NEPHRON Structure & Function Made Easy - Human Excretory System Simple Explanation.

hello and welcome to maths simplified a channel where we make biology and medicine simple in this video we are going to learn about the structure and function of a nephron nephron is the basic functional unit of the kidneys that consists of a renal corpuscle and the tubular attached to it the word nephron is derived from the Greek word Neph ROS meaning kidney each kidney contains approximately 1 million nephrons which performs several important functions of her body including waste excretion maintaining the body's pH regulation of blood pressure and several other functions so let's go through the structure and function of a nephron and learn more in detail about the different parts of nephron and the role of renal tubules in urine formation and excretion process you let's first start with the basic structure of a nephron so nephrons are microscopic structures located in the kidney and kidney has two important gross regions and outer cortex and an inner medulla and if you look at this nephron you can see that a part of this nephron is present in the cortex of the kidney and part of this nephron is placed in the medulla of the kidney this is an important point to remember as it plays a significant role in the formation of urine that we will discuss later in this video so the nephron is a tube-like structure whose length varies from 35 to 55 millimeters and the structure of nephron can be basically divided into two major portions the Bowman's capsule and the renal tubule at one end the tube is closed folded and expanded into a cup like structure which is known as the Bowman's capsule now the Bowman's capsule was discovered by this guy Sir Williams woman at the age of 25 he was an English surgeon and histologies who is also credited with the publication's of two historical books the physiological anatomy and physiology of man encyclopedia of anatomy and physiology so coming back to the nephron we discussed about the cup shaped structure at one end which is known as the Bowman's capsule the space inside the Bowman's capsule is known as the Bowman's space the Bowman's capsule encloses a cluster of blood vessels which is known as the glomerulus the world glomerulus is derived from the Latin word glue mer meaning a ball of thread so you can see why this is known as a glomerulus the blood vessel which brings the blood inside the glomerulus is known as the afferent vessel and the blood vessel taking the blood out of the glomerulus is known as the efferent vessel remember a comes before E so afferent brings the blood in and afferent takes the blood out the Bowman's capsule and clue marilla's together constitute the renal corpuscle okay so this was about one end of the nephron the other end is known as a renal tubules the word to view just means a small tube and as you can see the renal tubules is a long and folded tube like structure that emerges from the Bowman's capsule at one end and it ends into the duct system of the kidney the tube you'll is divided into three main parts based on its function the proximal convoluted tubule which is this part of the tube you'll shown in the light blue color then we have the loop of Henle which is shown in dark blue color and finally we have the distal convoluted tubules which is this part of tubular shown in orange color the distal convoluted tubules in turn ends into the collecting duct so the first part of the Tokyo is known as the proximal convoluted tubule proximal because it is close to the Bowman's capsule and convoluted meaning it is a highly folded structure that helps to increase the overall length of the tube you'll in a small space the proximal tubules is located in the cortex of the kidney the proximal tubules to the loop of Henle which is the second main part of the renal tubules this region forms a loop that is located in the renal medulla the loop has a descending limb and an ascending limb the ascending limb of loop of Henle leads into the distal convoluted tubule distal meaning away since it is located far from the Bowman's capsule as compared to the proximal tubules and convoluted since it is also folded structure to increase the overall length of the tubular the distal convoluted tubule drains into the collecting duct which also receives input from many other nephrons in the region the collecting duct drains into the larger collecting ducts and ultimately into the renal pelvis which is connected to the ureter the ureter drains the kidney to the bladder the distal convoluted tubules is also located in the cortex of the kidney now depending upon the length of the loop of Henle we have two types of nephrons in the kidney one type of nephron that have short loops of Henle and these are known as the short cortical nephrons cortical because a major portion of these nephrons is located in the cortex of the kidney these are short and comprise about 80% of the total nephrons the other type of nephrons that we have in our kidney are known as the juxta medullary nephrons which have long loops of Henley that are mostly present in the medulla of the kidney these two types of nephrons can concentrate urine up to different osmolarity that we will discuss when we talk about the function of nephron these are 20% in number along the whole length of the nephron runs this network of small blood vessels known as capillaries that brings in impure blood containing many wastes