Water Homeostasis - Lecture Notes PDF

‫االولىﮫ‬ ‫المحاضرةاﻟﺜﺎﻧﯿ‬ ‫اﻟﻤﺤﺎﺿﺮه‬ ‫اﻟﺠﺰء اﻟﺜﺎﻧﻲ ‪Water Homeostasis‬‬ ‫اﻋﺪاد‬ ‫د‪.‬أﻣري ﺳﻼم‬  * Mechanisms of Fluid Balance The body have mechanisms that regulate fluid levels within a narrow range, the body fluids remain within certain physiological limits, an importan...

‫االولىﮫ‬ ‫المحاضرةاﻟﺜﺎﻧﯿ‬ ‫اﻟﻤﺤﺎﺿﺮه‬ ‫اﻟﺠﺰء اﻟﺜﺎﻧﻲ ‪Water Homeostasis‬‬ ‫اﻋﺪاد‬ ‫د‪.‬أﻣري ﺳﻼم‬  * Mechanisms of Fluid Balance The body have mechanisms that regulate fluid levels within a narrow range, the body fluids remain within certain physiological limits, an important aspect of homeostasis, ‫ وتبقــى ســوائل الجســم ضمــن‬،‫لــدى الجســم آليــات تنظــم مســتويات الســوائل ضمــن نطــاق ضيــق‬ )،‫(التــوازن‬homeostasis ‫ وهــو جانــب مهــم مــن‬،‫حــدود فســيولوجية معينــة‬ four primary mechanisms regulate fluid homeostasis: -Antidiuretic hormone or ADH (‫)اﻟﻬﺮﻣﻮن اﳌﻀﺎد ﻹدرار اﻟﺒﻮل‬ -Thirst mechanism (‫)اﻟﻴﺔ اﻟﻌﻄﺶ‬ -Aldosterone (‫)اﻻﻟﺪوﺳﺘريون‬ -Sympathetic nervous system (‫)اﻟﺠﻬﺎز اﻟﻌﺼﺒﻲ اﻟﻮدي‬ Three of these mechanisms involve the kidneys. * Antidiuretic hormone or ADH Effect of ADH When loses water by sweating, his plasma becomes more concentrated in solutes. Osmoreceptors in the hypothalamus detect the increased osmolarity or concentration of solutes in the plasma. In response to this increased concentration, the antidiuretic hormone is released into the blood at posterior pituitary. The target tissue for ADH is the late distal convoluted tubule and collecting duct cells in the kidney. ١  ADH ‫ﺗﻮﺿﻴﺢ ﻋﻦ ال‬ ‫ راح ﺗﺘﺤﺴــﺲ‬hypothalamus ‫ﻣــﻦ ﻳــﺰداد ﺗﺮﻛﻴــﺰ اﻟﺒﻼزﻣــﺎ ﻣــﺎل اﻟــﺪم اﻛــﻮ ﻣﺴــﺘﻘﺒﻼت ﻣﻮﺟــﻮدات ﺑــﺎل‬ ‫ ﺑﻌــﺪ ﻣــﺎ ﺗﻜﺘﺸــﻒ‬osmoreceptors ‫ ال‬. osmoreceptors ‫ﻫــﺎي اﻟﺰﻳــﺎده ذين اﳌﺴــﺘﻘﺒﻼت اﺳــﻤﻬﻦ ال‬ ‫اﻟﺘﻐــري ﺑﱰﻛﻴــﺰ اﻟﺒﻼزﻣــﺎ راح ادز اﺷــﺎرات و ﻫــﺎي اﻻﺷــﺎرات اﺗﺨــﲇ اﻟﻔــﺺ اﻟﺨﻠﻔــﻲ ﻣــﻦ اﻟﻐــﺪه اﻟﻨﺨﺎﻣﻴــﻪ‬ ‫ راح ﻳﺸــﺘﻐﻞ ﻋــﲆ‬ADH ‫ اﻟــﲇ ﻫــﻮ اﻟﻬﺮﻣــﻮن اﳌﻀــﺎد ﻟــﻼدرار ال‬ADH ‫ ( ﻳﻔــﺮز ال‬posterior pituitary) collecting duct ‫ و ال‬late distal convoluted tubules Q-83 Increase solute concentration in the plasma causes …………… A-Release enzymes B-Increase pH C-Increase temperature D-Release ADH E-None of them ADH in the Nephron The cells of late distal convoluted tubule and collecting duct become permeable to water only in the presence of ADH. ‫ ﻓﻘــﻂ ﺗﺴــﻤﺢ مبــﺮور‬collecting duct ‫ و ال‬late distale convolutedv tubules ‫اﻟﺨﻼﻳــﺎ اﳌﻮﺟــﻮده ﺑــﺎل‬ ADH ‫اﳌــﺎء اذا ﺟــﺎن ﻣﻮﺟــﻮد ال‬ ‫ راح ﳾ ﺳــﻮي ﺑﻬــﺎي‬ADH ‫ ﻫــﻮ ال‬ADH ‫ﻫﺴــﻪ ﻧﻄــﺮح ﺳــﻮؤال واﻧﻜــﻮل ﻟﻴــﺶ اﻻ ﺑﻮﺟــﻮد ال‬ ‫اﻟﺨﻼﻳــﺎ ؟