Renal System Functions of kidney: Remove waste products from the blood Remove waste products from the blood Control the acid base balance (through HCO 3 - & H + ) Control the acid base balance (through HCO 3 - & H + ) Secrete Hormones and enzyme like erythropoietin and rennin. Secrete Hormones and enzyme like erythropoietin and rennin. Activates Vitamin D. Activates Vitamin D. Make G from non CHO sources ( make sugar from proteins at time of starvation (gluconeogenesis). ) Make G from non CHO sources ( make sugar from proteins at time of starvation (gluconeogenesis). )

Nitrogenous Wastes Urea Urea –proteins  amino acids  NH 2 removed  forms ammonia, liver converts to urea Uric acid Uric acid –nucleic acid catabolism Creatinine Creatinine –creatinine phosphate catabolism Renal failure Renal failure –azotemia: nitrogenous wastes in blood –uremia: toxic effects as wastes accumulate

Urinary System Two kidneys Two kidneys Two ureters Urethra

Anatomy of Kidney Renal cortex: outer 1 cm… cortical atrophy means damage to the kidney…in the cortex the glomeruli reside Renal cortex: outer 1 cm… cortical atrophy means damage to the kidney…in the cortex the glomeruli reside Renal medulla: different types of tubules…Striated appearance Renal medulla: different types of tubules…Striated appearance

Lobe of Kidney

Nephron Diagram Peritubular capillaries shown only on right Peritubular capillaries shown only on right

Renal pyramid Efferent vessel Renal artery Renal vein Renal hilum Renal pelvis Ureter Minor calyx Renal capsule Inferior renal capsule Inferior renal capsule Afferent vessel Nephron Minor calyx Major calyx Renal papilla Renal column

Functions of Nephron Structures Afferent Arteriole Afferent Arteriole –Transports arterial blood to the glomerulus for filtration Unit 1 - Objective 4

Functions of Nephron Structures Efferent Arteriole Efferent Arteriole –Transports filtered blood from the glomerulus, through the peritubular capillaries and the vasa recta, and to the kidney venous system Unit 1 - Objective 4

Functions of Nephron Structures Glomerulus Glomerulus –The site for blood filtration –operates as a nonspecific filter; in that, it will remove both useful and non-useful material –the product of the glomerulus is called filtrate or ultrafiltrated because it doesn’t contain proteins Unit 1 - Objective 4

Functions of Nephron Structures Bowman’s Capsule Bowman’s Capsule –A sac that transfers filtrate from the glomerulus to the Proximal Tubule Unit 1 - Objective 4

Functions of Nephron Structures Proximal Convoluted Tubule (PCT) Proximal Convoluted Tubule (PCT) –A thick, constantly actively segment of the nephron that reabsorbs most of the useful substances of the filtrate: sodium (65%), water (65%), bicarbonate (90%), chloride (50%), glucose (nearly 100%!), etc. –The primary site for secretion (elimination) of drugs, waste and hydrogen ions Unit 1 - Objective 4

Functions of Nephron Structures Descending Limb of the Loop of Henle Descending Limb of the Loop of Henle –freely permeable to water and relatively impermeable to solutes (salt particles) Unit 1 - Objective 4

Functions of Nephron Structures Ascending Limb of the Loop of Henle Ascending Limb of the Loop of Henle –impermeable to water and actively transports (reabsorbs) salt (NaCl) to the interstitial fluid of the pyramids in the medulla. “Saves salt and passes the water.” –the passing filtrate becomes dilute and the interstitium becomes hyperosmotic Unit 1 - Objective 4

Functions of Nephron Structures Distal Convoluted Tubule (DCT) Distal Convoluted Tubule (DCT) –receives dilute fluid from the ascending limb of the Loop of Henle –Variably active portion of the nephron –When aldosterone hormone is present, sodium is reabsorbed and potassium is secreted. Water and chloride follow the sodium. Unit 1 - Objective 4

Functions of Nephron Structures Collecting Duct Collecting Duct –receives fluid from the DCT –variably active portion of the Nephron –when antidiuretic hormone (ADH) is present, this duct will become porous to water. Water from the collecting duct fluid then moves by osmosis into the “salty” (hyperosmotic) interstitium of the medulla. –The last segment to save water for the body Unit 1 - Objective 4

