Lecture 2-Body Fluids and Membrane Transport

Question 1

how many litres makes up a humans total body water

Answer 1

42

Question 2

25 litres of TBW is what fluid?

Answer 2

Intracellular fluid (ICF)

Question 3

17 litres of TBW is what fluid?

Answer 3

extracellular fluid

Question 4

what are the three components of extracellular fluid?

Answer 4

interstitial fluid, plasma, transcellular fluid

Question 5

13 litres of ECF is what type of fluid?

Answer 5

Interstitial fluid (ISF)

Question 6

3 litres of ECF is what type of fluid?

Answer 6

Plasma

Question 7

1 litre of ECF is what type of fluid?

Answer 7

Transcellular

Question 8

Interstitial fluid

Answer 8

fluid that bathes the cell (tissue fluid)

Question 9

Transcellular fluid

Answer 9

any other fluid that has been produced and crossed an epithelial membrane e.g waste from urine

Question 10

6 examples of transcellular fluids

Answer 10

Cerebrospinal fluid (brain)
Urine (kidney and bladder)
Gastrointestinal secretions (saliva, gastric juice, pancreatic juice, bile)
Sweat
Aqueous and vitreous humours (eye)
Synovial fluid (joints)

Question 11

how does fluid from the blood plasma become interstitial fluid?

Answer 11

electrolytes and water passes the endothelium in the capillary

Question 12

what is the main difference between plasma and ISF composition

Answer 12

ISF contains no proteins

Question 13

in order for fluid to become intracellular, what membrane does it have to pass?

Answer 13

plasma cell membrane

Question 14

differences and similarities between ISF and intracellular fluid

Answer 14

electrolyte composition differs in different compartments however the osmolarity says the same

Question 15

why is composition of transcellular fluid non generalisable?

Answer 15

electrolyte composition varies depending on what fluid

Question 16

plasma-> ISF what membrane does it cross?

Answer 16

must cross endothelial cell layer (capillary)

Question 17

ISF->ICF what membrane does it cross

Answer 17

plasma membrane

Question 18

ISF->Transcellular fluid; what membrane must it cross

Answer 18

epithelium layer

Question 19

why do membranes separate the compartments

Answer 19

to help maintain the composition of different compartments

Question 20

what are the three features of the plasma membrane?

Answer 20

-highly selective permeability (only lipid soluble can enter and dissolve in the lipid layer, water soluble can’t enter without a transport process)
lots of transport proteins for uptake and removal of specific solutes
vital for regulation of the intracellular environment

Question 21

what is the phospholipid bilayer impermeable to?

Answer 21

ions and polar molecules

Question 22

what is permeability provided by for membrane transport?

Answer 22

membrane proteins (transporters)

Question 23

what are the 3 membrane transporters?

Answer 23

channels
carriers
pumps

Question 24

channels

Answer 24

selective for one type of ion and generally one direction

Question 25

transporters

Answer 25

transport pairs of ions

Question 26

pumps

Answer 26

use energy to move against the conc gradient

Question 27

passive transport

Answer 27

driven by gradients

Question 28

which transports are passive transports?

Answer 28

channels and carriers

Question 29

active transport uses...

Answer 29

ATP hydrolysis

Question 30

which transport mechanism uses active transport?

Answer 30

pumps

Question 31

what are the 3 types of carriers?

Answer 31

facilitator/uniport cotransporter/symport exchanger/ antiport

Question 32

uniport

Answer 32

facilitator one type ion only down conc gradient in isolation (one direction)

Question 33

symport

Answer 33

cotransporter -two ions (usually pos and neg to maintain electrical neutrality) in same direction

Question 34

antiport

Answer 34

exchanger swaps one ion in for another ion out (generally the same charge to maintain electrical neutrality)

Question 35

functions of transport proteins

Answer 35

-Uptake of nutrients, substrates, cofactors… -export of waste products -Regulation of intracellular ions, pH, cell volume

