Urinary System pptx
Page 1: Overview of the Urinary System
Front View of Urinary Tract:
Kidney
Ureter
Bladder
Sphincter
Urethra
Page 2: Chapter Objectives
Objectives:
Describe urine composition.
Label urinary system structures.
Characterize functions of the urinary system parts.
Illustrate kidney structures (macroscopic and microscopic).
Trace blood flow through the kidney.
Outline kidney nephron filtration process.
Provide kidney failure symptoms.
List solutes filtered, secreted, and reabsorbed in nephron.
Describe kidney portal system.
Explain hormonal regulation of urine osmolarity.
Describe major ion regulation by the kidney.
Summarize kidneys' role in acid–base balance.
Page 3: Physical Characteristics of Urine
Objectives:
Compare blood plasma, glomerular filtrate, and urine characteristics.
Describe normal urine sample characteristics (pH, osmolarity, volume).
Page 4: Functions of the Urinary System
Functions:
Filters blood to concentrate waste for excretion.
Regulates blood pressure by controlling water release.
Works with lungs to regulate blood pH.
Page 5: Components of Urine
Urine Composition:
Composed of small waste products.
Variability based on water intake, exercise, temperature, nutrient intake.
Color due to RBC destruction products.
Urochrome: yellow pigment from hemoglobin breakdown; dilute with high water intake.
Certain foods (e.g., beets, berries) can affect urine pigment.
Page 6: Urinalysis for Disease Detection
Urinalysis:
Detects kidney disease through specific urine contents.
Abnormal contents: glucose, leukocyte esterase, protein, blood, ketone bodies.
Page 7: Urine Production Rates
Average Urine Output:
Humans produce 1-2 L of urine daily.
Polyuria (excess) can indicate diabetes.
Oliguria (less than 0.5 L) suggests dehydration or kidney disease.
Anuria (no urine production).
Page 8: Anatomy of the Urinary Tract
Objectives:
Identify the ureters, bladder, urethra, structure, location, histology.
Compare male and female urethras.
Describe the micturition reflex and neural control.
Page 9: Urine Transport Structures
Urine Transport:
Urine requires specialized structures for safe transport.
Filtering occurs steadily; bladder stores urine.
Urine pH (4.5-8) and osmolarity vary widely; needs separation from body tissues.
Page 10: Urethral Structure
Urethra Function:
Transports urine from bladder for disposal; shows sexual dimorphism.
Lined with transitional epithelium, controlled by sphincters.
Sphincters: Internal (involuntary) and external (voluntary) urinary sphincters.
Page 11: Differences in Urethra Length
Female Urethra:
Short (approx. 4 cm), more prone to infection.
Exits near anterior vaginal wall beneath the clitoris.
Male Urethra:
Longer (approx. 20 cm) with four regions:
Preprostatic, Prostatic, Membranous, Spongy/Penile urethra.
Also transports sperm; bulbourethral glands neutralize pH during intercourse.
Page 12: Urinary Bladder Anatomy
Bladder Composition:
Elastic, transitional epithelium lining allows stretching.
Detrusor muscle contracts to push urine into urethra.
Partially retroperitoneal, with a peritoneal-covered dome.
Page 13: Potty Training and Micturition Reflex
Micturition Reflex:
Involuntary and voluntary control through sphincters.
Reflex sensing bladder stretch results in detrusor stimulation.
Functional pudendal nerve required for voluntary control.
Page 14: Ureters and Urine Flow
Ureter Structure:
Retroperitoneal; urine drains from the kidney calyces to the bladder via the ureters.
Peristalsis propels urine; one-way valve created by urine entry into bladder.
Page 15: Ureter Wall Anatomy
Layers of the Ureter Wall:
Label the following:
Muscularis
Mucosa
Adventitia
Page 16: Ureter Layers Continued
Layers of the Ureter Wall:
Label the following:
Muscularis
Mucosa
Adventitia
Page 17: Kidney Anatomy Objectives
Objectives:
Describe the external kidney structure, support, and covering.
Identify kidney divisions and structures.
Trace the blood path through the kidney.
Compare cortical and juxtamedullary nephrons.
Describe physiological characteristics and structures in kidney.
Page 18: Kidney Location and Protection
Kidney Position:
Left kidney: T12 to L3 vertebrae, right kidney displaced downward.
Retroperitoneal, protected by ribs and renal fat pad.
Page 19: Internal Anatomy of the Kidney
Internals:
Outer region: Renal cortex; Inner region: Renal medulla.
Renal columns provide division between pyramids; papillae transport urine to the calyces.
Renal hilum: entry/exit site for vessels, nerves, lymphatics, ureters.
Page 20: Kidney Anatomical Features Labeling
Label the Kidney Features:
Renal medulla
Renal cortex
Ureter
Renal pelvis
Page 21: Kidney Features Continued
Label again for reinforcement:
Ureter
Renal cortex
Renal medulla
Renal pelvis
Page 22: Nephrons Overview
Nephrons:
Functional units of kidneys; cleanse blood, balance circulation.
