Human Kidneys – Structure and Functions

Human kidney, structure, function of kidney and so on.

Introduction

The function of kidneys in the human body is to get rid of waste products, maintain balanced solution levels and regulate blood pressure. The kidneys work as a natural filter for the human body as they excrete waste in the urine.

The kidneys are a pair of bean-shaped organs found high within the back of the abdominal cavity, just under the rib cage, one on either side of the spine. The left kidney is slightly above the right due to the position of the livers.

Adult kidneys are roughly 10 to 12 cm long and 5 to 7 cm broad and weigh approximately 150 grams.

The Structure of Human Kidneys

At the back of the abdominal cavity lies the pair of kidneys on either side of the spinal cord. The right kidney is smaller than the left kidney to make space for the liver.

In a typical male body, the kidney weighs around 125 to 170 grams, whereas it weighs around 140 grams in a female body. Both the two kidneys are covered with a fibrous and tough renal capsule along with two layers of fat to protect them. Each kidney has three internal areas: the renal pelvis, renal cortex , renal medulla and three outer layers: the renal fascia, the perirenal fat capsule and the renal capsule. The insides of both the kidneys have pyramid-like lobes, which consist of the inner light-coloured renal medulla, and the outer part has a renal cortex which is dark-coloured, forming the urine-producing part of the kidneys. Kidneys have an important function to play in the human body which allows them to consume 20-25% of the output given by the heart.

The end part of the two kidneys is called the ureter, a tube-like thing that moves the produced urine to the bladder.

The renal cortex, a layer of tissue that is also covered by renal fascia (connective tissue) and the renal capsule, surround the kidneys. The existence of nephrons—the functional unit of the kidney—deeper within the kidney, within the renal pyramids of the medulla, causes the renal cortex to be granular tissue. Arterioles and venules from the renal artery and vein, as well as glomerular capillaries, perfuse the nephrons of the kidney through the cortex. The renal cortex also produces erythropoietin, a hormone required for the formation of new red blood cells.

The medulla is the innermost part of the kidney’s parenchyma. The renal pyramids, which are triangular structures that contain a dense network of nephrons, are made up of several pyramidal tissue masses in the medulla.

Bowman’s capsule is a cup-shaped structure found at one end of each nephron in the cortex of the kidney. It encircles the glomerulus, which is a tuft of capillaries that transports blood from our renal arteries to our nephron, where the capsule filters plasma.

After passing through the capsule, the filtered fluid travels down the proximal convoluted tubule to the Henle loop, then to the distal convoluted tubule collecting ducts, where it enters the ureter. Each of the nephron’s components is selectively permeable to distinct molecules, allowing for the body’s complicated management of water and ion concentrations.

The Hilum or renal pedicle is found in the renal pelvis. The hilum is the concave area of the bean shape from where the blood vessels and nerves enter and exit the kidney. Also, if we look at the urinary system in the human body, it’s also where the ureters—urinary-bearing tubes that exit the kidney and drain into the urinary bladder—exit. The renal pelvis is the part of the body that links the kidney to the rest of the body.

The Functions of Human Kidneys

There are mainly six functions of the human kidneys:

Keeping the acid-bases control: In a human body, the acids and bases are in equilibrium which is shown by a parameter – pH, which usually ranges between 7.35 to 7.45 in a normal human body. The kidneys act as a controller for these acids and bases, as it excretes or retains these compounds on the basis of the requirement

Maintenance of the blood electrolyte: The kidneys play a role in filtering electrolytes in the blood; it either pushes it back to circulation or excretes it in the form of urine

Regulates blood pressure: The kidneys produce Renin, which gives birth to Angiotensin II. This increases the blood pressure by constricting the blood vessels. Additionally, if the blood pressure is high, the kidneys regulate it by producing more urine

Removing toxins: The kidneys act as an agent to remove the water-soluble toxins and waste from the human body

Activation of Vitamin D: Kidneys transform Calcifediol into Calcitriol, which is an active form of Vitamin D in the human body that keeps the bones healthy through the regulation of calcium and phosphate in the blood

Control the water: A major function of kidneys in the human body is to keep the water stable within the body through the regulation of urine, depending on the water intake of the person on a day to day basis

Maintaining Healthy Kidneys

Drink plenty of water every day at regular intervals

Limit the sodium intake in the body to a maximum of 2300 grams each day

Control the amount of alcohol intake. More than one drink per day can harm the functioning of the kidney

Through regular exercise, one can regulate their blood pressure and obesity, which will, in turn, keep the kidney healthy

Most importantly, one should have a balanced and healthy diet, which has the least amount of junk food intake