cells are in the anterior pituitary with each cell having different receptors and responding to different signals from the hypothalamus o GH Cascade: o 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) o GH is released then by the anterior pituitary and travels in the blood stream to affect any cells with the GH receptor o 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 o 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 - Direct Actions of GH: o 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 o 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 o 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 o GH encourages the breakdown and release of glucose from glycogen in the liver = diabetogenic effect (Releasing glucose from the storage of glycogen) o 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 - Indirect Actions of GH: o Indirect actions of GH function through IGF (Insulin-like Growth Factors) o IGFs are produced by the liver and require GH presence for activity o GH stimulates an increase in IGFs by the liver o GH binds to IGFs and stimulates the uptake of AA from the blood into cells that stimulates protein synthesis o 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 b) Thyroid Stimulating Hormone (TSH) - TSH is produced by the anterior pituitary gland - Stimulates the development of the thyroid gland and secretion from the thyroid gland - TSH Cascade: o 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 o 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 c) 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.) - ACTH Cascade: o 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 o Increased levels of glucocorticoids shut off CRH which stops the production of ACTH which stops the production of glucocorticoids o Fever, hypoglycemia, and other stressors cause CRH to be produced in the hypothalamus d) 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) - Male o FSH: Stimulates sperm production o LH: Stimulates production of testosterone, which is produced in the tests by the interstitial cells o Testes: Produce gametes (sperm) and testosterone - Female o 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 o LH: Triggers ovulation and development of the female sex hormones (estrogen and progesterone) o After puberty, the FSH and LH work together to cause maturation of some of the ova in the follicles, cyclically - Gonadotropin Cascade o At puberty, the hypothalamus secretes GnRH (Gonadotropin Releasing Hormone) that stimulate the gonadotrope cells of the anterior pituitary gland to secrete FSH and LH o FSH and LH cause the gonads to mature and produce their own hormones o The production of these hormones by the gonads are then what shut off the production of LH and FSH when there are increased levels e) 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 - Prolactin Cascade (Pregnant) o 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 o Estrogen levels don’t get very high until the end of pregnancy so then the production of milk begins at this point o Oxytocin then kicks in to deliver the baby and milk is released here o Suckling is what maintains the production of prolactin so as long as breast feeding is occurring, prolactin is being produced o When the mother weans the baby and the suckling stops, the PIH is produced by hypothalamus and prolactin production stops Hormone-Producing Structures 15. Identify the hormone producing organs, list the hormones each produces, and discuss the actions of each product. a) Thyroid Gland: Thyroid Hormone (Thyroxin) • Two lobes connected by isthmus across the front • Located around the trachea beneath the larynx • Largest pure endocrine gland à Meaning that it only produces hormones • TH is actually 2 separate hormones: a) T 3 Thryoglobulin + 3 iodine b) T 4 Thyroglobulin + 4 iodine • Almost every cell in the body has a receptor for Thyroxin (TH) except the brain, spleen, testes, uterus, and the thyroid gland itself • TH is a major hormone that regulates metabolic activity—Oxidation of glucose • Bringing it together: Hypothalamus releases TRH that stimulates that anterior pituitary gland to release TSH that stimulates the thyroid to release T3and T 4nto the blood stream to bind to specific receptors (Negative feedback mechanism) • TH stimulates the oxidation of glucose so that it is broken down by the cell to produce energy (Increases basal metabolic rate) and liberates heat -‐Calorigenic effect: Heat produced when glucose is broken down by the cell for energy • TH helps