Presentation on theme: "Anatomy of the Urinary System"— Presentation transcript:
1 Anatomy of the Urinary System Lab Exercise 28Anatomy of the Urinary SystemPortland Community CollegeBI 233
2 Urinary System Organs Kidneys: principal organs Urinary bladder: provides a temporary storage reservoir for urinePaired ureters: transport urine from the kidneys to the bladderUrethra: transports urine from the bladder out of the body
3 Kidney Location and External Anatomy Adrenal GlandRetroperitoneal position behind the peritoneumSuperior lumbar regionFrom the twelfth thoracic to the third lumbar vertebraeThe right kidney is lower than the leftHilum: Medial border where ureters, blood vessels, lymphatics, and nerves enter and exit
6 NephronNephrons are the structural and functional units that form urine, consisting of:Renal Corpuscle: The collective term for the glomerulus and the surrounding capsuleGlomerulus: Tuft of capillariesBowman’s capsule: Enlarged end of the renal tubule that surrounds the glomerulusRenal Tubule: Tube into which fluid passesProximal convoluted tubuleLoop of HenleDistal convoluted tubule
7 Nephron Afferent arteriole Efferent arteriole Descending limb of the loop of HenleAscending limb of the loop of Henle
8 Cortical Nephrons Cortical Nephrons: 80-85% of all nephrons Their renal corpuscles lie in the outer portion of the renal cortexHave short loops of HenleLie mainly in the cortexPenetrate only into outer region of the renal medulla
10 Juxtamedullary Nephrons Juxtamedullary nephrons: % of nephronsRenal corpuscle lies deep in cortex near medullaHave long loops of HenleResponsible for creating medullary concentration gradient that allows the kidney to change dilution of urineVasa Recta capillaries around the loops of Henle
13 Glomerulus The primary filtering device of the nephron Blood is transported into the Bowman's capsule from the afferent arterioleWithin the capsule, the blood is filtered through the glomerulus and then passes out via the efferent arteriole.Filtered water and aqueous wastes are passed out of the Bowman's capsule into the proximal convoluted tubule.
14 Glomerulus + Bowman’s Capsule = Renal Corpuscle The first part of the nephronThe afferent arteriole leads to the glomerulus, which is a specialized capillary bed.Filtration: The hydrostatic force of the blood pressure pushes the fluid from the blood out into Bowman’s capsule.Filtrate: The fluid pushed out consists of everything except blood cells and large proteins.
15 Renal Corpuscle The capsular space contains the filtrate Podocyte (visceral layer of Bowman's capsule)
16 Filtration Membrane 2. Podocytes Fenestrations: Holes in the capillary endothelium3. Fused basement membranes#1 Stops all cells and platelets#2 Stops medium-sized proteins, not small ones#3Stops large plasma proteins
17 ReabsorptionReabsorption is the process of moving substances from the filtrate back into the bloodReabsorbed substances must pass through 3 membranes in order to reach the blood:Apical (lumen) side of the tubule cellsBasal (capillary) side of the tubule cellsCapillary endothelium
18 SecretionSecretion is moving substances from the blood and putting them into the filtrateSecreted substances must pass through 3 membranes in order to reach the filtrate:Capillary endotheliumBasal (capillary) side of the tubule cellsApical (lumen) side of the tubule cells
19 NephronsNotice how the distal convoluted tubule folds around and is next to the afferent arteriole.
20 Macula DensaThere is a portion of the DCT that abuts the afferent arteriole.At that region of the DCT, there are tall, closely-packed DCT cells that collectively are known as the macula densa.Macula densa cells are osmoreceptors that are responsible for measuring filtrate Na+If Na+ is low in the filtrate, the macula densa send a chemical signal to the juxtaglomerular cells to release renin.
21 Juxtaglomerular Cells In the afferent arteriole where the DCT is touching, there are specialized smooth muscle cells known as juxtaglomerular cells.Act as baroreceptorsThese JG cells contain large amounts of secretory granules containing reninWhen blood pressure low, the JC cells release their renin
23 Nephron VasculatureConsists of 2 capillary beds separated by the intervening efferent arteriole.The 1st capillary bed (the glomerulus) produces the filtrateThe second capillary bed (peritubular capillaries) reclaims most of that filtrateVasa recta - bundles of long straight vessels that run beside the loops of Henle deep into the medulla.
26 Histology of Renal Tubule & Collecting Duct Proximal convoluted tubuleSimple cuboidal with brush border of microvilli that increase surface areaThin segment descending limb of loop of HenleSimple squamousThick segment descending limb of loop of HenleSimple cuboidalThick Ascending limb of loop of HenleSimple cuboidal to low columnarThin segment of ascending limbDistal convoluted & collecting ductsSimple cuboidal composed of principal & intercalated cells which have microvilli
32 Kidney Medulla Histology Collecting DuctThick segment: Loop of HenleThin segment: Loop of HenleVasa Recta
33 BladderIt lies retroperitoneally on the pelvic floor posterior to the pubic symphysisMales: Prostate gland surrounds the neck inferiorlyFemales: Anterior to the vagina and uterusThe bladder wall has three layersTransitional epithelial mucosaA thick muscular layerA fibrous adventitia
36 Female Bladder and Urethra UreterUreter OpeningsFemale Bladder and UrethraTrigoneInternal Urethral SphincterExternal Urethral SphincterUrogenital Diaphragm
37 Female UrethraThe female urethra is tightly bound to the anterior vaginal wallIts external opening lies anterior to the vaginal opening and posterior to the clitorisLength 3-4 cmShorter length can lead to more frequent bladder infections
39 Spongy (penile) urethra Male UrethraThe male urethra has three named regionsProstatic urethra: runs within the prostate glandMembranous urethra: runs through the urogenital diaphragmSpongy (penile) urethra: passes through the penis and opens via the external urethral orificeLength: 20 cmSpongy (penile) urethraMembranous urethraProstatic urethra
40 Lab Activities Identify structures on the models View kidney and bladder/ureter under the microscopeDissect kidney