Question 36

uptake of glucose and AAs

Answer 36

Uniporter picks up glucose (down conc gradient) AAs transported usually with sodium using symport/ cotransporter

Question 37

export of waste products

Answer 37

-Urea/ nitrogenous waste comes out the cell via uniporter -Hydrogen ions and lactate come out using a cotransporter to rid of waste products

Question 38

Regulation of intracellular ions, pH, cell volume

Answer 38

Regulate internal pH using exchangers e.g pH too low, rid of hydrogen ions and swap for sodium ions (antiport/ exchanger) pH too high: swap bicarbonate ion out and chloride ion in (exchanger/ antiport) -don’t actively transport water, use ions to generate gradient to allow water to follow

Question 39

ICF vs ECF: Pottassium ions

Answer 39

ICF: high ECF: low

Question 40

ICF vs ECF: sodium ions

Answer 40

ICF: low ECF: high

Question 41

ICF vs ECF: Calcium ions

Answer 41

ICF: very low ECF: low

Question 42

ICF vs ECF: Chloride ions

Answer 42

ICF: low ECF: high

Question 43

ICF vs ECF: organic ions

Answer 43

ICF: high ECF: low

Question 44

ICF vs ECF: proteins

Answer 44

ICF: high ECF: low

Question 45

why do cells not have a water pump?

Answer 45

it would take too much energy/ ATP

Question 46

how is water distribution determined?

Answer 46

by osmosis

Question 47

what is the osmotic pressure at equilibrium

Answer 47

290

Question 48

3 properties of capillary endothelium

Answer 48

-very thin layer of cells lining blood vessels -highly permeable in some organs, not in others (e.g. brain) -important role in regulation of the interstitial fluid

Question 49

distribution of solutes across the capillary endothelium

Answer 49

ISF: low solute conc Plasma: high solute conc as proteins can't cross the endothelial cells or between them

Question 50

what is water distribution decided by?

Answer 50

hydrostatic and osmotic forces

Question 51

colloid

Answer 51

due to proteins

Question 52

what happens at the arterial end of the capillary?

Answer 52

hydrostatic pressure> colloid osmotic pressure -fluid is forced out of the plasma

Question 53

what happens at the venous end of the capillary?

Answer 53

colloid osmotic pressure> hydrostatic pressure forcing fluid back into the plasma

Question 54

4 features of epithelia

Answer 54

-layers of cells covering internal and external surfaces of organs and tissues -protective/barrier function -important roles in absorption and secretion -selective

Question 55

apical membrane of gut

Answer 55

faces inwards (centre of the gut)

Question 56

basolateral membrane of gut

Answer 56

faces outwards

Question 57

in the gut, what are the epithelial cells connected by

Answer 57

tight junctions which are impermeable

Question 58

in the gut, what facilitates the movement of water

Answer 58

sodium glucose cotransporter by creating an osmotic gradient

Question 59

what allows glucose to move through in the gut? where is this located?

Answer 59

glucose uniporter on the basolateral membrane allowing water to be absorbed to your gut

Question 60

what ions facilitates the movement of water into the gut from plasma

Answer 60

chloride ions

Question 61

role of sodium pottassium ATPase in the gut

Answer 61

creates a high pottassium inside and a low sodium inside the cell causing a gradient

Question 62

what allows the potassium ions into the gut leading to chloride and sodium ions coming in causing water to follow and into the cell

Answer 62

sodium potassium two chloride cotransport

Question 63

on the apical membrane of epithelial cells in the gut, what channel opens to allow water out

Answer 63

chloride channels allowing chloride ions to diffuse out and down the conc gradient causing water to follow

Question 64

how does diarrhoea occur from food poisoning

Answer 64

toxins generated from bacteria open the chloride channels and allows water to pour in

Question 65

role of chloride channel in cystic fibrosis

Answer 65

chloride channel does not open causing less water to be produced leading to sticky thick mucus as can’t move water across membrane