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The endocrine system
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- 1diabetes type 1insulin producing cells in the islets of Langerhans are destroyed, is an auto immune disease
- 2diabetes mellitus 2end organ insensitivity to insulin
- 3why is diabetes dangerous, both type 1 and type 2can cause blood glucose to be ten times higher than normal, which can cause damage to several organs such as the retina of the eye, the glomeruli of the kidneys, the coronary vessels of the heart and cerebral vessels of the brain and the nerve extremeties
- 4coronary vesselsthe two vessels, artery and vein that supply the muscles of the heart itself
- 5diseases caused by diabetesdiabetes can cause blindness, kidney failture, heart attacks and strokes and amputation
- 6glandsorgans of the endocrine system, secretes hormones
- 7how do hormones workhormones travel throuhg the bloodstream to travel to distant target tissue, at the tissue the hormones bind to receptors and induce a change in gene expression or cellular functioning
- 8how can hormones be classified by their chemical identitieshormoens can be peptides, steroids or amino acid derivatives
- 9peptide hormonespeptide hormones are all derived from largerpolypeptides that are cleaved during posttranslational modification, small units are transported to golgi for mods that can activate the hormone and direct tocorrect location in the cell, these hormones are released by exocytosis after being packaged into vesicles
- 10how do peptide hormones bind to the target?peptide hormones are charged and thus cannot pass through the plasama membrane, so these hormones can only bind to extracelluar receptors, they are FIRST MESSENGERS, they trigger the transmission of a second messenger
- 11signaling cascadethe connection between the hormone at the surface and the effect brought by the second messenger within the cell, at each step there is a possiblity of AMPLIFICATION
- 12what are some common secondary messengers?cyclic adenosine monophosphate (cAMP), inositol triphosphate (IP3) and calcium
- 13G coupled protein receptorsbinding of a peptide hormone triggers the receptor to activate or inhibit the adenylate cyclase enzyme, which either raises or lowers cAMP levels, cAMP can bind to intracelluar targets such as protein kinase A which phosphorylates transcription factors like cAMP response element binding protein (CREB) to exert the hormone's ultimate effect, kinase A can also modify other enzymes as well as transcription facotr and can have a rapid or slow effect on the cell
- 14how would you describe the effects of peptide hormones in general?peptide hormones are usually rapid but short lived because these hormones act through transient second messenger systems, they are quick to turn on and off but their effects do not last long without constant stimulation
- 15how do peptide hormones travel?peptides are generally water soluble and can freely travel through the blood stream and thus do not require carriers, which is in stark contrast to steroid hormones
- 16where are steroid hormones made and what are they generally made from?steroid hormones are derived from cholesterol and are produced primarily by the gonads and adrenal cortex
- 17how do steroid hormones target the cell?steroids are generally derived from nonpolar molecules and can easily cross the PM, their receptor are usually intracelluar or intranuclear, upon binding to the receptor, the steroid hormone receptor complexes undergo conformational changes, the receptor can bind directly to DNA resulting in increased or decreased transcription of particular genes, depending on the steroid
- 18dimerizationone common form of conformational change for steroids, the pairing of two receptor hromone complexes
- 19in general what are the effects of the hormone molecules?effects of steroid hormones are slower but longer lived than peptide hormones because steroid hormones cause alterations in the amount of mRNA and proteins present in a cell by direct action on DNA
- 20insulin is what type of hormone?insulin is a peptide hormone, so it has to be released at every meal in order to be active, it has a fast onset but is slow acting
- 21how are steroid hormones transported?steroid hormones are not water soluble and thus must be carried by proteins in the bloodstream to be able to travel around the body, some of these proteins are very specific and only carry one hormone
- 22are steroid hormones active when traveling?generally no , when a steroid is attached to a carrier it is usually inactive, it must first dissociate from the carrier to function
