6D: Regulation of water balance

Question 1

Osmolality

Answer 1

total concentration of solute in a given weight of water

Question 2

Osmosis can cause

Answer 2

Normal cells (isotonic - equilibrium), Hypertonic (water goes out of cells –>cell shrinkage), Hypotonic (water goes into cell–>cell swelling)

Question 3

Hypertonic

Answer 3

high solute concentration

Question 4

Hypotonic

Answer 4

low solute concentration

Question 5

Isotonic

Answer 5

equilibrium

Question 6

Osmoregulation

Answer 6

the regulation of osmolality - total concentration of solute in a given weight of water

Question 7

Stimulus response model for low water balance

Answer 7

)when water levels decrease
-osmolality (increases) –> due to increased solute concentration
-Blood pressure and volume (decreases) –>

)Stimulus response model (negative feedback) - when water levels decrease
-Stimulus (decrease in water levels)
-Receptors (baroreceptors detect fall in blood pressure and volume)(osmoreceptors detect change in blood solute concentration (osmolality))
__________Baroreceptor Pathway (renin–>alsosterone–>sodium-potassium pumps)
-modulator (release of renin from kidney cells, causing release of aldosterone) –>increase in consumption of fluid)
-effector (activation of sodium-potassium pumps, increasing reabsorption of sodium)
-response (increased reabsorption of water from kidney filtrate –>increase in consumption of fluid)
_________Osmoreceptor Pathway (
-modulator (hypothalaus causes release of ADH from posterior pituitary gland)
-effectors (aquaporins inserted into the nephron, stimulation of cells in the thirst center)
-response (underlined is the response)(aquaporins inserted into the nephron –>increased reabsorption of water from kidney filtrate), (stimulation of cells in the thirst center –>increase in consumption of fluid)

Question 8

Antidiuretic Hormone (ADH) and Aquaporins

Answer 8

REVIEW THIS AND HOW TONICITY WILL ACT IN RELATION TO SODIUM AND POTASSIUM –>ASK TEACHER/Look at powerpoint

Question 9

If hydrated

Answer 9

Low ADH–>less aquaporins (within the collecting duct lumen)–>tubule cells–>blood (less water reabsorbed)

Question 10

If dehydrated

Answer 10

High ADH–>more aquaporins (within the collecting duct lumen)–>tubule cells–>blood (more water absorbed)

Question 11

Stimulus-response model

Answer 11

)Stimulus response model (negative feedback)
-stimulus (change in water volume causing change in osmolality (concentration of water), blood volume, and blood pressure (closely linked to blood blood volume and visa versa)
-Receptors (baroreceptors, osmoreceptors)
-Modulator (baroreceptors–>cells in the kidney, the hypothalamus and pituitary gland, osmoreceptors –> the hypothalamus amd pitutitary gland (The underlined stuff is the modulators)
-effectors (cells in the kidney–>Cells in the distal condulated tububle and collection duct (NEPHRON - is all that needs to be written), the hypothalamus and pituitary gland –>The hypothalamus, Cells in the distal condulated tububle and collection duct (NEPHRON - is all that needs to be written)) - underlined stuff in the effectors
-response (alteration in the reabsorbtion of water (kidney) which changes the osmolality of blood and blood pressure and volume

Question 12

stimulus-response model of water absorption

Answer 12

PART 1
-Stimulus (change in water levels (decreased))
-Receptor (2 receptors recognise this –> Osmoreceptors, Baroreceptors)
-Modulator (osmoreceptors–>solute concentration)(Baroreceptors–> Blood volume+pressure)
-Effector (changes made to kidneys at nephron + brain at hypothalamus)

PART 2
-Kidney releases Renin–>stimulates aldosterone–>activate Na^+/K^+ pumps which activate at the collecting duct of the nephron
-Hypothalamus–>pituitary gland–>releases ADH–>increase of aquaporins at collecting duct of nephron

Question 13

aldosterone is

Answer 13

a hormone that regulates the salt and water balance of the body by increasing the retention of sodium and water and the excretion of potassium by the kidneys