Urinary System Review (Chap 25)

• Which organs make up the urinary system?

  Kidneys filter blood and produce urine

  Ureters transport urine from kidneys to urinary bladder

  Urinary bladder stores urine

  Urethra transports urine from bladder to body exterior
• And what are their functions? What else does the kidney do besides produce urine?


  Kidneys regulate fluid levels in body: prevent dehydration and maintain blood pressure

  Regulate total concentration of solutes in blood; especially ions

  Regulate acid-base balance of blood

  Produce hormones: EPO and renin
• Where are the kidneys located? What gland sits on their superior surface?

  Located on lower posterior body wall; Adrenal gland
• Most superficial region within kidney:

  renal cortex
• Region within kidney that is deep to the cortex and structured as pyramids:

  renal medulla
• Funnel-shaped tube:

  renal pelvis
• Transparent capsule that prevents spread of infection to kidney:

  fibrous capsule
• Fatty mass that surround kidney and cushions kidneys against blows and punches:

  perirenal fat capsule
• Outer layer of dense fibrous connective tissue:

  renal fascia
• How much of the cardiac output is found in the kidneys at any moment?

  25%
• Place these arteries in the correct order from largest to smallest: afferent arteriole, efferent arteriole, arcuate artery, cortical radiate artery, renal artery, abdominal aorta

  Abdominal aorta, renal artery, arcuate artery, cortical radiate artery, afferent arteriole, efferent arteriole
• What do the ureters connect?

  Kidneys to bladder
• What type of epithelium makes up the mucosa of the ureter? Why do ureters need smooth muscle?

  Transitional epithelium

  Smooth muscle propels urine towards bladder, even if a person lying down
• What is another name for kidney stones? What are they caused by?

  Renal calculi

  Caused by crystallization of calcium, magnesium, or uric acids salts in urine

  May obstruct ureters and block urine drainage
• What structures are around or near the bladder in a male and female?

  In males, the prostate gland surrounds the bladder neck

  In females, the vagina and uterus are posterior to the bladder
• In the bladder, what is the trigone?

  Trigone: smooth triangular region at the base of bladder; contains opening for both ureters and urethra; leads into bladder neck which leads into the urethra
• What type of epithelium makes up the mucosal lining? What is the muscular layer called? Does the bladder contain rugae?

  Bladder made up of transitional epithelium

  Thick muscular layer is called detrusor

  The bladder contain rugae when empty
• Which urethral sphincter is under voluntary control? Involuntary control?


  External urethral sphincter

  Internal urethral sphincter
• How are male and female urethra different? How does this affect the susceptibility of urinary tract infections?


  Male urethra:

  Longer than female urethra

  Contains 3 different regions: prostatic, membranous (intermediate), spongy

  Carries urine and semen

  
  

  Female urethra:

  Only carries urine

  Shorter length makes women more susceptible to getting urinary tract infections

  Also commonly affects women because the external urethral opening is very close to exit of anal canal
• As urine accumulates in the bladder, ______ receptors are activated. They send signals to the central nervous system. When _____ nervous fibers are excited, the _____ _____ will contract and the internal urethral sphincter will _____. If _____ neurons are inhibited, the external urethral sphincter will _____.

  stretch

  parasympathetic

  detrusor muscle

  relax

  voluntary

  relax
• What is urinary incontinence? What can be used to fix urinary retention?

  Inability to control urination

  Due to weakened pelvic muscles

  Or caused by brain or nerve damage

  During urinary retention, catheter inserted through urethra to drain urine from bladder
• What is a nephron? What are its 2 main structures?

  Nephron is the structural and functional unit of the kidneys

  Where blood is actually filtered and processed

  
  

  Nephron composed of renal corpuscle and renal tubule
• What do the collecting ducts do?