metabolic products and takes out pure blood that has been filtered by the nephron the impure blood or the arterial blood comes into the kidney by the renal artery and the pure blood which has been filtered of all the metabolic and other waste products goes back to the body by other renal vein so this was about the structure of nephron next let's have a look at its basic function so the nephron uses four main mechanisms to convert blood into urine which are filtration reabsorption secretion and excretion now I have seen most of the biology teachers here on YouTube and what they do is they just explain what is filtration what is reabsorption what is secretion and job done this is how urine is formed well not quite right see in this video we will understand the mechanism of your information in a better way we will look at how the blood is filtered at the level of renal corpuscle and then we will understand how the urine moves forward in the renal tubules and how different mechanisms like reabsorption and secretion apply in different parts of the renal tubules so the blood enters the kidney via the renal artery this is a large artery and a branch of Volta after entering the kidney the renal artery gets divided into many small divisions until it reaches the smallest one that enters the nephron this is the efferent vessel that brings the blood into the glomerulus and this is the blood vessel that takes the blood out of Rome areolas and this is known as the efferent blood vessel in between these afferent and efferent blood vessels is a jumble of mass of capillaries that is known as a glomerulus like we discussed earlier glomerulus is derived from the world bloomer which means a ball of thread the glomerulus is a tuft of blood vessels that is located inside the Bowman's capsule this tuft of vessels greatly increases the surface area for filtration that comes in contact with the Bowman's capsule and this is where the mechanism of your information takes place that is known as the filtration and understand the filtration at their side you have to know a little bit about the glomerular filtration barrier so if you take this part of the renal corpuscle and look at its microscopic view it would look something like this this is the wall of the blood vessel outside this is the basement membrane of the glomerulus which is in contact with the wall of the Bowman's capsule the wall of the Bowman's capsule contains special type of cells which are known as podocytes and between these photo sites we have small caps as you can see and these are known as the filtration slits together these three layers form the glomerular filtration barrier that acts like a filter paper so we have blood coming in in this blood vessel that gets filtered through this glomerular filtration barrier to form the impure plasma that is passed down into the union-tribune the glomerular blood pressure provides the driving force for water and solutes to be filtered out of the blood plasma and into the interior of the Bowman's capsule called the Bowman's space only about 1/5 of the plasma is filtered in the glomerulus and the rest passes into the efferent arteriole the things that do not get filtered are things like red blood cells or larger molecules like proteins also one important thing you should note here is a difference in the diameter of the afferent and the efferent blood vessel as you can see the efferent vessel is of smaller diameter as compared to the efferent vessel which means that the blood is coming in through a vessel of larger diameter and leaving through a vessel of smaller diameter this increases the pressure inside the glomerulus which provides a driving force which makes this filtration possible the kidneys can adjust the rate of glomerular filtration by adjusting the pressure inside the glomerulus and this is all possible because a diameter of afferent and efferent blood vessels can be adjusted the plasma that gets filtered into the Bowman's space is known as the glomerular filtrate the glomerular filtrate next moves into the renal tubules where it is further processed to form urine this further processing is very important as an initial glomerular fluid that is filtered into the Bowman's space contains a lot of things that shouldn't be excreted out with urine like sodium chloride glucose amino acids and excess water the first part of in LD Buell is the proximal convoluted tubule where approximately two-thirds of the filtered salts and water almost all glucose and amino acids are reabsorbed we don't want to lose glucose that's hard-earned stuff that we ate that was good for energy we don't want to lose necessarily as much sodium chloride as well this is achieved by the method of a reabsorption the whole length of the renal tubule is surrounded with blood vessels which are known as the peritubular capillaries whatever that gets reabsorbed is then passed back into the blood circulation now this is known as a reabsorption and not absorption because the same nutrients have been absorbed once from your gut into your blood by the similar mechanism the wall of the renal tubules has many types of protein channels that reabsorb some of the important things that shouldn't be excreted with urine now about 70 percent of sodium chloride gets reabsorbed in the proximal convoluted tubules and same 70 percent water gets reabsorbed here and more than 95 percent of glucose and amino acids get reabsorbed in the proximal convoluted