Transport and CirculationTransport and CirculationTransport and CirculationTransport and Circulation

We’ll be discussing

1. Cellular Transport

2. Plant Tissues and Transport in Plants

3. Trends and Various Strategies Used by Strategies Used by Animals to Transport Materials

4. Transport in Man

5. Disorders of the Circulatory System

Membranes and cellular transport

Active vs Passive Transport

Transport of large large

molecules

Summary of Transport Processes

Diffusion Osmosis Facilitated

Diffusion

Pumps Endocytosis

/exocytosis

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

Transport Pores Pores Channels Pumps MembraneTransport

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 endend

• Vacuole– large membrane bound

sacs

– usually stores undigested nutrients

Cyclosis/cytoplasmic streaming

TTRANSPORT IN

PLANTS

VVASCULARASCULAR TISSUESTISSUES: :

XYLEMXYLEM ANDAND PHLOEMPHLOEM

� Xylem� Tracheids*

� Vessel elements*

� Parenchyma cells

� Fiber� Fiber

� Phloem� Sieve-tube members

� Companion cells

� Sclerenchyma fibers

� Parenchyma cells

� Both are continuous

throughout the plant

body

TRANSPORT OCCURS

ON THREE LEVELS

1. Uptake and release

of water and solutes

by individual cells

2. Short-distance

transport of transport of

substances by tissues

and organs

3. Long-distance

transport of minerals

in water and sap

within xylem and

phloem by the whole

plant body

CO2 O2

H2O Sugar

Light

A VARIETY OF PHYSICAL PROCESSES ARE

INVOLVED IN THE DIFFERENT TYPES OF

TRANSPORT

Sugars are produced by

photosynthesis in the leaves.

5Through stomata, leaves

take in CO2 and expel O2.

The CO2 provides carbon for

photosynthesis. Some O2

produced by photosynthesis

is used in cellular respiration.

4

Transpiration, the loss of water3

Minerals

H2O CO2

O2

Sugars are transported as

phloem sap to roots and other

parts of the plant.

6

Transpiration, the loss of water

from leaves (mostly through

stomata), creates a force within

leaves that pulls xylem sap upward.

3

Water and minerals are

transported upward from

roots to shoots as xylem sap.

2

Roots absorb water

and dissolved minerals

from soil.

1 Roots exchange gases

with the air spaces of soil,

taking in O2 and discharging

CO2. In cellular respiration,

O2 supports the breakdown

of sugars.

7

TRANSPORT OF IONS AT THE CELLULAR LEVEL

DEPENDS ON SELECTIVELY PERMEABLE MEMBRANES

� Controls the movement of solutes into and out of the cell

� With specific transport proteins

� Enable plant cells to maintain an internal environment different from their surroundingsenvironment different from their surroundings

SHORT-DISTANCE H2O TRANSPORT

IN THE ROOT

WATER AND MINERALS

ASCEND FROM ROOTS TO

SHOOTS THROUGH THE

XYLEMROOT PRESSURE

TRANSPIRATION–COHESION–

TENSION THEORY

Tension

– negative

pressurepressure

STOMATA HELP

REGULATE THE RATE

OF TRANSPIRATION

Leaves – broad surface areas

� Increase photosynthesis

� Increase water loss through

stomata (transpiration) Lower epidermal

tissue

Trichomes

(“hairs”)

Cuticle Upper epidermal tissue

Stomata 100 µm

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

Vessel

(xylem)

H2O

H2O

Sieve tube

(phloem)

Source cell

(leaf)

Sucrose1

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

1

2 This 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

3

Transpiration stream

Pressure flow

� Mostly sucrose

� Sugar source � sugar

sink

� Source is a producer of

sugar

� Sink is a

consumer/storage

facility for sugar H2O

Sink cell

(storage

root)

Sucrose

43

by the unloading of sugar

and the consequent loss

of water from the tube

at the sink.

4In the case of leaf-to-root

translocation, xylem

recycles water from sink

to source.Transpiration stream

Pressure flow

PRESSURE – FLOW MODEL

1. high solute

concentration at

source

2. increase in

hydrostatic hydrostatic

pressure

3. sugars in sink

draw water out of

phloem