Urinary System Overview and Components
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Questions and Answers

What percentage of nephrons in the human kidney are cortical nephrons?

  • 95%
  • 85% (correct)
  • 65%
  • 75%
  • What is the primary function of the glomerulus in the nephron?

  • Storage of urine
  • Secretion of hormones
  • Filtration of blood (correct)
  • Reabsorption of water
  • Which structure specifically carries blood away from the kidney after filtration?

  • Afferent arteriole
  • Cortical radiate artery
  • Arcuate vein (correct)
  • Interlobar vein
  • What is one of the main functions of the nephron during urine processing?

    <p>Reabsorption of organic materials</p> Signup and view all the answers

    Which structure is NOT part of the renal blood supply?

    <p>Ureter</p> Signup and view all the answers

    What is one of the primary functions of the urinary system in relation to blood?

    <p>Regulates blood volume and pressures</p> Signup and view all the answers

    Which component temporarily stores urine prior to elimination?

    <p>Urinary bladder</p> Signup and view all the answers

    Which artery directly supplies blood to the kidneys?

    <p>Renal artery</p> Signup and view all the answers

    What anatomical feature differentiates the position of the left kidney from the right kidney?

    <p>The left kidney is positioned higher than the right</p> Signup and view all the answers

    Which layer of connective tissue directly surrounds the kidneys?

    <p>Fibrous capsule</p> Signup and view all the answers

    What is NOT a function of the urinary system?

    <p>Regulates hormone levels</p> Signup and view all the answers

    Which structure conducts urine from the kidneys to the urinary bladder?

    <p>Ureter</p> Signup and view all the answers

    What is the role of the nephron in the kidneys?

    <p>Filters blood and produces urine</p> Signup and view all the answers

    Which structure transports urine to the exterior of the body?

    <p>Urethra</p> Signup and view all the answers

    What mineral does the urinary system help synthesize the active form of?

    <p>Vitamin D</p> Signup and view all the answers

    What is the primary function of macula densa cells in the nephron?

    <p>Monitor electrolyte concentration</p> Signup and view all the answers

    Which hormone is mainly responsible for regulating blood pressure?

    <p>Renin</p> Signup and view all the answers

    What is the primary role of the proximal convoluted tubule?

    <p>Reabsorption of nutrients and ions</p> Signup and view all the answers

    Which statement best describes the nephron loop's ascending limb?

    <p>It pumps sodium and chloride ions out</p> Signup and view all the answers

    What does the collecting system primarily consist of?

    <p>Collecting ducts and papillary ducts</p> Signup and view all the answers

    What structural adaptations does the urinary bladder possess for urine storage?

    <p>Rugae and three muscular layers</p> Signup and view all the answers

    What unique feature distinguishes the male urethra from the female urethra?

    <p>It passes through the prostate gland</p> Signup and view all the answers

    How do the ureters transport urine from the kidneys to the bladder?

    <p>Using peristaltic contractions of smooth muscle</p> Signup and view all the answers

    Which cell type provides physical support for the arteries in the kidney?

    <p>Mesangial cells</p> Signup and view all the answers

    In which part of the kidney does erythropoietin secretion primarily occur?

    <p>Juxtaglomerular apparatus</p> Signup and view all the answers

    What structures join the collecting duct to the minor calyx?

    <p>Papillary ducts</p> Signup and view all the answers

    What physiological role does the external urethral sphincter serve?

    <p>It allows voluntary control of urination</p> Signup and view all the answers

    What percentage of sodium and chloride ions is reabsorbed in the proximal convoluted tubule?

    <p>60%</p> Signup and view all the answers

    Which type of muscle tissue is primarily found in the wall of the urinary bladder?

    <p>Smooth muscle</p> Signup and view all the answers

    Study Notes

    Urinary System Overview

    • The urinary system is responsible for regulating plasma ion concentrations (Na+, K+, Cl-), blood volume and blood pressure, and blood pH.
    • It also prevents the loss of valuable nutrients, eliminates organic matter/waste (like urea), synthesizes calcitriol (active form of vitamin D), and prevents dehydration.
    • It aids the liver by detoxifying poisons

    Urinary System Components

    • Kidneys: Produce urine
    • Ureters: Transport urine to the urinary bladder
    • Urinary Bladder: Temporarily stores urine prior to elimination
    • Urethra: Conducts urine to the exterior; in males, it also transports semen

    Kidney Structure and Position

    • Right Kidney: Located behind the liver, hepatic flexure, and duodenum.
    • Left Kidney: Located behind the spleen, stomach, pancreas, splenic flexure, and jejunum; positioned slightly higher than the right kidney.
    • Both kidneys are capped by the suprarenal glands.

