The Urinary System

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Chapter 26

• The Urinary System
• Lecture Outline

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INTRODUCTION

• Study of the structure, function, and diseases of
  the kidneys is nephrology. The branch of surgery
  related to the urinary system is called urology.
• The urinary system helps maintain homeostasis by
• Altering blood composition, pH, volume, and
  pressure
• Maintaining blood osmolarity
• Excreting wastes
• Producing hormones
• Regulates ions in our blood, like Na, K, Ca2,
  and Cl-

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Components

• The urinary system consists of 2 kidneys, 2
  ureters, 1 bladder, and 1 urethra.
• The main function of the kidneys is to filter the
  blood and produce urine.
• Urine is made up of water and solutes removed
  from our blood.

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External Anatomy of Kidney

• Paired kidney-bean-shaped organ
• 4-5 in long, 2-3 in wide,1 in thick
• Found just above the waist between the peritoneum
  posterior wall of abdomen

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Internal Anatomy of the Kidney

• The outside of a kidney is called the renal
  cortex and is reddish brown in color.
• The inside of a kidney is called the renal
  medulla.

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Nephrons

• The functional unit of a kidney is a nephron
• There are millions of nephrons found in each of
  your kidneys.

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Nephron Anatomy

• Blood enters the kidney through the glomerulus
  which is a ball of capillaries.
• It is surrounded by a protective capsule called
  the Bowmans capsule.
• Blood is filtered here and then moves on to the
  rest of the nephron.

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Nephron Anatomy

• Blood then goes through the proximal tubule, down
  the descending Loop of Henle, up the ascending
  Loop of Henle, and through the distal tubule.
• At each step, the nephron is removing useful
  things from blood, like water, nutrients,
  minerals, and salts that were absorbed by the
  digestive system.

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Nephron Anatomy

• After going through the nephron, all thats left
  is waste.
• The waste is collected in the collecting duct and
  sent to the ureter to travel to the bladder for
  storage.

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Urine

• You produce 1 to 2 liters of urine every 24
  hours.
• Urine should be clear to pale yellow in color.
• Urine should be transparent (clear)
• It is mildly aromatic and smells like ammonia
  when left standing
• pH of urine ranges from 4.6 to 8.0, with an
  average of 6.0
• 95 of urine is water, the remaining 5 is
  electrolytes, salts, and drugs.
• There should never be protein in your urine

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The Bladder

• The bladder is a hollow, stretchable muscular
  organ located in the pelvic cavity.
• Urinary bladder capacity ranges from 700-800mL,
  slightly less in females because of the uterus

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Urethra

• The urethra is a small tube leading from the
  bladder to the exterior of the body.
• In men, it also carries sperm.

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Development of the Urinary system

• By week 3 of pregnancy, kidneys begin to form
• Fetuses go through 3 pairs of kidneys before
  birth, only the last one remains at the time of
  birth
• By month 3, fetuses begin producing urine, which
  remains in the amniotic fluid

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Aging and the Urinary System

• After age 40, the effectiveness of kidney
  function begins to decrease.
• Kidneys shrink
• Filters less effectively, you are more thirsty
• Diseases and infections are more common
• Cancer of prostate is common in elderly men

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Diseases and Disorders

• Nephroptosis or floating kidney, is an inferior
  displacement or dropping of the kidney.
• Common in thin people who dont have enough fat
  to hold the kidney in place.
• Its dangerous because it may block urine flow.

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Diseases and Disorders

• Glucosuria is when you have too much glucose in
  your blood for the kidney to filter (common in
  diabetics)
• Some glucose then remains in the urine causing
  increased urinary output, decreased blood volume,
  and dehydration.

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Diseases and Disorders

• Diuretics are substances that slow renal
  reabsorption of water and cause elevated urine
  flow.
• These include coffee, tea, soda, and alcohol.
• These all inhibit the secretion of ADH and cause
  you to pee more.

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Diseases and Disorders

• During cytoscopy a small camera is inserted
  through the urethra into the bladder and/or
  prostate.
• The bladder can be visually inspected and tissue
  samples can be collected

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Diseases and Disorders

• In urinary incontinence you no longer have
  control over your bladder muscles and pee leaks
  out.
• This is common in small children and older
  adults.
• It can also be caused by physical stress on the
  bladder (lifting heavy things, sneezing,
  laughing, being pregnant)

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Diseases and Disorders

• Kidney stones are insoluble salt crystals that
  lodge in the ureter.
• Causes include poor diet, not enough water, or
  too much calcium
• They can be dissolved through sending high energy
  shock waves through the body

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Diseases and Disorders

• A UTI is a urinary tract infection.
• They are caused by bacteria getting into the
  urethra and are more common in females because
  they have shorter urethras.
• Symptoms include painful or burning urination and
  low back pain
• Cured by antibiotics

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Diseases and Disorders

• Renal failure is when the nephrons in your
  kidneys either decrease in function or stop
  working.
• Can be caused by illness or injury, drugs, or low
  blood pressure.
• Dialysis and kidney transplant are possible
  treatments.

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Draw a Kidney

• Use page 996 as a reference
• Include a picture and labels of important
  structures.
• Must be colored
• Due at the end of the period