Kidney Location & Structure

There are few organs in the body as important as the kidneys, which are responsible for filtering all the waste our body doesn’t need. The kidneys are one of the first lines of defense our bodies have against infection and the spread of basic disease, and kidney failure can lead to serious complications.

The kidneys function in several specific ways, and are connected to the bladder as they help filter bodily waste through urine. Let’s learn about the basic location, structure and functions of kidneys in the human body.

Kidney Location

Every healthy human body has two kidneys, the left and the right. Each kidney is about four or five inches long, shaped somewhat like a bean. The left kidney sits a bit higher in the body because of the size of the liver, which is also on the right side.

Muscles in your back and your ribcage protect your kidneys from both the front and the back sides of your body. There is also fat tissue, called perirenal fat, that surrounds the kidneys for protection. The kidneys are considered “retroperitoneal” organs, which means they sit behind a lining in the abdominal cavity, unlike all other abdominal organs.

Kidney Structure

Each kidney has several specific parts, each of which perform their own specialized functions.

Renal hilus: An indentation on the side of the kidney that allows a place for arteries, veins and the ureter (the pathway from the kidney to the bladder) to enter the kidney.
Renal capsule: This is a thin layer of tissue that forms a hard shell on the outside of the kidney.
Renal cortex: Inside the renal capsule is a soft layer called the renal cortex, which contains seven cone-shaped renal pyramids that form the renal medulla.
Minor calyces: The renal pyramids connect to the minor calyx, which is a tiny tube that collects waste in the form of urine.
Major calyces: Several minor calyces feed into three major calyces.
Renal pelvis: This is the center of the kidney, and is fed from the major calyces. The renal pelvis then connects to the renal hilus, which drains the urine out into the ureter and eventually into the bladder to be eliminated from the body.

There are several processes that take place in order to keep the kidney stocked with blood through arteries flowing in and out of the renal hilus.

Functions

The parts of your kidneys that actually filter blood to produce urine, are called nephrons. There are around a million microscopic nephrons in each kidney, and each nephron contains two primary parts:

1. Renal corpuscle: The renal corpuscle is the place where blood collects in the kidney, and is then processed or filtered into urine.
2. Renal tubule: The renal tubule is a collection of tubes that help collect the urine, concentrate it and extract any beneficial substances that may have been collected in the urine.

The kidneys have a few specific jobs:

Filtration: The main job of the kidneys. Filtering blood and waste into urine for the body to eliminate.
Absorption and secretion: As filtering is taking place, the kidneys are also absorbing positive elements and secreting them back into the bloodstream. They’re also absorbing extra waste still left in the blood, and passing that back into the filtrate.
Homeostasis: This is a process where the kidneys regulate different bodily functions and chemical levels. It can be done for water, acids and bases, electrolytes, blood pressure and hormones. This keeps the body “even” in many important elements.