- 23how can the levels of protein carriers affect hormone concentration (steroids)?levels of carrier proteins can change the levels of active hormone, if a lot of carriers bind to the hormones then were would be little free hormones left and the body would perceive this as less hormones
- 24amino acid derivative hormonesless common then peptide and steroid hormones, but include some very important hormones, I.E epinephrine, norepinephrine, triiodothyronine, and thyroxine, these hormones are derived from one or two amino acids with few add mods
- 25chemistry of amino acid derivative hormones?they are a lot less predictable, the catecholamines (epinephrine and norephinephrine) bind to G protein coupled receptors and have fast onset / short lived like peptide hormones while the thyroid hormones bind intracellularly and have a slower onset but longer duration like steroid hormones, they regulate metabolic rate over a long period of time
- 26direct hormonesare secreted and then act directly on a target tissue, I.E insulin released by the pancreas causes increased uptake of glucose by muscles
- 27tropic hormones- require an intermediary to act, IE gonadotropin relasing hormone (GnRH) from the hypothalamus stimulates the release of luteinizing hormone (LH) and FSH, LH then acts on the gonads to stimulate testosterone production in male and estrogen production in female, GnRH and LH do not cause direct changes in the physiology of muscle, bone and hair follicles, rather they stimulate the production of another hormone by another endocrine gland that acts on these target tissues, tropic hormones usually originate in the brain and anterior pituitary gland, as these structures are involved in coordination of multiple processes within the body
- 28most peptide and amino derivaitve hormones have names that end in-in or -ine, (insulin, vasopressin, thyroxine, triiodothyronine)
- 29most steroid hormones have names that end in-one, -ol, or -oid (testerone, aldoesterone, and other mineral corticoids, cortisol and glucocorticoids)
- 30list of endocrine organshypothalamus, pituitary, thyroid, the parathyroid glands, the adrenal glands, the pancreas, the gonads, and the pineal gland are endocrine glands
- 31organs that have endocrine functions but are not endocrine organsthese organs are not endocrine organs because it is not their primary function, these organs include, the kidneys, gastrointestinal glands, heart and thymus
- 32hypothalamusthe bridge between the nervous and endocrine system, by regulating the pituitary gland through tropic hormones, the hypothalamus is capable of having organism wide effects
- 33where is the hypothalamus located?the hypothalamus is located in the forebrain, directly above the pituitary gland and below the thalamus
- 34what are the three sections of the hypothalamus?the three sections are the lateral, ventromedial and anterior hypothalamus, these nuclei play roles in emotional experience, aggressive behavior, metabolism, temperature regulation and water balance
- 35hypophyseal portal systemis a blood vessel system that directly connects the hypothalamus with the anterior pituitary, hormones travel directly to the anterior pituitary and cannot be found in appreciable amounts in the rest of the systemic circulation
- 36gonadotropin relasing hormone (GnRH)releases follicle stimulating hormone (FSH) and luteinizing hormone (LH) in the ANTERIOR PITUITARY
- 37growth hormone releasing hormone (GHRH)growth hormone (GH) anterior pituitary
- 38thyroid releasing hormone (TRH)thyroid stimulating hormone (TSH)
- 39corticotropin releasing factor (CRF)adrenocorticotropic hormone (ACTH)
- 40prolactin inhibiting factor (PIF)is actually dopamine, and is the one exception in the hypohalamus which when released causes a decrease in prolactin secretion
- 41how is GnRH controlled?negative feedback
GnRH-> ACTH-> cortisol which inhibits both the GnRH and the ACTH - 42axesthree organ systems, examples are the hypothalamic-pituitary-adrenal (HPA) axis and the hypothalamic -pituitary - ovarian (HPO) axis
- 43can the anterior pituitary gland release hormones by itself?most hormones in the ant pituitary require a factor to be released from the hypothalamus with the exception of prolactin, where the PIF from the hypo actually inhibits its secretion
- 44how is the posterior pituitary activated?the post pituitary does not actually receive input from the hypophyseal portal system, rather the neurons in the hypothalamus send their axons down the pituitary stalk direct ly into the posterior pituitary
- 45vasopressin (ADH) antidiuretic hormoneADH is also called arginine vasopressin. It’s a hormone made by the hypothalamus in the brain and stored in the posterior pituitary gland. It tells your kidneys how much water to conserve.
