Urinary System Physiology Quiz
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Questions and Answers

What is the role of natriuretic hormone in diabetic kidney disease?

  • Inhibits aldosterone production
  • Blocks Na+ secretion (correct)
  • Promotes Ca++ reabsorption
  • Increases phosphate reabsorption

    • How do baroreceptors respond to an increase in blood pressure?

  • Trigger vasodilation (correct)
  • Release renin
  • Increase ADH levels
  • Cause widespread vasoconstriction

    • Which hormone is responsible for increasing red blood cell production?

  • Natriuretic hormone
  • Erythropoietin (EPO) (correct)
  • Aldosterone
  • Parathyroid hormone (PTH)

    • What is the primary function of renin?

    <p>Stimulates aldosterone release</p> Signup and view all the answers

    Which hormone plays a significant role in regulating sodium levels in the body?

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

    Why is the kidney essential for maintaining proper pH balance in the body?

    <p>To control hydrogen ion concentrations</p> Signup and view all the answers

    What is the role of the macula densa in the kidney?

    <p>Regulate renin release</p> Signup and view all the answers

    Which part of the urinary system is responsible for collecting filtrate from several nephrons?

    <p>Collecting duct</p> Signup and view all the answers

    What does anuria, a condition where less than 50 mL/day of urine is excreted, typically indicate?

    <p>Kidney disease</p> Signup and view all the answers

    What is the main purpose of the renal corpuscle in the kidney?

    <p>Form urine</p> Signup and view all the answers

    Which hormone controls sodium reabsorption in the distal convoluted tubule of the nephron?

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

    What is the purpose of the renal hilum in the kidney?

    <p>Serve as entry and exit for vessels and ureters</p> Signup and view all the answers

    Why do we excrete only 1-2 liters of urine daily despite about 200 liters of filtrate being produced by the glomeruli?

    <p>Due to reabsorption of water and essential solutes</p> Signup and view all the answers

    What is the function of the loop of Henle in the nephron?

    <p>Reabsorb water and solutes</p> Signup and view all the answers

    What is the direct role of aquaporin channels in the collecting ducts of the kidney?

    <p>Increasing water reabsorption based on osmolarity</p> Signup and view all the answers

    What is the purpose of the proximal convoluted tubule (PCT) in a nephron?

    <p>Aid in sodium reabsorption</p> Signup and view all the answers

    Study Notes

    Urine Formation and Excretion

    • The glomeruli produce approximately 200 liters of filtrate per day, but only 1-2 liters are excreted as urine.
    • Dehydration is indicated by darker urine, a slight scent of ammonia, and less frequent urination.
    • Normal urine excretion is a minimum of 500ml per day to remove waste.

    Urine Volume and Concentration

    • Polyuria: more than 2.5 liters/day, indicating diabetes mellitus, diabetes insipidus, excess water, caffeine, or alcohol consumption, kidney disease, or sickle cell anemia.
    • Oliguria: 300-500 mL/day, indicating dehydration, blood loss, diarrhea, cardiogenic shock, kidney disease, or enlarged prostate.
    • Anuria: less than 50 mL/day, indicating kidney failure, obstruction, or enlarged prostate.

    Urinalysis

    • The presence of leukocytes indicates a urinary tract infection.
    • The presence of trace protein indicates damage to the glomerulus.
    • The presence of ketones indicates diabetes or a high-fat diet.

    Urinary System Anatomy

    • The urethra transports urine from the bladder to the outside of the body, with internal and external sphincters.
    • The female urethra is 4 cm long, while the male urethra is 20 cm long and passes through the prostate gland.
    • The bladder collects urine from both ureters and can hold 500-600 ml.
    • The micturition reflex occurs with about 150 mL of fluid and is easily controlled.

    Ureters

    • The ureters propel urine by peristalsis from the kidney to the bladder, with a one-way valve to prevent reflux.
    • They are about 30 cm long and coated with protective mucous from goblet cells.