maintain blood pressure à It causes can increase of adrenergic receptors - TH binds to norepinephrine that then binds to the adrenergic receptors on the blood vessels that causes vasoconstriction so that blood pressure is increased • Regulates tissue growth and development, especially with skeletal and nervous systems -‐Ex: Permissiveness à Gonadotropins (LH and FSH) cause the development of sex organs and if TH is circulating at the same time as these, great sex organ development is stimulated • The thyroid is unique in that it can store hormones (2-3 months supply worth) • TSH normally is secreted around the time one gets tired (Peaks before sleep and remains high at night) • Produced TH is stored in the extracellular colloid • When energy is needed during the day, the thyroid secretes TH • Effect of sleep deprivation: Not producing as much TH and therefore energy is lost b) Thyroid Gland: Calcitonin • Hormone produced by the parafollicular cells = C cells (C is for calcitonin) • Its effects are to lower blood calcium levels à It takes calcium out of circulation and stores it in bone and muscle • Calcitonin is most important during rapid skeletal growth and reformation à Plays the biggest role in childhood (And does not have as big of a role once one hits puberty) • Inhibits osteoclast activity à Shuts off osteoclasts so that the breaking down of bone to release calcium is inhibited c) Parathyroid Gland: Parathyroid Hormone (PTH) • Embedded in the posterior portion of the thyroid gland • Has 2 types of cells: Oxyphil and Chief • PTH is the most important hormone in controlling blood calcium balance of blood • Calcitonin causes a reduction in blood calcium • PTH is an antagonist so that is causes an increase in blood calcium • Therefore, triggers for PTH to be produced by the chief cells is low blood calcium • PTH stimulates the osteoplasts to release calcium and some phosphates into the blood stream (Breaking down bown) • PTH also enhances reabsorption of calcium in the kidneys so that it is kept in the body and not excreted out via urination • PTH increases absorption of calcium in the intestines • Promotes the kidneys to convert Vitamin D to its active form, calcitriol (D 3—Necessary to be present in the intestines in order for calcium to be absorbed by the body d) Adrenal Glands: General Information • Paired glands located atop each kidney • Each is comprised of a cortex and medulla • Cortex: Glandular epithelium = secretory epithelial cells • Medulla: Part of the sympathetic nervous system • Norepinephrine is a neurotransmitter that is released by post-ganglionic sympathetic fibers (Secreted by the medulla) • The cortex secretes steroid hormones • All adrenal secretions help fight off stress • 3 classes of steroids (Corticosteroids) are produced by the cortex: Mineralocorticoids, glucocorticoids, gonadocorticoids • This means that there are 3 different regions and different types of cells that correspond with each steroid as a result • ATCH (Adrenocorticotropic Hormone) is secreted from the anterior pituitary gland and affects the cortex which causes the production of many of the steroids e) Adrenal Glands: Mineralocorticoids (Aldosterone) • Major hormone from mineralocorticoids is aldosterone (95%) • Aldosterone helps regulate electrolyte concentrations of extracellular fluids in our body—Particularly the sodium-potassium combination that are involved in membrane potentials • As aldosterone regulate concentration of electrolytes, water will follow concentration gradients so aldosterone is very important with regulating blood pressure • Aldosterone stimulates reabsorption of sodium in the kidneys à As blood is filtered, substances are in the filtrate that will go out as urine unless they are reabsorbed into the circulatory system • An osmotic gradient is created with the reabsorption of sodium back into the blood stream by the kidneys so that there is more sodium in the blood stream than in the filtrate that is to be urinated out of the body à Water follows the sodium and this regulates blood volume and therefore blood pressure • Other ions are also linked to sodium and play a role in blood pressure and blood volume control • Essentially, with the reabsorption of sodium by the kidneys, the blood volume changes and this affects the blood pressure • Reabsorption of sodium in the kidneys is aldosterone’s primary action but the corticosteroid is able to affect other glands as well: Sweat, saliva, gastric juice glands for example f) Adrenal Glands: Glucocorticoids (Cortisol) • The