ADH constantly regulates and balances the amount of water in your blood. Higher water concentration increases the volume and pressure of your blood. Osmotic sensors and baroreceptors work with ADH to maintain water metabolism.
Osmotic sensors in the hypothalamus react to the concentration of particles in your blood. These particles include molecules of sodium, potassium, chloride, and carbon dioxide. When particle concentration isn’t balanced, or blood pressure is too low, these sensors and baroreceptors tell your kidneys to store or release water to maintain a healthy range of these substances. They also regulate your body’s sense of thirst. - 46oxytocinis a hormone that stimulates uterine contraction during labor, as well as milk letdown during lactation
- 47FLAT PEGproducts of the anterior pituitary
Folicle stimulating hormone, lutenizing hormone, adrenocortocotropic hormone, thyroid stimulating hormone, prolactin, endorphins, growth hormones
all four of the hormones in FLAT are tropic hormones and the three hormones in PEG are direct hormones - 48how does lactation begin in femalesprolactin is unsual in that dopamine from the hypothalamus actually decreases its secretion, high levels of estrogen and progesterone prepare the milk ducts for lactation, but it isnt till after the expulion of the placenta (afterbirth) when estrogen, progesterone and dopamine drop for lactation starts
- 49growth hormonesprevent glucose uptake in certain tissues ( those not growing) and stimulates the breakdown of fatty acids, increases the availability of glucose overall
- 50acromegalyadults, the long bones are sealed off (epiphyseal plates) but small bones are still exposed, this causes bones like the hands, feet and heat to expand
- 51ADH (textbook)ADH is secreted in response to low blood volume (as sensed b y baroreceptors) or increased blood osmolarity (as sensed by osmoreceptors) its action is at the level of the collecting duct, where it increases the permeability of the duct to water, this causes greater reabsorption of water from the filtrate in the nephron, this causes increased blood volume and higher blood pressure
- 52oxytocinreleased during childbirth for coordinated contractions, secretions also promote milk ejection, may also be involved in bonding behavior, POSITIVE feedback loop, causes more and more uterine contractions, until child birth ends
- 53does the posterior pituitary synthesize any hormones?no, the hormones are synthesized in the hypothalamus and released in the posterior pituitary gland
- 54function of the thyroidsetting basal metabolic rate (regulates by releasing triidothyronine (T3) and thyroxine (T4) and calcium homeostasis (calcitonin)
- 55triiodothyronine (T3) and thyroxine (T4)produced by the iodination of the amino acid tyrosine in the follicular cells of the thyroid, the numbers 3 and 4 refer to the number of iodine atoms attached to tyrosine
- 56how do T3 and T4 work?makes energy production more or less efficient, increased amounts will lead to celluar respiration, this leads to a greater amount of protein and fatty acid turnover by speeding up both synthesis and degradation of these compounds, high levels of T3 and T4 negatively feedback into TSH and TRH
- 57what is one way the negative feedback loop of the thyroid works?the thyroid hormones, T3/T4 would decrease the sensitivity of TSH of the anterior pituitary to TRH from the hypothalamus
