B3.3 Maintaining Water Balance Flashcards
how is water lost from body
lost through sweat and urine
urine is composed of water, urea and waste (produced at the liver)
urea is filtered out of the blood by the kidney, which then produces urine and stores it in the bladder waiting to be excreted
what happens when water level is too low/high
too much water - cell lysis
too little water - cell shrivels
what blood vessels carry blood to kidneys?
renal artery brings blood to kidneys
renal vein takes blood away from the kidneys
urethra and ureter
urethra- tube through which urine passes to outside of your body
ureter - tube which urine passes from kidney to bladder
what happens in the bowman’s capsule
ultrafiltration
there is a high pressure blood which pushes all the small molecules out of the blood (water, urea, glucose) into the nephron while bigger molecules like protein remain in the blood stream
selective reabsorption
where glucose, some water and salts are reabsorbed into the capillaries
loop of Henle
it is very big to allow more time for some extra water and salt regulation
how volume of urine is controlled
when there is too little water
hypothalamus detects this and tells pituitary to secrete a lot of ADH
lot of ADH causes more water to be reabsorbed into the blood stream so urine water concentration is low.
(opposite when there is too much water)
lack of water
thirsty
kidney produces more concentrated, less volume urine
become dehydrated:dark urine, dizziness, kidney and liver damage
excess of water
kidneys produce a lot of urine
cell lysis (osmosis)
sodium concentration in blood drops: cramping, confusion, seizure, death
hypertonic
low water potential
hypotonic
high water potential
isotonic
water potential = blood plasma water potential
