TEST 8

• What are the main characteristics of the Male Urethra

  ~20 cm long

  
  

  3 main regions

  - prostatic urethra: transitional epithelium turning into stratified columnar & sperm, sperm motility and viability factors

  - intermediate (membranous) urethra: stratified columnar & shortest through perineum

  - spongy urethra: stratified squamous, longest segment

  
  

  --> internal = smooth, external = skeletal
• How are ions absorbed in both the thick and thin region?

  Passively in the thin region, and actively in the thick region
• What are some of the main characteristics of the female anatomy

  ~4cm

  mucosa and muscularis

  - transition, stratified columnar, then stratified squamous
• What triggers the micturition reflex?

  Bladder walls stretch
• When do we make concentrated urine?

  Low water intake, and too much perspiration, so we need to conserve the water and reabsorb it so we have more ADH
• Which spinal levels receive signals during the micturition reflex?

  S2 and S3
• What happens when the parasympathetic nervous system is activated during the micturition reflex?

  Contracts detrusor muscle and internal sphincter
• How can the cerebrum influence the micturition reflex?

  By controlling the external sphincter
• Trigone


  triangular area in the urinary bladder
• Key characteristics of the Urinary Bladder

  Rugae

  Detrusor muscle

  Internal urethral orifice

  Urethra

  peritoneum

  internal urethral sphincter

  external urethral sphincter

  external urethral orifice
• What is the Histology of the Urereters

  3 layers

  - Mucosa (trans. epi and lamina propria --> accommodates stretch and mucus prevents large pH toxins

  - Muscaliris (smooth muscle) --> inner longitudinal and outer circular layer

  - adventitia (blood vessels and nerves)
• What is the capacity of the bladder

  700-800 mL
• What is the length of the ureters?

  25-30 cm
• Where do the ureters extend from and to?

  From the renal pelvis to the bladder
• The distal 1/3 of the ureter has what type of extra muscle?

  Outer longitudinal layer
• where does the principal cells collect ions from?

  interstitial fluid
• Are the ureters retroperitoneal or intraperitoneal?

  Retroperitoneal
• Where do the ureters enter the bladder?

  Posterior wall of the bladder
• How is the flow of urine through the ureters controlled?

  By a physiological valve which is then controlled by the flow of urine from the kidney to the ureter
• What causes the flow from kidney to urinary bladder

  Gravity, hydrostatic pressure, peristalsis
• What are some common characteristics of Urine

  1-2L per day

  yellow or amber from the urochrome and urobilin (kidney stones cause blood)

  transparent (cloudy if diseased)

  ammonia smell (diabetics have fruity smell)

  pH between 4.6 and 8.0 (becomes alkaline if vegetarian)
• How does ADH influence urine concentration

  if we have enough ADH, then we have more concentrated urine. If we have less ADH, then we have dilute urine
• How does osmolarity change in the medulla

  as we move towards the papilla region, we increase it with the aquaporin-1
• Why does water stay trapped in the collecting duct

  we don't have aquaphorin1
• Define Glomerular Filtration


  the filtration of blood through the glomerulus, not selective
• Define Tubular Reabsorption


  ions, water, and other substances are reabsorbed into the peritubular capillaries
• Define Tubular Secretion


  wastes, drugs, and excess ions are secreted from the peritubular cap into the renal tubule
• Renal Blood Flow


  20-25% of CO (~1.2L/min)
• Plasma flow rate


  55% of renal blood flow (650ml/min)
• Filtration Fraction


  125 ml/min or 180 L per day
• How much filtrate does the capillaries reabsorb

  99% of it
• What is net filtration pressure?

  The difference between net hydrostatic pressure and net osmotic pressure
• How much is the typical value of net filtration pressure?

  10 mmHg
• What is the role of net filtration pressure?

  It is the driving pressure from the arterioles into the plasma
• What is Capsular Hydrostatic Pressure?

  Pressure exerted by fluid in the glomerular capsule
• What does Capsular Hydrostatic Pressure do?

  It acts against the fluids coming out of the glomerulus
• What is Blood Colloid Osmotic Pressure?

  The largest driving force for pulling fluid from the interstitial spaces back into the capillaries based on protein concentration; 30 mmHg. Causes the proteins to attract water back into the afferent arteriole
• What is the main function of Blood Colloid Osmotic Pressure?

  To pull fluid from the interstitial spaces back into the capillaries, primarily influenced by protein concentration.
• What is Glomerular blood hydrostatic pressure (GBHP)?


  The main force responsible for moving water and solutes out of blood plasma through the filtration membrane; 55mHg.
• How is Glomerular blood hydrostatic pressure (GBHP) generated?


  It is based on the afferent (larger) and efferent (smaller) arterioles being of different sizes and changing the resistance.