12 Water And Fluid Transport

Front 1

Osmoregulation

Back 1

- Balancing water and ions in the cells and the body to allow physiological function

- Principles to cells to organisms

Front 2

Water

Back 2

Highly polar

- hydrogen bonding

- high heat of fusion and vaporization

- Large thermal capacity

- Cohesion and adhesion

Universal Solvent for Life

Front 3

Water in cells (2)

Back 3

Animals: determines cell volume

- Vol = bottom level of regulation of water/ion balance

Plants: determines cell turgor

- Positive (turgor/rigidity) pressure in plant cells keeping them turgid (swollen).

Front 4

Plasmolysis

Back 4

Cell wall prevents cell from changing size, so inside vacuole size changes

- vacuole shrinks within set volume of cell wall, moves away from cell wall --> cell wall becomes less rigid

Front 5

Diffusion vs. Osmosis

Back 5

- Diffusion: movement of ions/solute in response of concentration gradient

- Osmosis: movement of water in response of concentration gradient (selectively permeable membrane)

Front 6

Water has no ________ transporters

Back 6

- No active water transporters.

- All passive movement (no ATP)

- Passes through channels, pores, and via membrane.

Front 7

Moving of water requires...

Back 7

Creation of a gradient, which might require ATP

...and some ion pumps only work in one direction

...doesn't have to be same solutes to maintain isotonicity

Front 8

Efflux vs. Influx

Back 8

Efflux: water leaves cell

Influx: water enters cell

Front 9

Water potential equation

Back 9

- Water moves toward lower water potential

- Measures in MPa (pressure units)

Water potential = solutte potential + pressure potential + gravitational potential

- Water potentials are normally negative

Front 10

Osmotic potential

Back 10

- increasing solute concentration lowers water potential.

Front 11

Osmotic potential

Back 11

- Based on solute concentration

- Compatible solutes (ie. proline, sorbital, charged solute) do not interfere w/ enzyme activity

Front 12

Osmotic adjustment

Back 12

changing solute concentration to change water potential

Front 13

Moving water: Pressure

Back 13

Positive pressure in cell = tugor pressure

- pushes water out of cell

Front 14

Metabolic water

Back 14

break down chemical species and release water in process

(lipid = most release of water, Protin w/ urea production = lowest)

Front 15

Bound water

Back 15

Fuel molecules have lots of bound water to them. (ie. glycogen ~3 x mass in water bound to outside)

- Metabolise fuel = lots of bound water, and few metabolic water

Front 16

Anhydrobisis

Back 16

- some small aquatic animals can tolerate the loss of >99% of their body water

- resurrection plants (like Selaginella pilifera)

Front 17

Nematodes

Back 17

roundworm

Front 18

Artemia (cysts)

Back 18

Brine shrimp

Front 19

Rotifers

Back 19

Microscopic aquatic animals

Front 20

Tardigrades

Back 20

water bears/moss piglets

- boss microscopic animals that can withstand extreme conditions

- recall in Cosmos

Front 21

Polypedilum vanderplanki

Back 21

- looks like cyst, looks normal with water added (angydrobiosis).

Front 22

Vascular transport

Back 22

Movement of fluids thru tubes (gas/liquid)

Pushed:

- animal circulatory systems

- sometimes plants

Pulled:

- plant vascular systems

Front 23

What determines how much fluid can circulate and how fast it can go?

Back 23

Front 24

Flow rate determined by:

Back 24

- Pressure at start of system

- Pressure loss in system

- Resistance in system

Pressure (proportional to) flow rate & resistance

Front 25

Resistance

Back 25

Front 26

Resistance factors

Back 26

- Longer systems have more resistance

- More viscosity = higher resistance

- Resistance is proportional to 4th power of radius of tube

- small change in radius = huge change in resistance

Front 27

Flow rate

Back 27

Front 28

What also affects pressure?

Back 28

Gravity

Front 29

Pressure gradients in animals & plants

Back 29

Animals: use + pressure to push fluids through veins/arteries

Plants: use - pressure to pull fluids through xylem

Both: fluids move from higher to lower pressures, down a gradient.

Front 30

Xylem

Back 30

Translocates water & inorganic nutrients from roots to leaves

Front 31

Phloem

Back 31

Translocates sugars/proteins/signaling molecules from source tissue to sink tissue.

Front 32

Xylem are made up of what?

Back 32

- made of dead cells: tracheids (edge-to-edge) & vessel elements (end-to-end)

- are supported by fibres and other lignified cells (in trees)

Front 33

Tracheids

Back 33

- secondary in angiosperms

- primary vessel type in gymnoperms

- have permeable pit membranes

- allows lateral movement to provide long connected vessels

Front 34

Vessel elements

Back 34

- primary vessel type in angiosperms

- end-to-end stacking + perforation plates = continuous tubes

- pits connect vessel elements laterally

- some lateral movement (slower than vertical)