Blood Supply of the Kidneys: Videos & Practice Problems

The kidneys receive about one-fourth of the total cardiac output through the renal artery, filtering blood and removing waste. Blood enters the nephron via afferent arterioles, reaching the glomerulus, and exits through efferent arterioles. In cortical nephrons, efferent arterioles form peritubular capillaries for reabsorption, while in juxtamedullary nephrons, they create vasa recta, which help concentrate urine. Understanding this blood supply is crucial for grasping renal function and homeostasis.

Blood Supply to the Kidneys

The kidneys play a crucial role in filtering blood and removing waste products, receiving approximately one-fourth of the total cardiac output. Blood enters the kidneys through the renal artery and exits via the renal vein. Understanding the anatomy of the kidney's blood supply is essential for grasping how these organs function.

Within the renal cortex, the renal arteries branch into afferent arterioles, which are responsible for delivering blood to the renal corpuscle. A helpful mnemonic to remember this is that "afferent" means to "arrive." The afferent arterioles lead to the glomerular capillaries, forming a structure known as the glomerulus. After filtration occurs in the glomerulus, blood is drained by the efferent arterioles, which can be remembered by the phrase "efferent exit." This blood then enters a network of capillaries that differ between cortical and juxtamedullary nephrons.

In cortical nephrons, the efferent arterioles supply peritubular capillaries that surround the renal tubule, facilitating the reabsorption of water and solutes. In contrast, juxtamedullary nephrons have efferent arterioles that form the vasa recta, a straight network of capillaries that run parallel to the nephron loops. The vasa recta play a vital role in concentrating urine, which is a key function of juxtamedullary nephrons.

In summary, the renal artery is the primary source of blood supply to the kidneys, while the renal vein is responsible for blood exit. Afferent arterioles bring blood into the nephron, and efferent arterioles allow it to exit. The peritubular capillaries are essential for reabsorption around the renal tubule, and the vasa recta are crucial for urine concentration in juxtamedullary nephrons. Understanding these components is fundamental to comprehending kidney function and the overall process of blood filtration.

Blood Supply of the Kidneys Example 1

Juxtamedullary nephrons are essential for the formation of concentrated urine due to their unique anatomical features. These nephrons are located near the medulla of the kidney and have long loops of Henle that extend deep into the medulla, allowing for a greater concentration gradient. A critical structure associated with juxtamedullary nephrons is the vasa recta, which are specialized capillaries that run parallel to the loops of Henle. The vasa recta play a vital role in maintaining the osmotic gradient established by the nephron, facilitating the reabsorption of water and solutes, thus contributing to the concentration of urine.

In contrast, other structures such as afferent arterioles and renal arteries serve different functions. Afferent arterioles supply blood to the glomeruli, while renal arteries provide blood to the entire kidney. The glomerular capillaries are involved in the filtration process but do not directly contribute to urine concentration. Therefore, the vasa recta is the unique structure that supports the function of juxtamedullary nephrons in forming concentrated urine.

The arteriole that exits the glomerular capillaries and goes on to form the peritubular capillaries is the:

• A. Afferent arteriole.
• B. Efferent arteriole.
• C. Vasa recta.
• D. Renal vein.

Answer: (B)

Here’s what students ask on this topic:

What is the main blood supply to the kidneys?

The main blood supply to the kidneys comes from the renal artery. The renal artery branches off from the abdominal aorta and delivers about one-fourth of the total cardiac output to the kidneys. This high volume of blood is essential for the kidneys to perform their primary function of filtering blood and removing waste products. The blood exits the kidneys through the renal vein, which drains into the inferior vena cava.

How does blood enter and exit the nephron?

Blood enters the nephron through the afferent arteriole, which brings blood to the glomerulus, a network of capillaries within the renal corpuscle. After filtration in the glomerulus, blood exits the nephron via the efferent arteriole. The efferent arteriole then forms either peritubular capillaries in cortical nephrons or the vasa recta in juxtamedullary nephrons, facilitating further processes like reabsorption and concentration of urine.

What is the function of peritubular capillaries in the kidneys?

Peritubular capillaries form a network around the renal tubules in cortical nephrons. Their primary function is to reabsorb water and solutes from the renal tubule cells back into the bloodstream. This reabsorption process is crucial for maintaining fluid and electrolyte balance in the body. The peritubular capillaries weave in and out of the renal tubules, ensuring efficient reabsorption of essential substances.

What role do the vasa recta play in the kidneys?

The vasa recta are a network of capillaries that run parallel to the long nephron loops in juxtamedullary nephrons. They play a crucial role in concentrating urine by maintaining a gradient of solutes in the renal medulla. This gradient allows for the reabsorption of water from the filtrate, leading to the production of concentrated urine. The vasa recta's unique structure and function are essential for the kidneys' ability to conserve water and produce concentrated urine.

What is the difference between cortical and juxtamedullary nephrons in terms of blood supply?

Cortical nephrons and juxtamedullary nephrons differ in their blood supply structures. In cortical nephrons, the efferent arteriole forms peritubular capillaries that surround the renal tubules, facilitating reabsorption. In contrast, in juxtamedullary nephrons, the efferent arteriole forms the vasa recta, which run parallel to the nephron loops and help concentrate urine. These differences are crucial for the distinct functions of each nephron type in the kidney.