Excretory System Flashcards
What is the functional unit of the kidneys?
the nephron
What are the two subunits of the nephron?
the renal corpuscle and the renal tubule
Where is the renal corpuscle located?
in the renal cortex
Ureters
two tubes from each kidney that urine drains into
Urethra
one tube that releases urine into the external environment
What is the release of urine controlled by?
internal and external sphincter
internal sphincter is controlled by ANS and is unconciously controlled
What makes up the renal corpuscle?
the glomerular capillaries and Bowman’s capsule
Renal tubule 3 parts
1) proximal convulted tube
2) loop of henle
3) distal convulted tube
What molecule is reabsorbed from the nephron in large quantities?
glucose
Descending limb of the loop of Henle
permeable to water only
the outside environment is very concentrated
water leaves the loop of Henle
Ascending limb of the loop of Henle
not permeable to water, only permeable to filtrate
filtrate is so concentration that ions flow out
towards the end of the loop, active rather than passive transport is needed
Countercurrent multiplier system
blood travels around loop of Henle in an opposite direction than the filtrate
Does the loop of Henle change the concentration of the filtrate?
not particularly, it more reduces the volume of the filtrate
Collecting duct
the last part of nephron and then H2O is reabsorbed
What 4 things does the excretory system regulate?
1) BP
2) Osmoregulation
3) Acid-Base balance
4) Nitrogenous waste
Relationship between BP and volume?
as volume increases, BP increases
How does aldosterone work?
aldosterone increases Na+ in collecting duct and DCT which makes water follow
increases BP
What is aldosterone regulated by?
Renin-Angiotensin-Aldosterone System (RAAS)
General steps of RAAS
Renin is released by lowered BP
Renin makes angiotensin I by cleaving angiotensinogen
ACE converts angiotensin I to angiotensin II
Triggers release of aldosterone
First step of RAAS
a drop in BP triggers the release of renin
ACE
converts angiotensin I to angiotensin II
angiotensin II ultimately triggers the release of aldosterone
ADH
also known as vassopressin
increases BP by adding aquaporins to the collecting duct
Where is ADH released from?
the posterior pituitary gland
ANP
lowers BP by promoting Na+ retention in urine
water follows into urine
How can the kidneys increase blood pH?
excreting more H+ ions in urine
How can the kidneys regulate nitrogenous waste?
excrete nitrogen as urea