Biochemistry

Question 1

what hormone controls water balance

Answer 1

ADH

Question 2

which part of the pituitary releases ADH

Answer 2

Posterior

Question 3

What are the basics of what ADH does?

Answer 3

Makes you pee less

Question 4

What are the basics of what ADH does?

Answer 4

Makes you pee less

Question 5

How does ADH work

Answer 5

It causes water to be reabsorbed from the renal tubules.
Retains water!

Counter current multiplication

Increased ADH –> small volume of concentrated urine

Decreased ADH –> large volume of dilute urine

Question 6

How do you measure urine concentration/dilution

Answer 6

Urine osmolality

Concentrated urine = high osmolality
Dilute urine = low osmolality

Question 7

what is countercurrent multiplication?

Answer 7

inside the kidneys there are two countercurrent systems (henle’s loop and vasa recta). Blood flows in opposite directions in the two arms of the tubes causing countercurrents.
This creates an osmotic gradient that allows you to reabsorb water from tubular fluid and produce concentrated urine

Question 8

How sodium balance controlled?

Answer 8

By steroids from the adrenals, known as mineralocorticoid activity
Sodium is reabsorbed in renal tubules in exchange for potassium and hydrogen ions

Question 9

what is the main steroid with mineralocorticoid activity

Answer 9

Aldosterone (mainly

Cortisol - a little

Question 10

How does mineralocorticoid activity relate to sodium levels

Answer 10

Too much mineralocorticoid activity = sodium gain

Too little mineralocorticoid activity = sodium loss

Question 11

water follows which ion

Answer 11

Sodium ions

so if you lose or gain sodium you will also lose or gain water

Question 12

Which body compartment will you find sodium confined to, how is it kept there?

Answer 12

Extracellular fluid

There is a pump in the plasma membrane that keeps it there

Question 13

How will someone with decreased sodium present

Answer 13

Increased pulse
postural decrease in BP
Decreased urine output
decreased consciousness
dry mucous membranes

Question 14

How will someone with increased sodium present?

Answer 14

Coughing
Tiredness
SOB
pulmonary oedema
Heart pumping action weaker
Pleural effusion
Swelling in abdo (ascites)

Question 15

What can cause decreased sodium ion levels?

Answer 15

Too little sodium
Too much water

Decreased water excretion (SIADH)
Increased water intake
Decreased intake of sodium
Sodium losses through skin, adrenal, kidney and gut

Question 16

What can cause increased sodium levels?

Answer 16

Too much sodium
Too little water

Some IV medications
Near drowning
Increased water loss though diabetes insipidus
decreased water in take in the very young or very old
Sickness causing dehydration

Question 17

Mechanism of oedema

Answer 17

oedema signifies the patient has too much sodium and water

when a low blood volume is detected (due to HF) ADH and aldosterone are secreted to try and restore the volume but a lot of this water is retained and ends up in interstitial fluid

Question 18

How do you treat oedema (too much blood)

Answer 18

Loop diuretics

They cause a loss of sodium and water