‬ ADH promotes the addition of water channels into the cells of the late distal convoluted tubule and collecting duct, allowing water to move from the filtrate to the plasma by way of osmosis. ٢ ‫ و ال‬late distal convoluted tubules ‫ ﻳﻌــﺰز اﺿﺎﻓــﻪ ﻗﻨــﻮات اﳌــﺎء ﰲ ﺧﻼﻳــﺎ ال‬ADH ‫ﻫﺮﻣــﻮن ال‬ ‫ ﻋــﻦ‬plasma ‫ اﱃ ال‬filtrate ‫ و ﺑﺘــﺎﱄ ﻫــﺎي اﻟﻘﻨــﻮات راح ﺗﺴــﻤﺢ ﺑﻌﺒــﻮر اﳌــﺎء ﻣــﻦ ال‬, collecting duct osmosis ‫ﻃﺮﻳــﻖ ﻋﻤﻠﻴــﻪ اﻟﺘﻨﺎﺿــﺢ اﻟــﲇ ﻫــﻲ ال‬ ADH therefore increases the reabsorption of water. Q3/The hormone promoting the addition of water channels into the cells of late distal convoluted tubule and collecting ducts is called: A/ Aldosterone B/ Angiotensin II C/ADH D/ Renin Q48/ Water reabsorption by kidneys is E/ None promoted by A/ ADH B/ Epinephrine C/ Prolactin D/ Renin E/ Catalase  * Thirst Mechanism (‫)اﻟﻴﺔ اﻟﻌﻄﺶ‬ The thirst mechanism is the primary regulator of water intake and involves hormonal and neural input as well as voluntary behaviors. ‫ ﻫــﻲ اﻟﻄﺮﻳﻘــﻪ اﻟﺮﺋﻴﺴــﻴﻪ اﻟــﲇ ﻣــﻦ ﺧﻼﻟــﻪ اﻟﺠﺴــﻢ ﻳﻨﻈــﻢ ﻋﻤﻠﻴــﺔ ال‬thirst mechanism ‫اﻟﻴــﺔ اﻟﻌﻄــﺶ ال‬ ‫ اي ﺗﺸــﻤﻞ ﺛــﻼث ﺷــﻐﻼت ﻫﻨــﻪ ال‬involve ‫ اي ﴍب اﳌــﺎء و ﻳﻜﻠﻠﻨــﻪ اﻧــﻮ ﻫــﺎي اﻟﻌﻤﻠﻴــﻪ‬water intake voluntary behaviours ‫ اي اﻻﻳﻌــﺎزات اﻟﻌﺼﺒﻴــﻪ و ال‬neural input ‫ اي ﻫﺮﻣﻮﻧــﺎت و ال‬hormonal ، ‫اي اﻟﺴــﻠﻮك اﻻرادﻳــﻪ‬ There are three major reasons why dehydration leads to thirst: :‫ ﻫﻨﺎك ﺛﻼﺛﺔ أﺳﺒﺎب رﺋﻴﺴﻴﺔ ﺗﺠﻌﻞ اﻟﺠﻔﺎف ﻳﺆدي إﱃ اﻟﻌﻄﺶ‬ 1. When saliva production decreases, the mouth and throat become dry.>>>>> Impulses go from the dry mouth and throat to the thirst center in the hypothalamus, stimulating that area. 2. When you are dehydrated, blood osmotic pressure increases,>>>> >stimulating osmoreceptors in the hypothalamus and the thirst center in the hypothalamus is now further activated. 3. Decreased blood volume>>>>> causes a decrease in blood pressure>>>>> that stimulates the release of renin from the kidney.>>>>> This causes the production of angiotensin II>>>>> stimulates the thirst center in the hypothalamus. Stimulation of the thirst center in the hypothalamus gives you the desire to drink. ٤ ‫‪Results of Fluid Ingestion‬‬ ‫‪1. Relieves the dryness in the mouth and throat.