The Kidney

Study Notes

Kidney Location and Structure

Kidneys are located on either side of the spine, just below the rib cage.
They are retroperitoneal organs, meaning they are positioned behind the peritoneum.

Nephron Function

The primary function of the nephron is to filter blood and form urine through processes of filtration, reabsorption, and secretion.
Nephrons regulate electrolyte balance, maintain fluid homeostasis, and excrete waste products.

Juxtaglomerular Cells

Juxtaglomerular cells are located in the walls of the afferent arterioles supplying blood to the glomeruli.
They play a critical role in blood pressure regulation by secreting renin, which initiates the renin-angiotensin-aldosterone system.

Glomerular Capillary Walls

Glomerular capillary walls consist of three layers:
- Endothelial cells with fenestrations, allowing selective filtration.
- A basement membrane that acts as a filter for large molecules.
- Podocytes, specialized cells with foot processes that provide additional filtration.

Mesangial Cells and Matrix

Mesangial cells are located within the glomerulus and contribute to structural support and regulation of blood flow.
The mesangial matrix provides a scaffolding for the capillaries and has a role in the phagocytosis of trapped residues.

Nephron Composition

A nephron is composed of several parts:
- Renal corpuscle (containing the glomerulus and Bowman’s capsule)
- Proximal convoluted tubule
- Loop of Henle (with descending and ascending limbs)
- Distal convoluted tubule
- Collecting duct

Function of Mesangial Cells

Mesangial cells contribute to the maintenance of glomerular architecture and help regulate glomerular filtration rate (GFR) by contracting or relaxing to alter blood flow inside the glomeruli.

Juxtaglomerular Cell Location

Juxtaglomerular cells are situated next to the glomerulus, adjacent to the afferent arterioles.

Primary Kidney Function

The primary function of the kidney is to filter blood, removing waste and excess substances while maintaining bodily fluid balance and regulating electrolytes.

Continuity with the Ureter

The structure continuous with the upper end of the ureter is the renal pelvis, which collects urine from the kidneys before it travels to the bladder.

Description

Test your knowledge of the human kidney with this quiz. Explore the primary functions, anatomical location, and composition of this vital organ. Gain a deeper understanding of how the kidney maintains balance and supports overall health.