what is the name for the “ball” of capillaries found in the renal corpuscle? This is a topic that many people are looking for. militaria-agent.com is a channel providing useful information about learning, life, digital marketing and online courses …. it will help you have an overview and solid multi-faceted knowledge . Today, militaria-agent.com would like to introduce to you Renal corpuscle, Bowmans capsule, glomerulus, JGA. Following along are instructions in the video below:
Were looking at here is a renal corpuscle. We can see bowmans capsule capsule around the outside and the gama lilas inside and in essence. Its straightforward blood goes in via the afferent arteriole labeled six here from here.
The blood goes into the capillary network or the ball of capillaries. Which is the glomerulus as the blood goes through the gamaliel as the process of ultra filtration takes place and glomerular filtrate. Is formed the gamaliel of filtrate moving from the gamellia.
The capillaries into the space. This clemente l.espace.
Then the blood goes out again. Via the efferent arteriole labeled seven in this model. And the filtration is on grounds of molecular size.
So large molecules like proteins or large structures like blood cells will not be filtered out because its an ultra filtration. But smaller molecules like water amino acids of glucose and atomic scale structures. Such as ions will be freely filtered into the glomerular filtrate.
So lets look at this in a little more detail now if we take this out actually we can see the capsule. What were looking at there is bowmans capsule. Still called bowmans capsule.
And this is the parietal epithelium. The outside layer the parietal epithelium and all this area in here is bowmans space. The bowmans space.
And its into bowmans space that the gamellia filtrate. Well be filtered out into and then we notice once the glomerular filtrate is formed it goes down into the first part of the renal tubule that is the proximal renal tubular and as we can see this has got a brush border. This is composed of micro villi and this increases greatly the internal surface area for the reabsorption processes that need to take place.
The brush border made of micro villi. Im gonna try and put my blue mailing list back in now malleolus back in more or less and now we can see that the ultra filtration takes place between the capillaries of the glomerulus and bowmans space. Once the glomerular filtrate is formed we can see it can go from the space down into the proximal part of the nephron for the processes of reabsorption to start to take place so.
The afferent arteriole is bringing blood in from a branch of the renal artery and we can see theres a swollen bit here. Thats part of the juxtaglomerular apparatus. Which well be thinking about later on but for now we notice that these cells these granular cells that form the juxtaglomerular apparatus are in close proximity to this structure perched on top here now what this structure is is this is actually the distal convoluted tubules art of the distal convoluted tubules of the very same nephron that started there at the bottom.
So this goes down the descending loop around the loop of henle back up and it finds its own implementing us again and the juxtaglomerular apparatus. Chuckster means beside. So you can see that this is beside the glomerulus and this part.
Here where the cells are closer together is called the macula densa and the juxtaglomerular apparatus. Is that bit and the cells in the wall of the afferent arteriole as well so thats the distal tubule with the macula densa and then we can see that the efferent arteriole is leaving there and the afferent and the efferent arteriole aligned with vascular endothelial cells.
So the capsule are epithelial cells. But the blood vessels are lined with endothelial cells. Now its fairly obvious when we look at this grim analyst that its in two colors.
Weve got a white bit on one side and a red bit on the other side. Whats that about well this does not represent a histological change. Its just this model trying to explain things to us so if we look at the left part first what were actually seeing theyre labeled nine on this model.
But were actually seeing there if we looked at it from the outside. We would see that the capillary. The gamellia capillary is covered with these cells called podocytes and these podocytes pod means feet.
They are cells with feet as well see this forms the visceral epithelium. So bowmans capsule is the parietal epithelium and the podocytes of the vessel epithelium of the glomerular capsule. And we noticed that there are very fine red lines here these fine red lines.
There and they represent the filtration slits between the individual potter sites. So the pod. The sites have these feet like structures that wrap around the glomerular capillaries and those red lines that we see there are actually filtration slits.
The gamellia filtrate is physically filtered through those slits from the lumen of the capillary into bowmans space. And theyre actually covered with something called a slit membrane. As well.
Which is also dial izing as it generates glomerular filtrate. Now when we look at the other side of the capillary here labeled catepillar is labeled. 8.
What were actually seeing there is these are exactly the same cells. But theyre exactly the same structure has saw the glomerular capillaries. But its modeled without the pata sites.
