Transport and CirculationTransport and Circulation

We’ll be We’ll be discussingdiscussing

1.1. Cellular TransportCellular Transport2.2. Plant Tissues and Plant Tissues and

Transport in PlantsTransport in Plants3.3. Trends and Trends and

Various Strategies Various Strategies Used by Animals to Used by Animals to Transport Transport MaterialsMaterials

4.4. Transport in ManTransport in Man5.5. Disorders of the Disorders of the

Circulatory SystemCirculatory System

Membranes and cellular Membranes and cellular transporttransport

Active vs Passive Active vs Passive TransportTransport

Transport Transport of large of large

moleculesmolecules

Summary of Transport Summary of Transport ProcessesProcesses

Diffusion Osmosis Facilitated Diffusion

Pumps Endocytosis/exocytosis

Direction High to Low High to Low High to Low Low to High N/A

Transport Mechanism

Pores Pores Channels Pumps Membrane

Energy Required?

No No No Yes Yes

Type of particle

Small, nonpolar

Water Small-medium

Ions Small-large

Examples of particles

CO2, O2 H2O Glucose, fructose, Na+, Ca+2

Na+, K+, H+ Food, waste

Transport within the eukaryotic cell

Endomembrane system

• Endoplasmic reticulum– manufacturing and

transport facility– proteins produced in rough

ER are packaged in vesicles• Golgi apparatus

– modification and storage facility

– receiving end and shipping end

• Vacuole– large membrane bound sacs– usually stores undigested

nutrients

Cyclosis/cytoplasmic streaming

TRANSPORT IN PLANTS

VASCULAR VASCULAR TISSUES: TISSUES: XYLEM AND XYLEM AND PHLOEMPHLOEM

Xylem Tracheids* Vessel elements* Parenchyma cells Fiber

Phloem Sieve-tube members Companion cells Sclerenchyma fibers Parenchyma cells

Both are continuous throughout the plant body

OVERVIEW OF TRANSPORT IN A VASCULAR PLANT

CELLULAR LEVEL TRANSPORT

Plant cells can maintain an internal environment different from their surroundings

SHORT-DISTANCE H2O TRANSPORT IN THE ROOT

WATER AND MINERALS ASCEND THROUGH THE XYLEMROOT PRESSURETRANSPIRATION–COHESION–TENSION THEORY

Tension – negative pressure

STOMATA HELP REGULATE THE RATE OF TRANSPIRATION

Leaves – broad surface areas Increase photosynthesis Increase water loss

through stomata (transpiration)

Lower epidermaltissue

Trichomes(“hairs”)

CuticleUpper epidermal tissue

Stomata 100 m

Turgid Flaccid

TurgidFlaccid

ORGANIC NUTRIENTS ARE TRANSLOCATED THROUGH THE PHLOEM(PRESSURE – FLOW MODEL)

Translocation – transport of organic molecules in the plant

Phloem sap Mostly sucrose Sugar source

sugar sink Source is a producer

of sugar Sink is a

consumer/storage facility for sugar

Vessel(xylem)

H2O

H2O

Sieve tube(phloem)

Source cell(leaf)

Sucrose

H2O

Sink cell(storageroot)

1

Sucrose

Loading of sugar (green dots) into the sieve tube at the source reduces

water potential inside the sieve-tube members. This causes the tube to take up water by osmosis. 2

43

1

2This uptake of water generates a positive pressure that forces the sap to flow along the tube.

The pressure is relieved by the unloading of sugar and the consequent loss of water from the tubeat the sink.

3

4In the case of leaf-to-roottranslocation, xylem recycles water from sinkto source.T

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