Urinary System

Question 0

Kidneys-Location

Answer 0

• protected by lower rib cage
• under muscles of back and behind parietal peritoneum (ab.)
• fat encases each and holds in place
• L&R renal arteries emerge directly from ab. aorta at L1&L2
• 20% of blood vol. of heart pumped through kidneys each minute

Question 1

Overview

Answer 1

• constancy of body fluid volume and chemical levels
• produce and excrete urine
• maintains normal blood composition
  
  • kidneys clean blood of waste
• uremia
  
  • uremic poisoning
  • toxic levels of waste
• maintain BP, stim. RBC prod., reg. electrolyte, water, blood and pH levels

Question 2

Kidneys-Internal Structures

Answer 2

Renal cortex-outer part of kidney
Renal medulla-inner portion
Renal Pyramids-triangular diversions of medulla
Renal Papilla-narrow, innermost end of a pyramid
Renal pelvis-expansion of upper end of a ureter
Calyx-division of renal pelvis

Question 3

Kidneys-Microscopic Structure

Answer 3

• nephrons make up interior
  
  • tiny funnel with long, convoluted stem

Renal Corpuscule

• Bowman capsule
  
  • cup-shaped top
• Glomerulus
  
  • network of blood capillaries
  • high BP required to filter wastes

Renal Tubule

• proximal convoluted tubule
  
  • 1st segment, bends
• nephron loop
  
  • loop of Henle
  • straight down, loop, then straight up
• distal convoluted tubule
  
  • distal to upper limb
• collecting tubule
  
  • straight part of tubule

Question 4

Kidney-Function

Answer 4

• form urine
  
  • wastes filtered into nephron
• adjust output to =intake
• homeostasis (reaches toxic level quickly)
• regulate levels of chemical substances in blood
• regulate BP
• maintain adequate RBCs

Question 5

Urine Formation

Answer 5

-nephrons form urine

Filtration

• continually in renal corpuscules
• rate of 125mL/min (180L/day)
• fluid and nutrients quickly reclaimed

Reabsorption

• movement of substances out of tubules into blood
• PCT-nephron loops-DCT-collecting tubules
• both active and passive transport
• renal threshold (max level able to absorb glucose)

Secretion

• moves substances out of blood into urine
• maintains fluid, electrolyte, acid-base balance

Question 6

Control of Urine Volume

Answer 6

-normal output is 1500-1600mL/day

ADH

• makes collecting tubules permeable to water and is reabsorbed
• less water lost

Aldosterone

• controls reabsorption of Na
• increases tubular water reabsorption and reabsorb Na faster

ANH

• atrial natriuretic hormone
• opposite of aldosterone
• secrete more Na and lost more water

Question 7

Ureters

Answer 7

• urine drains out of collecting tubules, down ureter, into bladder
• renal pelvis is basin-like end of ureter
• 6mm wide, 25-30cm long
• contraction produces peristaltic-type movement
  
  • moves urine down ureters

Question 8

Urinary Bladder

Answer 8

• in pelvis, just behind pubic symphysis
• when full projects upward into ab. cavity
• expands to hold urine
• when empty wrinkled and lies in folds (rugae)
• Trigone
  
  • one triangular area on posterior surface
  • free of rugae and therefore smooth

Question 9

Urethra

Answer 9

• lowest art of urinary tract
• urinary meatus is external opening
• narrow tube
  
  • 4cm long in women, 20cm in men
• passageway for movement of reproductive fluid (semen)

Question 10

Micturition

Answer 10

• regulatory sphincters seal off bladder without leaking
• internal urethral sphincter–>involuntary, smooth muscle
• external urethral sphincter–>voluntary, striated muscle
• little increase in pressure until 300-400mL
  
  • then nerve impulse transmitted to spinal cord and emptying reflex initiated
• urinary retention
  
  • kidneys produce but bladder can’t empty
• urinary suppression
  
  • kidneys don’t produce, bladder can empty
• overactive bladder
  
  • urge to urinate frequently
• cystitis–>bladder infection