So if you like in the red capillaries. The pata sites have been dissected off to reveal the vascular endothelial cells and we notice in the vascular endothelial cells that there are dark areas representing the nuclei of the cells and if we look at greater detail. We can probably see that theres lots of smaller dots.
All over these are actual little physical pores called fenestrations so this means that the blood is exposed sometimes to the capillary membrane and sometimes to these fenestrations little holes and in life these endothelial to pillory cells. Where we see the fenestrations are actually covered with a basement membrane that goes round like that like this piece of film. There completely surrounded by that basement membrane and its this basement membrane surrounding.
The vascular endothelium and the fenestrations of the glomerular capillaries that is the dialyzer membrane. So in order to be dialyzed in order for ultra filtration to take place material goes through the fenestrations through the dialyzer membrane through the slip filters in the pata sites and through these filtration slits in the body sites before it can get out into bowmans space. Where it is then glomerular filtrate after this dial izing process of ultra filtration has taken place.
And its interesting that when you take into account. The various forces involved the positive pressure inside the capillaries is only around 10 millimeters of mercury overall.
When we account for the osmotic pressure and the reverse pressures. So the dialyzer process is taken place under a pressure of 10 millimeters of mercury. Any material left in the capillaries that is not subject to ultra filtration will leave via the efferent arteriole.
So the process through is afferent arteriole glomerular capillary cells. Where the blood is subject to this physical filtration process out through the efferent arteriole and exiting the glomerulus from the efferent arteriole. Now i want to spend a little bit of time on this fascinating structure here.
The juxtaglomerular apparatus. Now these cells in the wall and extending out from the wall of the afferent arteriole are modified smooth muscle cells and these are the juxtaglomerular cells. Theyre sometimes called granular cells because theyre yet appear granular and the reason that they appear granular is they contain vesicles of renin.
So this is the place where the renin is produced and secreted and these cells are sometimes described as myo endocrine cells because they have the characteristics of muscle cells. Theyre part of the smooth muscle wall of the afferent arteriole. But theyre also secretory they secrete the renin now the renin as you probably know axon the renin angiotensin mechanism.
And that will cause vaso constriction raising blood vessels raising blood pressure by constricting blood vessels throughout the body and it will also increase the amount of how to steer own present in the blood. Which will increase sodium reabsorption and this happens in two basic ways first of all if the blood pressure passing through the afferent arteriole is reduced thats detected in the afferent arteriole and if the blood pressure is low these cells will respond by producing remington and renin will stimulate the angiotensin mechanism and that will raise blood pressure by increasing the amount of sodium in the blood therefore increasing intra giller volume and also via the mechanism of peripheral vaso constriction. So that will increase blood pressure.
But theres a second mechanism here and its related to these macula densa cells. Now these macula densa cells are cells. Which appear closer together the nuclei are closer together and theyre different from the cells in other areas of the distal.
Convoluted tubule and indeed other parts of the nephron and these macula densa cells are able to respond to sodium levels in the filtrate. So if the sodium levels in the filtrate are low these cells will produce messages chemical based messengers. Which will go to the granular cells stimulating them to produce venom.
So the venom can be produced directly it can be stimulated by low blood pressure in the afferent arteriole. But renin can also be stimulated when these macula densa cells detect low levels of sodium in the filtrate and the point about low levels of sodium in the filtrate is that that indicates a reduced lamellar filtration rate. So if the glomerular filtration rate is reduced that can be detected in this distal.
Tubular and the distal tubules can release chemicals locally here cytokine type chemicals that can cause renin to be released and can also alter the vaso tone of this after an arteriole so if theres a reduced glomerular filtration that can be regulated by dilation of the afferent arteriole allowing more blood to go into the glomerulus thereby increasing the gamellia filtration rate. So its very clever that the distal tubules there with the macula densa is actually controlling the formation of the gamellia filtrate. Which will shortly begin that jus buell.
So each nephron is auto regulating itself and this is called 2 bureau glomerular feedback feedback between the tube the nephron and the yellow malleolus jubilantly manila feedback and that controls and regulates gfr glomerular filtration rate. So the nephron is via this juxtaglomerular apparatus is controlling its own activity. But its also relating or controlling whole body blood pressure and in fact.
The most common cause of essential hypertension. Is that the kidney for some reason is producing too much renin stimulating. The angiotensin mechanism excessively.
So thats a brief introduction to the glomerulus and the renal corpuscle and the juxtaglomerular apparatus. .
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