A&PII Kidney Lectures.final F10

A&PII Kidney Lectures.final F10 - The Urinary System...

Info iconThis preview shows page 1. Sign up to view the full content.

View Full Document Right Arrow Icon
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: The Urinary System The - Anatomy You are responsible for the material in Chapter 25 and part of Chapter 26. We will not have class on November 5, 7 or 9. Terminology Terminology The Urinary system: = Kidney Kidney = “Renal” “Renal” Purpose of the Urinary System Purpose Filters 200 L (liters!) of fluid from the bloodstream Filters EVERY DAY! EVERY Clears toxins, metabolic waste products and excess Clears ions from your body ions Returns needed molecules to your body Anatomy and Function of the Urinary System Anatomy Kidneys – Kidneys filtration filtration urine formation urine regulation of blood volume regulation maintain salt/water balance maintain maintain pH maintain Urinary bladder – urine storage Ureters – urine transport from kidneys to Ureters bladder bladder Urethra – urine transport from bladder Kidneys Kidneys There are two of them, shaped like kidney beans, located in There your lower back (superior lumbar region) your Covered by the fibrous renal capsule Cortex Renal Hilus Medulla Adrenal Gland Pyramids Calyx Renal Sinus Renal Pelvis Ureter http://users.stlcc.edu Renal Capsule http://images.main.uab.edu Kidney cortex vs. medulla Kidney Look at the glomeruli! Cortex Medulla http://webanatomy.net/histology/urinary_histology.htm Blood supply to the kidneys Blood Heart Vena Cava http://www.medical.philips.com Aorta http://www.mhhe.com Know the ones in green: Nerve supply to the kidney Nerve The Renal Plexus: Network of autonomic nerve fibers Network autonomic (involuntary) Mainly sympathetic nerve fibers Mainly sympathetic (excitatory) Regulate renal blood flow (vasoconstriction) Ureters, Bladder and Urethra Ureters, Ureters: play an ACTIVE role in transporting urine from Ureters: kidneys to bladder. kidneys Muscularis Lumen Urethra: muscular tube similar to ureters Urethra: muscular - sphincter muscles like in the digestive system sphincter Bladder: muscular sac capable of expanding or collapsing capable “detrusor muscle” - normally holds ~500 mL - maximum = 800-1000 mL Gender Differences (1) Gender Many of the same Many structures and functions structures Gender Differences (2) Gender Female Male Smaller bladder Uterus Shorter urethra Larger bladder Prostate Longer urethra http://www.nslc.wustl.edu/courses/Bio121/section3/images/Bladder-male.jpg Some important differences The Urinary System The - Nephron Structure/Function- The Nephron The Structural and functional unit of the kidney >1 million per kidney Nephrons Collecting ducts Renal pelvis Ureter Nephrons Nephron Structure (1) Nephron Blood comes in from renal artery Renal corpuscle Afferent arteriole Proximal convoluted tubule Blood goes out to peritubular capillaries and renal vein Efferent arteriole Distal convoluted tubule Loop of Henle Glomerulus Bowman’s capsule Collecting duct Glomeruli are in kidney cortex To Renal Pelvis Blood Filtrate (multiple nephrons converge here) Nephron Structure (2) Nephron From renal artery Blood vessels wrap around Loop of Henle “peritubular capillaries” To renal vein Nephron Structure (3) Nephron Movement of electrolytes/nutrients/other into and out of the nephron: http://www1.shore.net/~straub/labsk_nephron.gif Nephron Nephron Structure (4) Types of nephrons Types of Nephrons Cortical (85% of nephrons) Cortical (Have peritubular capillaries) Juxtamedullary (15%) (Their peritubular capillaries (Their are called “vasa recta”) are http://sprojects.mmi.mcgill.ca/nephrology/presentation/images/83no1.gif Special functions: Special Podocytes (“foot cells”) in Bowman’s capsule aid filtration from glomerulus into nephron nephron http://www.meddean.luc.edu/lumen/MedEd/Histo/HistoImages/hl7A-68.jpg “Brush border” in the in proximal convoluted tubule increases surface-area-tosurface-area-toJust like ratio! volume in the small intestine! http://microvet.arizona.edu/Courses/MIC420/lecture_notes/ecoli/brush_border.gif Special functions: Special Juxtaglomerular Juxtaglomerular apparatus—initial part of apparatus—initial DCT runs next to afferent arteriole and senses blood pressure and osmolarity pressure Descending limb of the Descending Loop of Henle—thin segment—water can flow in and out and Ascending limb of the Loop of Henle—thick segment—water can’t move segment—water http://www.nature.com/ng/journal/v21/n1/images/ng0199_68.gif The Urinary System The - Renal Physiology - Nephrons… Nephrons… Cortical Cortical Juxtamedullary Juxtamedullary 85% Shallow Loop of Henle Shallow Peritubular capillaries Peritubular Normal urine concentration 15% Deep Loop of Henle Deep Vasa recta Higher urine concentration Cortex Medulla Steps in the formation of urine Steps Glomerular filtration Tubular reabsorption Tubular secretion Glomerular filtration Glomerular Is a passive process Works because of hydrostatic pressure in capillaries (higher in glomerular capillaries [55 mmHg] than any others [20 mmHg]) Large surface area and increased permeability as Large compared to other capillaries compared Small molecules (water, ions, glucose, amino acids) Small pass easily, while larger molecules (proteins) stay in the capillaries the Glomerular filtration Glomerular Net filtration pressure (NFP): Glomerular capillary Bowman’s capsule Glomerular hydrostatic pressure Colloid osmotic (oncotic) pressure Capsular hydrostatic pressure NFP = HPg – (OPg + HPc) = 10 mmHg normally Glomerular filtration rate (GFR): - The volume of filtrate formed each minute - Depends on surface area and permeability - Directly proportional to NFP - Decreasing HPg 15% completely stops filtration! To renal tubules What controls glomerular filtration? What Renal autoregulation: (intrinsic) myogenic tubuloglomerular feedback (juxtaglomerular apparatus) Extrinsic controls: neural (sympathetic nervous system) (sympathetic hormonal (renin-angiotensin system) (renin-angiotensin Decreased renal blood flow/volume/pressure Decreased Intrinsic Extrinsic Hormonal Myogenic Tubuloglomerular Fig. 25.10 JG cells Neural Baroreceptors Renin Vascular smooth muscle Macula densa cells Afferent arteriole diameter Angiotensinogen Angiotensin II Kidney Na+ absorption Sympathetic nervous system Systemic arterioles Increased blood pressure GFR! Tubular reabsorption Tubular Complete reabsorption: Variable reabsorption: Glucose Amino acids Vitamins Water Ions (Na+, K+, Ca++, Cl-, HCO3-) Urea Absorption can be ACTIVE or PASSIVE! What is reabsorbed and where? What Prox. Conv. Tub. Na+, glucose, amino acids, Na+, vitamins, K+, Ca++, Mg++, Cl-, HCO3-, water, urea, Cl-, -, small proteins small Loop of Henle Water, Na+, Cl-, K+, Ca++, Water, Mg++ Mg++ Dist. Conv. Tub. Na+, Ca++, Cl-, water Coll. Duct Na+, H+, K+, HCO3-, Cl-, -, water, urea water, Reabsorption Reabsorption “Fine tunes” Na+, Cl-, and water Also K+ All of glucose, amino acids, vitamins 65% of Na+ and water 90% of bicarbonate 50% of Cl55% of K+ Na+, K+, ClWater Tubular secretion Tubular Filtered substances that DO NOT get reabsorbed are Filtered secreted from the tubules and excreted in the urine! secreted Drugs, waste products, excess K+ Control of blood pH Mostly in proximal convoluted tubule… Except for K+ which is mostly at collecting ducts Countercurrent multiplier and exchanger Countercurrent Regulates urine concentration and volume This is important!!! The Urinary System - Control of Body Fluids - Regulation of: Regulation Body fluid levels + Electrolytes = “Salt-Water Balance” “Salt-Water Acid-Base Balance (pH) Where’s the water? Where’s Intracellular fluid Extracellular fluid - Blood plasma - Interstitial fluid Babies > Adults > Older people Men > Women Muscle > Bone > Fat Electrolytes Electrolytes Chemical compounds (SALTS) that dissociate into that IONS when they are dissolved in water. IONS Ions = charged particles that conduct electrical currents NaCl Na+ + ClNaCl KCl K+ + ClKCl MgCl2 Mg++ + 2Cl- Movement of salts and water Movement If there are no barriers: If no salts move down their concentration gradient from salts high to low (just like gases)… high If there are barriers (membranes): If are Salts can move through channels, or be actively Salts transported across a membrane, either WITH or AGAINST their concentration gradients AGAINST Water follows the movement of salts because the body tries to maintain osmolality: HOMEOSTASIS body Thirsty? Thirsty? Stimulated by salt/water imbalance: Stimulated - increased osmolality increased “Thirst center” in the hypothalamus - Osmoreceptors Osmoreceptors - Baroreceptors Baroreceptors - Angiotensin II Angiotensin Emotional responses… (advertising) (advertising) How do we GAIN and LOSE water? How Drinking (60%) Eating (30%) Metabolism (10%) Lose: ------ 2500 mL / day ------ Gain: Gain Urine (60%) Skin and lungs (28%) Sweat (8%) Feces (4%) ADH and water ADH Normally, water follows the movement of salts In the collecting duct, water that has passed through In the kidney (nephrons) is excreted in urine the When ADH is present, aquaporins (water channels) When are inserted into the collecting duct membrane and virtually all water is reabsorbed. virtually “Antidiuretic hormone” (= vasopressin) Sodium (Na+) balance Sodium Critical for nervous system function, cardiovascular Critical system function, blood pressure maintenance system ~100% of Na+ is reabsorbed from kidney: 65% in proximal convoluted tubule 65% 25% in Loop of Henle 25% 10% in distal convoluted tubule 10% Aldosterone Na+ reabsorption Aldosterone Atrial natriuretic peptide (ANP) Na+ secretion Atrial Sodium (Na+) Sodium Decreased Na+ (or increased K+) in plasma Renin-Angiotensin system Adrenal cortex Stretching of heart atria ANP Aldosterone ADH Kidney tubules Increased K+ secretion Increased blood pressure Increased Na+ reabsorption CD water channels Homeostasis: salt/water balance, blood volume/pressure Decreased Na+ and water reabsorption Decreased blood volume Potassium (K+) Potassium In extracellular fluid: Too much decreased membrane potential Too Too little hyperpolarization Too Important regulatory site = the collecting duct tubular secretion! Influenced by plasma K+ concentration (Diet) and aldosterone Calcium (Ca++) / Phosphate Calcium Stored in bones Important for cellular function, muscle contraction Important and blood clotting and Regulated by: Regulated parathyroid hormone (increases circulating Ca++) parathyroid calcitonin (decreases circulating Ca++) calcitonin Bone and kidney, mainly… The Urinary System - Control of pH – (acid-base balance) pH in our bodies: Arterial blood = 7.4 Arterial Intracellular fluid = 7.0 Venous blood = 7.35 (7.35 – 7.45) What keeps our pH normal? What Buffering systems: Dr. G.’s favorite equation… Bicarbonate H2O + CO2 H2CO3 H+ + HCO3 (extracellular) HCl + NaHCO3 H2CO3 + NaCl NaOH + H2CO3 NaHCO3 + H2O Phosphate Protein (plasma) (intracellular) similar to bicarbonate buffer system similar ¾ of buffering capacity; hemoglobin! of Remember the difference between plasma and cerebrospinal fluid? When pH is abnormal: When Acidosis (too much acid, pH is low) - respiratory (high CO2) - metabolic (low HCO3-) Alkalosis (too much base, pH is high) - respiratory (low CO2) - metabolic (high HCO3-) Respiratory and Urinary (kidney) systems work Respiratory together to maintain pH! Main players are carbon dioxide and bicarbonate Main Kidneys and disease Kidneys High blood pressure Diabetes Polycystic kidney disease Kidney stones ...
View Full Document

{[ snackBarMessage ]}

Ask a homework question - tutors are online