Sodium and Water balance Flashcards

1
Q

What is the main hormone involved in the control of the bodies water balance?

A

ADH

Anti-Diuretic Hormone

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2
Q

Where is ADH released from?

A

The posterior pituitary

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3
Q

What is another word for ADH?

A

AVP

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4
Q

If there is a high concentration of ADH what happens to the urine?

A

Small amount of very concentrated urine

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5
Q

If there is a low concentration of ADH what happens to the urine?

A

Large amount of very dilute urine

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6
Q

How is the concentration of urine measured?

A

Urine osmolality the more concentrate the higher the osmolarity

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7
Q

How is water reabsorbed?

A

Via a countercurrent between the vascularised medulla and the collecting duct.

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8
Q

How is the medullas high osmolarity maintained?

A

Na+ and Cl- is actively transported out of the loop of henle producing a concentration gradient.

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9
Q

What is the importance of this concentration gradient?

A

Water moves via osmosis from an area of low osmolarity to an area of high, this gradient creates the conditions needed for water to leave the collecting ducts.

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10
Q

Are the walls of the collecting duct permeable?

A

No, water can only pass through with the aid of Aquaporins.

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11
Q

What are aquaporins?

A

Specific ion channels which are inserted into the wall of the collecting duct and allow water to leave via osmosis.

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12
Q

What is the function of ADH?

A

Triggers the insertion of aquaporins into the collecting duct allowing more water to leave the collecting duct and enter the blood via osmosis.

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13
Q

Once inserted do the aquaporins stay in the wall of the collecting duct?

A

No they have a very short lifespan, must be a continuous stimuli resulting in addition of more aquaporins.

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14
Q

How is the sodium balance controlled?

A

Steroids

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15
Q

What is the main mineralocorticoid that controls Na+?

A

Aldosterone

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16
Q

What do steroids do to the sodium balance?

A

They increase reabsorption of Na+ in exchange for K+

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17
Q

Where about does the Na+ reabsorption take place?

A

Within the distal tubules

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18
Q

As a result of increased Na+ reabsorption what else happens?

A

Water follows via osmosis

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19
Q

What is hypernatraemia?

A

High Na+ concentration

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20
Q

What is hyponatraemia?

A

Low Na+ concentration

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21
Q

What are the two reasons for being hypernatraemic?

A

High Na+ levels

Low water volume

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22
Q

What are the two reasons for being hyponaetremic?

A

Low Na+ levels

High water volume

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23
Q

Where is sodium most concentrated within the bodies fluid?

A

Within the extracellular fluid

140mmol/L

24
Q

Where is sodium most diluted within the bodies fluid?

A

Within the intracellular fluid

4mmol/L

25
Q

What compartment makes up most of the bodies fluid?

A

Intracellular around 66%

26
Q

What does intracellular fluid comprise off?

A

Fluid contained within the bodies cells

27
Q

What makes up the extracellular fluid?

A

Plasma

Interstitial fluid

28
Q

What happens between the compartments if water is lost?

A

Water is free to move between all compartments, as a results water loss is shared equally between compartments.

29
Q

What happens between the compartments if Na+ is lost?

A

Na+ is only lost from the extracellular fluid

30
Q

Why is sodium only lost from the extracellular fluid?

A

As it is confined to the ECF by the Na+/K+ ATPase

31
Q

Why is fluid also lost from the ECF if Na+ is lost?

A

As water follows via osmosis

32
Q

Loss of Na+ is more impactful on the body that simply loss of water?

A

True, BEWARE can look the same on lab results

33
Q

List some clinical symptoms that manifest as a result of a high Na+ concentration

A

Hypertensive
Raised JVP
Oedema
Coughing

34
Q

List some clinical symptoms that manifest as a result of a low Na+ concentration

A

Hypotensive
Dry mucous membranes
Decreased skin turgor
Concentrated urine

35
Q

What is the most common issue surrounding Sodium water balance?

A

A low Na+ concentration due to a high H2O volume

36
Q

What are some causes of a high H2O volume leading to low Na+ concentration?

A

Compulsive drinking

Reduced H2O excretion (SIADH)

37
Q

What is the treatment for Low Na+ due to high H2O volume?

A

Fluid restriction

38
Q

How likely is a low Na+ concentration due to increased Na+ excretion?

A

Very Rare

39
Q

What are some causes of a low Na+ concentration due to increased Na+ excretion?

A

D+V
Excessive sweating
Severe burns
Low sodium intake - V.Rare

40
Q

What is the treatment for a low Na+ concentration due to increased Na+ excretion?

A

Give sodium

41
Q

List some causes of an increased Na+ level

A

Near drowning
Some IV medication
Increased Na+ intake
Malicious - purposely giving to much

42
Q

What is the treatment for an increased Na+ concentration?

A

Remove Na+

Loop diuretics

43
Q

List some causes of an increased Na+ concentration due low H2O volume

A

Increased water loss

Reduced rate intake

44
Q

Give a common cause of increased water loss?

A

Diabetes mellitus

45
Q

What is the treatment for too little water resulting in a high Na+ concentration?

A

IV dextrose 5%

46
Q

What are the types of IV fluid?

A

Blood and plasma
0.9% Saline
5% Dextrose

47
Q

What is blood and plasma used for?

A

Simple plasma volume replacement

48
Q

What is 0.9% saline used for?

A

Extracellular volume increased

Resuscitation fluid

49
Q

What is 5% dextrose used for?

A

‘Too little water’

Increases all volumes within all body compartments

50
Q

What is SIADH

A

Syndrome of Inappropriate ADH

51
Q

What does SIADH mean?

A

ADH is inappropriately released for the bodies osmotic status

52
Q

What are the two stimuli for ADH release?

A

Osmotic (healthy)

Non-osmotic ( Disease)

53
Q

What are common non osmotic stimuli for ADH release?

A

Hypovalaemia
Hypotension
Pain
Vomiting

54
Q

What is the pathology behind oedema

A

Blood volume loss leads to…
Increased ADH and aldosterone release
Increased water retention
However most is retained as interstitial fluid

55
Q

What are some causes of oedema?

A

Heart failure

Hypoalbuminaemia

56
Q

Within the lab what causes Pseudohyponatraemia

A

An increased concentration of lipids and proteins causes machines to record Na+ Conc as low.