Urinary System Notes PDF

URINARY SYSTEM RENAL CIRCULATION 20-25% of cardiac output FUNCTIONS OF URINARY SYSTEM (KIDNEY) Regulate fluid balance (fluid volume) of the body Excrete organic waste produ...

URINARY SYSTEM RENAL CIRCULATION 20-25% of cardiac output FUNCTIONS OF URINARY SYSTEM (KIDNEY) Regulate fluid balance (fluid volume) of the body Excrete organic waste products and conserve nutrients, etc. Stabilize pH Regulate electrolyte concentrations in the blood Endocrine functions KIDNEY LOCATION Lateral to vertebral column high on body wall, under floating ribs, in retro-peritoneal position (posterior to the parietal peritoneum) The right kidney is slightly inferior (higher) to the left kidney in order to accommodate the liver Surrounded by the renal capsule with a fat pad 12 x 6 x 3 cm o Bean-shaped o Hilus – indentation ▪ Where the arteries & veins passes through INTERNAL ANATOMY KIDNEY – filters blood CORTEX Blood – mainly coming from the renal artery → segmental artery → outer layer interlobar artery → arcuate arteries → cortical radiate arteries → afferent light reddish brown arterioles → NEPHRONS granular appearance (due to many corpuscles) From the NEPHRONS, filtration occurs o outer part Once the blood is being filtered, the liquid (filtrate) goes to the proximal convoluted tubule and the filtered blood goes back MEDULLA to the heart for reoxygenation darker striped appearance (due to tubules). IDENTIFYING THE PHOTO: subdivided into distinct renal Each segmental artery branches into interlobar arteries. pyramids, terminating with a The afferent arterioles (indentation) supply blood to the papilla glomerulus. o 6 renal pyramids Filtration occurs in the nephrons, specifically in the separated by renal columns glomerulus. Once the filtrate (which forms urine) is separated, from the cortex the blood flows back through the efferent arterioles to the venules, then to the interlobular veins, arcuate veins, PELVIS interlobar veins, and finally through the renal vein back to the Expanded proximal ureter heart. All the openings go into here, what we called renal pelvis The correct blood flow through the kidney: renal artery → segmental arteries → interlobar arteries → arcuate arteries → interlobular arteries → afferent arterioles → glomerulus. NEPHRON = FUNCTIONAL UNIT OF THE KIDNEY (>106/kidney) Nephron = o Renal Corpuscle ▪ Glomerulus ▪ Bowman’s (Renal) Capsule o PCT (Proximal Convoluted Tubule) o LOH (loop of Henle) o DCT (Distal Convoluted Tubule RENAL PYRAMIDS – The renal pyramids have their apex, called the renal papilla, which opens into the minor calyx. From there, urine flows DISCUSSION: TRANSES into the major calyx and then into the renal pelvis, which leads to the ureter. The nephron is where filtration occurs Each pyramid has a common pathway, once you open, that’s your Renal Artery → Segmental → Interlobular → Arcuate → each arcuate papilla → minor calyx → major calyx → converge into the renal pelvis artery has interlobular artery and has an afferent it goes inside linked to the glomerulus → the glomerulus filters the blood → in the glomerulus you’ll see podocytes Glomerulus is bounded by Renal Capsule / Bowman’s Capsule CERILO, MARIKARL PAULYN | DMD2B ’24 | 1 ST SEMESTER Once the blood is filtered, the blood goes back to the system and this TWO BASIC STRUCTURES OF KIDNEY: Cortex & Medulla is where the urine is being formed. From the Glomerulus → Proximal CONTENT OF MEDULLA: Renal pyramids convoluted → Descending Henle → Loop of Henle → Ascending Henle Renal pyramids are very important because the arteries and → Renal Papilla → Renal Pyramids → Papilla veins follow the anatomy of the pyramids 2 DIVISION OF NEPHRONS In our discussion: 1. Renal Corpuscle The collecting tubules are not part of the renal tubules ▪ What forms: Glomerulus & Bowman’s Capsule 2. Renal Tubules Also known as VENULE: Efferent & Afferent Arteriole ▪ What forms: Proximal Convoluted Tubule (PCT), Loop of Henle (includes Descending and Ascending limbs), FUNCTIONS: Distal Convoluted Tubule (DCT) Renal Corpuscle – production of filtrate Proximal Convoluted Tubule – absorption of water Proximal down to Distal → Pathway for Urine Formation Loop of Henle – Further reabsorption of water (descending Goes out to the system → Blood Circulation limb) & both sodium and chloride ions (ascending limb) Distal Convoluted Tubule – secretion of ions, acids, drugs, URINIFEROUS TUBULE toxins; variable reabsorption of water, sodium ions, calcium Nephron + Collecting Duct (tubule) ions (under hormonal control) – no filtration occur (removal) ▪ Renal Corpuscle Collecting Tubules & Collecting Ducts – variable ▪ PCT reabsorption of water & reabsorption or secretion of sodium, ▪ LOH potassium, hydrogen and bicarbonate ions ▪ DCT Papillary Duct – delivers urine to minor calyx ▪ CD QUESTION: What particular part of the nephron secretes drugs & toxins – distal convoluted