URINARY SYSTEM

URINARY SYSTEM

• Group of organs in the body concerned with filtering out excess fluid and other substances from the bloodstream

• Eliminate waste from the body

• Regulate blood ionic composition

• Regulate blood volume

• Regulate blood pressure

• Control levels of electrolytes and metabolites

• Regulate blood pH

• Production of hormones

Functions of the Urinary System are…

Nephrology

study of the anatomy, physiology, and pathology of the kidneys

Urology

nephrology + reproductive system

• Kidneys

• Ureters

• Bladder

• Urethra

What are the organs of the urinary system?

T12 and L3

• Right kidney is lower because of the space occupied by the right liver

• What is the level of the kidneys?

Retroperitoneal

What is the location of the kidneys

150 grams

What is the weight of the kidneys?

Hilum

indented region on the medial side of the kidney

1. renal capsule

2. adipose tissue

3. renal fascia

What are the layers of tissues surrounding the kidneys?

Renal Capsule

barrier to trauma; inner layer

Adipose tissue

composed of fats; middle layer

Renal Fascia

anchors the kidney to the abdominal wall; outer layer

Renal Cortex

outer region

Renal Medulla

inner region

Renal Pyramids

• cone-shaped masses of tissue

  • Division of Medulla

Papilla

• termination of the base of each pyramid

  • Originates at the border of the cortex and medulla

Renal Pelvis

• funnel-shaped continuation of the ureter

  • Where the Papilla projects into

Major Calyces

• open-ended pouches

  • Division of the outer border of the Pelvis

Minor Calyces

• collect urine from the tubules of each Papilla

  • Division of Major Calyces

1. Renal Artery

2. Segmental Artery

3. Interlobar Artery

4. Arcuate Artery

5. Interlobular Artery

6. Afferent Arteriole

7. Glomerulus

8. Efferent Arteriole

9. Peritubular Capillaries

10. Interlobular Vein

11. Arcuate Vein

12. Interlobar Vein

13. Renal Vein

What is the sequence of renal flow?

NEPHRON

• Functional unit of kidneys

• Responsible for urine formation

• 1 million for each kidney

  • 2 million total

• Renal Corpuscle

• Renal Tubule

What are the 2 major structures of a nephron?

Cortical Nephron

•  part of a nephron that lies in the Renal Cortex

  • Short Loops of Henle

  • Surrounded by Peritubular Capillaries

Juxtamedullary Nephrons

• part of a nephron that lies in the Renal Medulla

  • Long Loops of Henle

Vasa Recta

specialized peritubular capillaries that extend to the medulla

1. Glomerulus

2. Proximal convoluted tubule

3. descending loop of henle

4. ascending loop of henle

5. distal convoluted tubule

6. collecting duct

What is the flow of urine formation?

Glomerulus

1.  special ball of capillaries where blood vessels enter

   • Rested within the Bowman’s Capsule

   • Where filtration occurs

Proximal Convoluted Tubule

where reabsorption occurs

Distal convoluted tubule

 where secretion occurs

• Gains water and loses salt during secretion

Collecting Duct

where the Distal Convoluted Tubule empties into

• Yellow-amber

  • Varies according to recent diet and concentration of urine

What is the color of urine?

Fresh urine

mild smell

Aged urine

• Stronger odor similar to ammonia

• 4.6-8

  • Typical average: 6.0

  • Variations occur due to diet

pH level of urine

•  0.001-0.035

  • “Specific Gravity”

  • Ratio of the weight of a volume of a substance compared to the weight of the same volume of distilled water

What is the density of urine?

• Either clear or very slightly cloudy (fresh urine)

  • Gauged subjectively

  • Reported as:

    • Clear

    • Slightly Cloudy

    • Cloudy

    • Opaque (“Flocculent”)

What is the turbidity?

GLOMERULAR FILTRATION

• Test used to check how well the kidneys are working

• Estimates how much blood passes through the Glomeruli each minute

• 150 liters in females; 180 liters in males

What are the values of a normal GFR?

FILTRATION MEMBRANE

• Formed by: Glomerular capillaries and Podocytes

• Leaky barrier

• Allows filtration of water and small ions

• Prevents filtration of most plasma proteins, blood cells, and platelets

Podocytes

•  located in the visceral layer of the Bowman’s Capsule

NEURAL REGULATION OF GFR

• Kidneys are supplied by sympathetic fibers of the ANS

• Releases norepinephrine

  • Causes vasoconstriction through the activation of a₁ receptors

• Reduces urine output

• Permits greater blood flow to other body tissues

Angiotensin II

• reduces GFR

  • Potent vasoconstrictor

  • Narrows afferent and efferent arterioles and reduces renal blood flow

Atrial Natriuretic Peptide (ANP)

•  increases GFR

  • Increases the capillary surface area available for filtration

Ureter

• Length: 25-30 cm

• Composed of smooth muscle

  • Peristalsis contraction

URINARY BLADDER

STORES URINE

500 ml

What is the normal capacity of the urinary bladder?

700-800 ml

What is the maximum capacity of the urinary bladdeR?

(+) Dribbles

pee is dripping at this point

Detrusor Muscle

• smooth muscle

Nerve Innervation: S2-4

Micturition Reflex

• urge to urinate

  • “Voiding”

  • Activated: 200-300 mL of urine

MICTURITION REFLEX STEPS

1. Bladder fills until tension in its walls rises above threshold level

2. Micturition Reflex empties the bladder or creates a conscious desire to urinate

URETHRA

Terminal portion of the urinary system

20 cm

What is the length of urethra in males?

3-4 cm

What is the length of urethra in males?

External Urinary Sphincter

voluntary sphincter

Internal Urinary Sphincter

involuntary sphincter

Calcitriol

• active form of Vitamin D

  • “1.25 Dihydroxycholecalciferol”

Erythropoietin

stimulates new RBC formation in the bone