  Collects fluid from several nephrons and transport fluid to minor calyx
• The 2 components of the renal corpuscles are the _____ and the _____ _____ (Bowman's capsule). The glomerulus is a group of _____ that contain many _____. This allows blood to be filtered and enter into the glomerular capsule. The glomerular capsule surround the _____. The inner layer that covers the capillaries contains _____. This helps to further filter blood. Once the blood is filtered, the fluid is called _____. The filtrate will move from the capsule into the _____ _____.

  glomerulus

  glomerular capsule

  capillaries

  pores

  glomerulus

  podocytes; filtrate

  renal tubules
• In which renal tubule does most reabsorption and secretion occur?


  PCT
• In which renal tubule is there an ascending and descending limb?


  Nephron loop
• In which renal tubule do hormones have an effect?

  DCT (hormones also affect collecting duct)
• The afferent arteriole arises from the _____ _____ arteries that run through the renal cortex. The _____ arteriole leads into the glomerular capillary bed. The efferent arteriole leads _____ _____ the glomerular capillary bed. It will then feed into either the _____ _____ or _____ _____.

  cortical radiate

  afferent

  away from

  peritubular capillaries

  vasa recta
• Where is the juxtaglomerular complex located? What do the macula densa cells monitor? What do the granular cells monitor?

  JGC located between afferent arteriole and DCT

  Macular densa cells monitor NaCl amount in filtrate entering DCT

  Granular cells monitor blood pressure within afferent arteriole; also release renin
• What are the 3 main steps of urine formation? Where do they take place?

  Glomerular filtration:

  Occurs in renal corpuscle

  Produces filtrate

  
  

  Tubule Reabsorption:

  Occurs in renal tubules and collecting ducts

  Moving substances from filtrate back into blood

  Anything not reabsorbed will end up in urine

  
  

  Tubular Secretion:

  Occurs in renal tubules and collecting ducts

  Moving substances from blood into filtrate

  Substances secreted will end up in urine
• What are the 3 parts of the filtration membrane?

  3 layers:

  Fenestrated endothelium of glomerular capillaries

  Basement membrane between capillaries and podocytes

  Foot processes of podocytes of glomerular capsule
• Which particles are able to pass through the membrane? What particles are unable to pass through the membrane?

  Particles small enough do get filtered: salts, nutrients, nitrogenous waste

  Particles too large do not get filtered and stay within capillaries: blood cells and plasma proteins
• What is the chief force pushing fluid out of the glomerulus and into the capsule? Why is it higher compared to other capillaries throughout the body?

  Hydrostatic pressure in glomerular capillaries (HPgc) (glomerular blood pressure)

  Very high because efferent arteriole is smaller than afferent arteriole

  More blood gets into capillary than is able to get out
• What is Net Filtration Pressure (NFP)?

  Net filtration pressure calculated by: outward pressures-inward pressures

  NFP= HPgc - (HPcs + OPgc)

  NFP= 55- (15+30)= 10 mmHg

  NFP causes the net flow of fluid out of the capillaries into the capsular space

  Main factor that determines GFR
• What is the Glomerular Filtration Rate (GFR)?

  GFR is the volume of filtrate formed each minute by the combined activity of all glomeruli within the kidneys

  Normal values: 120-125 ml/min
• An increase in the glomerular hydrostatic pressure (HPgc) will have what effect on NFP and GFR?


  Increase HPgc = increase NFP = increase GFR
• A decrease in the glomerular hydrostatic pressure (HPgc) will have what effect on NFP and GFR?


  Decrease HPgc = decrease NFP = decrease GFR
• Intrinsic controls of GFR include _____ and _____ mechanisms. These act locally to maintain _____. They are able to handle _____ changes in blood pressure. Extrinsic controls of GFR include _____ and _____ systems. These act to maintain systemic _____ _____. If blood pressure is very low or very high, the _____ controls will override the _____ controls.

  myogenic

  tubuloglomerular

  GFR

  small

  endocrine

  nervous

  blood pressure

  extrinsic

  intrinsic
• The myogenic mechanism maintains GFR in response to slight changes in blood pressure / NaCl concentrations in renal tubules.

  blood pressure
• When blood pressure increases / decreases, the arteriole walls are stretched.

  increases