Body fluids lecture 2

Question 1

What percentage of males and females are solids and fluid? Why is it different?

Answer 1

females
-55% fluid
-45% solid

Males
-60% fluids
-40% solids

Question 2

Of your total body fluid, what percentage are intracellular fluids and extracellular fluids?

Answer 2

2/3rds are intracellular fluids
1/3rd are extracellular fluids

Question 3

Of your extracellular fluids what percentage of them are interstitial fluid and what % is blood plasma?

Answer 3

interstitial fluids make up 80%
plasma makes up 20%

Question 4

Define intracellular fluid

Answer 4

the fluids within cells (the cytoplasm) (includes GI tract

Question 5

Define extracellular fluid

Answer 5

the fluids between cells

Question 6

Define interstitial fluid

Answer 6

fluid that surrounds cells of tissues, including synovial fluid, CSF, lymph plasma

Question 7

Define blood plasma

Answer 7

fluid in blood vessels that RBC travel through, yellow fluid that is 90% water

Question 8

How is osmotic balance maintained between different fluid compartments?

Answer 8

it is maintained through the continuous exchange of water through different compartments

Question 9

Define transcellular fluid

Answer 9

fluid in CSF, Ocular fluid, G-I tract, it comes from the interstitial fluid

Question 10

Is osmolality equivalent in all body fluids?

Answer 10

yes it is generally equal to maintaining homeostasis between solute concentrations and yes because the solvent is almost always water

Question 11

Table all the ions in body fluid compartments in ISF and extracellular (ISF+PLASMA)

Answer 11

ions in ISF
Na- 10
K- 142
Ca- 0.1
Mg-1
Cl- 10
Hco3- 10
A-132
pH-7
osmolality-290

ions in ISF+plasma
Na- 143
K- 4
Ca- 1.5
Mg-1
Cl- 118
Hco3- 24
A-10
pH-7.4
osmolality-290

Question 12

Is osmolality higher in inter or extracellular fluid?

Answer 12

the concentrations of the solutes needs to be the same to prevent net movement of water between the compartments- so osmolality is equal in all body fluid compartments

Question 13

Draw a table of ions in the intracellular fluid, interstitial fluid and plasma

Answer 13

the main ions are K, Na, Cl, Hco3 and proteins

-interstitial and plasma the ion concentrations are all equal.
-The plasma has more proteins

-The intracellular compartment has higher protein and K concentrations

Question 14

Do all ions express the same osmotic pressure?

Answer 14

no because different ions are different sizes

Question 15

What is osmotic pressure?

Answer 15

osmotic pressure is the pressure created via the movement of solvent particles across membranes in order to equalise the concentration of solute particles on both sides

Question 16

What process’ affect the total volume in each of the body fluid compartments?

Answer 16

filtration
reabsorption
diffusion
osmosis

Question 17

Why is there continual change between the fluid compartments?

Answer 17

concentrations of ions change or proteins levels change or a variable is affected by a stimuli

Question 18

What is the biggest source of water movement between the intracellular and interstitial fluid and what determines the direction of the movement?

Answer 18

osmosis is the biggest source of water movement between intracellular and interstitial fluid

Question 19

Despite this movement is the volume of each compartment consistent?

Answer 19

yes

Question 20

Define osmosis.

Answer 20

the movement of water from low solute concentrations to high solute high solute concentrations across a semi-permeable membrane

Question 21

Draw a figure that shows osmosis

Question 22

what is osmotic pressure

Answer 22

related to the number of water particles that move from a place of high to low concentration.

Osmotic pressure is the pressure that must be applied to oppose osmosis
the difference in concentration of the impermeable solute exerts an osmotic pressure

Question 23

What does the amount of water movement depend on?

Answer 23

the concentration of the solutes at the 2 sides of the semi-permeable membrane

Question 24

What happens if 2 chambers contain different concentrations of a solute what will the water do?

Answer 24

water will move to equalise the concentration

Question 25

What can water movement be counterbalanced by?

Answer 25

by a physical pressure

Question 26

What are and what is the difference between osmolarity and osmolality?

Answer 26

Osmolality- total number of dissolved particles (ions of molecules or both) dissolved per kg of water Osmolarity- total number of dissolved particles (ions of molecules or both) per litre of solution -Molarity x number of particles per molecule once the particles dissolve -for undissolved particles- 1 mole=1 osmole for a fully disassociated solute (e.g NaCl)- 1 mole= 2 osmoles for proteins- 1 moles= 1 osmole

Question 27

Why is molarity easier to measure than molality?

Answer 27

because it is easier to measure the volume of a solution in a medical setting since it is harder to separate water from the body fluids plus the solutions are very diluted anyway

Question 28

How do the properties of the membrane determine which solutes are osmotically active?

Answer 28

the membranes are semi-permeable so only let the selected solutes through

Question 29

In the ECF what are the major osmolytes?

Answer 29

Na+ and Cl-

Question 30

What is nearly impermeable to sodium ions?

Answer 30

the cell membrane

Question 31

Where is water lost from?

Answer 31

the extracellular space causing things like dehydration

Question 32

How is water replaced in the extracellular space?

Answer 32

from the inside of the cell; water moves from the intracellular space to the extracellular space due to the increase in Na+ concentration caused by dehydration outside the cell. this increases extracellular osmolality

Question 33

What organ plays an important role in maintaining normal osmolality?

Answer 33

the kidney

Question 34

What happens if extracellular Na+ increases and why?

Answer 34

water flows out of the cell via osmosis to equalise the concentration of solutes

Question 35

How can osmosis cause problems?

Answer 35

during inflammation due to an increase in extravascular osmolality -the capillary wall is freely permeable so not osmotically active - it is however impermeable to plasma proteins -is extravascular proteins build up they can exert an osmotic pressure

Question 36

What is an isotonic solution?

Answer 36

solutions that do not make cells swell or shrink - same osmolality than plasma

Question 36

What is a hypotonic solution? What affect can this have on cell volume?

Answer 36

a solution that causes cellular swelling Cells would have higher osmolality than plasma

Question 36

what are colloid pressures?

Answer 36

an alteration of osmotic pressures due to changes of large molecule distribution

Question 36

What are hypertonic solutions? What affect can this have on cell volume?

Answer 36

a solution that causes cellular shrinkage - cell has low osmolality than plasma

Question 36

How is water lost by the body?

Answer 36

through skin, lungs, urine and faeces

Question 36

What does water in need to equate to?

Answer 36

water gain needs to equate to water loss

Question 36

How is water gained by the body?

Answer 36

food drink and metabolism