Fluid Balance

Question 1

Why is water important?

Answer 1

• Transport of nutrients, electrolytes, waste.
• Temp regulation.
• Lubrication.
• Chemical reagent.
• Blood pressure.

Question 2

What percentage of the body weight is water?

Answer 2

40-80%.

Question 3

What are the 2 fluid compartments in the body?

Answer 3

1) . Extracellular fluid (ECF).

2) . Intracellular fluid (ICF).

Question 4

What are the 2 types of extracellular fluid?

Answer 4

1) . Interstitial fluid =
- found outside the cells.
2) . Intravascular fluid =
- in blood plasma.

Question 5

What percentage of body fluid is ECF?

Answer 5

40%.

Question 6

Where is intracellular fluid found?

Answer 6

Within the cell.

Question 7

What percentage of body fluid is ICF?

Answer 7

60%.

Question 8

What separates the 2 fluids?

Answer 8

Cell membrane.

Question 9

How is blood volume determined?

Answer 9

• Amount of water + sodium ingested.
• Excreted by kidneys into the urine.
• And lost through GI tract, lungs and skin.

Question 10

What happens to arteries when there is a higher volume of fluid?

Answer 10

Greater the pressure against arterial walls.

• rise in blood pressure.

Question 11

What happens when there is lower arterial blood volume?

Answer 11

Lower arterial blood pressure.

Question 12

Summarise the homesostatic response to a fall in blood volume?

Answer 12

ADH release from hypothalamus/posterior pituitary gland.

• water content in blood becomes normal.

Question 13

What is the homesostatic response to a fall in blood volume?

Answer 13

• Detected by baroreceptors/osmoreceptors.
• Hypothalamus produces ADH.
• Posterior pituitary releases more ADH.
• ADH increases water reabsorption in DCT and collecting ducts in nephrons.
• Blood volume increases.
• Blood pressure increases.

Question 14

What hormonal system regulates blood pressure/fluid balance?

Answer 14

Renin-Angiotensin-Aldosterone System (RAAS).

Question 15

When does the RAAS kick in?

Answer 15

When blood volume is low.

Question 16

Which specialist cells in the kidneys secretes renin?

Answer 16

Juxtaglomerular cells.

Question 17

What is the effect of secreting renin?

Answer 17

Causes angiotensinogen to be converted to angiotensin I.

Question 18

Where is angiotensinogen preoduced?

Answer 18

Liver.

Question 19

Where does angiotensin I travel to in order to be converted?

Answer 19

Lungs.

Question 20

What is angiotensin I converted to once it has reached the lungs?

Answer 20

Angiotensin II.

Question 21

What enzymes causes angiotensin I to convert to angiotensin II?

Answer 21

Angiotensin converting enzyme (ACE).

Question 22

How does angiotensin II increase blood pressure?

Answer 22

Vasoconstriction =

• increases peripheral resistance.

Question 23

What gland does angiotensin II stimulate?

Answer 23

Adrenal glands =

• to secrete aldosterone.

Question 24

What are the effects of aldosterone?

Answer 24

Decreases urine production in the kidneys.

Question 25

How does aldosterone decrease urine production in the kidneys?

Answer 25

Exchanging potassium for sodium in distal renal tubule = - sodium reabsorption. - potassium secretion.

Question 26

What are the effects of aldosterone on blood pressure?

Answer 26

Raises it.

Question 27

What other hormone does angiotensin II stimulate?

Answer 27

ADH (acts of DCT + collecting ducts) = - increases water reabsorption.

Question 28

Summarise the process of RAAS?

Answer 28

1) . Renin --> angiotensin --> angiotensin I. 2) . Angiotensin --> angiotensin II (via ACE). 3) . Angiotensin II --> aldosterone (adrenal).

Question 29

What are the actions of angiotensin II?

Answer 29

- Causes vasoconstriction. - Stimulates aldosterone secretion. - Stimulates thirst sensation. - Stimulates ADH secretion to increase water reabsorption.

Question 30

Where is the oscoreceptors located?

Answer 30

Hypothalamus.

Question 31

Where are baroreceptors located?

Answer 31

- Carotid sinus. | - Aortic arch.

Question 32

What are the receptors, controllers and effectors in the regulation of blood pressure by ADH?

Answer 32

1). Receptor = - baroreceptor. - osmoreceptor. 2) . Controller = - ADH. 3) . Effectors = - distal convoluted tubules (DCT). - collecting ducts.

Question 33

What way does ADH and RAAS regulate blood pressure?

Answer 33

Hormonally.

Question 34

What is high blood pressure also known as?

Answer 34

Hypertension.

Question 35

What is the pharmacological approach to blood pressure management (hypertension)?

Answer 35

Diuretics.

Question 36

What are the different classes of diuretics that manage blood pressure?

Answer 36

- Loop diuretics. - Thiazides. - ACE inhibitors.

Question 37

Name some loop diuretics?

Answer 37

- Furosemide. - Bumetanide. - Lasix.

Question 38

What do loop diuretics do?

Answer 38

- Act on the loop of Henle. - Inhibit the reabsorption of sodium. - Sodium excreted through urine.

Question 39

When are loop diuretics used?

Answer 39

More serious cases of hypertension.

Question 40

Why are loop diuretics used sparingly?

Answer 40

- Toxicity. | - Potential to cause dehydration.

Question 41

Name some thiazides?

Answer 41

- Bendroflumenthiazide. - Indapamide. - Xipamide.

Question 42

What do thiazides do?

Answer 42

Inhibit sodium reabsorption at the beginning of the distal convoluted tubule.

Question 43

Name some ACE inhibitors?

Answer 43

- Lisinpril. - Perindopril. - Captopril. - Enalapril.

Question 44

What do ACE inhibitors do?

Answer 44

- Produce vasoconstriction by inhibiting the formation of angiotensin II. - Decrease blood pressure.

Question 45

Summarise the different classes of antihypertensive drugs?

Answer 45

1) . Loop diuretics = - inhibit sodium reabsorption. 2) . Thiazides = - inhibits sodium reabsorption in DCT. 3) . ACE inhibitors = - produce vasoconstriction --> inhibit angiotensin II.