Problem 38 - Objective Biology for NEET

Question

Which of the following is correct about hilum of kidney? (a) It is present on the convex outer surface. (b) It is present at the inner convex surface. (c) It is notch through which ureter, nerve and blood vessel enter. (d) It is the place where the calyces are open.

Step-by-Step Solution

Answer

(c) It is notch through which ureter, nerve and blood vessel enter.

Step 1: Identifying Incorrect Options

Firstly, let's rule out (a) and (b). The hilum of the kidney is neither located on the overall outer convex surface, nor on the inner convex surface.

Step 2: Comparing Remaining Options

Now we are left with (c) and (d). Consider both the details: (c) suggests it's a notch for ureter, nerve and blood vessel entrance and (d) suggests it's the place where calyces open.

Step 3: Choosing Correct Answer

Based on anatomical facts, the hilum of the kidney is the point through which the renal arteries, renal veins, nerves, and ureter pass. Hence, option (c) is correct.

Key Concepts

Renal Anatomy

The study of renal anatomy forms a foundational aspect of understanding the urinary system. Each kidney holds vital significance for filtering blood, removing waste, and balancing electrolytes. The hilum of the kidney plays a central role in this process.

Describing the hilum of the kidney as a gateway is both fitting and anatomically accurate. Located medially and facing the spine, it's an indented area through which the ureter, nerves, lymphatic vessels, and renal blood vessels pass. It is the point where these structures either enter or exit the kidney. This function makes it a bustling hub of renal activity.

Incorrect Location Myths

Contrary to some misunderstandings, the hilum is not on the convex outer surface, which is smooth and rounded. Neither is it present at any sort of inner convex surface; such a description doesn't exist in renal anatomy. Understanding the correct position of the hilum helps in visualizing the kidney's connectivity with the rest of the body.

Kidney Structure

Delving into the kidney's internal structure reveals a complex and efficient system. The outermost layer, the renal cortex, contains nephrons—the kidney's filtration units. Beneath this area lies the renal medulla, which is composed of pyramid-like structures (renal pyramids) and tissues that transport urine to the renal pelvis.

The renal pelvis spans the central portion of the kidney, funneling urine into the ureter. The calyces—minor and major, are part of this drainage system. They don’t directly interact with the hilum but funnel the urine they collect into the renal pelvis, which then proceeds to the ureter. Thus, learning the kidney's layout clarifies the journey of waste from blood filtering to urine excretion.

Hilum Vs. Calyces

It is essential to distinguish between the hilum and calyces. The hilum, as described earlier, is the concave notch facilitating passage of vessels and nerves. In contrast, calyces serve as chambers where urine is collected before being passed down to the ureter—no openings occur at the hilum.

Urinary System

Beyond the kidney, the urinary system is a diligent network responsible for creating, storing, and excreting urine. It includes two kidneys, two ureters, the urinary bladder, and the urethra. The function and health of the urinary system are definitely interdependent on the structures within the kidney, such as the hilum.

For the system to work effectively, a coordinated sequence of processes takes place. Blood filtration occurs in the kidneys, urine is then transported through the ureters, stored in the bladder, and eventually excreted through the urethra. Each component, from the microscopic nephron to the expansive bladder, is intricately linked through a physiological circuit that maintains our body’s homeostasis.

Hilum's Role in the System

The hilum's role cannot be overstated; it is the logistical heart of the kidney. As nerves and blood vessels enter and leave, the ureter emerges from the hilum, beginning its path to the bladder. This explains why understanding the hilum's placement and function is crucial for grasping the broader context of the entire urinary system's operation.