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Endocrine Thyroid
Endocrine Thyroid Parathyroid
| Question | Answer |
|---|---|
| what are the two major types of glands? | exocrine and endocrine |
| exocrine glands | discharge secretions through a duct onto a surface.(surface of external body or cavity inside body) Secretions will have a lubricating or digestive function. |
| endocrine glands | discharge secretions directly into the extracellular fluid, which are then picked up by the nearby bloodstream. |
| what are the secretions of endocrine glands? | hormones |
| Endocrine System | A "group of glands," this system secretes chemical regulators, or "hormones" into the bloodstream to affect target cells or organs. |
| which two systems of the body coordinate the functions of all the body activities together? | nervous system & endocrine system |
| nervous system and endocrine system function to what? | together, both the nervous system and the endocrine system coordinate the functions of all the body activities |
| hormone | biologically active molecule that has an effect on the functions of another cell |
| what does hormone mean? | "to excite" |
| hormones are made of what? | almost always a protein |
| explain how much hormone is needed to have effects? what kind of effects do they have in general? | tiny amounts have an effect. Hormones have widespread and diverse effects |
| how many hormones are there? | there are 50 or so hormones |
| how do hormones effect a cell? | they will chemically bind to a receptor protein in the cell membrane |
| what four main things do hormones regulate? | 1)contraction of smooth muscle, cardiac muscle and the secretion of glands 2)reg chemical composition and volume of ECF. 3) metabolism and energy balance 4)the immune system |
| what other 3 things do hormones play a role in? | 1) maintain homeostasis despite emergency environmental disruptions 2) play a role in the smooth, sequential process of growth and development 3) contribute to the basic process of reproduction |
| hormone receptors: what happens to them, in general? | receptors are constantly synthesized and broken down, depending on the need for them |
| down regulation | hormone is in excess, so the number of receptors are reduced |
| up regulation | hormone is deficient, so the number of receptors are increased |
| what two process happen to receptors on a cell membrane? | down regulation or up regulation, depending on the need for receptors |
| how many types of hormones are there and how are they classified? what are the three types? | there are 3 types of hormones, classified by whether their targets are local or far away. they are paracrines, autocrines, endocrines. |
| paracrines | paracrine cell releases paracrines. they target the immediate viscinity (a cell that's nearby). |
| example of a paracrine? | pancreatic somatostatin |
| pancreatic somatostatin is what kind of hormone and why? | a paracrine. It is released by cells in the pancreas, targeting and inhibiting nearby cells |
| autocrines | autocrine cell releases autocrines. an autocrine targets itself. |
| example of an autocrine? | prostaglandin |
| prostaglandins are what kind of hormone and why? | an autocrine. they are released by smooth muscle cells, causing these same cells to contract |
| endocrines | target somewhere else in the body |
| water-soluble hormones: how do they travel? | circulate freely in the blood |
| water-soluble hormones, how do they enter a cell? | they cannot cross the cell membrane. they bind to the receptor, and this binding activates a "2nd messenger" which has a cascading effect in the cell. |
| which hormones circulate freely in the blood? | water-soluble hormones |
| which hormones can't cross the cell membrane | water-soluble hormones |
| lipid-soluble hormones: how do they travel | are carried in the bloodstream attached to a transport protein |
| lipid-soluble hormones, how do they enter a cell? | they are able to diffuse across the cell membrane. They are carried by transport protein, detach near the cell then move into the cell. |
| where are lipid-soluble hormones made? | made by the liver |
| "bound" hormones: what are they? | attached to transport protein (i.e. lipid-soluble hormones) |
| why are transport proteins important with regards to lipid-soluble hormones? | important because it stops the hormones from being broken down by enzymes in the blood stream or filtered by the kidney |
| which hormones are carried by a transport protein in the bloodstream? | lipid-soluble hormones |
| which hormones are able to diffuse across a cell membrane? | lipid-soluble hormones |
| which hormones are made by the liver? | lipid-soluble hormones |
| what are the three different kinds of hormonal interactions? | 1)permissive effect 2)synergistic effect 3)antagonistic effect |
| permissive effect | the effect of one hormone on a target cell requires a previous or simultaneous exposure to another hormone |
| what is an example of permissive effect and why is it permissive? | permissive effect of estrogen: est induces synthesis of progesterone receptors in the endometrium and thereby permits the uterus to respond to progesterone when it shows up. estrogen=permissive effect b/c the effect of prog requires prev exposure 2 est |
