Urinary System Anatomy and Physiology

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					    Urinary System
Anatomy and Physiology
         Part I
                    Urinary System
   Kidneys (2)
       Most important excretory organ
       Eliminate waste
   Ureters (2)
   Bladder (1)
   Urethra (1)
   Nephron Unit
       Functional unit of the kidney
       Formation of urine
       Tubular and vascular structures
    Kidney Location and Protection
   Kidneys are located in the posterior wall of the
    abdominal cavity
   In the retroperitoneal space
   Connective tissue (renal fascia) hold the kidneys
    in place
   Adipose tissue cushion the kidneys
   The lower rib cage partially enclose the kidney
    and protect them
   Urinary System –
Anterior/Posterior Views
              Kidney Structures
   Kidney is reddish-brown
   Looks like a bean
   Approximately 4 inches x 2 inches
   Hilus – indentation where blood vessels and
    structures enter or exit the kidney
   Three Regions in the kidney if sliced in half –
    renal cortex, renal medulla, renal pelvis
                  Renal Cortex
   Light, outside region
   Cortex means “bark”
                  Renal Medulla
   Dark, triangular structure
   Form small cone shaped
    regions called renal
    pyramids
   Each pyramid is
    separated by renal
    columns
   The lower ends of the
    pyramids point to the
    renal pelvis
                     Renal pelvis
   A basin that collects the
    urine made by the kidney
    and helps form the upper
    end of the ureter
   The edges of the renal
    pelvis closest to the renal
    pyramids are called
    calyces
   Calyces collect the urine
    formed in the kidney
            How do they work?
   Need a blood supply
   Brought to the kidney via the renal artery
   Renal artery stems from the abdominal aorta
   20-25% of cardiac output goes to the kidneys
   Smaller arteries supply blood to the nephron
    unit
   Blood leaves the kidney via the renal veins
   The renal veins empty into the inferior vena
    cava
        Functions of the Kidneys
   Excrete nitrogenous waste from the body
     Urea
     Ammonia

     Creatinine

   Regulate blood volume
   Help regulate electrolyte content of the blood
   Regulate acid-base balance (pH)
   Regulate blood pressure
   Regulates red blood cell production
         The Formation of Urine
   The Nephron Unit
   Each kidney contains about 1 million nephron
    units
   The number does not increase after birth
   They cannot be replaced if damaged
   2 parts
     Tubular component (renal tubule)
     Vascular component
                Renal Tubules
   Glomerular capsule (Bowman’s Capsule) – “C”
    shaped capsule surrounding the glomerulus
   Glomerulus – cluster of capillaries
     Proximal convoluted tubule
     Loop of Henle – ascending and descending limb

     Distal Convoluted tubule

     Collecting duct
Nephron
                Renal Vasculature
   Receives blood from the renal artery
   Renal artery branches into the afferent arterioles
   Afferent arterioles feed into Bowman’s capsule
   The efferent arterioles exit Bowman’s capsule
   The efferent arterioles form the peritubular capillaries
   The peritubular capillaries empty into the venules, large
    veins, and then into the renal veins
   It is imperative you know the relationship between the tubular
    and vascular structures.
               Urine Formation
   Formed in the nephron unit
   Water and dissolved substances move through
    the renal tubules and vessels
   Three processes are involved in urine formation
     Glomerular filtration
     Tubular reabsorption

     Tubular secretion
           Composition of Urine
   Sterile
   95 % water
   Nitrogen containing waste – urea, uric acid,
    ammonia, creatinine
   Electrolytes
   Light yellow color of urine is due to a pigment
    called urochrome
   Urochrome is formed from the breakdown of
    hemoglobin in the liver
            Urine Specific Gravity
   Ratio of the amount of solute to the total
    volume
   Solute = substance dissolved in the urine
   The greater the solute = greater the specific
    gravity
   Concentrated Urine = high specific gravity
       Ex. dehydration
   Dilute Urine = low specific gravity
       Ex. Overhydration, diabetes insipidus
           Urine Characteristics
   Amount – 1500 ml in 24 hours
   pH – average 6.0
   Specific Gravity – heavier than water (1.001-
    1.035)
   Color – yellow (amber, straw colored,
    concentrated, orange, brown, red, sediment,
    clear or cloudy)
   Dehydrated = deep yellow, dark
   Overhydrated = pale yellow, colorless
     Abnormal Constituents of Urine
   Albumin (protein)
   Glucose
   Red blood cells
   Hemoglobin
   White blood cells
   Ketone bodies
   Bilirubin
                Urine Testing
   Urinalysis
   Microscopic exam
   Culture and sensitivity
   Urine dipstick
   Urine Drug and alcohol screening
   24 hour urine testing
Your Plumbing – The Urinary Tract
(Ureters, Urinary bladder, Urethra)
   Ureters
   Transport urine, they do not alter it in any way
   Urine moves in response to gravity and
    muscular movements called peristalsis through
    ureters.
Your “Plumbing”
                      The Bladder
   Stores urine temporarily until elimination
   Located behind the symphasis pubis
   A distended bladder or full bladder can be palpated
    above the syphasis in the abdominal cavity.
   Bladder has 4 layers
       Mucous membrane
       Submucosa
       Detrusor muscle – involuntary smooth muscle
       Serosa
   Contain rugae to allow for stretching
   Trigone – triangular area in the floor of the bladder
        Urination – “Micturition”
   Expelling urine from the bladder
   The urge to urinate (void) happened at about 200 ml of
    urine in the bladder
   At about 300 ml urine in the bladder, the urge becomes
    more uncomfortable
   Moderately full = 500 ml urine
   Overdistended bladder may have over 1000 ml urine
   Bacteria in your bladder doubles every 4 hours.
   Stimulated by stretch receptors
                        Urethra
   Carries urine from the bladder to the outside of the
    body
   Internal sphincter prevents urine from emptying;
    composed of smooth muscle; involuntary
   External sphincter at the upper portion of the urethra
    allows you to resist the urge to urinate; composed of
    skeletal muscle; voluntary
   Female – short, opens to the outside at the urethral
    meatus
   Male – longer, passes through the prostate gland;
    carries urine and sperm
    Urinary Retention and Suppression
   Retention - Inability to void
     Post operative; anesthesia
     Bladder dysfunction

   Suppression – no urine formation
       Kidney dysfunction
    Data Collection & Documentation
   Characteristics of urine
       Color
       Sediment
       Clear or cloudy
       Odor
   How does the patient/resident void?
   Urinary diversions?
   Signs and symptoms
       Urgency
       Frequency
       Burning sensation
       Hesitancy
What is the Costovertebral Angle?

                          T11

            R. Kidney             L. Kidney
                          T12


                          L1
 12th Rib

                                Costovertebral Angle
                        Region to assess for kidney tenderness
    Disorders of the Urinary System
   Glomerulonephritis
   Polycystic Kidney
   Pyelonephritis
   Renal Calculi – kidney stones
   Renal Failure
   UTI – urinary tract infection
               As We Age
   By age 80 there is a 50% reduction in nephron
    units; therefore a decreased ability to
    concentrate urine
   Urinary bladder shrinks and becomes less able to
    contract and relax; therefore the elderly must
    void frequently
   Bladder infection incidence increases
   Increase in bladder incontinence due to
    weakened muscles