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.