| why is it important for estrogen to have permissive effect on progesterone? | you want to promote growth of uterine lining and to prepare for implantation of the fertilized egg |
| define the interaction of estrogen and progesterone in the endometrium? | estrogen has a permissive effect on progesterone |
| synergistic effect | 2 or more hormones complement each other's actions and both or all are needed for full expression of hormonal effects |
| example of synergistic effect? why is it synergistic? | milk production: needs estrogen, progesterone, prolactin and oxytocin. these hormones have synergistic effects on eachother because their actions complement eachother and all are needed for milk production to occur |
| which hormones make milk? (when synergistically combined?) | estrogen, progesterone and prolactin |
| which hormone ejects milk once it is made? | oxytocin |
| define the interaction of estrogen, progesterone, prolactin and oxytocin in milk production? | these hormones have synergistic effects on eachother |
| antagonistic effect | the effect of one hormone on a target cell is opposed by another hormone |
| an example of antagonistic effect? why is it antagonistic? | insulin has an antagonistic effect on glucagon. they are antagonistic because insulin functions to decr blood sugar level while glucagon functions to incr blood sugar level |
| what is insulin's main function and why? | insulin functions to decrease blood sugar levels, by making cells bring in more glucose or stimulating the liver to make and store glycogen |
| what is glucagon's main function and why? | glucagon functions to increase blood sugar level by stimulating the liver to break down its glycogen stores to release glucose into the blood |
| define the interaction of insulin and glucagon? | the two hormones have antagonistic effect on one another, since insulin decreases blood sugar level and glucagon increases blood sugar level |
| hormones that influence other endocrine glands are called what? | tropins |
| tropins | hormones that influence other endocrine glands |
| example of tropin? | hormone secreted by the pituitary is sent to the thyroid, which causes it to releases another hormone |
| normal/physiological range of hormones vs pharmacological ranges? example of pharmacological range? | physiological ranges are what are normal for the human body while pharmacological ranges (resulting from drug use) imply that something is wrong (there is too much or too little of the hormone)example: someone who is taking steroids |
| (5) bad results of pharmacological ranges of hormones?(i.e. being on steroids) | liver cancer, sterility, antisocial behavior, increased size of breasts, increased levels of cholesterol |
| hormone clearance: what is it and how does it happen? | removal of hormones from the body. they are broken down by the liver or the kidney (or target cell) |
| removal of hormones from the body is..? | hormone clearance |
| MCR | metabolic clearance rate : volume of biological fluid completely cleared of hormones as measured in unit time |
| half life | length of time to clear 50% of hormone from the blood |
| what is the only endocrine gland that stores its product? | the thyroid gland |
| how long does the product supply of the thyroid gland last? | about 2 weeks |
| what is the thyroid gland, anatomically? | a 'butterfly shaped' gland composed of 2 lateral lobes connected by a narrow isthmus |
| where is the thyroid located? how is it connected. | located below the larynx. it is fixed to the anterior surface of the upper trachea by loose connective tissue |
| what is the largest endocrine gland? | the thyroid gland |
| how much does the thyroid gland weigh | 20-30 grams |
| what units is the thyroid composed of? | composed of microscopic spherical sacs called thyroid follicles |
| thyroid follicles | microscopic spherical sacs that make up the thyroid gland |
| draw a thyroid follicle and label it | draw a circle surrounded by cuboidal cells, labeled follicular cells. inside is filled with colliod (made of TGB, or thyroglobulin) |
| what are thyroid follicles lined in? | lined by cuboidal follicular cells |
| follicular cells | cuboidal cells that line a thyroid follicle |
| how many thyroid follicles are there in a healthy adult? | 3 million thyroid follicles in a healthy adult |
| what are thyroid follicles filled with? | filled with protein-rich colloid |
| colloid: what is it (where, color, texture) and what is it made of | protein-rich substance that fills thyroid follicles. amber-colored and sticky. It is made of thyroglobulin (TGB), which is produced and secreted by the follicular cells and accumulates in the lumen of the follicle, making the colloid substance |
| TGB | Thyroglobulin: a very large glycoprotein that makes up the protein-rich colloid in the thyroid follicle |
| how many amino acids long is TGB? How many of these are tyrosine? | thyroglobulin is about 5,000 amino acids long (more than 100= tyrosine) |
