Week 107: Hypovolaemia

Question 1

What is hypovolaemia?

Answer 1

20% loss of circulatory volume (can be caused by dehydration or blood loss)

Question 2

Why would you not try to normalise blood pressure in cases of hypovolaemia?

Answer 2

Because the medication needed would wash out clotting factors

Question 3

What are the four types of shock?

Answer 3

• Hypovolaemia
• Maldistributive (anaphylactic)
• Cardiogenic
• Obstructive

Question 4

What test can you do to assess the severity of shock?

Answer 4

Lactic acid test
Glucose
Check SATS - 98%

Question 5

What would you do when a hypovolaemic patient is anaemic?

Answer 5

Give them EPO

Vitamin D

Question 6

What is a portal system?

Answer 6

Two capillary beds in series - heart > capillary bed > capillary bed > heart

• Occurs in kidneys around each nephron

Question 7

What is the juxtaglomerular apparatus?

Answer 7

Macula densa cells in distil tubules, granular cells found in blood vessels next to distil tubules

• Produce renin as part of monitoring sodium excretion in urine

Question 8

What is blood pressure?

Answer 8

Product of cardiac output x resistance

Question 9

Where is the antidiuretic hormone produced?

Answer 9

In the pituitary gland in the brain

Question 10

What is the function of the antidiuretic hormone (ADH)?

Answer 10

• Reserves water and sodium

- Stops peeing

Question 11

Where is atrial natriuretic peptide produced?

Answer 11

Right atrium

Question 12

When is atrial natriuretic peptide produced?

Answer 12

In response to high blood pressure

• High blood pressure causes increased sodium excretion and water loss

Question 13

What is ADH?

Answer 13

A vasopressin

Question 14

What is Starling’s Law of the Heart?

Answer 14

• As the heart expands more (actin and myosin fibres come together and spread under tension) it has to contract more
• The greater the filling, the greater the contraction
• Stroke volume increases as end diastolic pressure increases

Question 15

What is the Windkessel effect?

Answer 15

• The beginning of aorta is the Windkessel device which causes the effect
• Heart pumping out causes a rise in blood pressure
• If arteries were non-elastic then would shoot blood
• Device absorbs some of the shock and recoil
• Maintains systolic going through elastic protection
• Without effect: high systolic blood pressure 200/80
• Windkessel smooths out the two

Question 16

What is the baroreceptor reflex?

Answer 16

• A fast response that deals with blood pressure very quickly
• In carotid arteries the stretch is detected: if increase then reduce heart rate and stroke volume which relaxes the heart and reduces blood pressure
• In carotid arteries chemo receptor complex: determines how oxygenated - fast response and can increase heart rate

Question 17

What percentage of total body water occurs in the plasma?

Answer 17

13% (3.5l)

Question 18

What percentage of total body water occurs in the interstitial fluid?

Answer 18

22% (9.5l)

Question 19

What percentage of total body water occurs intracellularly?

Answer 19

65% (27l)

Question 20

What is osmolality?

Answer 20

The concentration of a solution expressed as the total number of solute particles per kilogram

Question 21

What is the osmolality of plasma?

Answer 21

290 mosmol/kg H2O

Question 22

What is the osmolality of interstitial fluid?

Answer 22

290 mosmol/kg H2O

Question 23

What is the osmolality of intracellular fluid?

Answer 23

290 mosmol/kg H2O

Question 24

What is a capillary wall permeable to?

Answer 24

Everything except plasma proteins

Question 25

What is interstitial fluid?

Answer 25

Fluid between cells

Question 26

What comprises extracellular fluid?

Answer 26

Interstitial fluid

Plasma

Question 27

What does the barrier between interstitial fluid and plasma consist of?

Answer 27

Walls of the capillaries

Question 28

What are the intracellular and extracellular fluids separated by?

Answer 28

Plasma membranes of cells

Question 29

What is an isotonic fluid?

Answer 29

A fluid at the same osmotic potential as plasma

Question 30

What is a hypertonic fluid?

Answer 30

A fluid at a higher osmotic potential than plasma

Question 31

What is a hypotonic fluid?

Answer 31

A fluid at a lower osmotic potential that plasma

Question 32

Define osmotic potential

Answer 32

Depends on the number of osmotically active particles (molecules) per litre irrespective of their identity

Question 33

What is osmotic potential expressed in?

Answer 33

Osmoles: 1 osmole = 1 mole of particles

Question 34

What types of substances diffuse easily across capillaries?

Answer 34

Crystalloid fluids

• Glucose
• Urea

Question 35

What does not pass through capillary walls?

Answer 35

Proteins

Question 36

There are three main fluid compartments. Within each single one what is it important to maintain?

Answer 36

Electrical neutrality: the total number of positively charged ions must equal the total number of negatively charged ions

Question 37

What does the Na+ - K+ ATPase or Na+ pump do?

Answer 37

Prevents the steady movement of ions across membranes with Na+ and K+ following their concentration gradients from leading to an equalisation of the compositions of intracellular and extracellular compartments - if they equalised then all bioelectrical signalling would stop

Question 38

What is normal blood volume?

Answer 38

70ml/kg

Question 39

What is normal plasma volume?

Answer 39

40ml/kg

Question 40

What percentage of body weight is total fluid volume?

Answer 40

60% in men

50% in women

Question 41

What percentage of body fluid does intracellular fluid account for?

Answer 41

65%

Question 42

What percentage of body fluid does extracellular fluid account for?

Answer 42

34%