urinary system Flashcards
Know the functions of the urinary system
-Regulates blood volume and blood pressure
-Regulates plasma ion concentrations
-Helps stabilize blood pH
-Conserves valuable nutrients
-assists liver
Describe the functions of the kidneys
- Filter 200 liters of blood daily, which allows for toxins, metabolic wastes, and excess ions to leave the body in the urine
- Regulation of blood volume, chemical composition,
and pH - Gluconeogenesis during prolonged fasting
- activation of vitamin D
Define nephron
the functional unit of the kidney ( about 1 million nephrons in 1 human kidney)
- made up of renal corpuscles and renal tubules
- structure that actually produces urine
Know the blood vessels associated with the nephron
afferent arteriole, glomerular capillaries, efferent arteriole, peritubular capillaries, vasa recta
Understand the structure of the nephron:
Renal corpuscle
- glomerulus
- afferent and efferent arteriole: affeernt leads to glomerulus. Efferent away from
- glomerular capsule
Understand the structure of the nephron:
Renal tubule
proximal convoluted tubule, Loop of Henle (descending and ascending limb), distal
convoluted tubule, collecting duct
What are the 3 steps of urine formation?
Glomerular filtration
Tubular reabsorption
Tubular secretion
Describe glomerular filtration. Which substances are filtered?
Substances move from the glomerular blood to the
glomerular capsule
- water, small dissolved molecules and ions can filter
What force drives glomerular filtration? Why is the afferent arteriole larger in diameter than the efferent
arteriole?
Force: hydrostatic pressure of the blood
- to provide for the increased blood pressure in the glomerulus for ultrafiltration to take place
List the 4 processes that control glomerular filtration
- autoregulation
- Increased sympathetic impulses that decrease GFR by causing afferent arterioles to constrict
- renin-angiotensin system
- the hormone atrial natriuretic peptide
(ANP) affects sodium causing an increase in GFR
Understand the renin-angiotensin system.
d. What are the functions of aldosterone and ADH?
e. What is the overall goal of the renin-angiotensin system?
aldosterone: water salt balance
ADH: helps blood vessels constrict
- critical regulator of blood volume, electrolyte balance, and systemic vascular resistance
Define tubular reabsorption. What percentage of reabsorption occurs in the proximal convoluted tubule?
Substances move from the renal tubules into the interstitial fluid where they then diffuse into the peritubular capillaries
- 70%
Define tubular secretion. Which substances are usually secreted? Why is it important to secrete hydrogen ions?
Substances move from the plasma of the peritubular capillaries into the fluid of the renal tubules
- drugs and ions
- important in regulating the pH of body
fluids
How does the kidney concentrate urine? Which structures are involved? Which hormones?
by reabsorbing large volumes of water
- aldosterone and ANP
- distal convoluted tubule and collecting duct
Describe the countercurrent mechanism. Know which sections of the loop of Henle are isotonic, hypertonic, and
hypotonic.
in nephron loops , ensures that the medullary
interstitial fluid becomes hypertonic
- hypertonic - descending loop of helen
- hypotonic: ascending loop of helen
isotonic: PCT
Describe the effects of water reabsorption at the distal convoluted tubule and the collecting duct with and without the presence of ADH.
If ADH is present, these segments become permeable, and water is reabsorbed by osmosis into the extremely hypertonic medullary interstitial fluid ( concentration of water in blood decreases).
If ADH is not present distal convoluted tubule and collecting duct is very little permeable to water and will not reabsorb water effectively, so urine excreted out will be dilute in nature.
Describe the composition of urine.
- about 95% water
- contains urea, uric acid, and creatinine
- may contain trace amounts of amino acids and electrolytes
What does a high BUN and creatinine levels indicate?
Azotemia
Know the pathway of urine from the collecting ducts to the urethra. Can you put them in the correct order?
Collecting duct –>Ureter –>Bladder –>Urethra
Define and describe the functions of the following structures: ureter, urinary bladder, trigone, and urethra
ureter: ducts were the urine passes
unirany bladder: stores urine and empties it
Trigone: site of anti-reflux mechanism
urethra: The tube through which urine leaves the body. It empties urine from the bladder
