Lecture 4- Principles of solute and water movement

Question 1

in a 70kg man how much of him is water

Answer 1

60% of 70kg= 42L

men are 60% water- Kg=L

Question 2

how much of total water volume in humans is intracellular

Answer 2

2/3

Question 3

how much of total water volume in humans is extracellular

Answer 3

1/3

Question 4

extracellular spaces are also called

Answer 4

interstitial

Question 5

therefore in a 60kg man with 42 L of water, how much is intracellular

Answer 5

28L

2/3 of 42

Question 6

therefore in a 60kg man with 42 L of water, how much is extracellular

Answer 6

14L

1/3 of 42

Question 7

E.g. if someone’s put on 1.5kg and has oedema they will have increased how much fluid in ECF

Answer 7

• 1.5kg=1500ml

* 1/3 of 1500 = 500 ml

Question 8

what counts as intracellular fluid

Answer 8

within cvcells

Question 9

what counts as extracellular fluid

Answer 9

• interstitial
• plasma
• lymph
• trancellular fluid

Question 10

ionic concnetrations within ECF

Answer 10

• High [sodium]
• Low [potassium]
• High [chloride]

Question 11

ionic concentrations within the ICF

Answer 11

• Low [ sodium]

- high [potassium]

Question 12

osmolarity of of the ECF

Answer 12

between 285-310 mOsm

Question 13

osmolarity of ICF

Answer 13

290mOsm

Question 14

osmolarity of ICF and ECF should be

Answer 14

equalise- prevent water flooding into he cell- ions in equilibrium

Question 15

phospholipid membrane permeable to

Answer 15

uncharged and non polar molecules, small hydrophobic molecules e.g. ammonia and water

Question 16

cell membrane lets what in

Answer 16

CHO, sugars, proteins amino acids lipids, salts, O2 and water into the cell

Question 17

cell membrane lets what out

Answer 17

lets Water, ammonia. Salts, CO2 out

Question 18

what maintains cholesterol fluidity

Answer 18

cholesterol

Question 19

what can slip through the membrane

Answer 19

lipid soluble molecules e.g. fats and lips

Question 20

large hydrophobic molecules

Answer 20

struggle to pass the membrane

Question 21

what sort of molecule can pass the membrane

Answer 21

• Small uncharged non-polar
• Small hydrophobic molecules can get through e.g. gases
• Urea can easily diffuse through membrane (accept in kidneys)

Question 22

what sort of molecule cannot pass the membrane

Answer 22

• Large uncharged molecules e.g. glucose cannot just pass through the membrane
• Large charged molecules cannot pass through (e.g. ATP, amino acids)

Question 23

cell membrane example of permeability

Answer 23

• permeable to urea and water.

- not permeable to ions

Question 24

capillary example of permeability

Answer 24

Permeable to urea, water,Na or K (fenestrations). Not permeable to plasma proteins

Question 25

types of movement between compartments

Answer 25

passive transport active transport vesicular transport

Question 26

passive transport

Answer 26

* No energy needed- diffusion * Movement down concentration gradient * E.g. Facilitated diffusion (water through an aquaporins) * E.g.Osmotic, oncotic and hydrostastic

Question 27

active transport

Answer 27

* Uses ATP | * Movement against conc gradient

Question 28

vesicular transport

Answer 28

* Pinocytosis (cell drinking) * Phagocytosis * Form of active transport * Not using channels

Question 29

diffusion

Answer 29

Solute movement across a lipid bilayer through entry into the lipid phase occurs by simple diffusion- movement occurs downhill and is passive

Question 30

diffusion is irrespective of

Answer 30

other substances

Question 31

flux describes

Answer 31

• ‘Flux’ describes how molecules move expressed in moles/cm2/second

Question 32

when there is no movement

Answer 32

flux is 0

Question 33

movement of change is proportional to

Answer 33

gradient of conc difference

Question 34

if membrane is thicker

Answer 34

flux will be slower e..g single cell wall of alveolus

Question 35

diffusion of 2 solute

Answer 35

Concentration gradient of different substances are independent of each other

Question 36

facilitated diffusion e.g. aquporins

Answer 36

Move from, high to low concentration through a protein channel • Protein molecules spans the membrane • Permeable to the movement of that substance (specific) • No energy needed • Facilitated= with help • E.g. aquaporins

