Download as PDF, PPTX
This is a PDF containing important stuffs
- 1. URINARY SYSTEM Lecturer Dr.FirdousM.Jaafar Department of anatomy/Histology section Lecture 1
- 2. Objectives 1- Describe thedifferent parts of urinary system. 2- Describe the structure of kidney. 3- Define nephron, and list its histological parts. a- Define renal corpuscle, describe its structure, and name its parts. b- Define Podocyte, and relate between its histological structure and process of filtration. c- Define filtration slit, describe its structure, and list its components. 4- Recognize some clinical problems related to filtration. 5- Describe Mesangial cell, and identfy some of its functions.
- 3. Urinary system • Consistsof two kidneys, ureters, and one bladder and ureter. • Function: • 1- Maintenance of homeostasis by production of urine through filtration, absorption, and secretion. • 2- Regulation of fluid and electrolytes balance of the body. • 3- Production of Renin (important in regulation of blood pressure). • 4- Production of Erythropoietin (stimulates the production of erythrocytes).
- 4. Kidney Each kidney issurrounded by a connective tissue capsule that is surrounded by a mass of peri renal adipose tissue. The kidney is divided into an outer cortex and an inner medulla. Renal medulla consists of 10-18 conical or pyramidal structures; the medullary pyramids. The tips of pyramids are called renal papillae, where the collecting ducts open into. Kidney lobe consists of medullary pyramid and associated cortical tissue at its base and sides.
- 5.
- 6. Medical appliation Polycystic kidneydisease is an inherited disorder in which normal cortical organization of both kidneys is lost due to the formation of multiple, large, fluid-filled cysts. The cysts may arise from any epithelial cells of the nephron and can lead to gross kidney enlargement and loss of renal function.
- 7.
- 8.
- 9. Nephron Is the functionalunit of the kidney. It consists of: • Renal corpuscle, an initial dilated portion in the cortex • Proximal convoluted tubule, located primarily in the cortex • Thin and thick limbs of the nephron loop (loop of Henle), which descend into the medulla, then ascend back to the cortex • Distal convoluted tubule • Collecting tubule.
- 10.
- 11. Renal corpuscle It isabout 200 µ in diameter, and consists of a tuft of capillaries; the glomerulus, and a double-walled epithelial capsule; glomerular(Bowman's capsule).
- 13. Glomerulus Afferent arteriole will divideinto many glomerular capillaries, which are fenestrated with no diaphragm.
- 14. Bowman's capsule Composed oftwo layers; 1- Parietal layer consists of simple sequamus epithelium supported by a basal lamina and a thin reticular fibers.
- 15. Bowman's capsule 2- Viscerallayer is modified during embryonic life and the cells are called Podocytes.
- 16.
- 17. Podocyte The cell bodygives rise to several primary processes from which arise numerous secondary processes that called pedicels. These pedicels embrace the capillary of glomerulus and come in contact with the basal lamina at a periodic distance of 25nm. The pedicels interdigitate with each other defining a space about 25nm wide; the filtration slit which is bridged by a diaphragm of 6nm thick.
- 18.
- 19.
- 20. A thick basement membrane(0.1µm) is formed by fusion of the basal laminae of both capillary and podocytes, forming a filtration barrier that separates urinary space and capillary blood.
- 21. Filtration apparatus • Consistsof: • 1- Endothelium of glomerular capillaries: they are fenestrated, with no diaphragm, and posse a large number of aquaporin-1(AQP-1) water channels that allow fast movement of water through epithelium. • 2- Glomerular basement membrane. • 3- Podocytes.
- 22. Medical applications • Indiseases such as diabetes mellitus and glomerulonephritis, the glomerular filter is altered and becomes much more permeable to proteins, with the subsequent release of protein into the urine (proteinuria).
- 23. Mesangial cell This cellis found adherent to the wall of glomerular capillaries where the basal lamina is shared by two or more capillaries. It has cytoplasmic processes that extend to the endothelial cells.
- 24.
- 25. Functions of mesangialcell • Physical support and contraction—the mesangium provides internal structural support to the glomerulus and like pericytes, its cells respond to vasoactivesubstances to help maintain hydrostatic pressure for the optimal rate of filtration. • Phagocytosis—mesangial cells phagocytose protein aggregates that adhere to the glomerular filter, including antibody-antigen complexes abundant in many pathological conditions. • Secretion—the cells synthesize and secrete several cytokines, prostaglandins, and other factors important for immune defense and repair in the glomerulus.