Lecture 35: Collecting Duct, Urine Storage, and Micturition Flashcards
Objectives – Explain how water and ion retention is regulated within the collecting ducts. – Identify the structures that store urine and allow it to pass outside of the body. – Describe the physiological control of micturition.
by end of distal CT…
90-95% solutes and water reabsorbed and retuned to blood
collecting duct cells
make final adjustments
principal cells
intercalated cells
principal cells
reabsorb NA, secrete K+ (aldosterone effect) reabsorb water (ADH effect
intercalated cells
reabsorb K and bicarb ions
secrete H+
Na and Principal cells
Na+ enters through leakages chanles
NA pumps keep Na conc insde low
cells secrete varyig K to adjust for diet changes of K intakde (due to Na/K pump)
aldosterone and principal cells
INC Na+ and water reabs
inc K+ secretion
hpw???
stims synth of new pumps and chanels
Antidiuretic hormone and principal cells`
inc water permeablity of CD cells
stim insertion of aquaporin-2 channels
lets water molecs move faster) (these channels come and go
Diuretics def
substances that slow renal reabs of water
and cause diuresis
diuresis
inc urine flow rate
diuretics examples
caffiene
alcohol
some perscripton meds
caffeine
inhibits Na reabs
inhibs obligatory water reabs
alcohol
inhibits secretion of ADH
inhibits facultative water reabs
prescription meds
like beta blockers, antihypertensives
can act on PCT, loop of Henle, or DCT
micturition reflex
stretch receptors singal spinal cord and brain when vol is over 200-400 mL
impluslses sent to micturition center
filling=sensation of fullness and desire to urinate b4 reflex occurs
conscious control of external sphincter
cerebral cortex can initiate or delay micturation for limited time period
micturation center
in sacral spinal cord
S2 and S3
parasymp fibers=detrusor muscles contract
external and internal sphincter muscles relax