Composed of glomerulus, Bowman’s capsule (renal corpuscle).
Page 23: Nephrons and Vessels
Renal Portal System:
Glomerulus drains into an efferent vessel that leads to a second capillary bed.
Cortical nephrons have short loops; juxtamedullary nephrons have long loops extending deep into medulla.
Page 24: Nephron Functions
Nephron Functions:
Function by filtration, reabsorption, secretion to create urine.
Additional functions: regulate blood pressure, promote erythropoiesis (EPO), enhance calcium absorption.
Page 25: Microscopic Anatomy of the Kidney Objectives
Objectives for This Section:
Distinguish renal cortex and medulla histology.
Describe filtration membrane and major renal structures.
Explain functions of peritubular capillaries and vasa recta.
Identify juxtaglomerular apparatus.
Page 26: Glomerulus and Bowman’s Capsule
Filtration Structures:
Glomerulus: high-pressure capillary bed.
Bowman’s capsule surrounds glomerulus; captures filtrate.
Parietal layer: simple squamous epithelium; visceral layer: podocytes with filtration slits.
Page 27: Filtration Size Control
Fenestrations:
Control which substances filter into the nephron; blood cells and large proteins cannot pass.
Mesangial cells regulate filtration rate.
Page 28: Juxtaglomerular Apparatus Function
JGA Role:
Affects blood flow and glomerular filtration rate (GFR).
Macula Densa: monitors fluid Na+ concentration; releases paracrine signals.
Page 29: Renin Regulation
Renin's Role:
Converts angiotensinogen to angiotensin I; latter converted to angiotensin II (in blood).
Angiotensin II increases blood pressure by vasoconstriction; stimulates aldosterone release for Na+ reabsorption.
Page 30: Increasing Water Reabsorption in Collecting Ducts
Collecting Ducts Function:
Contain aquaporin proteins enhancing water movement back into circulation.
ADH stimulates insertion of aquaporins to manage urine concentration.
Page 31: Urine Formation Physiology Objectives
Objectives:
Describe forces affecting filtration and the glomerular filtration rate (GFR).
Calculate daily urine production and recognize kidney failure related symptoms.
Page 32: Kidney Failure Symptoms
Kidney Failure:
Symptoms arise from gradual or sudden failure in renal function.
Laboratory findings indicate dysfunction.
Page 33: Constant Urine Production
GFR Overview:
20% of cardiac output filters through kidneys; ~125 mL/min (men) & 105 mL/min (women).
99% reabsorption results in 1-2L of daily urine production.
Page 34: Factors Affecting GFR
GFR Influences:
Hydrostatic and osmotic pressures determine filtration.
Higher glomerular hydrostatic pressure aids filtration into Bowman’s capsule.
Page 35: Net Filtration Pressure (NFP)
NFP Calculation:
NFP = GBHP - (CHP + BCOP) = 10 mm Hg; indicates steady glomerular filtration rate despite blood pressure changes.
Page 36: Tubular Reabsorption Overview
Objectives for Reabsorption:
List mechanisms of transport in nephron; differentiate passive and active reabsorption processes.
Explain nephron tubule permeability.
Page 37: Reabsorption Processes in Nephron
Reabsorption Sites:
Major recovery occurs in PCT, loop of Henle, and DCT; 10% enters collecting ducts.
ADH influences water recovery in collecting ducts.
Page 38: Substances in Nephron**
Substances Transported:
Glucose, amino acids, and ions have specific reabsorption locations and mechanisms (e.g., symport, diffusion)
Table 25.5 categorizes filtrate dynamics.
Page 39: Daily Filtration and Reabsorption Data
Filtration Metrics:
Water, proteins, and electrolytes show substantial reabsorption.
Monitoring substances filtered vs. reabsorbed indicates kidney function efficiency.
Page 40: PCT Role in Filtration
Filtrate Journey in PCT:
Major absorption and secretion occurs; substances return to systemic circulation.
Page 41: PCT Cell Structure
PCT Cells:
Two membrane surfaces: apical (facing lumen) and basal (facing connective tissue).
Page 42: Sodium Transport Mechanisms
Sodium Movement in PCT:
Uses symport mechanism for various ions (Na+, Cl-, Ca++, amino acids).
ATP actively exchanges Na+ for K+ in basal membrane.
Page 43: Bicarbonate Recovery Mechanism
Bicarbonate Function:
Maintains acid-base balance; catalyzed by carbonic anhydrase within kidney cells.
Operates through Na+/H+ antiporter activity.
Page 44: Loop of Henle Function
Loop Composition:
Two sections (descending and ascending) specializing in Na+ and water recovery through osmosis and active transport.
