SCIENTIFIC ARTICLE: RENAL VASCULAR PHYSIOLOGY AND HISTOLOGY

Аннотация

The kidney plays a central role in blood filtration, fluid balance, and blood pressure regulation. Its vascular network is uniquely adapted to support these functions. This paper reviews the renal vascular system's physiological control mechanisms and histological organization, emphasizing the structural-functional relationships essential for homeostasis. Keywords: Renal blood flow, Glomerulus, Afferent arteriole, Juxtaglomerular apparatus, Renin, Kidney histology, Vasa recta, RAAS, Filtration barrier, Tubuloglomerular feedbac 1 Introduction The renal vascular system ensures adequate blood flow for filtration, reabsorption, and secretion processes. Each kidney receives about 20–25% of the cardiac output, highlighting its vascular importance. Understanding the physiology and histology of renal vasculature is essential for comprehending kidney function and related diseases. 2. Renal Vascular Physiology 2.1 Renal Blood Flow (RBF) Renal blood flow is tightly regulated by autoregulatory mechanisms such as: Myogenic response Tubuloglomerular feedback (TGF) Выпуск журнала №-26 Часть–7_ Май –2025 144 MODERN EDUCATION AND DEVELOPMENT These mechanisms maintain a stable glomerular filtration rate (GFR) despite fluctuations in systemic blood pressure. 2.2 Glomerular Filtration The afferent arteriole brings blood into the glomerulus, where filtration occurs. The efferent arteriole carries blood away and supplies the peritubular capillaries and vasa recta. 2.3 Role in Blood Pressure Regulation The juxtaglomerular apparatus (JGA) secretes renin, initiating the renin– angiotensin–aldosterone system (RAAS), which regulates blood pressure and volume. 3. Renal Vascular Histology 3.1 Glomerulus Structure The glomerulus is a tuft of fenestrated capillaries surrounded by Bowman’s capsule. Filtration is facilitated by: Fenestrated endothelium Basement membrane Podocytes with filtration slits 3.2 Arterioles and Capillaries Afferent arteriole: wider lumen, smooth muscle-rich wall Efferent arteriole: narrower, maintains pressure for filtration Peritubular capillaries: surround proximal and distal tubules Vasa recta: specialized capillaries in the medulla, important for countercurrent exchange 3.3 Juxtaglomerular Apparatus (JGA) Located at the vascular pole, the JGA consists of: Macula densa (senses sodium in distal tubule) Juxtaglomerular cells (secrete renin) Extraglomerular mesangial cells 4. Clinical Relevance Выпуск журнала №-26 Часть–7_ Май –2025 145 MODERN EDUCATION AND DEVELOPMENT Disruption in renal blood flow can lead to acute kidney injury (AKI), hypertension, or chronic kidney disease (CKD). Histological changes, such as glomerulosclerosis or capillary rarefaction, are hallmarks of pathology. 5. Conclusion The kidney's vascular physiology and histology are intricately designed for efficient filtration and homeostatic regulation. Detailed knowledge of this system aids in diagnosing and treating renal and cardiovascular disorders.