Nephron Anatomy

Anatomy and Physiology is the single most important topic to master if you want to succeed in nursing school.  If you’ve never been a fan of anatomy and physiology, then you’re in the right place! I believe in breaking through all the confusing technical jargon to get right to the point of what’s most important to remember.  What does that mean for you?  Clear, understandable explanations that give you that “lightbulb” moment you’ve been hoping for.

The nephrons are where all the magic in the kidneys happens, and it’s all due to the interaction of Fluids and Electrolytes.  Specifically, the nephron is where all the diffusion and osmosis happen to filter “bad stuff” out of the blood, and put it into the urine.  Here’s an overview of what you should be familiar with when it comes to the A&P of the nephron:

Picture showing the Anatomy of a Nephron

Click to enlarge picture

Afferent Arteriole:  If you remember you’re medical terminology vocabulary, then you should recall that afferent means “going into or toward.”  So this is the blood vessel that goes into the Bowman’s Capsule.

Efferent Arteriole:  The definition of efferent is the opposite of afferent, and is easier to remember because of a nifty mnemonic.  Efferent means “going outward or away.”  I think of it as Efferent = Exit.  So this is the blood vessel that leaves the Bowman’s Capsule.

Renal Corpuscle (not labeled):  In case you ever see this term, it simply refers to the Bowman’s Capsule AND the Glomerulus together as a single unit.

Glomerulus:  The Glomerulus is a network of tiny capillaries that allow the blood to be filtered.  With the processes of diffusion and osmosis, waste products, electrolytes, and water start to leave the blood stream and enter Bowman’s Capsule.

Bowman’s Capsule:  Bowman’s Capsule is a “capsule” that contains the Glomerulus and catches the water, electrolytes, and waste products that are being filtered out of the Glomerulus.  It’s sort of like a funnel that catches everything, then allows it to drain into the Proximal Tubule.  Voila!  We have the beginnings of urine….it’s nothing more than filtered blood.

Loop of Henle (not labeled):  This term refers to the “loop” shape that you see, which is where a lot of diffusion takes place.  (If you’re studying pharmacology, this is also where Loop Diuretics have their action).

Proximal (Convoluted) Tubule:  The body doesn’t want to get rid of everything that was filtered out of the Glomerulus, so now we start the process of concentrating our urine by resorbing some of the electrolytes and water.  Once again, diffusion and osmosis play a really cool role in the process, as items the body wants to keep (i.e. sodium or glucose) leave the proximal tubule and enter the interstitial fluid that is outside of it.  As the electrolytes leave, water follows along.

Distal (Convoluted) Tubule: The Distal Tubule continues the process of reabsorption of electrolytes (especially sodium) and water.  If the body needs to retain water, such as when you’re dehydrated, then this tubule will either continue to reabsorb water, which concentrates the urine further, and causes the urine to look darker.  If the body needs to get rid of water, such as when you drank 2-liters of soda, then the distal tubule will allow more water to stay in the urine, which causes it to look much lighter in color.

Collecting Duct:  The Collecting Duct is the final step of the urine concentration process, and it carries the concentrated urine into the Renal Pyramid to start the journey towards the bladder.

Peritubular capillaries:  When electrolytes and water leave the Proximal or Distal Tubule and enter the interstitial fluid, they will eventually pass into the system of Peritubular capillaries and return to the main blood stream.


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4 Comments

  1. julia ibeuike

    This explanation of the nephron is simplified, understandable and part of the best for student and even non nursing students.

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