major hormone is cortisol • Cortisol regulates energy metabolism of most cells in the body and helps resist stress • Examples of stimulants of stress for cortisol: Cold weather, emotional stresses, etc. • Cortisol affects energy metabolism by maintaining blood glucose levels by promoting gluconeogenesis (This is not the main way to regulate blood glucose levels though) • Gluconeogenesis: The production of new carbohydrate from non- carbohydrate sources – FA and proteins are broken down to be used for making glucose and therefore for energy • Cortisol also is related to blood volume and maintaining it à It prevents water from leaving the blood and going into body cells (Inhibits water uptake by body cells) g) Adrenal Glands: Gonadocorticoids (DHEA) • Gonadocorticoids are produced by zona reticularis of the adrenal cortex • The major hormones of the gonadocorticoids are weak androgens à DHEA • DHEA is a precursor for testosterone or estrogen • Glucocorticoids (DHEA included) contribute to the onset of puberty; Prior to puberty there is little produced by the adrenal cortex • DHEA also provides sex drive for women h) Adrenal Medulla: Epinephrine and Norepinephrine • The adrenal medulla is sympathetic nervous tissue à It uses norepinephrine and epinephrine as a neaurotransmitter that also work as hormones too by making sugars available for energy, increasing circulation, and increasing heart rate • Essentially the adrenal medulla produces modified sympathetic neurons that are released into the circulatory system to the liver and throughout the body (They are not sent to a synapse) • Epinephrine and norepinephrine together makeup adrenaline • Stress promotes sympathetic nervous activity (Fight or flight response) which leads to the release of epinephrine and norepinephrine because the nervous tissue has been activated which has also led to an increase in blood sugar as a result • Fight or flight: Means the body is getting ready to fight stress or flee from it and to do this, there has to be energy available which is accomplished by stimulating the release of glucose into the bloodstream • Norepinephrine especially causes the constriction of blood vessels à increase in blood pressure • The fight or flight response causes blood to be sent from the extremities to the brain, heart, and skeletal muscles and circulation is also geared primarily more towards preganglionic sympathetic nerve endings • The release of epinephrine and norepinephrine is also a much shorter response for stress and demonstrates the link between the nervous and endocrine systems i) Pancreas: General Information • The pancreas is located in the abdominal cavity behind the stomach • Has both endocrine and exocrine functions à Therefore, more than one type of cell is present • Exocrine part: Secretes enzymes into a duct that dumps into the small intestine where there is digestion involvement • Endocrine part: Secretes hormones that go to the surface and get into the blood stream (Insulin and glucagon) j) Pancreas: Glucagon • Functions on the liver to release glucose into the blood stream as free glucose via taking the glucose out of storage (Most glucose is stored in the liver as glycogen) • First, glycogen is broken down into glucose that is released into the bloods stream • Glucagon also stimulates glucose to be synthesized from lactic acid: -‐ When muscles are being used a lot, lactic acid is produced and then circulates throughout the body until it reaches the liver -‐ Liver uses lactic acid as an energy source which can then be converted back into glucose and be used by muscle (or other cells) again for energy -‐ Overall: The waste product of lactic acid from muscle contraction = food source for liver = food source for muscle again • Glucagon essentially function sin increasing blood glucose levels by releasing it into the blood k) Pancreas: Insulin • Insulin decreases blood glucose levels by signaling cells to take up glucose out of the blood stream • Influences protein and fat metabolism (Anabolic hormone so signals for the build up of these) • Signals for glucose to be taken out of the blood stream via enhancing membrane transport of glucose into cells • Inhibits the breakdown of glycogen into glucose (Left as storage) • Inhibits the conversion of AA or FA (Fats) to glucose • Promotes glycogen production predominantly in the liver when there is excess glucose • Rest of excess glucose goes to fatty acid synthesis and further triglyceride storage in adipose tissue • It is important to note that there