Fluid Balance

Question 1

What are the two pressures present in a capillary?

Answer 1

Hydrostatic pressure and oncotic/colloid osmotic pressure

Question 2

Is hydrostatic pressure higher at the arteriole end or venule end of a capillary?

Answer 2

Higher at the arteriole end

Question 3

Is oncotic/colloid osmotic pressure relatively greater or smaller than the hydrostatic pressure at the venule end of a capillary?

Answer 3

Relatively greater

Question 4

Is oncotic/colloid osmotic pressure relatively greater or smaller than the hydrostatic pressure at the arteriole end of a capillary?

Answer 4

Relatively smaller

Question 5

Does all fluid that leaves the capillary due to hydrostatic pressure return to the capillary?

Answer 5

No, only about 90% of it returns to the capillary

Question 6

Where does the fluid that doesn’t return to the capillary go?

Answer 6

It drains into the lymph system which returns the fluid to the cardiovascular system

Question 7

How is the thirst response activated?

Answer 7

Hypothalamic osmoreceptors detect increased blood osmolality, triggering the thirst centre in the hypothalamus to create the thirst response

Question 8

What does Antidiuretic hormone (ADH) do in relation to fluid loss?

Answer 8

ADH keeps fluid within the body and decreases urine excretion, resulting in a more concentrated urine and decreased blood osmolality

Question 9

What triggers the Renin-Angiotensin-Aldosterone System (RAAS) to activate?

Answer 9

Low blood volume (specifically decreased perfusion to the kidneys)

Question 10

Where is Renin secreted from?

Answer 10

The juxtaglomerular cells in nephrons

Question 11

In the Renin-Angiotensin-Aldosterone System (RAAS), Renin allows what conversion to happen?

Answer 11

Renin allows the conversion of Angiotensinogen into Angiotensin 1

Question 12

Where is Angiotensinogen created?

Answer 12

In the liver

Question 13

How is Angiotensin 1 converted into Angiotensin 2?

Answer 13

It’s converted by Angiotensin Converting Enzyme (ACE)

Question 14

What is the effect of Angiotensin 2 on the Adrenal Glands?

Answer 14

It causes the adrenal glands to release aldosterone, stimulating sodium and water reabsorption in the kidneys

Question 15

What is the effect of Angiotensin 2 on the Arterioles?

Answer 15

It causes vasoconstriction

Question 16

What is the effect of Angiotensin 2 on the Hypothalamus?

Answer 16

It stimulates the hypothalamus to trigger the thirst response, causing the body to drink water and increase blood volume

Question 17

What is the effect of Angiotensin 2 on the Posterior Pituitary gland?

Answer 17

It stimulates the Posterior Pituitary gland to release ADH, increasing water reabsorption in the kidneys

Question 18

Overall, what is the effect of Angiotensin 2 on blood volume?

Answer 18

It increases blood volume

Question 19

What triggers the release of Atrial Natriuretic Peptide (ANP)? Where is it secreted from?

Answer 19

High blood volume and pressure, leading to secretion from atrial muscle cells in the heart

Question 20

What is the effect of Atrial Natriuretic Peptide (ANP) on the Renin-Angiotensin-Aldosterone System (RAAS)?

Answer 20

ANP inhibits the secretion of Renin, ADH and Aldosterone

Question 21

What is the effect of Atrial Natriuretic Peptide (ANP) on water and sodium in the kidneys?

Answer 21

It increases water and sodium excretion, increasing urine output and decreasing blood volume

Question 22

What may cause Hypervolemia (Fluid volume excess)?

Answer 22

Too much in:
Drinking too much (Polydipsia)
Excessive IV fluid administration

Too little out:
Renal impairment
Heart Failure (tricks kidneys into thinking there’s a low blood volume, triggers RAAS)
Liver Failure

Question 23

What are some symptoms of Hypervolemia (Fluid Volume Excess)?

Answer 23

Increased Urination (Polyuria),
Headache and confusion,
Seizures and Coma,
Bulging (Distended) neck veins, increased blood volume and heart rate,
Oedema (Pulmonary oedema may include shortness of breath (dyspnoea) and coughing),
Weight gain

Question 24

What are some treatments for Hypervolemia?

Answer 24

Restriction of fluid and sodium intake,
Diuretics,
Close fluid balance monitoring,
Dialysis

Question 25

What may cause Hypovolemia?

Answer 25

Bleeding, vomiting, urinating, diarrhoea (among other things)

Question 26

At what percentage of body water loss may Hypovolemia become fatal?

Answer 26

Around 20%

10% causes serious signs and symptoms

Question 27

What are some symptoms of Hypovolemia?

Answer 27

Poor skin turgor (if you pinch the back of your hand and it doesn’t spring back),
Dry mucous membranes,
Thirst,
Lower urine ouput, heart rate and blood pressure,
Orthostatic hypotension (low blood pressure when standing up from sitting or lying down),
Confusion

Question 28

What are some treatments for Hypovolemia?

Answer 28

Rehydration
IV Fluid replacement
Replacement of Blood
Electrolyte imbalance corrections