Question 37

gated channels

Answer 37

Proteins that open only in presence of stimulus (signal) - Stimulus different from transported molecules - E.g. ion-gated - E.g. voltage gated

Question 38

active transport

Answer 38

Cells need molecules to moleucles against concentration gradients - Need protein pump - Requires ATP e. g. Na/K+ ATPase pump

Question 39

large molecules are transported bvia

Answer 39

vesicular transport- requires ATP

Question 40

two main types of vesicular transport

Answer 40

1) exocytosis | 2) endocytosis

Question 41

exocytosis

Answer 41

out of cell

Question 42

types of endocytosis

Answer 42

1) phagocytosis 2) pinocytosis 3) receptor mediated endocytosis

Question 43

phagocytosis

Answer 43

cellular eating

Question 44

pinocytosis

Answer 44

cellular drinking

Question 45

constitutive secretion

Answer 45

is the default pathway and is used primarily to replenish material at the plasma membrane and certain membrane-bound organelles.

Question 46

regulated secretion

Answer 46

Regulated secretion terminates in secretory vesicles that store secreted material until a signal triggers fusion with the plasma membrane. --> triggered by Ca2+!!!!!!!!!

Question 47

water moves across the membrane relatively

Answer 47

slowly

Question 48

aquaporins

Answer 48

allow water to move across the plasma membrane very quickly

Question 49

if the solution becomes hypotonic

Answer 49

then water will move across membrane by osmosis an enter the cell and the cells will swell and burst

Question 50

if the solution is isotonic

Answer 50

same osmolarity either side of the membrane) water molecules will enter and exit the cell in equilibrium- as many will enter as will leave

Question 51

in hypetonic solutions the cell will

Answer 51

shrinking because the water would move across the membrane into the ECF

Question 52

water will move until

Answer 52

osmotic forces on either side of the membrane is equal

Question 53

Osmole is the measure of

Answer 53

solutions ability to create osmotic pressure and move water | - Proportional to the number of osmotic particles formed in solution

Question 54

In normal conditions osmolality of plasma is

Answer 54

equal to interstitial fluid = intracellular fluid = 280-210 mOsm/kg

Question 55

clinically how is osmalility determined

Answer 55

``` by ECF (Na+ and Cl- =80%) - Serum osmolality can be estimated by doubling serum sodium ```

Question 56

hyperotnic

Answer 56

more solute, less water

Question 57

hypertonicity

Answer 57

hypertonic solution will loose water, shrivel and lyse

Question 58

hypotonic

Answer 58

less solute, more water

Question 59

hypotonicity

Answer 59

hypotonic solution will gain water, swirl and cytosolyse

Question 60

isotonic

Answer 60

equal solute, equal water- no movement of water

Question 61

aquaporins work through

Answer 61

facilitated diffusion

Question 62

how much quicker can water diffuse across the membrane using aquaproins

Answer 62

200x quicker

Question 63

structure of aquaporins

Answer 63

* Made up of 5 subunits - tetrameric * 6 transmembrane alpha helix protein * Inner cavity narrow and lined withy hydrophilic AA * At the centre (+) residues * Prevents movement of charged ions e.g. protons * Aquaporins don’t disrupt H+ ion gradient in ATP production

Question 64

what does aquaporins let through

Answer 64

just water- occasionally urea

Question 65

how many isoforms of aquaporins

Answer 65

10

Question 66

how does water move through aquaporins

Answer 66

Water molecules line up one behind the other and pass single file through the hydrophilic channel  1000,000 molecules/ min

Question 67

why is movement through aquaporins movement still osmosis

Answer 67

 Movement still depends on solute concentration gradient |  Still osmosis