tubule next the filtrate passes into the loop of Henle the loop of Henle has some role in reabsorption of important salts like about 25% of sodium gets reabsorbed here similarly 25% of calcium 20% of potassium and about 60% of magnesium gets reabsorbed in the loop of Henle but the loop of Henle has a major role in the concentration of urine and this is a complex topic and usually taught at the level of med school physiology but I'll try to simplify this as much as possible so pay close attention so here is our section of kidney and you can see how the structure of kidney is divided into an outer cortex and an inner medulla the inner medulla of the kidney is a very important region as this contains higher concentration of salts as compared to the cortex of the kidney this higher concentration of salts in the medulla is made possible by the loop of Henle of nephrons so here is our nephron inside the kidney and you can see how this loop of Henle is present inside the medulla of the kidney and the rest of the nephron is present up in the outer cortex the loop of Henle has a descending limb and an ascending limb so if you look at the ascending limb of loop of Henle it contains special ion channels that pump out ions like sodium and chloride thus making the renal medulla more salty or hypertonic the ascending limb however does not allow water to move out as it has no channels in its wall that allow the water to move out these types of channels that allow water to move out are known as the aquaporins and these type of channels are actually present in the descending limb of loop of Henle that makes it freely permeable to water so now this is all salty and the water will move out of the descending limb into the renal medulla and then eventually into the blood vessels and gets reabsorbed and this is the reason why loop of Henle is so long that is to give time for this water to secrete out and that is why it dips nice and pretty far down into this salty portion which is the renal medulla so this is the major mechanism of gaining back a lot of water that gets filtered up at the level of renal corpuscle so after the loop of Henle the water then passes into the distal convoluted tubules which is this part of the renal tubules and here we have more reabsorption of ions like calcium and sodium we are just reabsorbing more things that we didn't want to lose in the first place there's a lot of things we could talk about what gets reabsorbed here but this is just the overview in distal convoluted tubules the final mechanism of urine formation also takes place that is known as secretion you can view secretion as the opposite of reabsorption in secretion the waste ions and hydrogen ions pass from the capillaries into the renal tubules this is the final step in the formation of urine during which walls of the tube you'll actively remove waste substances which are harmful to the body from the blood that have escaped filtration the secreted ions combined with the remaining filtrate and become urine the major substances secreted into the distal convoluted tubules include hydrogen ions potassium ions and ammonium ions the mechanism secretion also takes place in the proximal convoluted tubules but to a lesser extent and some important stuff that gets secreted into the proximal convoluted tubules include substances like urea uric acid creatine ammonium ions and some other drugs then at the end right here we have our filtrate that has been processed a lot of water has been taken out it's a lot more concentrated we have reabsorbed a lot of salts electrolytes and we have reabsorbed all the glucose and amino acids that we could this waste fluid then gets dumped into the collecting duct you can see the collecting ducts like a common drain pipe that collects waste from all the houses in the neighborhood except in this case where this pipe is the collecting duct and the houses are individual nephrons the collecting duct is important functionally from two aspects first it dips back into the medulla and second because antidiuretic hormone acts on our collecting ducts to decide whether our urine should be concentrated or diluted the function of antidiuretic hormone is a whole different topic that we will discuss in some future video the urine in each collecting duct is drained into the renal pelvis which is this dilated portion of the kidney that is in turn connected to the ureters the ureters connect the kidney to the urinary bladder that is connected to the urethra now to learn more about the urethra and all the other organs of human excretion watch this upcoming video on our channel about a human excretory system I hope you liked the video and if you did kindly support us by linking this video and sharing with your friends thank you so much for watching subscribe to support our Channel

Channel: MEDSimplified

Views: 502,783

Rating: 4.9299269 out of 5

Keywords: NEPHRON, STRUCTURE, FUNCTION, EASY, SIMPLE, BIOLOGY, CLASS, LECTURE, SCIENCE, HUMAN, EXCRETION, EXCRETORY, structure and function of nephron, CLASS 10, CLASS 12, urinary system, urinary system anatomy and physiology, urinary system anatomy, urinary system physiology, life processes, nephron function, nephron function animation, nephron functional unit of the kidney, nephron function 3d, glomerular filtration rate, glomerular filtration physiology, glomerular filtration pressure

Id: uI-ByPDmsQw

Length: 18min 7sec (1087 seconds)

Published: Sun Feb 09 2020