5. Controllinf Blood Water Potential

Question 1

Where is water lost in body

Answer 1

Urine

Swear

Question 2

What organ regulates water potential of the bloood and urine

Answer 2

Kidneys to ensure body has right amount

This is called osmoregulation

Question 3

What happens if water potential of boood is too low ? Dehydrated

Answer 3

More water is reabsorbed by osmosis into blood from tubules of nephrons - urine more concentrated so less water lost during excretion

Question 4

What happens if water potential of the blood is too high ? Too hydrated f

Answer 4

Less water is reabsorved by osmosis from tucked of nephron into blood - urine diluted so more water lost

Question 5

Where is water reabsorved from ?

Answer 5

Along allnost all of the nephron

But regulation of water potential mainly takes place in loop of Heineken , DCT and collecting duct - volume is controlled by hormones

Question 6

Where is loop of henele located

Answer 6

Medulla of kidney

2 limbs - ascending and descending limb

Limbs control movement of sodium ions so water can be reabsorbed by blood

Question 7

What does ADH stand for ?

Answer 7

Antidiuretic hormone

Question 8

What cells monitor the bloods water potential ?

Answer 8

Osmoreceptors

Question 9

Where are osmoreceptors located ?

Answer 9

Part of the brain

Hypothalamus

Question 10

So what happens what the water potential of blood decreases ?

Answer 10

Water moves out of osmoreceptors by osmosis

This causes cells to decrease in volume

And sends a signal to other cells in the hypothalamus which then sends a signal to the posterior pituitary gland

Posterior pituitary gland released hormone called antidiuretic hormone in blood

Question 11

Summary of what happens when water potential in blood decreases

Answer 11

Osmoreceptors decrease

Signal send to hypothalamus

This sends signal to posterior pituitary gland

Which releases antidiuretic hormone into blood

Question 12

What is the function of ADH?

Answer 12

• Binds to receptors on the plasma membrane of the DCT and collecting duct
• protein channels called aquaporin insert into plasma membrane
• water passes through aquaporins via osmosis as DCT and collecting duct become permeable to water
• more water now In medulla and can be reabsorbed by capillary network into blood by osmosis

Question 13

What is ADH final outcome

Answer 13

More concentrated urine as little water is lost from body ( dehydrated )

Less concentrated urine as more water lost from body ( too hydrated )

Question 14

What is diuresis ?

Answer 14

Lots of dilute urine produced

Question 15

What happens when you’re dehydrated and blood water content is low ?

Answer 15

• water content in blood drops causing low water potential in blood
• osmoreceptors In hypothalamus detect this change and they decrease in volume
• this sends signal to posterior pituitary gland which releases ADH into blood
• ADH creates aquaporins In DCT and collecting duct and water diffuses out by osmosis into medulla and absorbed into blood
• small concentrated urine produced

Question 16

What happens when you’re hydrated and your blood water content is too high ?

Answer 16

• water content rises in blood rising blood water potential
• detected by osmoreceptors In hypothalamus
• posterior gland releases less ADH into blood
• less ADH means that DCT and collecting duct are less permeable so less water diffuses out by osmosis into medulla and then into blood
• lots of diluted urine produced

Question 17

Where is ADH broken down ?

Answer 17

Liver