Page 45: Loops Cellular Structure
Cell Types in Loops:
Descending loop: simple squamous; ascending loop: simple cuboidal, impermeable to water.
Thick segment actively reabsorbs NaCl, creating hypoosmotic filtrate.
Page 46: Countercurrent Multiplier System
Countercurrent Design:
Opposite fluid flows enhance osmolarity via solute pumps.
Urea produced from amino acid deamination aids in water recovery.
Page 47: Countercurrent Features
Countercurrent Summary:
Identifies passive water movement in descending limb and active Na+ transport in ascending limb.
Page 48: Countercurrent Reabsorption Effects
Effect on Reabsorption:
Increased osmolarity due to ascending limb action enhances descending limb recovering capacity.
Known as the countercurrent multiplier effect.
Page 49: Osmolarity Gradient in Nephron
Concentration Gradient Causes:
Driven by Na+ and Cl- transport to interstitial fluid from loop filtrate.
Page 50: Osmolarity Gradient Continues
Role of Transport in Gradient:
Discusses the concentration gradient from interstitial osmolarity increasing along the nephron loop.
Page 51: DCT Overview
DCT Role:
Recovers additional 10-15% water before entering collecting ducts.
Aldosterone influences Na+/K+ ATPase for solute movement.
Page 52: Recovery in Collecting Ducts
Collecting Duct Physiology:
Principal cells manage Na+/K+ channels; intercalated cells balance acid/base.
Page 53: Kidney Blood Flow Regulation Objectives
Objectives:
Explain myogenic and tubuloglomerular feedback mechanisms.
Describe JGA function.
Page 54: Sympathetic Nervous Influence
Sympathetic Control:
Increases sympathetic activity causes vasoconstriction, reducing GFR and blood flow.
Page 55: Autoregulation Mechanisms
Kidney Autoregulation:
Maintains consistent blood flow across varying pressure changes.
Myogenic and tubuloglomerular mechanisms operate simultaneously.
Page 56: Myogenic Mechanism
Mechanism Description:
Contracts with increased blood pressure to maintain consistent flow; relaxes when pressure decreases.
Page 57: Paracrine Regulation
Paracrine Effects on GFR:
ATP, adenosine, and NO influence afferent arteriole contraction/relaxation affecting GFR.
Page 58: Endocrine Regulation of Kidney Function
Endocrine Mechanisms:
Renin-angiotensin mechanism and natriuretic peptides regulate GFR and kidney functioning.
Page 59: Hormonal Control and Kidney
Renin Action:
Activates angiotensin II production; influences blood pressure and sodium retention via aldosterone.
Page 60: ADH Function in Kidney Regulation
ADH Mechanism:
Promotes aquaporin movement to control water reabsorption in collecting ducts, affecting urine output.
Page 61: ADH Overview
Urine Volume and ADH:
Increases urine volume via enhanced water recovery.
Page 62: ADH Effects on Urine Volume
Reintegration of Information:
ADH raises water reabsorption; urine concentration decreases with less sodium absorption.
Page 63: Endothelin's Role
Endothelin Effects:
Powerful vasoconstrictors; impact GFR and Na+ recovery in diabetic kidney disease.
Page 64: Natriuretic Hormones
Natriuretic Function:
Contrasts aldosterone's action, inhibits sodium recovery to affect blood pressure.
Page 65: Regulation of Volume & Composition Objectives
Objectives for Volume Regulation:
Explain diuretics' action mechanisms and nephron permeability necessity for urine formation.
Page 66: Volume-sensing Mechanisms
Blood Pressure Relations:
Reflects blood volume; baroreceptors sense changes linked to renal function.
Page 67: Regulation of pH
Acid-base Homeostasis:
Buffers act instantly; kidneys and lungs provide longer-term pH balance.
Page 68: Nitrogen Waste Elimination
Nitrogen Waste Process:
Protein breakdown produces ammonia; converted to urea for less toxicity in urine.
Page 69: Drug and Hormone Clearance
Drug Excretion:
Water-soluble drugs subject to glomerular filtration; larger molecules limited by kidney capillary filtering.
Page 70: Homeostasis and the Urinary System
Objectives:
Kidney roles in vitamin D activation; regulation of erythropoiesis and urinary system homeostasis functions.
Page 71: Vitamin D Activation
Vitamin D Synthesis:
Hydroxylation in kidneys convert calcidiol into calcitriol, essential for Ca++ absorption and health.
Page 72: Erythropoiesis Role
EPO Function:
Kidney-produced EPO stimulates red blood cell formation; secretion influenced by environmental factors.
Page 73: Blood Pressure Homeostasis
BP Regulation:
Renin-angiotensin system influences blood pressure changes across various physiological conditions.
Page 74: Osmolarity Regulation
Osmolarity Consequences:
Severe hypo/hyperosmolarity risks affecting overall hydration and cell physiology.