Urinary system Flashcards
functions of the kidneys
- filter nitrogenous wastes (urea, creatinine, uric acid)
- maintain proper balance of water, electrolytes (sodium, potassium), and acids
- release hormones: renin, erythropoietin (EPO), calciferol
- degrade and eliminate hormones from the bloodstream
major components of the urinary system
- kidneys
- ureters
- urinary bladder
- urethra
location of the kidneys
- under back muscles, behind parietal peritoneum (retroperitoneal) (not in abdominal cavity), just above waistline; right kidney usually lower than left
internal structure of the kidneys
- cortex: outer layer of kidney substance
- medulla: inner portion of kidney
- pyramids: triangular divisions of medulla
- papilla: narrow, innermost end of pyramid
- calyces: cup-like regions of the renal pelvis
- renal pelvis: expansion of upper end of ureter; lies inside kidney
- nephrons: filters blood and eventually makes urine (looks like tiny dots)
structure and function of ureters
structure:
- narrow, long tubes with expanded upper end (renal pelvis) located inside kidney and lined with mucus membrane
function:
- drain urine from renal pelvis to urinary bladder
structure and function of urinary bladder
structure:
- elastic muscular organ, capable of great expansion
- lined with mucous membrane arranged in rugae, as is stomach mucosa
functions:
- storage of urine before voiding
- voiding (micturition, urination) - all mean peeing
structure and function of urethra
structure:
- narrow tube from urinary bladder to exterior
- lined with mucous membrane
- opening of urethra to the exterior called urinary meatus
functions:
- passage of urine from bladder to exterior of body
- passage of male reproductive fluid (semen) from body
how does oxygenated blood enter the kidneys?
- enters through the renal arteries
- arterioles carry blood to capillaries
- glomeruli filter the blood
how does deoxygenated blood exit the kidneys?
- exits via the renal vein
what are nephrons?
- microscopic units of kidneys, consists of: renal corpuscle and renal tubules
what does the renal corpuscle consist of?
- glomerus: tiny ball of blood capillaries surrounded by Bowman’s capsule
- Bowman’s capsule (glomerular capsule): the cup shaped region which ‘catches’ the filtrate
what does the renal tubule consist of?
- proximal convoluted tubules: first segment
- loop of henle: extension of proximal tubules; consists of decending limb, loop and ascending limb
- distal convoluted tubule: extension of ascending limb of loop of henle
- collecting tubule: straight extension of distal tubule
how many nephrons are found in each kidney?
- about 1 million
what is the function of the renal corpuscle?
- consists of glomerulus and bowman’s capsule
- blood passes through the glomeruli
- bowman’s capsule surrounds each glomerulus (filtration)
- renal tubule is attach to each bowman capsule
3 steps in urine formation
1 - glomerular filtration
2 - tubular reabsorption
3 - tubular secretion
- happening in nepthron
what controls urine volume?
- mainly posterior pituitary hormone’s ADH, which decreases it
