The Urinary System

1
The Urinary System

• Organs Kidneys (creates urine), ureters
  (transport), urinary bladder (stores), urethra
  (transport)

2
Kidney Function

• Filter fluids from bloodstream and maintain
  homeostasis in body
• Rids body of wastes, excess ions, toxins, and
  drugs in urine
• Regulate blood volume, pH, salt content
• Secretes renin regulates blood pressure
• Secretes erythropoietin increases rbc
  production

3
Kidney Anatomy

• 5 long, 2.5 wide
• Renal capsule
• encloses kidney
• Renal cortex
• outer region
• Renal medulla
• deep to cortex w/ medullary pyramids separated by
  renal columns
• Renal hilus
• medial indentation
• Rich Blood Supply
• Renal artery ? segmental arteries ? lobar
  arteries ? interlobar artery ? afferent arteriole
  ? glomerulus capillaries ? efferent arteriole ?
  peritubular capillaries ? interlobular vein ?
  arcuate vein ? interlobar vein ? renal vein

4
Nephrons

• Nephrons form urine
• Glomerulus knot of capillaries
• Renal tubule w/ enlarged bowmans capsule at end
• Proximal convoluted tubule
• Loop of Henle
• Distal convoluted tubule
• Collecting ducts receive urine from many
  nephrons deliver urine to renal pelvis

5
Urine Formation

• Filtration
• Water and solutes smaller than proteins are
  forced thru capillary walls and pores of
  glomerular capsule into the renal tubule
• Tubular reabsorption
• Water, glucose, amino acids, and needed ions are
  transported out of the filtrate into the tubule
  cells and then enter the capillary blood
• Tubular Secretion
• Urea, H, K, creatinine, and drugs are removed
  from the peritubular blood and secreted by the
  tubule cells into the filtrate
• Urine 1-2 L produced every 24 hrs

6
Ureters

• 10-12 long tubes
• Carry urine from kidneys to bladder
• Peristalsis propels urine transport
• Valve-like folds prevent back flow from bladder

7
Urinary Bladder

• Smooth, collapsible muscular sac
• Temporarily stores urine
• Empty 2-3 long
• Full 5long and stores 1-2 pints urine

8
Urethra

• Thin walled tube
• Carries urine (by peristalsis) from bladder to
  outside the body
• Females 3-4 long, opening is anterior to
  vaginal opening
• Males 8 long, opening at tip of penis
• Double function passageway for sperm ejaculation
• internal urethral sphincter
• Involuntary smooth muscle, keeps closed when
  urine is not being passed
• External urethral sphincter
• Voluntary skeletal muscle through pelvic floor
• Micturition emptying the bladder
• 200mL urine collects and activates stretch
  receptors and cause bladder to contract to force
  open internal urtheral sphincterfeel urge to
  void

9
Fluid and Electrolyte Balance

• 2/3 water in intracellular fluid (ICF)
• 1/3 water in extracellular fluid (ECF)
• Electrolytes charged ions that conduct
  electrical current, alters blood volume and blood
  pressure
• Ex. sodium, potassium, calcium ions
• Electrolyte balance maintained by hormones
• Antidiuretic hormone (ADH)
• Aldosterone

10
Acid-Base Balance

• Proper function, blood pH between 7.35-7.45
• Alkalosis rise in blood pH above 7.45
• Acidosis drop in pH below 7.35
• Blood Buffers
• Respiratory System
• Renal Mechanisms
• Excreting bicarbonate ions
• Reabsorbing or generating new bicarbonate ions