Kidney

The kidney

The kidneys are dark red, bean-shaped organs located at the back of the abdominal cavity. Humans have two kidneys: the right kidney and the left kidney. These organs are vital for filtering waste and maintaining fluid and electrolyte balance.

Above each kidney is an adrenal gland, which secretes hormones that help regulate the reabsorption of sodium ions in the body. Two major blood vessels are connected to the kidney:

1. Renal Artery: This blood vessel supplies blood to the kidneys, bringing waste products and other substances to be filtered.
2. Renal Vein: After filtration, the renal vein takes the purified blood away from the kidney.

A ureter is a tube that connects each kidney to the bladder, allowing urine to pass through for storage. Once the bladder is full, nerve endings in its walls are stimulated, sending a signal to the brain that urges the person to urinate. The sphincter muscle at the base of the bladder then relaxes, allowing the urine to be released through the urethra, which in mammals is contained within the penis.

Composites of the kidney

The kidney is made up of three main regions:

1. Cortex: The outermost region where filtration begins.
2. Medulla: The middle region, which contains structures called renal pyramids that play a role in urine formation.
3. Pelvis: The innermost region that collects urine before it is sent to the ureter.

These structures work together to remove waste, regulate water and electrolyte balance, and ensure proper bodily function.