tubule Note: Heart for movement = sodium pump (exchange of sodium & potassium – for muscle to move DISCUSSION: TRANSES BLOOD SUPPLY FILTRATION / CIRCULATION 1. Renal Artery 2. Segmental Artery 3. Interlobar Artery 4. Arcuate Artery 5. Interlobular Artery 6. Enters Bowman’s Capsule by Efferent 7. From the Efferent → Glomerulus (filtration) 8. Once blood is being filtered, the toxic substances are removed SUMMARY OF THE PHYSIOLOGY OF A NEPHRON and goes back to the system via: 9. Venules Bowman’s Capsule – filter blood 10. Interlobular vein Filtered blood goes back to the system 11. Arcuate vein The excess will go to Renal Tubule 12. Interlobar vein Pass at the Proximal Convoluted Tubule for absorption of water 13. Segmental Vein All fluid goes down to the Henle – further reabsorption + sodium & 14. Renal Vein chloride 15. Heart Distal Convoluted Tubule – secretion of ions, drugs, toxins Collecting Tubules – reabsorption of water & reabsorption or URINE FORMATION secretion of sodium, potassium, hydrogen and bicarbonate ions 1. Renal Artery 2. Segmental Artery 3. Interlobar Artery 2 TYPES OF NEPHRONS 4. Arcuate Artery 5. From Arcuate Artery there are branches called Interlobular 1. CORTICAL NEPHRONS Artery 85% shorter, mostly in the cortex of kidney 6. Efferent Artery goes inside the Bowman’s Capsule Produce “standard” urine 7. Glomerulus (Inside BC) 8. Proximal Convoluted Tubules; process of urine formation 2. JUXTAMEDULLARY NEPHRONS 9. Distal Convoluted Tubules 15% 10. Connecting Tubule “juxta” = next to the medulla 11. Renal Papilla Responsive to ADH (Antidiuretic Hormone) 12. Collected by minor calyx Can produce concentrated urine due to longer loops of 13. Major calyx (big basin) Henle 14. Renal Pelvis – where everything is collected o Found at the border between the medullary & the cortex 15. Ureter NEPHRONS are many (functional unit) Most nephrons located at the cortex Some are located at the borders between the cortex & renal pyramids CERILO, MARIKARL PAULYN | DMD2B ’24 | 1 ST SEMESTER THE RENAL CORPUSCLE NEPHROLITHIASIS Filtration: Passage across 3 barriers Occurs when urine becomes too concentrated and substances crystallize. 1. Capillary Endothelium o Concentrated urine – juxtamedullary nephrons Fenestrated Symptoms arise when stones begin to move down ureter What gets through? – blood causing intense pain 2. Basement Membrane 3. Glomerular epithelium (= visceral layer of Bowman’s capsule) Slit pores between pedicles of podocytes NOTE: Capsular Epithelium is simple squamous epithelium Note: Cells associated with Glomerulus is PODOCYTES JUXTAGLOMERULAR (JG) APPARATUS Juxtaglomerular Apparatus = Macula densa + Juxtaglomerular cells (smooth muscle fibers from afferent arteriole) Macula densa monitors BP JG cells produce Renin & Calcium Stone Erythropoietin (EPO) Acid Stone What makes it different: o What does it do: Blocks the pathway of urine Concentrated Urine o Retention of fluid USUALLY: the kidney stones are found in the minor & major calyx & Ureter (difficult & painful) – needs radiation therapy URINARY BLADDER BLOOD PRESSURE Retroperitoneal, behind pubis INTERNAL FOLDS – rugae (permit expansion: max. holding capacity 1 LITER) TRIGONE – area at base delineated by openings of ureters & urethra – without muscle INTERNAL URETHRAL SPHINCTER – involuntary sphincter Antidiuretic Hormone – prevent too much urination o Diuretic = urine URINE COLLECTION Collecting ducts withing each renal papilla release urine into minor calyx → major calyx → renal pelvis → ureter → urethra URETERS URINARY BLADDER HISTOLOGY From kidney to bladder 1. Transitional epithelium from renal pelvis to neck of urethra Enter the bladder at an angle – Trigone a. Cuboidal – empty Retroperitoneal b. Squamous – full bladder 2. Detrusor muscle – smooth muscle Transitional Epithelium Nephroliths Urinary Bladder is below the Uterus 3 PARTS OF URETER: proximal, middle, distal Trace drop of urine from the afferent URETHRA – FEMALE arteriole to the outside world o External urethral sphincter – voluntary at pelvic floor o 3-5 cm – from base of bladder to vestibule Urine is stored in the bladder o UTIs (esp. E.coli) What do you call the muscle in the bladder = When pregnant: impingement of bladder DETRUSOR MUSCLE (they always pee, the capacity is fewer) CERILO, MARIKARL PAULYN | DMD2B ’24 | 1 ST SEMESTER URETHRA – MALE Male – 18-20 cm 1. Prostatic Urethra – from base of bladder through prostate gland 2. Membranous Urethra – between prostate gland & base of penis 3. Penile (spongy) Urethra – traverses’ penis to orifice A DROP OF FILTRATE Glomerular to capillaries Podocytes Bowman’s Space PCT LOH DCT Collecting Duct Minor calyx Major calyx Renal Pelvis Ureter Urethra – prostatic, membranous & penile in male Kidney may sustain 90% loss of nephrons and still not show apparent symptoms 2-4% of population only have 1 kidney CERILO, MARIKARL PAULYN | DMD2B ’24 | 1 ST SEMESTER