ANAPHY-URINARY SYSTEM PDF

TYPES OF NEPHRON URINARY SYSTEM AND 1. Juxtamedullary Nephrons FLUID BALANCE o 15% o Closer to renal medulla INTRODUCTION...

TYPES OF NEPHRON URINARY SYSTEM AND 1. Juxtamedullary Nephrons FLUID BALANCE o 15% o Closer to renal medulla INTRODUCTION o Loops of Henle extend deep into renal URINARY SYSTEM pyramids Major excretory system of the body 2. Cortical Nephrons Consists of: o 85% of all nephrons o 2 Kidneys o Loops of Henle that do not extend deep o 2 Ureters into the medulla o 1 Urinary bladder o 1 Urethra PARTS OF THE NEPHRONE Urine consists of: RENAL CORPUSCLE o Excess water Blood filtering component of nephron o Excess ions 1. Glomerulus – tuft of capillaries o Metabolic wastes 2. Glomerular capsule / Bowman’s o Toxic substances capsule – enlarged end of the nephron, which is indented to form a double-walled FUNCTIONS: chamber Excretion 3. Podocytes – specialized cells in the inner Regulation of blood volume and pressure layer of the bowman capsule; wrap Regulation of the concentration of solutes around the glomerular capillaries in the blood Regulation of extracellular fluid pH RENAL TUBULE Regulation of red blood cell synthesis 1. Proximal convoluted tubules Regulation of Vitamin D synthesis 2. Loop of Henle o Thin segment of the Descending limb KIDNEY o Thin segment of the Ascending limb o Thick segment of the Ascending limb Bean-shaped 3. Distal convoluted tubule Located against posterior abdominal wall 4. Collecting duct – where the fluid from the retroperitoneally DCT is emptied Right kidney is slightly lower than the left 5. Papillary duct – where the multiple collecting because of the liver ducts carry fluid from the cortex; papillary Renal capsule - a layer of connective tissue ducts empty their contents into a calyx that surround each kidneys Hilum – where the renal artery and nerves FILTRATION MEMBRANE enter and where the renal vein, ureter and Filtration membrane lymphatic vessels exit the kidney o Endothelium of the glomerular Renal sinus – a cavity where the hilum capillaries opens o Podocytes Extend from T12 to L3 o Basement membrane Cortex → Outer Filtrate – fluid that is forced across the Medulla → Inner filtration membrane Afferent arteriole – supplies blood to the Renal Pyramid → Minor Calyx (Calyces) → glomerulus for filtration Major Calyx → Renal Pelvis → Ureter Efferent arteriole – transport the filtered blood away from the glomerulus Juxtaglomerular cells – a cuff of NEPHRON specialized smooth muscle cells found at Histological and functional unit of the kidney the point where the afferent arteriole enters the renal corpuscle Each nephron consists of 4 components: o Renal corpuscle Macula densa - group of specialized cells o Proximal convoluted tubule in the section of the DCT o Loop of Henle Substance Location o Distal convoluted tubule  Glucose, PCT 2. Angiotensinogen – plasma protein produced Amino acid, by the liver Active salts 3. Renin converts angiotensinogen to Transport Chloride Ascending loop of angiotensin 1 Henle 4. Angiotensin 1 is rapidly converted to the Sodium PCT, DCT active hormone Angiotensin 2 by Water PCT, Descending Angiotensin-converting enzyme (ACE) loop of Henle, 5. Angiotensin 2 stimulates the adrenal cortex to Passive collecting ducts secrete Aldosterone Transport Urea PCT, Ascending loop of Henle Sodium Ascending loop of URINE MOVEMENT Henle URETERS Small tubes that carry urine from the renal ARTERIES AND VEINS OF THE KIDNEY pelvis to the posterior inferior position of the 1. Renal arteries urinary bladder 2. Interlobar arteries Urine flows from the kidneys to the urinary 3. Arcuate arteries bladder 4. Interlobular arteries 5. Afferent arterioles URINARY BLADDER 6. Efferent arterioles Hollow, muscular container 7. Peritubular capillaries Stores urine 8. Vasa recta – specialized portion of the peritubular capillaries that extend deep into URETHRA the medulla of the kidney and surrounds the Transports urine to the outside of the loops of Henle and collecting ducts body 9. Interlobular veins Trigone – triangle-shaped portion of the 10. Arcuate veins urinary bladder located between the 11. Interlobar veins opening of the ureters and the opening of 12. Renal Veins the urethra Internal urethral sphincter – prevents urine leakage from the urinary bladder URINE CONCENTRATION MECHANISM Responsible for concentration of urine o Vasa recta DISEASES AND DISORDER OF THE URINARY o Loop of Henle SYSTEM o Distribution of urea Inflammation of the Kidneys Medullary Concentration Gradient Glomerulonephritis o Ability to concentrate urine depends o Acute glomerulonephritis on maintaining a high concentration of o Chronic glomerulonephritis solutes in the medullary region of the Pyelonephritis kidney Renal Failure REGULATION OF URINE CONCENTRATION Acute renal failure AND VOLUME Chronic renal failure Hormonal Mechanisms o Aldosterone Other Inflammations o Renin Ureters → Ureteritis o ADH Bladder → Cystitis Urethra → Urethritis Renin-Angiotensin-Aldosterone Mechanism Initiated under low blood pressure conditions 1. Juxtaglomerular apparatuses in the kidney FLUID BALANCE secretes renin BODY FLUIDS  Intracellular fluid compartment (40% of total o When H+ is removed from a body weight) solution, the buffer replaces it → Includes all the fluid in the trillions of Three important buffers: body cells o Carbonic acid – Bicarbonate Extracellular fluid compartment (20% of total o Proteins body weight) o Phosphate compounds → Includes all the fluid outside the cells o Interstitial fluid → occupies the extracellular spaces outside the EFFECTS OF AGING ON THE KIDNEYS blood vessels The kidneys gradually decrease in size o Plasma → occupies the due to a decrease in renal blood flow. extracellular spaces within blood The number of functional nephrons vessels decreases. o Lymph o Cerebrospinal fluid Renin secretion and vitamin D synthesis o Synovial fluid decrease. The nephron’s ability to secrete and MAJOR SOLUTES IN BODY FLUIDS absorb declines. Cations Anions Sodium (Na+) Chloride (Cl-) Potassium (K+) Bicarbonate (HCO3-) Calcium (Ca2+) Phosphate (HPO42- plus HPO4-) Magnesium (Mg2+) Protein ACID-BASE BALANCE pH range of 7.35 to 7.45 Acidemia → state of low blood pH (7.45) Alkalosis → process reducing hydrogen ion concentration; blood pH increases above 7.45 - Major effect is hyperexcitability of the nervous system o Respiratory alkalosis o Metabolic alkalosis – rapid elimination of H+ from the body BUFFER SYSTEM A buffer resists changes in pH o When H+ is added to a solution, the buffer removes it o When H+ is removed from a solution, the buffer replaces it A buffer resists changes in pH o When H+ is added to a solution, the buffer removes it