Urinary System

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Urinary System

• John Minor and Jeremiah Shaw

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What are the major parts of the urinary system?
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Diagram of Urinary System
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Parts of Urinary System

• Kidneys organs that have excretory functions
  and produce urine
• Ureters tubes leading from the kidneys to the
  urinary bladder
• Urinary Bladder a muscular sac for temporary
  storage of urine
• Urethra a tube that conducts urine to the
  exterior

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What are the functions of the Urinary System?
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Functions of Urinary System

• Regulation of blood pressure
• Regulation of concentrations of ions in plasma
• Stabilizing blood pH
• Conserving valuable nutrients
• Assisting liver in detoxifying poisons

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What is the anatomy of the kidney?
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Structure of the Kidney
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Anatomy of Kidneys

• The kidneys lie on each side of the vertebral
  column between T12 and L3
• Surrounded by three layers of connective tissue
  renal capsule, adipose capsule and the renal
  fascia
• Average kidney 10cm x 5.5cm x 3cm, weighing 150g
• Left kidney lies slightly superior to the right
  kidney

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Anatomy of Kidneys (cont.)

• Hilum entry for the renal artery and nerves and
  an exit for renal vein and ureter
• Renal sinus internal cavity within the kidney
• Renal Pyramids Triangular structures with bases
  at the cortex and tips at the renal sinus
• Renal Medulla structure containing 6 - 18 renal
  pyramids
• Renal Columns bands of tissue that separate
  renal pyramids

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Anatomy of Kidney (cont.)

• Cortex superficial part of kidney
• Renal Papilla the tip of each renal pyramid
• Renal Lobe consists of a renal pyramid, the
  overlying renal cortex and adjacent columns
• Renal Pelvis a large funnel that drains the
  kidneys

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How does blood flow through the kidney?
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Blood flow of kidney
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Blood flow of kidney

• The kidney receives blood from the renal artery
  and blood is removed by the renal vein
• Through a system of various types of arteries and
  veins blood enters and exits the kidney
• At the lowest level the blood is passed through
  the nephron which starts urine production

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What is the anatomy of the nephron?
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(No Transcript)
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Anatomy of the nephron

• The nephron consist of two parts, the renal
  corpuscle and the renal tubule
• The renal tubule is a long tubular passage way
  measuring about 50mm
• The renal corpuscle is a spherical structure
  consisting of the Bowmans capsule and the
  glomerulus
• The renal tubule consist of the proximal
  convoluted tubule (PCT), distal convoluted tubule
  (DCT), and the Loop of Henle

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Anatomy of the Nephron (cont.)

• Glomerulus system of about 50 intertwining
  capillaries
• Bowmans Capsule a chamber that holds the
  glomerulus with a visceral epithelium

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How is urine produced?
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Filtration

• The renal corpuscle is the site where filtration
  occurs
• Blood pressure forces water and other solutes out
  of the glomerular capillaries
• This process produces a primarily protein free
  solution called filtrate

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Entry into the renal tubule

• After filtrate is formed it enters the renal
  tubule
• As filtrate travels through the renal tubule it
  becomes tubular fluid with more of the
  characteristics of urine
• The renal tubule has 3 major functions
• Reabsorbing all useful organic nutrients in the
  filtrate
• Reabsorbing more than 90 of water in the
  filtrate
• Secreting any waste products that failed to enter
  the renal corpuscle through filtration

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The Proximal Convoluted Tubule (PCT)

• The PCT is the first segment of the renal tubule
• The lining of the PCT is a simple cuboidal
  epithelium whose surface bears microvilli
• Reabsorption is the main function of the PCT and
  it reabsorbs organic nutrients, ions, water and
  plasma proteins (if present)

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Loop of Henle

• The second part of the renal tubule is the Loop
  of Henle
• The Loop of Henle is divided into the descending
  limb and ascending limb
• The descending limb flows toward the renal pelvis
  and is lined with a cuboidal epithelium
• The ascending limb flows toward the renal pelvis
  and is lined with a squamous epithelium

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Distal Convoluted Tubule (DCT)

• The third part of the renal tubule is the DCT
• It is lined with a cuboidal epithelium that is
  not lined with microvilli
• The DCT is necessary for three vital processes
• Selective reabsorption of Na and Ca ions
• Active secretion of ions, acids, drugs and toxins
• Selective reabsorption of water