is some oxidation of glucose when cells take up glucose by the cell for the needed amount of energy by the cell at that time • Glucocorticoids play a similar role with blood sugar levels l) Gonads: Testosterone, Estrogen, and Progesterone • Testes • Ovaries • Both produce the same sex hormones that the adrenal cortex produces (Acts as precursors at this point in the adrenal cortex) à Testosterone and estrogen • Male: Testosterone • Female: Estrogen, progesterone • Both genders produce all but in different amounts • Testosterone: -‐ Stimulates the maturation and maintenance of male reproductive organs -‐ Secondary sex characteristics à Enlarged muscle mass, increased body hair, oil production, deeper voice, etc. -‐ Promotes sex drive -‐ Stimulates male gamete (sperm) production • Estrogen: -‐ Stimulates the maturation and maintenance of the female reproductive organs -‐ Female secondary characteristics à Accumulation of fat in hips/breasts, smoother skin, less oil, higher voice, less hair, etc. • Progesterone: -‐ Functions with estrogen to promote breast development -‐ Functions with estrogen to cause cyclic changes in the uterine lining (menstrual cycle) m) Pineal Gland: Melatonin • Pea size gland that extends from the third ventricle of diencephalon and is made up of pinealocytes • Promotes drowsiness • Inhibits sexual maturation à Prior to puberty almost no gonadotropin is produced because melatonin shuts it off • Therefore, melatonin helps time puberty (Reduces in levels when puberty is about to occur) • Melatonin is continued to be produced in adulthood and is instead used to make us feel drowsy à Sunlight (UV radiation) inhibits the pineal gland so when the sun sets, inhibition is lost and melatonin levels increase so we sleep (Sleep-wake cycle) n) Thymus: Thymoproteins, Thymic Factor, Thymosins • Located beneath the sternum an don top of the heart (Deep to sternum in thorax) • Size diminishes with age à It’s very active in an embryo and child • 3 classes of hormones are produced that all influence the development of T lymphocytes (Specialized white blood cells that function to give us immunity): a) Thymoproteins b) Thymic Factor c) Thymosins • When there is an embryo/small child, the thymus produces these hormones that cause the T lymphocytes to be produced to get the body ready to have an immune system before they come in contact with pathogens • With age, immunity declines so it is important to have a strong immunity as a child because it will have to be carried with us until death 16. Describe the histological composition of each of the endocrine glands to illustrate how the hormones are produced. a) Thyroid Gland: Thyroid Hormone • The thyroid gland is composed of follicles that are made up of epithelial cells (cuboidalepithelium) that produce thyroglobulin protein which is stored in the follicles as colloid substance • Thyroid hormone is derived from colloid • TSH (Thyroid Stimulating Hormone) stimulates the follicles to produce thyroglobulin, which is a component of thyroid hormone (TH) • Thyroglobuilin will combine with iodine to make TH = thyroxin • The thyroid gland is unique because it is the only endocrine gland that can store its secretions à All other endocrine gland secrete hormones that are immediately released into the blood stream • The anterior pituitary gland secretes TSH which travels to the thyroid gland via blood vessels • TSH triggers the production of thyroglobulin by cuboidal cells that accumulates in the follicles as colloid • TSH also stimulates active transport of iodine into the follicles • Thyroglobulin is then iodized in 2 different circumstances: (Occurring in the colloid) a) Thyroglobulin + 1 iodine = T à1Leads to form T 3 b) Thyroglobulin + 2 iodine = T à2Leads to form T 4 • T and T are still in the colloid at this point and the thyroid will secrete 3 4 both from the colloid so that they move back into the follicular cells to be packaged into lysosomes • The lysosomes transport T a3d T to4where they are released into the bloodstream via lysosomal enzymes • Most TH is produced at night b) Thyroid Gland: Calcitonin • The thyroid gland also contains other cells located between the follicles called parafollicular cells that produce calcitonin (A different hormone) • Calictonin shuts off osteoplasts (Cells in bones) c) Parathyroid Gland: Parathyroid Hormone (PTH) • 2 Types of Glandular Cells: 1. Oxyphil: It is not clear what these cells do 2. Chief: Secrete parathyroid hormone (PTH) • Able to tell the difference between the thyroid and