‬‬ ‫‪2. Fluid ingestion also stimulates stretch receptors in the stomach and‬‬ ‫‪intestine to send inhibitory signals to the thirst center.‬‬ ‫‪3. When normal fluid volume is restored, dehydration is relieved. Renin‬‬ ‫‪secretion from the kidney and angiotensin II now decreases to baseline levels.‬‬ ‫‪Q-24 Thirst center is located in the:‬‬ ‫‪A-Adrenal glands‬‬ ‫‪B-Liver‬‬ ‫‪C-Kidneys‬‬ ‫‪D-Hypothalamus‬‬ ‫‪E-GI tract‬‬ ‫ﻣﻼﺣﻈﺎت ‪:‬‬ ‫ــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــ‬ ‫ــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــ‬ ‫ــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــ‬ ‫ــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــ‬ ‫ــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــ‬ ‫ــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــ‬ ‫ــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــ‬ ‫ــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــ‬ ‫‪٦‬‬  * Aldosterone (‫)اﻻﻟﺪوﺳﺘريون‬ Effect of Aldosterone When a person donates large amounts of blood, they lose salts as well as water. When electrolytes and water are lost at the same time, blood volume decreases, threatening hypovolemia. When a person experiences blood loss, blood pressure decreases. Because a hypovolemic person experiences a decrease in blood pressure, juxtaglomerular cells in the arterioles of the kidney release renin. ‫ تفــرز هرمــون ال‬kidney ‫ راح ال‬hypovolemia ‫ مــن يصيــر عنــد الشــخص‬: ‫االســتنتاج‬ ‫ بالــدم‬renin Renin to Aldosterone As renin travels through the bloodstream, it binds to an inactive plasma protein, angiotensinogen, activating it into angiotensin I. As angiotensin I passes through the lung and other capillaries, an enzyme called Angiotensin Converting Enzyme, or ACE, converts angiotensin I to angiotensin II. Angiotensin II continues through the blood stream until it reaches the adrenal gland. Here it stimulates the cells of the adrenal cortex to release the hormone aldosterone. Angiotensin II also has a vasoconstriction effect that helps to increase the blood pressure. Aldosterone can also be released when potassium concentrations in the blood are high. ‫ﺷــﻮﻓﻮا ﺧــﻞ ﻧﻔــﺮض اﻧــﻮ اﻧﺘــﻪ ﺻــﺎر ﻋﻨــﺪك ﻓﻘــﺪان ‪ water‬و ‪ salt‬ﻻي ﺳــﺒﺐ ﻣــﻦ اﻻﺳــﺒﺎب ﻧﺘﻴﺠــﻪ ﻟﻔﻘــﺪان‬ ‫اﻟــﺪم او اي ﺳــﺒﺐ اﺧــﺮ اﻟـﺮاح ﻳﺼــري اﻧــﻮ ﺣﺠــﻢ اﻟــﺪم ﺑﺎﻻوﻋﻴــﻪ اﻟﺪﻣﻮﻳــﻪ راح ﻳﻘــﻞ و ﻫــﺎي اﻟﺤﺎﻟــﻪ اﻧﺴــﻤﻴﻪ‬ ‫‪ hypovolemia‬ﺣﺘﻰ اﻟﺠﺴﻢ ﻳﻌﺎﻟﺠﻪ اﻟﻜﻠﻴﻪ اﻟﲇ ﻫﻲ ال ‪ kidney‬راح ﺗﻔﺮز ﻫﺮﻣﻮن ال ‪ renin‬ﺑﺎﻟﺪم ‪ ،‬ﻫﺮﻣﻮن‬ ‫اﻟﺮﻧــني ﺑﺎﻟــﺪم راح ﻳﺤــﻮل )ﺑﺮوﺗني ﻏري ﻓﻌــﺎل ( ﻣﻮﺟﻮد ﺑﺎﻟﺪم اﻧﺴــﻤﻲ ‪ angiotensinogen‬اﱃ ‪angiotensin I‬‬ ‫ﻫــﺬا ال ‪ angiotensin I‬ﻫــﻢ ﻣــﺎ ﻳﻜﻌــﺪ راﺣﻪ ‪ ،‬راح ميﴚ ﻟﻠﺮﺋﺘني و ﻳﺘﻔﺎﻋﻞ ﻣﻊ اﻧﺰﻳﻢ اﻧﺴــﻤﻲ ‪angiotensin‬‬ ‫‪ converting enzyme‬ﻳﺨﺘﴫوﻧﻪ ﺑﺎل ‪ ACE‬ﻣﻦ ﻳﺘﻔﺎﻋﻞ وﻳﺎ راح ﻳﺘﺤﻮل ال ‪ angiotensin I‬اﱃ ‪Angiotensin II‬‬ ‫ﺑﻌﺪﻳــﻦ ﻫــﺬا ال ‪ angiotensin II‬اﻟﺘﻜــﻮن ﻋﺪﻧــﻪ راح ﻳﻨﺘﻘــﻞ ﻋــﱪ اﻟــﺪم وميﺸــﻪ ﻟﻐــﺪه ﻣﻮﺟﻮده ﺑﺎﺟﺴــﺎﻣﻨﻪ‬ ‫ﺻﻐريوﻧــﻪ ﺗﻠﻜﺎﻫــﺎ ﻓــﻮك اﻟﻜﻠﻴﺘــني اﻧﺴــﻤﻴﻪ اﻟﻐــﺪه اﻟﻜﴬﻳــﻪ و ﺑﺎﻻﻧﻜﻠﻴــﺰي ﻳﺼﻴﺤﻮﻟــﻪ ‪ adrenal gland‬ﻓﻬــﺬا‬ ‫ال ‪ angiotensin II‬راح ﻳﺠــﻲ ﻳﺸــﺘﻐﻞ ﻋﻠﻴــﻪ و ﻳﺨﻠﻴــﻪ ﺗﻔــﺮز ﻫﺮﻣــﻮن اﻧﺴــﻤﻲ ﺑــﺎل ‪Aldosterone‬‬ ‫‪Aldosterone in the Nephron‬‬ ‫‪ In the absence of aldosterone, the cells in the late distal convoluted tubule‬‬ ‫‪and collecting ducts allow little sodium and potassium ions to pass because‬‬ ‫‪there are few sodium and potassium channels in the cell membrane facing‬‬ ‫‪the kidney tubule. There are also few sodium/potassium ATPase pumps on‬‬ ‫‪the basal side of these cells.‬‬ ‫‪ Aldosterone exerts its effect by inserting additional channels in the late‬‬ ‫‪distal convoluted tubule and collecting duct of the kidney. This allows more‬‬ ‫‪sodium to move from the filtrate into the blood and potassium to move‬‬ ‫‪from the blood into the filtrate.‬‬ ‫ﻫﻨﺎ ﻳﻮﻇﺢ اﻟﻨﻪ اﻧﻮ‬ ‫‪-١‬ﺑﻐﻴــﺎب ﻫﺮﻣــﻮن ال ‪ Aldosterone‬ال ‪ late distal convoluted tubules‬و ال ‪collecting‬‬ ‫‪ duct‬راح ﻳﺴــﻤﺤﻦ ﺑﻌﺒــﻮر ﻛﻤﻴــﻪ ﻗﻠﻴﻠــﻪ ﻣــﻦ ال ‪ Na‬و ال ‪ K‬و اﻟﺴــﺒﺐ اﻧــﻮ اﻛــﻮ ﻋــﺪد ﻗﻠﻴــﻞ‬ ‫ﻛﻠــﺶ ﻣــﻦ ال ‪ channels‬اي اﻟﻘﻨــﻮات ﺑﻐﺸــﺎء اﻟﺨﻠﻴــﻪ ﻣــﺎل ﻧﺒﻴﺒــﺎت اﻟﻜﻠﻴــﻪ )‪(kidney tubules‬‬ ‫وﻛﺬﻟــﻚ اﻛــﻮ ﻛﻤﻴــﻪ ﻗﻠﻴﻠــﻪ ﻣــﻦ ‪ Na/K ATPase‬ﻋــﲆ ال ‪ basal side‬ﻣــﺎل ذين اﻟﺨﻼﻳــﺎ ‪.‬‬ ‫‪-٢‬ال ‪ Aldosterone‬راح ﻳﺨــﲇ ﻗﻨــﻮات اﻟﺼﻮدﻳــﻮم و اﻟﺒﻮﺗﺎﺳــﻴﻮم اﳌﻮﺟــﻮده ﺑﺴــﺎﻳﺘﻮﺑﻼزم ﺧﻼﻳــﺎ ال ‪distal‬‬ ‫‪ convoluted tubules‬و ال ‪ collecting duct‬ﺗﺼﻌــﺪ ل ﻏﺸــﺎذ اﻟﺨﻠﻴــﻪ )‪. (cell membrane‬وﺑﺘــﺎﱄ‬ ‫ﻗﻨــﻮات اﻟﺼﻮدﻳــﻮم راح ﺗﻨﻘــﻞ ال ‪ Na‬ﻣــﻦ ال ‪ filtrate‬اﱃ ال ‪ blood‬اي ﺗﺮﺟﻌــﻪ ﻟﻠﺠﺴــﻢ ﺑﻴﻨــام ﻗﻨــﻮات‬ ‫اﻟﺒﻮﺗﺎﺳــﻴﻮم راح ﺗﻨﻘــﻞ ال ‪ K‬ﻣــﻦ ال ‪ blood‬ﺑﺘﺠــﺎه ال ‪ filtrate‬ﻓﻴﻄﻠــﻊ اﻟﺒﻮﺗﺎﺳــﻴﻮم