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The Collecting System

• The last segment of the nephron is the collecting
  system
• The nephron drains into a collecting duct, which
  drains into a larger papillary duct, which
  empties into the minor calyx
• Final osmotic pressure and urine volume is
  determined by the collecting system

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General Characteristics of Urine

• pH range 4.5 8.0 (average 6.0)
• Specific Gravity 1.003 1.030
• Water Content 93 - 97
• Color Clear yellow
• Odor Varies with composition

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Organic Waste Products

• Urea most abundant organic waste, generate from
  the breakdown of amino acids (21g)
• Creatinine generated in skeletal muscle through
  the breakdown of creatine phosphate (1.8g)
• Uric Acid waste product from recycling the
  nitrogenous base in RNA molecules (.48g)

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Basic Processes of Urine Formation

• Filtration blood pressure forces water from the
  blood across the walls of the glomerular
  capillaries
• Reabsorption the removal of water and solutes
  from the filtrate and their movement across the
  tubular epithelium
• Secretion the movement of solutes from the
  outside of the tubular epithelium (peritubular
  fluid) to the inside

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Glomerular Filtration Rate (GFR)

• GFR is the amount of filtrate produced each
  minute
• On average a GFR is about 125ml a minute, that is
  around 180 liters of filtrate a day
• About 99 of filtrate is then reabsorbed by the
  renal tubules
• One can test GFR with a creatinine clearance test
• The GFR can be regulate automatically or with the
  use of hormones

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What is the anatomy of the urinary bladder?
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Urinary Bladder
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Anatomy of the urinary bladder

• The urinary bladder is a hollow muscular organ
  that is a temporary reservoir for urine
• The superior surface of the bladder is covered
  with a peritoneum and is stabilized by the middle
  umbilical ligament and lateral ligaments
• The interior surface of the urinary bladder is
  thrown into folds called rugae
• The ureters enter the bladder through ureteral
  openings and meets the center of trigone
• The center of trigone lies superior to the neck
  which opens to the urethra

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Anatomy of urinary bladder (cont.)

• Internal Urethral Sphincter (sphincter vesicae)
  an involuntary sphincter that allows urine to
  leave the bladder to the urethra.
• External Urethral Sphincter a circular band of
  muscles that is under voluntary control to allow
  for urination

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Histology of the urinary bladder

• The wall of the urinary bladder has three layers
  mucosa, submucosa and muscularis
• Muscularis layer has two layers, longitudinal
  smooth muscular and circular muscle
• The two muscle layers form the detrusor muscle,
  which contracts to expel urine out the urethra

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What is the anatomy of the ureters?
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Anatomy of the ureters

• The ureters are a pair of muscular tubes that
  extend from the kidneys to the urinary bladder
• They are approximately 12in. in length
• The ureters are made from three tissues
• - An inner transitional epithelium layer
• - A middle muscle layer made up of circular and
  longitudinal layers
• - An outer connective tissue in conjunction with
  the renal capsule

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Micturition Reflex

• The process of urination is coordinated by the
  micturition reflex
• The urge to urinate arises when the urinary
  bladder contains around 200ml of urine
• Nerves receive the signal that the bladder is
  expanding
• The detrusor muscle contracts causing relaxation
  of the internal and external urethral sphincters

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What are the complications that occur with the
urinary system?
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Urinary issues

• Aminoaciduria amino acid loss in the urine
• Calculi insoluble deposits that form within the
  urinary tract
• Glomerulonephritis an inflammation of the renal
  cortex
• Hematuria the presence of blood in urine
• Polycystic Kidney Disease an inherited
  abnormality that affects the development of the
  kidney tubule
• Proteinuria the presence of protein in urine
• Renal failure an inability for kidneys to
  function to maintain homeostasis
• Urinary obstruction a blockage of the urinary
  tract

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Aging on the Urinary System

• A decline in the number of functional nephrons,
  30 -40 between 25 85
• A reduction in the GFR due to a lack of renal
  blow flow and fewer glomeruli
• Reduced sensitivity to ADH, a hormone that
  reduces the amount of water lost in urine

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Professions

• Urologist a doctor that specializes in urinary
  diseases and function
• Urology Oncologist a doctor that specializes in
  the cancers of the urinary system
• Nephrologist a doctor that specializes in the
  kidneys