parathyroid because each have different follicles and tissues d) Adrenal Glands: Mineralocorticoids (Aldosterone), Glucocorticoids (Cortisol), Gonadocorticoids (DHEA) • 3 zones where each zone produces a different class of corticosteroids: a) Zona glomerulosa (Mineralocorticoids) b) Zona fasiculata (Glucocorticoids) c) Zona reticularis (Gonadocorticoids) e) Adrenal Medulla: Epinephrine and Norepinephrine • Chromaffin cells are modified ganglionic sympathetic neurons that secrete epinephrine and norepinephrine (catecholamines) f) Pancreas: Glucagon and Insulin • Most of the pancreas is composed of the acinar pancreas that is made up of acinar cells = exocrine portion that produces enzymes for digestion • The Islets of Langerhans (Pancreatic islets) are located throughout acinar portion • 2 types of cell sin the Islets of Langerhans: Alpha (Produce glucagon) and beta (produce insulin) à Both of these hormones are antagonists g) Gonads: Testosterone, Estrogen, Progesterone à Information not provided on power point h) Pineal Gland: Melatonin • Pinealocytes are the hormone producing cells in the pineal gland • Responsible for the production of melatonin i) Thymus: Thymoproteins, Thymic Factor, Thymosins à Information not provided on power point 17. Outline the feedback mechanisms that control endocrine gland activity. a) Thyroid Gland: Thyroid Hormone • T and T are released into the blood stream and must bind to transport 3 4 proteins in order to reach specific cell receptors where they are going to have an effect • TBG (Thyroxin Binding Globulin) is the major transport protein where it delivers TH to target cells • TH is an AA based hormone that binds to intracellular receptors (An exception of AA based hormones normally binding to receptors on the surface of cells) à TH functions like a steroid then which is why TBG is so important so that it helps with getting TH inside the cell to its receptors • Transcription by TH is then promoted like a steroid • Increasing levels of T4(Thyroxine) inhibit TSH production while falling levels reversibly stimulate TSH production that produces the T 4Negative feedback) • An increase in body energy needs stimulate the release of TRH that stimulates TSH that stimulates TH release a) Thyroid Gland: Calcitonin • High calcium levels are humoral stimuli for C cell (parafollicular cell) activity • Low calcium levels inhibit C cell activity à As take out calcium out of circulation, levels get lower so the C cells shut off and calcitonin production stops b) Parathyroid Gland: Parathyroid Hormone (PTH) à Information not provided on power point c) Adrenal Glands: Mineralocorticoids (Aldosterone) • The anterior pituitary gland secretes ATCH that stimulates the adrenal cortex to produce hormones (This is one method of aldosterone production that is not the major method) • Aldosterone secretion by the adrenal cortex is stimulated by: a) Humoral effects: High potassium levels and low sodium levels in the bloodstream b) Low blood volume c) Low blood pressure • ** ATCH functions predominantly on glucocorticoids and not mineralocorticoids (Review) d) Adrenal Glands: Glucocorticoids (Cortisol) • The hypothalamus secretes CRH which stimulates the anterior pituitary gland to secrete ACTH which stimulates the adrenal cortex to produce cortisol (Zona fasiculata) • ** ACTH results are predominantly in the production of glucocorticoids • As cortisol is produced and levels rise, it inhibits CRH and therefore ACTH release that shuts cortisol production off e) Adrenal Glands: Gonadocorticoids (DHEA) • CRH from the hypothalamus stimulates ACTH from the anterior pituitary gland to stimulate the production of gonadotropins • There does not seen to be an inhibitor for the production of gonadotropins à Therefore, one the gonadotropins being producing, they continue to do so throughout life f) Adrenal Medulla: Epinephrine and Norepinephrine à Information not provided on power point g) Pancreas: Glucagon • Humoral control: Low blood glucose (sugar) levels and high AA levels stimulate the pancreas to produce glucagon from the acinar cells of the Islets of Langerhans • High blood glucose and low AA levels shuts off the production of glucagon • Sympathetic stimulation of the adrenal medulla promotes the release of: Epinephrine and norepinephrine à Help increase blood glucose levels as well and will stimulate glucagon production by the pancreas • Somatostatin (GHIH) production also shuts off glucagon – In terms of not needing as much energy when one is done growing h) Pancreas: Insulin • High blood sugar levels stimulate the beta cells of the Islets of Langerhans in the pancreas to produce • High levels of AA and FA also stimulate insulin production • Parasympathetic release of acetylcholine stimulates the release of insulin as well • Hormonal influences also exist • ** Sympathetic nervous activity relates to glucagon and parasympathetic nervous activity relates to insulin i) Gonads: Testosterone, Estrogen, Progesterone • Production of the sex hormones (gonadic hormones) are stimulated by gonadotropins • As high levels of gonadotropins are present, they shut themselves off j) Pineal Gland: Melatonin à Information not provided on power point k) Thymus: Thymoproteins, Thymic Factor, Thymosins à Information not provided on power point 18. Other Hormones: a) Heart • Releases ANP (Atrial Natriuretic Peptide) that shuts off aldosterone production by inhibiting renin production so that there is an increase in urinary output à Sodium is not reabsorbed • ANP production is promoted by high blood pressure, which is reduced by getting the fluids out of the blood via increasing urine production b) Gastrointestinal Tract • Many places along the GI tract secrete hormones that affect the digestive activity • Ex: Hormone produce by the small intestine will affect stomach activity; hormone produced by the stomach affects small intestine activity, etc. c) Placenta • Both the female and embryo produce the placenta organ • Hormone producing structure of estrogen, progesterone, and hCG (Human Chorionic Gonadotropin) • hCG = what pregnancy tests detect • All of these hormones produced by the placenta will influence the development of the fetus and ovary maintenance d) Kidneys • Produce erythropoietin that stimulates the production of red blood cells e) Skin • Produces cholecalciferol that is an inactive form of Vitamin D3 • It is converted to the active form of Vitamin D3 = calciferol under the influence of sunlight • Vitamin D3 is also important for the absorption of calcium in the digestive tract f) Adipose Tissue • Produces leptin • As one takes in excess calories, it is put into storage in adipose tissue, and as adipose tissue increases in amount, the production of leptin increases which reduces appetite and encourages an increase in energy expenditure to try to reduce the amount of energy stored • Also produces resistin that is an antagonist of insulin **Endocrine Gland Development • Endocrine glands can arrive from all 3 embryonic germ layers • Mesoderm: Gives rise to the steroid producing endocrine glands • Ectoderm and endoderm: Give rise to the AA derived hormones • Endocrine gland activity changes with age (Excellent ex: Thymus, reproductive hormone activity, etc.) • Endocrine gland activity can be influenced by environmental cuesà Ex: If one is cold, the thyroid gland can release more thyroid hormone to increase metabolic activity to increase heat production 19. Discuss four mechanisms of mineralocorticoid secretion. a) Renin-Angiotensin Mechanism • This is main method in which aldosterone is stimulated by • The liver is continuously producing a protein called angiotensinogen that is an inactive form of a protein • The kidneys, when stimulated properly, will produce renin that converts the inactive angiotensinogen into the active form called angiotensin • Angiotensin stimulates the adrenal cortex to produce aldosterone that has effects on the kidneys to reabsorb sodium • Low blood pressure also stimulates the kidneys to start producing renin • Because the liver is producing the inactive angiotensinogen all the time, the production of renin is key for aldosterone production • Overall, there are many other ways that stimulate aldosterone production: Combined effects of the nervous and endocrine activity that maintain homeostasis in the body so there’s a lot of interaction to fine tune all of the complexities that go into relations with aldosterone b) Plasma Concentration Mechanism • High potassium and low sodium in the blood have a direct effect on the zona glomerulosa (Where the mineralocorticoids are produced à stimulate aldosterone production) • Low potassium and high sodium in the blood inhibit the zona glomerulosa c) ACTH Mechanism • Stress stimulates CRH production in the hypothalamus à Stimulates corticotrope cells in the anterior pituitary gland to release ACTH à Stimulates aldosterone production in the zona glomerulosa of the adrenal cortex (Not much though with this mechanism) d) Atrial Natriuretic Peptide (ANP) • ANP is a hormone produced by the