L1 Histology Kidney I (Urinary System) PDF

 Prof. Dr. Samah Kandeel Histology &Cell Biology Department Faculty of Medicine Tanta University Contact: [email protected] Brain Storming  Urinary System Histology (Part I) Semester 3  iLOS By the end of this course the...

 Prof. Dr. Samah Kandeel Histology &Cell Biology Department Faculty of Medicine Tanta University Contact: [email protected] Brain Storming  Urinary System Histology (Part I) Semester 3  iLOS By the end of this course the student should be able to: Know & Describe the normal histological structure of different parts of the urinary system (Knowledge). Recognize the special cell types of Malpighian corpuscles ( Knowledge). Know the structure and functions of blood renal barrier. Differentiate between different cell types of Malpighian corpuscles (Intellectual skills). Identify, draw & label the different parts Malpighian corpuscles (Practical skills).  Urinary System Functions 1. Formation of urine. 2. Removal of waste products. 3. Production of hormones (renin &erythropoietin factor). 4. Regulation of balance between water and electrolytes and acid-base balance. Parts of the Urinary System  Each kidney is surrounded with CT capsule and peri-renal fat. Each kidney has a medial border called the hilum where renal vessels, lymphatics, sympathetic nerves, and pelvis of the ureter are present. Renal pelvis is divided into 2-3 major calyces and each one is subdivided into 2-3 minor calyces. Naked eye kidney shows: ✓ Outer granular cortex: due to renal corpuscles, convolution of proximal and distal convoluted tubules ✓ Inner striated medulla: due to presence of loops of Henle and collecting tubules.  Histological Structure ❑ kidney is divided into 1- Stroma: very scanty connective tissue. 2- Parenchyma: highly vascular and formed of uriniferous tubules. The uriniferous tubules consist of: ✓ Nephrons which produce urine. ✓ Collecting ducts that concentrate urine.  Nephron Definition - It is the structural and functional unit of the kidney. Each nephron consists of : 1- Malpighian corpuscle (Renal corpuscle). 2- Proximal convoluted tubule. 3- Loop of Henle. 4- Distal convoluted tubule.  I. Malpighian Corpuscle (Renal Corpuscle) It is found in the cortex and is formed of: 1. The glomerulus (Tortuous tuft of capillaries) 2. Bowman's capsule (Epithelial capsule covering the glomerulus) It has two poles: Vascular pole: the site where afferent arteriole enters and efferent arteriole leaves. Urinary pole: the site where the proximal convoluted tubule begins. I. Renal Corpuscles  I. Renal Corpuscles A. Glomerulus ❑ It is a tuft of anastomosing capillaries formed from afferent arteriole that enters the Malpighian corpuscle at its vascular pole and gives capillary loops of the glomerulus and unite to form efferent arteriole. ❑ Structure: The glomerular capillaries are lined by fenestrated endothelium and rests on thick basement membrane Intraglomerular mesangial cells: present in between loops of capillaries giving support to the capillaries in the places where the visceral layer of Bowman’s capsule (podocytes) does not come in contact with the capillaries. I. Renal Corpuscles A. Glomerulus  I. Renal Corpuscles B. Bowman's Capsule Formed of two layers: 1. The outer (Parietal layer) and is lined with simple squamous epithelium. 2. The inner (Visceral layer) is lined with modified cells called podocytes. The space between parietal and visceral layers is called capsular space (urinary space). I. Renal Corpuscles B. Bowman's Capsule  Podocyte ❑ L/M: 1. Podocyte is star shaped with multiple processes. 2. Podocytes are separated from glomerular capillaries by subpodocytic space.  Podocyte ❑ E/M It is a large cell consists of body, primary processes (major) and secondary processes (minor). The cell body consists of central nucleus with extended chromatin, mitochondria, Golgi body, RER, microtubules and microfilaments. In between the feet process, there are filtration slits that are covered with diaphragms. Primary and secondary processes contain only microtubules & microfilaments.  Podocyte Function of Podocyte: ▪ It has an important function in the blood renal barrier and in regeneration of basement membrane.  Blood Renal Barrier ❑ Formed of: 1. Fenestrated endothelium of blood capillaries. 2. Thick basement membrane (The only continuous layer of the barrier). 3. Filtration slits with their covering diaphragms. ❑ Function of blood-renal barrier: ▪ The principle function of the barrier is formation of the glomerular filtrate. Blood Renal Barrier Renal system Histology (Practical)  1 2 Q1. Identify the structure in the micrograph? - Kidney Q2. What does numbers 1, 2 refer to ? Q1. Identify the structure in the micrograph? - Kidney Q2. What does arrow refers to ? - Renal Corpuscles (Bowman’s capsule, parietal layer). Q1. Identify the structure in the micrograph? - EM (Electron micrograph) of Podocytes.  MCQ Q1. Which of the following is the epithelium lining of the parietal layer of Bowman’s capsule? A) Simple columnar epithelium. B) Simple squamous. C) Simple cuboidal. Q2. Which of the following structures are present in primary and secondary processes of podocytes? A) Microtubules & microfilaments. B) Intermediate filaments. C) RER.