lecture 7: urinary system (excretory system) Flashcards
why are kidneys important
maintain homeostasis
how many functions of the excretory system are there
5
name all 5 functions of excretory system
excretion
osmoregulation
produces erythropoietin
produces renin
activates vitamin D
describe excretion (functions of excretory system)
removal of nitrogenous waste products (urea)
describe osmoregulation (functions of excretory system)
regulating solute and water balance
maintains osmotic pressure
describe produces erythropoietin (functions of excretory system)
production of rbcs
describe produces renin (functions of excretory system)
enzyme that regulates blood pressure by activating angiotensin
which functions of excretory system regulate blood pressure
osmoregulation
produce renin
what is urea
nitrogenous waste
describe urea
made in liver by combining NH3 with CO2
~ 100 000x less toxic than ammonia
can be transported and stored at high concentrations
has a large impact on water balance (osmoregulation)
describe body’s strategy for osmoregulation
kidneys —> regulate composition of blood —> regulate composition of ISF —> regulate composition of cells
describe anatomy of urinary system
pathway of urine
kidneys —> ureters —> urinary bladder —> urethra
describe urinary bladder
stores urine
rugae for stretching
internal urethral sphincter (involuntary)
external urethral sphincter (voluntary)
describe kidneys
2 distinct regions =
outer renal cortex
inner renal medulla
contain nephrons and associated blood vessels
describe blood supply to kidneys
enters via renal artery and leaves via renal vein
20% of resting cardiac output passed through kidneys every minute
entire plasma volume is filtered 60 times per day
what are kidneys filled with
nephrons and collecting ducts are lined by transport epithelium that is specialized to reabsorb water and solutes to control composition of urine
what is a nephron
functional unit of kidney
how many nephrons does a kidney contain
around 1 million
name the 2 parts of a nephron
renal corpuscle
renal tubule
describe renal corpuscle
bowman’s capsule (nephron)
glomerular capillaries - glomerulus (stuck to nephron)
describe renal tubule
proximal convoluted tubule
nephron loop (loop of henle)
distal convoluted tubule
name the 3 processes of formation of urine
glomerular filtration
tubular reabsorption
tubular secretion
describe glomerular filtration (gen)
fluid is pushed out of glomerular capillaries into bowman’s capsule
mostly non selective (only depends on size)
describe tubular reabsorption
H2O and valuable solutes (glucose, amino acids, some salts) are reabsorbed back into blood
much more selective