    Kidney Structure: Sectional Anatomy

    • Cortex: Outer layer
    • Medulla: Inner layer, contains renal pyramids.
    • Renal Pyramids: Cone-shaped structures in the medulla.
    • Renal Columns: Tissue extending inward from the cortex between the pyramids.
    • Renal Papilla: Tip of the renal pyramid projecting into the minor calyx.
    • Renal Pelvis: Funnel-shaped structure that receives urine from the major calyxes.
    • Minor Calyx: Collect urine from the renal pyramids.
    • Major Calyx: Collect urine from the minor calyxes.
    • Renal Sinus: Cavity within the kidney containing the renal pelvis, calyxes, and blood vessels.

    Kidney Blood Supply

    • The renal artery supplies blood to the kidney. There are numerous branches leading to arterioles further into the kidney.
    • Arterioles are a key part of how blood is filtered and processed in the renal corpuscles.
    • The renal veins drain blood from the kidney.

    Nephron Structure and Function

    • The nephron is the basic structural and functional unit of the kidney
    • Glomerulus: Intertwining capillaries inside the Bowman's capsule, performs filtration.
    • Renal Tubule: Long tubular passageway that processes the filtrate.
      • Proximal Convoluted Tubule (PCT) - Reabsorbs water, ions, and most organic nutrients. This is important for re-absorption of valuable nutrients and water preventing dehydration.
      • Nephron Loop/Loop of Henle - Reabsorbs water and ions, crucial for creating a concentration gradient in the medulla. This is vital to establishing osmotic pressure and enabling high water reabsorption later. The thick ascending loop actively pumps sodium and chloride out.
        • Thin descending limb allows water to leave passively. The thick ascending limb actively transports sodium and chloride, making the medulla more concentrated in solutes. This is critical to the function of the nephrons.
      • Distal Convoluted Tubule (DCT) - Reabsorbs water, sodium, calcium, and secretes excess ions and waste products.

    Renal Corpuscle Structure

    • Glomerular Capsule (Bowman's Capsule):
      • Parietal Layer: Outer epithelial layer.
      • Visceral Layer: Inner epithelial layer made of podocytes. Podocytes have filtration slits to regulate what is passed into the Bowman's capsule (the initial filtrate collection space)
    • Glomerular Capillaries (glomerulus): Fenestrated (with holes) capillaries, enabling filtration of small molecules but preventing filtration of larger molecules
    • The renal corpuscle performs initial filtration.

    Filtration in the Renal Corpuscle

    • Filtration of fluid and solutes from the blood into the glomerular capsule/Bowman's capsule occurs through filtration membrane
    • filtration membrane is a 3-layered structure of:
      • capillary endothelium
      • the basal lamina
      • podocyte epithelium

    Juxtaglomerular Complex

    • Macula Densa cells: Monitor electrolyte concentration (sodium and chloride) in the DCT.
    • Juxtaglomerular cells: Secrete renin, regulating blood pressure and erythropoietin stimulating red blood cell production.

    The Collecting System

    • The collecting duct receives filtrate from several nephrons.
    • Filtrate passes through the collecting ducts and papillary ducts, then the minor calyx, major calyx into the renal pelvis. This enables final adjustments to the concentration of the urine.

    Urine Transport, Storage, and Elimination

    • Ureters: Peristaltic contractions move urine to the urinary bladder.
    • Urinary Bladder: Temporarily stores urine.
    • Urethra: Conducts urine outside the body; external urethral sphincter in both sexes allows for voluntary control of urine flow

    Additional information on the Male and Female differences in the Urinary System are included in the pages of the document.

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    Urinary System Lecture 8 PDF

    Description

    Explore the essential functions and components of the urinary system, including kidneys, ureters, bladder, and urethra. This quiz will assess your understanding of how these structures work together to regulate important bodily functions. Test your knowledge on kidney anatomy and its role in detoxification.

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