    Kidney Anatomy

    • The kidneys lie on either side of the spine, are about the size of a fist, and receive 25% of cardiac output.
    • The adrenal gland sits atop each kidney.
    • The renal hilum is the entry and exit point for vessels, nerves, lymphatics, and ureters.
    • The renal pelvis funnels urine into the ureters by peristalsis.

    Nephron Function

    • The nephron is the functional unit of the kidney, responsible for cleansing blood, balancing constituents, and forming urine.
    • The afferent arteriole becomes the glomerulus, which sits next to Bowman's capsule to form the renal corpuscle.
    • The efferent arteriole forms a network around the nephron before returning to the venous system.

    Renal Hilum Function

    • The renal hilum recovers water and solutes that need to be reabsorbed into circulation.
    • The main purpose of the kidney is to maintain homeostatic balance of plasma and excrete potential toxins.

    Filtration

    • The glomerulus pushes solutes through filtration slits and into Bowman's capsule.
    • The filtration slits match up with fenestrations along the capillary.
    • Proteins associated with pores are slightly negative, allowing more positive substances to pass through easier.

    Macula Densa

    • The macula densa measures sodium and flow rate.
    • It releases ATP and adenosine in response to changes in flow rate and sodium.
    • The juxtaglomerular cell contracts or relaxes based on osmolarity of plasma fluid.

    Proximal Convoluted Tubule (PCT)

    • The PCT is between Bowman's capsule and the loop of Henle.
    • Simple cuboidal cells with prominent microvilli for efficient absorption and secretion of solutes.
    • Lots of mitochondria for active transport.

    Loop of Henle

    • The loop of Henle has descending and ascending portions.
    • Thick cuboidal cells and thin simple squamous cells are closest to the peak of the loop.

    Distal Convoluted Tubule (DCT)

    • The DCT is similar to the PCT, but shorter and with fewer microvilli.
    • Aldosterone increases sodium reabsorption.
    • Parathyroid hormone causes a calcium channel to open in the luminal surface.

    Collecting Duct

    • The collecting duct regulates water reabsorption controlled by ADH.
    • The amount of aquaporin channels is related to the osmolarity of the blood.
    • Also, receptors for aldosterone to control Na+ reabsorption.

    Regulation of Renal Blood Flow

    • Reducing sympathetic stimulation increases blood flow, and vice versa.
    • The kidneys auto-regulate filtration rate very well despite changes in BP.

    Renin-Angiotensin-Aldosterone System

    • Increases BP by vasoconstriction and reabsorption of Na+.
    • Released due to changes in flow rate and sodium.

    Diuretics

    • Caffeine promotes vasodilation in the nephron.
    • Alcohol inhibits ADH release.
    • Sodium is controlled by aldosterone, natriuretic hormone, and ADH indirectly.

    Electrolyte Balance

    • Potassium moves opposite of sodium most of the time.
    • Calcium is controlled by PTH.
    • Phosphate is opposite of calcium.
    • Hydrogen is regulated due to acid-base homeostasis.

    Nitrogen Waste

    • Produced by the breakdown of proteins.
    • Converted into ammonia, ammonia ion, urea, and uric acid.

    Vitamin D Synthesis

    • Hydroxylation (-OH) must be added to make calcitriol.
    • Receptors are present in almost all cells of the body.

    Erythropoiesis

    • EPO increases RBC production.

    Blood Pressure Regulation

    • ADH, renin, and ANH regulate BP.
    • Loss of renal function leads to loss of effective vascular volume control and can lead to hypertension or hypotension.

    Osmolarity

    • Solutes must be balanced with water in the blood vessels and interstitial spaces to prevent lysis or widespread edema.

    pH Regulation

    • The kidney is essential for proper pH regulation and balance of hydrogen ions.

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    Description

    Test your knowledge on the urinary system physiology, including the process of urine formation, indicators of dehydration, and conditions such as polyuria and oliguria. Learn about the normal volume of urine excreted per day and the specific gravity of urine.

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