Renal Functions-
The kidneys perform four crucial functions:-
- Excretory: Eliminate waste products like urea, uric acid, creatinine, and excess ions (Na+, H+, K+) through urine.
- Homeostatic: Maintain a stable internal environment by regulating the volume and composition of body fluids, including electrolyte balance and blood pH.
- Endocrine: Synthesize and secrete hormones like renin (regulates blood pressure), erythropoietin (stimulates red blood cell production), and activate vitamin D3.
- Metabolic: Contribute to glucose regulation and amino acid metabolism.
Kidney Structure-
- Cortex (outer layer): Contains glomeruli, proximal and distal convoluted tubules, and the beginning of collecting ducts.
- Medulla (inner layer): Contains loops of Henle, collecting ducts, and the vasa recta.
- Renal pyramids: Subdivisions of the medulla, separated by renal columns, and containing nephrons (functional units of the kidney).
- Calyces: Collecting structures that drain urine from the pyramids into the renal pelvis and then the ureter.
Nephrons
- Cortical nephrons: Located mainly in the cortex, responsible for solute reabsorption.
- Juxtamedullary nephrons: Located near the corticomedullary border, have longer loops of Henle, and play a key role in concentrating urine.