Kidney Structure and Function

Study Notes

Bowman's capsule is a cup-shaped structure located in the renal cortex, containing a large number of blood capillaries that filter the blood and retain cells and large molecules.
Each Bowman's capsule has an arteriole that enters and splits into a fine network of capillaries called a glomerulus.

The nephron is the functional and structural unit of the kidney, composed of Bowman's capsule, proximal convoluted tubule, loop of Henle, and distal convoluted tubule.
The proximal convoluted tubule is located in the cortex and receives the filtrate from Bowman's capsule.
The loop of Henle dips minimally into the medulla before ascending back into the cortex, allowing for concentration of urine in mammals and birds.
The loop of Henle consists of a descending limb and an ascending limb.
The distal convoluted tubule is located in the cortex and drains into a collecting duct.

Filtration: fluid in the blood is filtered into the tubule system, leaving cells and large proteins in the blood and a filtrate composed of water and all blood solutes.
Reabsorption: selective movement of important solutes, such as glucose, amino acids, and inorganic ions, out of the filtrate and back into the bloodstream via peritubular capillaries.

The collecting duct empties into the renal pelvis, which then drains into the ureter.
The ureter is made of smooth muscle and carries urine to the urinary bladder.
The urinary bladder is a flexible muscular sac that stores urine temporarily until it is expelled through the urethra.

The adrenal gland is located on top of each kidney and secretes hormones that play a role in urine formation.
The adrenal gland's hormones help regulate the process of reabsorption and secretion in the kidneys.

The kidneys are a pair of bean-shaped organs located on either side of the vertebral column, below the ribs and behind the stomach.
Each kidney is covered in a layer of fat known as the adipose capsule of the kidney.
The left kidney is slightly more superior to the right kidney.