| how are thyroid hormones (TH) formed? | formed by attaching iodine to the amino acid tyrosine. there are more than 100 spots to do this |
| two main types of cells in the thyroid gland? | follicular cells and parafollicular cells ("C" cells) |
| what is TH? | Thyroid hormone: T3 and T4 |
| what do follicular cells produce? | they produce thyroid hormone: |
| where is Thyroid hormone produced? | in the follicular cells of the thyroid follicles. |
| T3 | triiodothyronine: it is the most potent |
| what percentage of follicular cells' product is T3? | 10% of product is triiodothyronine |
| T4 | thyroxine |
| what percentage of follicular cells' product is T4? | 90% of product is T4 |
| what is the primary effect of TH? | primary effect of thyroid hormone is to increase the body's metabolism |
| what physiological effects does TH have on the body? | TH causes: incr heart rate, incr respiratory rate, incr contraction strength, incr heat production, raises 02 consumption, promotes alertness, promotes bone growth, promotes development of skin, hair, nails and teeth |
| how does TH travel? | most travel (98%) attached to a transport protein (TBG) |
| TBG | thyroxine-binding globulin. binds thyroid hormone in circulation in the bloodstream. |
| explain what happens to thyroid hormone when it reaches its destination | thyroid hormone TH, bound to thyroxine-binding globulin TBG, is transported in the bloodstream and released from its carrier at its target cell. both T3 & T4 enter the cell, where T4 is changed to T3 (since it is most potent), then T3 enters the nucleus |
| parafollicular cells AKA? | "C" cells |
| "C" cells AKA? | parafollicular cells |
| parafollicular cells: what do they do and where are they located? | cells in the thyroid that produce and secrete calcitonin. they are located adjacent to the thyroid follicles and reside in the connective tissue |
| where is calcitonin produced? | in the parafollicular cells of the thyroid gland |
| primary function of calcitonin (and how does it do this?) | calcitonin (produced by the parafollicular cells) function to decr blood calcium levels, by promoting calcium deposition into bone and stimulating osteoblast activity |
| hypothyroidism | Abnormally low activity of the thyroid gland, resulting in retardation of growth and mental development. |
| hypothyroidism in a child: what is it called and what are the symptoms | cretinism: abnormal bone development. child will be shorter. thickened facial features, low body temperature, irreversible brain damage. they child will be mentally retarded |
| cretinism | hypothyroidism in a child |
| hypothyroidism in an adult: what is it called and what are the symptoms? | myxedema: low metabolism rate, dry skin and hair, sluggishnes (physically and mentally), weight gain & edema |
| hyperthyroidism | Overactivity of the thyroid gland, resulting in an increased rate of metabolism. |
| myxedema | hypothyroidism in an adult |
| hyperthyroidism in an adult: what is it called and what are the symptoms? | Graves' disease: elevated metabolic rate, heart rate, nervousness, weight loss, abnormal sweating, bulging of the eyes |
| Graves' disease | hyperthyroidism in an adult |
| Goiter | pathological enlargement of thyroid gland |
| how does Goiter occur? | without iodine, cannot make T3 & T4. Pituitary sends out TSH (thyroid stimulating hormone) to stiumulate the thyroid to make more T3 & T4. But all the thyroid can make is colloid, which builds up as a huge growth in the neck. |
| pathological enlargement of thyroid gland? | Goiter |
| 4 pea-sized glands attached to back of thyroid? | parathyroid glands |
| describe the parathyroid glands | most people have 4 pea-sized glands, attached to the posterior surface of the thyroid |
| what are the cell types of the parathyroid glands? | 2 kinds of cells: chief cells and oxyphil cells |
| chief cells: what are they and what do they produce? | type of cell of the parathyroid gland. smaller, more numerous. they produce PTH (parathyroid hormone) |
| PTH | parathyroid hormone, produced by chief cells of the parathyroid glands |
| oxyphil cells | type of cell of the parathyroid gland. unknown what they do. there are fewer. |
| PTH: what does it do? | incr blood calcium levels (so incr the # and activity of osteoclasts). also they induce Ca++ reabsorption in the kidney(incr rate of vitamin D synthesis, and so then incr the rate of Ca++ absorption in the small intestine |
| antagonistic hormones? (2) | Calcitonin & PTH glucagon & insulin |
| hypoparathyroidism: what is it and how does it affect blood calcium levels? | Diminished concentration of parathyroid hormone in the blood, which causes deficiencies in in blood levels of calcium and phosphate ions |
| how can hypoparathyroidism occur? | due to glands possibly being accidentally removed with the thyroid in surgery, or due to damage with trauma |
| hyperparathyroidism: what is it and how does it affect blood calcium levels? | excessive secretion of parathyroid hormone resulting in abnormally high blood levels of calcium and phosphate ions. |
