Urine Outputmore water in usually means more urine out
Increased water intake = increased urine outputDecreased water intake = decreased urine output
some liquids encourage increase urine excretion – diuretics
frequency of urination dependent on hormonal signals
Three Effects of Urine1. Osmotic Pressure
2. Blood Pressure
3. pH Balance
Osmotic Pressureosmotic pressure (osmolarity) –
water pressure due to presence of solutesThe more concentrated a
solution, the higher its osmotic pressure (osmolarity)
antidiuretic hormone (ADH) – regulates blood osmotic pressure through kidneysa short peptide hormone
Osmotic PressureWhat type of situation would
cause increased osmotic pressure of our blood/interstitial fluid?sweating / dehydration
causes increased ADH productionincrease water reabsorptiondilutes bloodconcentrates urine
COLLECTING DUCT OF THE
NEPHRON
NaCl
Urea
Water
INTERSTITIAL FLUID/BLOOD
osmoreceptors in hypothalamus detect increased osmotic pressure sends signals to pituitary gland
ADH produced in hypothalamus and is transported to the pituitary gland
Osmoreceptorsin hypothalamus
Drinking reducesblood osmolarity
to set point
H2O reab-sorption helpsprevent further
osmolarity increase
STIMULUS:The release of ADH istriggered when osmo-receptor cells in the
hypothalamus detect anincrease in the osmolarity
of the blood
Homeostasis:Blood osmolarity
Hypothalamus
ADH
Pituitarygland
Increasedpermeability
Thirst
Collecting duct
Distaltubule
Osmotic Pressureincreased osmotic
pressure
osmoreceptorspituitary gland; release ADH
decreased osmotic pressure
increased sensation of thirst
increased water reabsorption by kidney
ADH AnimationThe following animation will contain some terminology
not covered.
Animation
Blood Pressureblood pressure – increase
force of blood on blood vessels
aldosterone – hormone which increases Na+ reabsorption in kidneysincreased H2O in blood
increased blood pressure
Blood Pressure
aldosterone produced in adrenal gland, above kidney
Blood Pressure
Blood PressureWhat part of the kidney would be affected by low blood
pressure?glomerulus; high blood pressure needed for filtration
decreased blood pressure detected by juxtaglomerular apparatus (JGA)receptors next to
the glomerulus
Blood Pressurethe enzyme renin, is released
angiotensinogen angiotensinrenin
Blood Pressure
Two important functions of angiotensin:
1. causes blood vessel constriction
2. stimulates aldosterone release
Increased Na+
and H2O reab-sorption in
distal tubules
Homeostasis:Blood pressure,
volume
STIMULUS:The juxtaglomerular
apparatus (JGA) respondsto low blood volume or
blood pressure (such as dueto dehydration or loss of
blood)
Aldosterone
Adrenal gland
Angiotensin
Angiotensinogen
Reninproduction
Renin
Arterioleconstriction
Distal tubule
JGA
low blood pressure
juxtaglomerular apparatus
cells to release renin; produce
angiotensin
blood pressure increases
constrict blood vessels
induce aldosterone release;increase Na+ reabsorption
pH BalanceHow do living systems regulate the amount of acid /
base in their systems?
buffers – conjugate acid-base pairs
H3PO4 H2PO4- + H+
pH Balanceconversion of CO2 to other compounds help regulate
blood pH
H2O + CO2 H2CO3 HCO3- + H+
Bicarbonate ions eliminate excess H+ ions, thus preventing a change in pH
HCO3- is reabsorbed in the proximal and distal tubules
carbonic acid bicarbonate ion
Classwork/HomeworkSection 7.6 – Pg. 356 #1-8, 10