Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Intro to Clinical Biochemistry > BW&EH > Flashcards

BW&EH Flashcards

1
Q

What are the main fluid compartments?

A

Intracellular (interstitial fluid, lymph), extracellular fluid compartment (Pleural fluid, pericardial fluid, CSF) and vascular (plasma)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Which fluid compartment is used in routine measurements?

A. Intracellular fluid compartment
B. Extracellularfluid compartment
C. Vascular

A

C

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What percentage of the water is plasma?

A

Firstly 60% of body weight is water. Calculate water first 0.6xbody weight= water

But

  1. 6xBWx0.083=plasma (L)
  2. 3%
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Match the where the majority of specific electrolyes are most common in compartments.

A. ICF
B. ECF

  1. Potassium
  2. Sodium
  3. Magnesium
A

A1,3

B2

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Why is there an increase in potassium during haemolysis?

A

Because the K can shoot up coming from ICF into the plasma, which is being measured

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Causes for raised anion gaps?

A

Increase in the unmeasured anions
- Lactate, Ketones and alcohols (ethanol)

Rarely decrease in umeasured cations
- Calcium, Magnesium

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Describe with example the importance of electrolytes in the correct compartment?

A

Sodium is required to be in the ECF to maintain blood pressure

Potassium have important roles in intracellular reactions

Thus, the two electrolytes relationship with compartment is maintained by the Na-K-ATPase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Factors affecting water movement

A

Osmotic pressure
- Created by electrolytes and non-electrolytes

Oncotic pressure
- Created by proteins

Hydrostatic pressure
- Mechanical pressure generated by the heart

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What occurs in oncotic pressure?

A

Using vascular and extra vascular space.

Water is remained at the vascular space because the proteins are too big to cross the capillary walls, therefore controlling the amount of water in vascular and extravascular space

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Describe osmotic pressure.

A

High osmotic pressure refers to the amount of osmotically active particles in the space.
- Movement of water occurs low to high osmotic pressure in order to dilute the high osmotic pressure

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Difference between osmotic and oncotic pressure

A

Osmotic pressure is determined by the number for particles.
- E.g. more sodium particles in the ECF than there are protein particels. Therefore sodium exerts a greater effect than protein

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Define osmolality

A

The number of solute particles /kg of solvent

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Define osmolarity

A

Number of particles /L of solution

  • Affected by temperature
  • Includes the solute space
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Define omsolarity/osmolality

A

Conc of solutes in a solution that contribute to the osmotic pressure

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Why is osmolality more frequently used as a measurement rather than osmolarity?

A

It is not affected by solute space or temp changes

In water: osmolarity=osmolality

In plasma some of the volume is occupied by proteins/lipids making water volume less than 6% total volume

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What is measured osmolality?

A

Measures the amount of osmotically active particles present in the plasma

17
Q

What is calculated osmolality?

A

Calculate the expected osmolality using other measured analytes
=(2xNa) + K + urea + glucose (if abnormal)

18
Q

How is the osmolar gap calculated?

A

Difference between measured and calculated osmolality

19
Q

Importance of water retention in cells?

A
  • No water= shrivel up
  • Blood needs appropriate pressure to ensure the blood can keep circulating and supply the heart and organs with essentials
  • To do this, water moves when required. Controlled by different forces
20
Q

Describe cerebral dehydration.

A

Describes the process where water moves from brain cell (low solute) to dehydrated vasculature (higher solute)

  • This causes the brain cell to shrink - cerebral dehydration
  • Blood vessels may tear (haemorrhage)
  • Can cause central pontine myelinosis
21
Q

Mechanism to limit cerebral dehydration

A

The brain cell is able to synthesis osmolytes to raise its osmolality and prevent water loss to vasculature.

22
Q

Describe the rehydration process of cerebral dehydration

A

Rehydration must occur slowly. If it occurs quickly then the osmolytes will not clear quickly enoguh from the brain cells

  • Causes the ECF to be significantly more dilute than the brain
  • Water rush into the brain cells causing cerebral oedema
23
Q

What is water overload?