ﻣــﻊ اﻟﺒــﻮل‬ ‫‪٨‬‬ Results of Aldosterone Action The net result of aldosterone action is the reabsorption of sodium and the secretion of potassium. If ADH is also present, water is reabsorbed into the blood at the kidney, preventing further water loss from the body. As a result, blood volume and blood pressure are stabilized until water is consumed. Q-9 One mechanism in balancing water through kidney involving: A- Thyroid hormone B- Sugars C- Aldosterone D-PTH hormone E-Lipids Q-45 ……………..regulates renal sodium loss and controls the sodium content of the ECF A-Antidiuretic hormone B-Thirst mechanism C-Aldosterone D-Sympathetic nervous system E-All of them are involved Q74/The action of aldosterone in the kidney is …… A-increase secrtion of K only B-reabsorption of Na and secretion of K and H C-reabsorption if water D-increase secretion of H ion E-Reabsorption of bicarbonate ٩  * Sympathetic Stimulation A decrease in blood volume and therefore blood pressure will further stimulate the sympathetic nervous system. When blood pressure is low, baroreceptors in the heart, aortic arch, and carotid arteries send sensory information to the medulla. The information sent from the baroreceptors to the medulla will cause an increase in the sympathetic impulses to the kidney. Sympathetic Stimulation in the Nephron Release of neurotransmitters from the sympathetic nerves in the kidney stimulates smooth muscle cells in the afferent arteriole to constrict. This process causes a decrease in blood flow into the glomerulus and a drop in glomerular filtration rate and results in less urine formation. Less water leaves the body. Sympathetic stimulation also causes the release of renin which, by stimulating aldosterone secretion, will increase the reabsorption of sodium. As a result, blood volume will stop decreasing and blood pressure may stabilize. However, because the blood pressure and blood volume have not yet returned to normal, the baroreceptors will continue to be stimulated to prevent further loss of blood volume. In order to bring this person back into to homeostasis, we need to increase the blood volume by drinking fluids. In fact, after an individual has given blood, they are encouraged to drink juice to increase their plasma level. Q\ Enumerate steps of binary fission of a rod shaped bacterium? ١٠