- 58what causes hypothyroidism?a defieciency in iodine or inflmmation of the thyroid may result in decreased or no thyroid hormones from being secreted,
- 59cretinismdevelopmental delay and mental retardation, may be caused by hypothyroidism
- 60what can cause hyperthyroidism?may result from a tumor or thyroid stimulation
symptoms - heigthened activity level, increased body temperature, increased respiratory and heart rate, heat intolerance and weight loss - 61where is calcitonin produced and what does it do?calcitonin is produced in the C cells (parafollicular cells) of the thyroid and it TONES down the production of calcium in the blood
- 62how does calcitonin accomplish what it needs to do? (three ways)calcitonin decrease plasma calcium levels in three ways, increased calcium excretion from the kidneys, decreased calcium absorption from the gut and increased storage of calcium in the bone
- 63what stimulates calcitonin production?increased levels of calcium in the bloodstream
- 64parathyroidare four small pea sized structures that sit on the posterior surface of the thyroid, releases parthyroid hormone which is the opposite compared to calcitonin
- 65what does the parathyroid hormone do?it increases blood calcium levels by decreasing kidney excretion, increases calcium absorption at the gut (via vitamin D) and also causes increased bone resorption, also functions to maintain phosphorus homeostasis ( not net change to phosphorus levels)
- 66PTH and vitamin Danother function of parathyroid hormone is the activation of vitamin D which is neccesary for the absorption of calcium and phosphorus in the gut
- 67why is calcium important>bone structure and strength, release of neurotransmitters from neurons, regulation of muscle contraction, clotting o f blood (Calcium is a cofactor), calcium also plays a role in cell movement and exocytosis of celluar materials
- 68adrenal glandslocated on top of the kidneys, each adrenal gland contains a cortex and a medulla, each part of the gland is responsible for the secretion of a different hormone
- 69what hormone does the adrenal cortex secrete?the adrenal cortex secretes corticosteroids, these are steroid hormones that can be divided into three functional classes, glucocorticoids, mineralcorticoids and cortical sex hormones
- 70what do glucocorticoids do?are steroid hormones taht regulate glucose level, also affect protein metabolism, most common are cortisol and cortisone
Pathway
CRF-> ACTH -> glucocorticoids - 71what does cortisol do?cortisol and cortisone raise glucose by increasing gluconeogenesis, decreases protein synthesis, also can decrease inflammation and immunologic responses, cortisol is known as a stress hormone, it increases blood sugar and provides a ready source of fuel in case the body must quickly react
- 72mineralcorticoids? what is the most noteworthy one?used in salt and water homeostasis, most profound effects are on the kidneys
aldosterone increases sodium reabsorption in the distal convoluted tubule and collecting duct of the nephron - 73aldosteronealdosterone increases sodium reabsorption in the distal convoluted tubule and collecting duct of the nephron, water follows the sodiu cations into the bloodstream INCREASING BLOOD VOLUME/PRESSURE, but plasma osmolarity remains the same, also decreases the reabsorption of potassium and hydrogen ions in the same segments of the nephron promoting their excretion
- 74osmolaritythe concentration of a solution expressed as the total number of solute particles per liter.
