 Kidney also help in osmoregulation, we know that osmoregulation, the regulation of water inside the body is one of the very important components of the functioning of human body because water is an essential part, this makes a 92 percent of plasma and if concentration of water in plasma changes then this may result in changes in blood pressure. Kidney also help in osmoregulation, if the concentration of water in the body is increased then kidneys are stimulated to produce a dilute urine which means that at the renal tibials reabsorption of water is reduced, there are different mechanisms for it, but the ultimate result is that the urine is diluted that is less reabsorption of water occur at the renal tibials, the result is in urine the organism excretes more water, we call it a dilute urine, the situation could change, if there is a drop in the plasma volume for example, due to an injury due to excessive sweating, this is possible that the blood volume drops because during sweating we know if there is an excessive sweating for example, during sports or running or in warm weather due through sweat lot much water is removed. So, plasma volume is reduced which may reduces the blood pressure, kidneys also help controlling the situation, in this case if blood volume is reduced kidneys produces the concentrated urine that is at the renal tibials they absorb more than normal water, when they absorb more than normal water then the urine which is produced have lesser quantities of water and more concentration of salts and other ingredients, we call it a concentrated urine, when this situation comes then a reflux arises for thirst and this reflux actually gives message to the brain that the body needs to drink water, this is called thirst reflux, then we feel thirst we have to drink water to actually compensate the blood volume to a normal level, let us have a look on the another diagram, in case of lowering of blood pressure, many times we know it occurs, this animation shows that if blood pressure lowers then for body it could be sometimes even problematic, person become unconscious for some time, this may become more dangerous because if blood pressure drops then a specific threshold then the brain cells will not receive blood and they may damage, to control the situation a hormone come in action, as you can see that in the center there is the renal tibial the collecting duct on one side is a paretibular capillary, the other side there is another capillary, through one capillary a hormone is produced called ADH anti diuretic hormone, anti diuretic hormone as its name says give a reflux or give a stimulus to the renal tibial to reabsorb more water from the renal tibial the collecting duct, the last part of the renal tibial called the collecting duct, when more water is reabsorbed the result is concentrated urine that is urine with lesser quantities of water, when this water goes back excessive water goes back towards the blood capillary the blood volume of the body is temporarily restored, but if this situation continues the body have to find out some permanent solution or may be thrust, but this mechanism as we know that in both kidneys lot many renal tibules are not many renal tibules are always producing urine, so if anti diuretic hormone comes in action actually it is conserving lot much of water which can temporarily at least handle the situation of low blood pressure by increasing the volume of blood inside the vessels, many times it occur when we have done some excessive sports or there is lot much of sweating due to sometimes warm weather, sometimes due to injury and there is a blood loss this may also result in lowering blood pressure because blood volume is released, so this is a temporary solution to increase the blood pressure to a normal or near normal level for the time, time being when the next help comes out, for example if there is a loss of blood this mechanism and this is not an excessive loss, then this mechanism will rise up the blood pressure, but later on if the blood is excessively lost then this have to be replaced by more blood or plasma, this situation sometimes also happen when we give blood as a donation because blood is going out of our body this is a good quantity, I hope you know that when you give a blood, when you give some blood to the as a donation to some say organization they always ask you to drink some more juice, some juices in water, so this is actually to compensate your volume of water inside the body to maintain your blood pressure, so this was about the excretory system, system of excretion, we covered excretion in animals and a more detailed human excretory system, I hope you understand what we talked about today about the excretory system.