heart and is secreted due to high blood pressure • High blood pressure puts a lot of stress on the heart so ANP is secreted to inhibit renin which in turn inhibits aldosterone production Reproductive System 20. Describe the structure and function of the testes, and explain the importance of their location in the scrotum. • The testes are where gametes (Sperm) are produced • There are 2 testis that are divided into different compartments called lobules • Seminiferous tubules: Site of sperm production (Spermatogenesis) but are not capable of fertilization at this site • The seminiferous tubules have a hollow center = lumen containing cells on the edges that allows for the passage of immature sperm to pass through to the tubulus rectis à rete testis à efferent ductules à epididymis • Epididymis: Where sperm is stored and maturation occurs • Sperm will only be released via sexual stimulation; otherwise, sperm is able to be stored for several months and then it will be phagocytized if not released • The interstitial cells of the testes are not related to the testes tubules but produce testosterone and other hormones that stimulate sperm production in the seminiferous tubules • In order for the testes to produce viable sperm, the testes must be 3 degrees below body temperature (34 degrees C) – Testes are located outside of the pelvic cavity • Testicular blood flow to maintain lower temperature: - Testicular arteries supply blood to the scrotum and they pass out of the body cavity, pass through the pampiniform plexus, and then are drained by the testicular veins - How the lowering of the blood temperature works: When the testicular arteries pass through the pampiniform plexus, the heat is transferred from the arterial supply to the drain of the testicular veins to ensure that the blood is cooled before reaching the testes • Scrotum: - Sac-like structure composed of skin and superficial fascia that houses the testes - The testes are separated into 2 different compartments - Allows the maintenance of optimal temperature via the dartos and cremaster muscles à Able to contract and relax to change how close the testes are to the abdominal cavity based on temperature changes 21. Describe the structure of the penis, and identify the physiological changes that occur during the reproductive process. • The penis is a specialized copulatory organ that deposites sperm inside the female reproductive tract and is the pathway for urine flow • Base: Root of the penis • Most of the penis is the shaft • Glans: Head of the penis and covered with prepuce (foreskin) • Erectile Tissue: Composed of cavernous tissue that is spongy epithelial and connective tissue + highly vascularized - Made up of corpora cavernosa (2 units that make up mass of penis) and corpus spongiosum (1 unit that surrounds the urethra) - Sexual arousal causes blood to be diverted towards the penis that fills the cavernous tissue so that it becomes erect (Due to parasympathetic response to nitric oxide when sexually aroused) - Both of the erectile tissue is composed of smooth muscle and vascular space - As blood fills the cavernous tissue, the arteries that supply blood and the veins that drain blood of the penis get squeezed so that the blood cannot leave (Leaves when sexual arousal removed) - Referring to slide 8 in the Reproductive System PPT: In the front in the figure, there is a separate body of corpus spongiosum tissue so that as the blood fills the cavernous tissue, the corpus spongiosum body prevents crushing of the urethra in order to keep it open so sperm can be released from the male’s body • Penis and scrotum together = external genitalia • Male Reproductive Physiology Erection: - Sexual arousal in the male is divided into two components: a) Parasympathetic portion (Erection phase): o Sexual stimulation will stimulate parasympathetic nervous activity to release nitric oxide as the base of the penis that causes the blood flow to increase the penis size (Dilation of the arterioles) o As blood is delivered to the penis, the erectile bodies fill with blood o Corpora cavernosa expands, which compressed the drainage veins so that the blood is trapped o Parasympathetic stimulation also releases the pre- ejaculatory fluid by the bulbourethral glands b) Sympathetic portion: o Continued tactile stimulation provokes massive sympathetic nerve discharge which will result in ejaculation o Smooth muscle contraction, peristaltic contractions, and accessory gland contraction (Ex: Pr
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