Regulation of Kidney Function

Kidney function is one of the most important processes of the human body. The functions of the kidney include removing excess fluid and wastewater products from the body, maintaining healthy bones by producing an active form of vitamin D, balancing minerals in the human body and controlling blood pressure. The kidney is also responsible for the production of red blood cells. 

Structure of the Kidney

The kidneys are located on either side of the abdomen. They are two bean-shaped organs about the size of a fist. Each kidney is surrounded by a thick, fibrous renal capsule that protects the soft tissue within. Additional protection is provided by two layers of fat. The adrenal glands surround the kidneys. 

A variety of pyramid-shaped lobes can be found inside the kidneys. An outer renal cortex and an inner renal medulla make up each kidney. Between these parts, nephrons flow. The glomerulus and tubule are found in each nephron. The glomerulus filters the blood when it enters and exits the kidneys through the renal arteries and veins. The tubule returns vital nutrients to the bloodstream while removing waste, which is eventually excreted as urine. The ureter is a tube that connects the kidneys to the bladder, from where urine is excreted.

Functions of the Kidney

The kidneys perform the following functions:

1)    Kidney function related to Juxtaglomerular (JGA) 

The juxtaglomerular apparatus (JGA) is made up of a few glomerulus cells, a distal tubule, and afferent and efferent arterioles. It’s a complex structure found in a specialised part of the nephron where the afferent arteriole and the distal convoluted tubule (DLT) are in direct touch. 

Juxtaglomerular cells are specialised cells present in the afferent arteriole that make up the juxtaglomerular apparatus(JGA). JGA detects detects blood pressure and releases renin. When glomerular blood pressure falls, juxtaglomerular cells become activated and produce renin.

Renin converts angiotensinogen in the blood to angiotensin I, which is then converted to angiotensin II. The resulting angiotensin II is a potent vasoconstrictor that raises blood pressure and increases the filtration rate. 

Angiotensin II promotes aldosterone production in the adrenal cortex. The rate of sodium ion and water absorption from the distal convoluted tubule is increased by aldosterone. Blood pressure and the glomerular filtration rate both rise as a result of this. The renin-angiotensin system increases blood pressure.

2)    Kidney function that involves the hypothalamus

Osmoreceptors activate and stimulate the hypothalamus (posterior pituitary gland) to release antidiuretic hormone (ADH) or vasopressin from the neurohypophysis when there is an excessive loss of fluid from the body. 

ADH prevents diuresis by stimulating water reabsorption from the tubules’ later sections (DCT and CD). The osmoreceptors are deactivated, and ADH is suppressed when the body’s fluid volume is increased.

Hormones That Help in the Regulation of Kidney

The hormone mainly responsible for kidney function regulation is renin. Renin is an enzyme secreted by the kidneys that is involved in the body’s renin-angiotensin-aldosterone system (RAAS). It is also known as the renin-angiotensin-aldosterone axis.

It regulates arterial vasoconstriction and the volume of extracellular fluid comprising blood plasma, interstitial fluid, and lymph). As a result, it keeps the body’s mean arterial blood pressure under control.

How Does the Kidney Function?

About a million filtering units called nephrons make up each kidney. A filter called the glomerulus and a tubule are found in each nephron. The glomerulus filters the blood, and the tubule returns the required components to the blood while removing wastes.

The glomerulus is a collection of microscopic blood arteries where blood enters each nephron as it rushes in. Smaller molecules, wastes, and fluid—mostly water—can pass through the Glomerular thin walls and enter the tubule. Proteins and blood cells stay in the blood vessel because they are larger molecules.

An artery surrounds the tubule. The blood vessel absorbs nearly all of the water, as well as the minerals and nutrients the body needs as the filtered fluid passes down the tubule. The tubule helps to eliminate excess acid. Urine is formed from the tubule’s leftover fluid and wastes.

A significant drop in kidney function can result in an accumulation of toxins and pollutants in the bloodstream. This can make people fatigued and weak. Anaemia, which can induce weakness and weariness, is another effect of kidney illness.

Conclusion

Kidneys play several important regulatory functions. Electrolyte regulation, acid-base balance, and blood pressure control are all dependent on them. They help the body by filtering blood to eliminate wastes that would otherwise be excreted through the urinary bladder. 

The kidneys are responsible for excreting wastes such as urea and ammonium, as well as reabsorbing water, glucose, and amino acids. Calcitriol, erythropoietin, and the enzyme renin are all produced by the kidneys. 

The body will fill up with additional water and waste products if the kidneys stop working.