| what does hypothyroidism cause and what is the physiological result of this? | causes Na+ channels to open, so increases cell permeability to Na+. which results in depolarizations & muscle spasms, cardiac arrhythmias |
| how can hyperthyroidism occur? | when a tumor starts growing on the parathyroid gland |
| bone resorption | the process by which osteoclasts break down bone and release the minerals, resulting in a transfer of calcium from bone fluid to the blood. |
| what does hyperparathyroidism cause and what is the physiological result of this? (hint: result of incr osteoclast activity) | causes high levels of bone resorption (increased activity of osteoclasts which are chewing up the bone and "leeching" the calcium out of it). This results in bones becoming soft, deformed and fragile. |
| physiological result of hyperparathyroidism (hint: result of incr Ca++ blood levels) | promotes the formation of kidneystones (composed of calcium phosphate). this is the result of Ca++ deposits in the kidney tubules |
| what are the steps of TH production in the thyroid? | 1)iodide trapping 2)synthesis of thyroglobulin TGB, 3) oxidation of iodide, 4)iodination of tyrosine, 5)coupling of T1 and T2 6)pinocytosis & digestion of colloid 7) secretion of thyroid hormones 8)transport in blood (bound 2thyroxine-binding glob) TBG |
| explain iodide trapping | thyroid follicular cells trap I- by actively transporting them from blood into cytosol. I- conc inside cell is much greater than blood plasma. (thyroid gland normally contains most of the I- in the body) |
| iodide | I- |
| iodine | I2 |
| I- | iodide |
| I2 | iodine |
| explain synthesis of thyroglobulin (TGB) | TGB is produced in the RER, modified in the Golgi complex, and packaged into secretory vesicles. these undergo exocytosis which releases TGB into the lumen of the follicle. the material that accumulates in the lumen this way is the colloid |
| TGB | thyroglobulin: a protein present in the colloid of the thyroid gland from which thyroid hormone is synthesized. the iodinated tyrosine components of thyroglobulin form the active hormones thyroxine (T4)and triiodothyronine (T3) |
| TBG | thyroxine-binding globulin |
| describe the oxidation of iodide | negatively charged I- cannot bind to tyrosine. These anions must undergo oxidation to iodine (I2). this rxn is catalyzed by the enzyme peroxidase, which is concentrated in the membrane adj to colloid. after oxidation they pass thru membr into the colloid |
| descibe the iodination of tyrosine | as soon as I2 forms, it attaches to tyro amino acids that are part of the TGB molecules in the colloid. binding of one I2 yields T1 and a second iodination gives T2 |
| describe the coupling of T1 and T2 | last step in synthesis of TH: two T2 molecules join to form T4, and a T1 and T2 join to form T3. thus thyroid hormones are stored as part of TGB molecules within the colloid |
| explain pinocytosis and digestion of colloid | droplets of colloid reenter follicular cells by pinocytosis and merge with lysosomes. digestive enzymes break down TGB, cleaving off molecules of T3 & T4. (T1 & T2 are also released, but they undergo deiodination, and iodine is reused to synth more TH |
| explain secretion of thyroid hormones | since T3 and T4 are lipid-soluble, they diffuse through plasma membrane to enter the blood |
| explain transport of TH in the blood | more than 99% of both the T3 and T4 combine with transport proteins in the blood, mainly thyroxine-binding globulin (TBG) |
| draw a follicular cell | draw cell with microvilli facing the lumen (colloid) of the follicle. the smooth base is adjacent to the curving capillary/blood plasma |
| draw iodide trapping in the thyroid | draw a few iodide (I-) in blood plasma and a high concentration diffusing into the follicular cell. it is actively concentrating iodide into itself. |
| draw synthesis of TGB | while cell is trapping I-, thyroglobulin is being synthesized first in the RER, then modified in the Golgi and packaged into secretory vessicles. draw vesicles undergoing exocytosis, releasing the squiggle into the lumen |
| draw oxidation of iodide | draw arrow out of cell w word "peroxidase" inside. draw a few I2 molecules in lumen. as iodide ions are oxidized, they pass thru the membrane into the colloid |
| draw iodination of tyrosine & coupling of T1 & T2 | draw arrow from tiny squiggle in colloid to larger version of squiggle w tiny tyrosine notches. draw a zoom in of squiggle showing 3 lg tyrosine notches. arrow from I2 TGB. show tiny I2 branches off tyrosine (label T1, T2 & T4) |
| draw pinocytosis and digestion of colloid | droplets of colloid reenter follicular cells by pinoicytosis. show iodinized squiggle reentering via pinocytosis. draw attached lysosome. show empty circle w cleaved off T3 & T4 triangles underneath. digestive enzymes break down TGB, cleaving off TH molec |
| draw secretion of TH & transport into bloodstream | arrow from triangles into capillary, show triangles binding to thyroxine-binding globulin (triangles/transport proteins). draw arrow showing transport in blood. T3 & T4= lipid soluble, they diffuse thru membrane, enter blood w TBG & r dispersed into blood |
Created by:
kalmetina
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