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What is the Renal Medulla?

Meshell Powell
Meshell Powell

The renal medulla is a term used for the innermost portion of the kidney. It is divided into several sections known as renal pyramids because of their cone-like appearance. Inside are structures known as nephrons, and they have the responsibility of maintaining the balance of water and salt within the blood.

The renal artery provides the blood supply to the kidney, then branches into what are known as arcuate arterioles. These blood vessels are located at the border of the renal medulla and are responsible for renal, or kidney, circulation. The arcuate arterioles are so named due to the fact that they are shaped like arcs due.

Decreased kidney function may occur if the renal medulla is damaged, requiring immediate medical attention.
Decreased kidney function may occur if the renal medulla is damaged, requiring immediate medical attention.

The arcuate arterioles branch even farther into interlobular arterioles, which are smaller arteries that branch off at right angles. These blood vessels finally reach their destination at the glomeruli, the plural form of the word glomerulus. These are small capillaries responsible for starting the process of filtering toxins from the blood and forming urine.

A diagram of a kidney, including the renal medulla in pink.
A diagram of a kidney, including the renal medulla in pink.

When the blood reaches the glomeruli, pressure begins to build. This forces the portion of the blood known as serum into the structures known as renal tubules. Serum, another name for serous fluid, is the liquid part of blood remaining after the clotting process has occurred. The renal tubules contain the resulting liquid that will later be converted to urine.

A diagram of a nephron, located inside the renal medulla.
A diagram of a nephron, located inside the renal medulla.

Once the blood has left the renal medulla and the serum is removed and forced into the renal tubules, the fluid exits the kidney through the collecting duct. It then makes its way to the ureter, the tube designed to carry urine from the kidney to the bladder. After this process, the urine leaves the bladder and exits the body.

Damage to the kidney can occur due to traumatic injury or a naturally occurring disease process, and when the renal medulla is damaged, the results can be devastating. Decreased kidney function is possible, with complete renal failure becoming a possibility. Medical intervention is crucial with this type of kidney damage. Hypertension, also known as high blood pressure, is the most common symptom. A urologist or a nephrologist is well qualified to treat this type of damage, with urologists specializing in the urinary system and nephrologists specializing in the kidney itself.

Discussion Comments

Perdido

@seag47 - I know this one! Since the renal cortex contains so many blood vessels, it gets to filter the blood. It removes waste from the body. Thanks for asking!

seag47

@Perdido - I’ve got a question for you, since you have your head in the topic. What is the function of the renal cortex?

Perdido

In my biology class at college, we are studying the anatomy of the kidney now. Today, we focused on the renal cortex. I’m hoping that typing this information will help me remember it for our quiz tomorrow.

I would just like to add that the renal cortex is the kidney’s outer portion. It lies between the renal medulla and the renal capsule. The renal cortex is continuous and smooth. It has several columns that project downward between the pyramids.

The renal cortex also houses the renal corpuscles and renal tubules, other than the portions of the loop of Henle that project into the renal medulla. It contains cortical collecting ducts and blood vessels.

shell4life

I have polycystic kidney disease. Another name for this disease is medullary cystic kidney disease. This condition has caused me to develop high blood pressure at the age of 27. I have to take medication to lower the blood pressure and keep my kidneys protected.

I have kidney pain from time to time, usually when a cyst ruptures. Sometimes I feel the pain in my abdomen. Other times I just have general discomfort in my sides and back.

Though there is no treatment for this disease, I am involved in a clinical trial for a drug that will likely soon be approved by the FDA to stop the development of new cysts and shrink old ones.

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    • Decreased kidney function may occur if the renal medulla is damaged, requiring immediate medical attention.
      By: Tyler Olson
      Decreased kidney function may occur if the renal medulla is damaged, requiring immediate medical attention.
    • A diagram of a kidney, including the renal medulla in pink.
      A diagram of a kidney, including the renal medulla in pink.
    • A diagram of a nephron, located inside the renal medulla.
      By: designua
      A diagram of a nephron, located inside the renal medulla.
    • Long-term use of narcotics may damage the renal medulla.
      By: aaabbc
      Long-term use of narcotics may damage the renal medulla.
    • High blood pressure is the most common symptom of a damaged renal medulla.
      By: dambuster
      High blood pressure is the most common symptom of a damaged renal medulla.