L10: Osmoregulation

Question 1

What is ADH also known as

Answer 1

Vasopressin

Question 2

Where is ADH Synthesised

Answer 2

In the hypothalamus

Question 3

Where is ADH stored and released from

Answer 3

The posterior pituitary gland

Question 4

Where is osmolality in the brain detected

Answer 4

Anterioventral third ventricle (AV3)

Question 5

What does the AV3 region contain

Answer 5

Neurones that synthesis ADH

Question 6

Which protein is ADH released with

Answer 6

Neurophysin

Question 7

What is the half life of ADH

Answer 7

Short

Question 8

Which receptors does ADH act on in the kidneys

Answer 8

V2 receptors

Question 9

What type of receptors are V2 receptors

Answer 9

GPCRs with Gi attached

Question 10

What happens when ADH binds to V2 receptors

Answer 10

Gi stimulates adenylyl cyclase
Adenyly cyclase produces CAMP
CAMP increases the synthesis of AQP2 in the collecting duct
CAMP activates PKA which causes the insertion of AQP2 into the apical membrane

Question 11

What receptors do ADH bind to in the veins

Answer 11

V1 receptors

Question 12

What does ADH/vasopressin cause in the veins

Answer 12

Vasoconstriction

Question 13

What is the structure of Aquporins

Answer 13

4 subunits

Each subunit has a pore for water= 4 pores

Question 14

What other hormone does the posterior pituitary gland release

Answer 14

Oxytocin

Question 15

What is the role of oxytocin

Answer 15

Trigger milk production

Question 16

Which receptors do oxytocin act on

Answer 16

V1 and V2 receptors

Question 17

What does less water intake do to the osmolality

Answer 17

Increase it

Question 18

When do we get a decreased osmolality

Answer 18

When we have a great intake of water

Question 19

What happens to ADH levels when there is a decreased osmolality

Answer 19

ADH levels are suppressed

Question 20

With max ADH what is the volume of urine we produce a day

Answer 20

300-400ml

Question 21

When there is no ADH what is the volume of urine we produce a day

Answer 21

25 litres

Question 22

What is the concentration of urine like when there is max ADH

Answer 22

Concentrated

Question 23

What is the concentration of urine like when there is no ADH

Answer 23

Dilute

Question 24

What is the max urine osmolality we can produce

Answer 24

1400 mosmkg-1

Question 25

Why can we not drink sea water

Answer 25

The osmolality of sea water is high and to get rid of this high osmolality we lose water

Question 26

Which 2 ions area big impact on osmolality

Answer 26

Sodium

Potassium

Question 27

Why is sodium important in osmolality

Answer 27

Sodium stays in the extracellular space for a long time and does not get taken up into cells
Therefore sodium is the main contributor to osmolality because it is not taken up into cells

Question 28

Does potassium stay in the body more or it is secreted

Answer 28

Mostly secreted

Question 29

In diabetes mellitus why do patients drink lots of water

Answer 29

An increase in glucose increases osmolality

This increased osmolality induces thirst and patient drink more

Question 30

Why do patients with diabetes mellitus have confusion

Answer 30

When they are thirsty due to an increase in glucose
ADH is released
This reabsorbed water and sodium concentration falls leading to hyponatremia
This results in seizures and confusion

Question 31

When does osmoregulation regulate the concentration

Answer 31

When we change the solute content

Question 32

When does osmoregulation correct the volume change

Answer 32

When we change the water content of the body

Question 33

Overall what are the roles of osmoregulation i.e ADH

Answer 33

Correct body volume

Correct solute content