Functions of Nephron Structures Peritubular Capillaries Peritubular Capillaries –transport reabsorbed materials from the PCT and DCT into kidney veins and eventually back into the general circulation –help complete the conservation process (reabsorption) that takes place in the kidney Unit 1 - Objective 4

Path of Blood Through Kidney Renal artery…you don’t need to memorize the whole thing..only the underlined Renal artery…you don’t need to memorize the whole thing..only the underlined  interlobar arteries (up renal columns, between lobes)  arcuate arteries (over pyramids)  interlobular arteries (up into cortex)  afferent arterioles  glomerulus (cluster of capillaries)  efferent arterioles (near medulla  vasa recta)  peritubular capillaries  interlobular veins  arcuate veins  interlobar veins Renal vein Renal vein

Blood Supply Diagram

Anatomy of kidneys: Cortex : contain glomeruli ----->filtration Cortex : contain glomeruli ----->filtration Medulla : contain tubules ----->secretion Medulla : contain tubules ----->secretion and reabsorption and reabsorption (each tubule is 5-6 cm long) (each tubule is 5-6 cm long) * Cortical atrophy : glomerulonephrits * Cortical atrophy : glomerulonephrits * Medullary atrophy : tubular nephritis * Medullary atrophy : tubular nephritis Cortical nephron have short loop of Henle Cortical nephron have short loop of Henle Juxta-medullary nephron Have long loop of Henle and this is important in urine concentration (15-20%). Juxta-medullary nephron Have long loop of Henle and this is important in urine concentration (15-20%). In each kidney we have 1 million afferent arteriole & nephron. In each kidney we have 1 million afferent arteriole & nephron.

Functional Anatomy of the Kidney Structure & function of the kidney are closely matched. The kidney is a combination of: Structure & function of the kidney are closely matched. The kidney is a combination of: 1. Ultrafiltation device (the glomerular apparatus). 2. Epithelium (tubules), which modifies the ultrafiltarte by: - addition (secretion) or - removal (reabsorption).

Filtration in kidney is also affected, as systemic capillaries, by Starling forces ( Hydrostatic & Osmotic pressure in & out …4 forces)…in the kidney only 3 forces Filtration in kidney is also affected, as systemic capillaries, by Starling forces ( Hydrostatic & Osmotic pressure in & out …4 forces)…in the kidney only 3 forces Bowman ’ s capsule stands for the interstitium Bowman ’ s capsule stands for the interstitium To be discussed with regulation of GFR To be discussed with regulation of GFR

RBF Kidneys are reconditioning organs i.e. Receive too much blood. RBF= 20-25% of Q →→ This makes the A-V oxygen difference small. Kidneys are reconditioning organs i.e. Receive too much blood. RBF= 20-25% of Q →→ This makes the A-V oxygen difference small. Nevertheless, kidneys consume twice O 2 /per gm tissue as brain. Nevertheless, kidneys consume twice O 2 /per gm tissue as brain. This O 2 consumption is directly related to Na + reabsorption. If GFR is high → Na+ reabsorption is high → O 2 consumption is high. When GFR is severely depressed (Acute RF) → decrease need for O 2 This O 2 consumption is directly related to Na + reabsorption. If GFR is high → Na+ reabsorption is high → O 2 consumption is high. When GFR is severely depressed (Acute RF) → decrease need for O 2 If RBF decreases →→ acute renal Failure If RBF decreases →→ acute renal Failure

BLOOD FLOW To Different Tissues Not to memorize the number…just to understand the concept A-V difference Vol% Blood flow (ml/g/min) Tissue 110.8Heart Brain Sk muscles Liver Kidney Carotid bodies

RPF 650 ml is the RPF…renal blood flow 650 ml is the RPF…renal blood flow 125 is filtered (GFR). 125 is filtered (GFR). How much is the filtration fraction?...20% How much is the filtration fraction?...20% 525 leave through efferent arteriole and go to peritubular capillaries. 525 leave through efferent arteriole and go to peritubular capillaries. 1 ml/min is the urine output. 1 ml/min is the urine output.