A

When the kidneys excretion rate of up to 20mL/min is exceeded

24
Q

What is cerebral oedema?

A
  • Describes when water moves to area of higher conc. Overloaded vasculature -> brain cell
  • Brain cells swells, cerebral oedema
25
Q

Protective mechanims against cerebral oedema?

A

Achieved by reducing concentration gradient.
Step 1 - Brain cells lose sodium
Step 2 - Brain cells synthesis and lose osmolytes

26
Q

How would correction of cerebral oedema occur?

A

Correction must be slowly administered.

  1. Brain cell has lost osmolytes and sodium
  2. Therefore rapid increase in vasculature osmolality will cause water to rush out the brain cell resulting in cerebral dehydration
27
Q

Describe the sodium and water relationship.

A

Sodium is the major ECF electrolye and exerts majority of the osmotic effect. Sodium balance is therefore inextricably linked to water balance - water follows sodium

28
Q

Describe the axis that regulate sodium regulation. (Draw for extra points)

A

Sodium levels are regulated by the renin-angiotensin-aldosterone axis. The axis is stimulated by low Na, low aterial pressure, low ECF volume, sympathetic NS stimulation.

  • Liver is stimulated to release angiotensinogen which is cleaved by renin (from the kidney) to cleave angiotensin I.
  • Angiotensin I is converted to angiotensin II by angiotensin converting enzyme (ACE)
  • Angiotensin II stimulate ADH and the adrenal cortex to release aldosterone.
  • Aldosterone act on kidney to reabsorb sodium and excrete potassium
29
Q

Describe sodium regulation in the distal tubule.

A

Principal cells - aldosterone

  • Aldosterone binds to its receptor to stimulate reabsorption
  • Generates an electrochemical gradient to allow K+ and H+ excretion
  • One H+ or K+ for each Na+ reabsorbed
30
Q

By what hormones are potassium regulated by?

A

Aldosterone, insulin, catecholamines

31
Q

Describe effect of aldosterone on potassium regulation.

A

Aldosterone promotes sodium reabsorption and potassium excretion in the distal convoluted tubule

32
Q

Describe effect of insulin on potassium regulation.

A

Has a direct interaction with the Na/K ATPase, independent of glucose

  • Drives potassium intracellularly
  • Hypercalcaemia in plasma
33
Q

Describe effect of catecholamines on potassium regulation.

A

Adrenaline drives potassium intracellularly

Noradrenaline allows potassium to leave cells

34
Q

Match the following hormone with effect to potassium regulation

A. Aldosterone
B. Noradrenaline
C. Insulin
D. Adrenaline

  1. Allows potassium to leave cells
  2. Drives potassium intracellularly
  3. Excrete potassium in the distal convoluted tubule
  4. Drives potassium intracellularly by Na/K-ATPase interaction
A

A3
B1
C4
D2

35
Q

Describe the control of water balance

A

System between the collecting duct and ADH.

  • Draw the axis
  • Stored in pPituitary
  • Release of ADH
36
Q

What are some osmotic factors stimulating ADH?

A

Osmoreceptors in the hypothalamus

  • Swell/shrink in response to omsolality
  • Dehydration - contract - ADH release
  • Hydration - swell -ADH inhibited
37
Q

What are some non-osmotic factors stimulating ADH?

A

Nausea, ECF hypovolaemia, hypotension, certain drugs

38
Q

Describe the specific actions of ADH

A

The luminal cells lining the collecting ducts are impermeable to water. During rehydration, channels (aquaporin II) are inserted into the membrane to allow water reabsorption
- ADH binds V2 on basolateral surface, which allows insertion of aquaporin 2 channels into the luminal membrane - to enable water reabsorption

39
Q

What is the effects of aldosterone on electrolyte composition in DCT?

A

Stimulates Na+ absorption by actions of the aldosterone receptor
- Generates a gradient to allow H+ and K+ to leave

Intro to Clinical Biochemistry (12 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions