Physiology of Urinary System

Function of Urinary System Excretion of Metabolic waste products as urea, uric acid Drugs toxic metabolite and food additives. 2. Regulation of Water and inorganic ion balance Blood-osmotic pressure through filtration of the blood Blood volume Blood-pH (maintain the Acid-base balance) Blood pressure through the Renin-angiotensin system 3.Retention of vital substances as glucose, proteins, ions and vitamines 4.Endocrine function through secretion of: Erythropoietin (synthesis of erythrocytes) Synthesis of 1,25-Dihydroxvitamin D3 5.Inactivation of Histamine by histaminase enzymes Organic phosphate by phosphatase enzymes 6.Synthesis of amonia, hipuric acid and glucose (gluconeogenesis)

Kidney Anatomy renal pyramids renal pelvis renal cortex renal capsule renal medulla renal capsule ureter

Internal Anatomy of Kidneys:

Renal circulation

Internal Anatomy of Kidney Arrows review basic parts rest of picture shows details of drainage system minor calyx accepts tip of pyramid where urine is dripping off papilla 3 minors empty into major in yellow major empty into pelvis which is the top of the ureter variability between kidneys

Renal circulation Renal blood flow is about 20% of the COP this mean that in a person having COP about 5.5 L/min. Kidneys receive 1.1 L/min

Only vessels you need to know are renal A & V coming in & going out glomerular capillaries bringing in blood to be filtered peritubular capillaries in the cortex & vasa recta in the medulla carrying away useful substances

Kidneys functional unit : the nephron Total of about 2.5 million in the 2 kidneys. Each nephron consists of 2 functional components: The tubular component (contains what will eventually become urine) The vascular component (blood supply) The mechanisms by which kidneys perform their functions depends upon the relationship between these two components.

Structure of Nephron Renal Corpuscle Tubes Bowman’s capsule glomerulus Parietal layer Bowman’s space Visceral layer PCT Thick DLLH Thin DLLH Thin ALLH Thick ALLH DCT Collecting duct The nephron is the functional unite of the kidneys Each human kidneys is made up of about one million nephrons Nephron are classified according to their location into Thick DLLH;Discending limb of loob of henel Superficial Cortical nephron Jaxtamedullary nephron.

Kidneys perform its functions through three main processes Function of kidneys Kidneys perform its functions through three main processes Glomrular filtration Tubular reabsorption Tubular secretion

The three basic renal processes Glomerular filtration Tubular reabsorption Tubular secretion GFR is very high: ~180l/day. Lots of opportunity to precisely regulate ECF composition and get rid of unwanted substances. N.B. it is the ECF that is being regulated, NOT the urine.

Structure of the Bowman’s (glomerular) capsule Afferent arteriole Parietal layer of glomerular capsule Juxtaglomerular cell Capsule space Proximal convoluted tubule Efferent arteriole Endothelium of glomerulus Podocyte Pedicel The glomerulus is a tuft or cluster of blood vessels from which the filtrate is formed The glomerulus is surrounded by the bowman’s capsule and contain the bowman’s space or the renal space at which the filtrate is collected The renal courpusle is the term indicates to the bowman’s capsule and the glomerulus

Function of different part of the nephron

Normal range of daily urine Production is about 2L stored in the UB till the time of urination When it is completely filled, the bladder can hold approximately (500 to 530 ml) of urine