Title Homeostasis Notes+MCQS.pdf ✅

Homeostasis Dr. Muhammad Sohail, PhD 1 NIT # 15 SCAN QR CODE to Watch MDCAT Lectures, Test Discussions, and Past Papers Discussion on ‘’Homeostasis’’ U Homeostasis Content: ➢ Explain different organs of urinary system. Describe the structure of kidney and relate it with its function. ➢ Explain the processes of glomerular filtration, selective re-absorption and tubular secretion as the events in kidney functioning. ➢ Justify the functioning of kidneys as both excretion and osmoregulation. ➢ Compare the function of two major capillary beds in kidney i.e. glomerular capillaries and peritubular capillaries. ➢ Explain the causes and treatments of kidney stones. ➢ Outline the causes of kidney failure. ➢ Describe thermoregulation and explain its needs ➢ List various nitrogenous compounds excreted during the process of excretion.


Homeostasis Dr. Muhammad Sohail, PhD 4 Structure of Nephron Part Location Function Bowman's Capsule / Glomerulus capsule Renal cortex Collects filtrate from glomerulus Glomerulus Capillaries cluster inside Bowman's capsule. Podocytes are specialized cells in glomerulus that are wrapped around blood capillaries. Filters blood (ultrafiltration) Proximal Convoluted Tubule (PCT) Renal cortex Reabsorbs 70–80% of water, ions, nutrients Loop of Henle Extends into renal medulla Creates concentration gradient in medulla Descending limb (Cortex → medulla) Reabsorbs water Ascending limb (Medulla → cortex) Reabsorbs salts (Na+, Cl−), impermeable to water Distal Convoluted Tubule (DCT) Renal cortex Regulates ions, pH; site of secretion Collecting Duct Cortex through medulla Final concentration of urine; regulated by ADH Types of Nephrons Feature Cortical Nephron Juxta-medullary Nephron Location Mostly in the renal cortex Close to cortico-medullary junction Percentage in kidney About 85% of total nephrons About 15% of total nephrons Loop of Henle Short loop, barely enters medulla Long loop, extends deep into medulla Vasa recta Absent or poorly developed Well developed Role in urine concentration Less important Very important (concentrates urine) Capillary network Surrounded mainly by peritubular capillaries Surrounded by vasa recta Filtration rate Slightly lower Slightly higher