- 75ADH vs aldosteroneADH changes plasma osmolarity, aldosterone does not change it
- 76renin-angiotensin-aldosterone systemdecreased blood pressure causes the juxtaglomerular cells of kidney to secrete renin, which cleaves an inactive plasma protein, angiotensinogen to its active form angiotensinI, angiotensin I is then converted to angiotensen II by angiotensin converting enzyme (ACE) in the lungs, angiotensin stimulates the adrenal cortex to secrete aldoesterone, once the blood pressure is restored negative feedback causes a decrease in renin production
- 77cortical sex hormonesandrogens and estrogens, adrenal testerone plays a small role in males because the testes already produces it, however females are more sensitive to disorders, certain enzyme deficiencies of the adrenal cortex result in excess androgen production, , females may be born with ambiguous or masculinized genitalia due to the prescence of excess cortical sex hormones
- 78SSSfunctions of the corticosteroids
-salt (mineralcorticoids)
-sugar (glucocorticoids)
-sex (cortical sex hormones) - 79adrenal medullanestled inside of the adrenal cortex, derivative of the nervous system, responbile for the production of sympathetic hormones epinehrine and norepinephrine, specialized nerve cells can secrete these compounds directly into the nerve cell
- 80epinephrine and norepinephrine are what types of hormonesamino acid derivative hormones that belong to a larger class called the catecholamines
- 81what does ephinephrine do?increase breakdown of glycogen to glucose (glycogenolysis) in both liver and muscle, increase basal metabolic rate, increase heart rate, dilate the bronchi, and alter blood flow to supply the systems that would be used in a sympathetic response, vasoconstriction decreases bloodflow to the gut, kidneys and skin
- 82cortisol vs catecholaminecortisol is thought of to be importnat for long term (slow) stress responses, catecholamines are thought of to be important for short term (fast) stress responses, however cortisol actually increases the synthesis of catecholamines
- 83pancreashas both exocrine and endocrine functions, pancreas produces digestive enzymes (exocrine)
endocrine - small groups of hromone producing cells are grouped together into islets of langerhans throught the pancreas - 84exocrine glandExocrine glands are glands that produce and secrete substances onto an epithelial surface by way of a duct. Examples of exocrine glands include sweat, salivary, mammary, ceruminous, lacrimal, sebaceous, and mucous.
- 85islet of langerhanislets contain three distinct type of cells alpha, beta, delta
alpha - glucagon
beta- insulin
delta - somatostatin - 86glucagonsecreted during times of fasting (low glucose), causes break down of fats and muscles and glycogen to glucose, and production of new glucose through gluconeogenesis, in addition to low blood glucose concentrations, certain gastrointestinal hormones such s cholecystokinin and gastrin cause increased glucagon release) high glucose concentrations inhibit glucagon
- 87insulinantagonistic to glucagon, is secreted when blood glucose levels are high, insulin induces muscle and liver cells to take up glutcose and store it as glycogen, insulin stimulates anabolic processes such as fat and protein synthesis
- 88what does abnormally high levels of insulin docauses hypoglycemia, low blood glucose concentration
- 89what causes diabetes mellitus?insufficient secretion, under production or insensitivity to insulin, characterized by hyperglycemia (excess glucose levels in blood)
- 90diabetes and kidneysexcessive levels of glucose in blood overwhelms the kidneys ability to reabsorb glucose so that glucose would be found in urine, this would further cause excessive secretion of water
- 91polyuria and polydipsiapolyuria - increased frequency of urination
polydipsia - increased thrist - 92what are the four hormones that increase blood glucose?epinephrine, gluccocorticoids, glucagon, growth hormones, these hormones are commonly called the counterregulatory hormones
- 93type 1 vs type 2 diabetestype 1 - autoimmune destruction of B cells of pancreas, they require constant insulin injections as they can produce little to no insulin
Type 2 - take medicine to help body more effectively use insulin, only need insulin when bodies can no longer control glucose levels even with medication - 94somatostatinis an inhibitor of both insulin and glucagon secretion, high blood glucose and amino acid concentrations stimulate its secretion, in addition somatostatin is also produced by the hypothalamus where it functions to decrease growth hormone secretion
- 95pineal glandlocated deep within the brain and secretes melatonin, pineal glands receive projections directly from the retina but is not involved in vision
- 96erythropoietinstimulates bone marrow to increase production of erythrocyes (red blood cells), secreted in response to low oxygen levels in blood
- 97ANPatrial natriuretic peptide is released by the heart to help regulate salt and water balance, when cells in atria are streched from excess blood volume they release ANP, this hormone promotes excretion of sodium and therefore increases urine volume, the effect if functionally antagonistic to aldosterone because it lowers blood volume and pressure, and has no effect on blood osmolarity
- 98thymuslocated directly behind the sternum releases thymosin which is important for proper T cell development and differentiation, thymus atrophies by adulthood and thymosin levels drop
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- Fichas sobre The endocrine system, creado por Xiao Yuan el 09/12/2017.
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