Transport and Circulation Well be discussing 1 Cellular

Transport and Circulation

We’ll be discussing 1. Cellular Transport 2. Plant Tissues and Transport in Plants 3. Trends and Various 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 molecules

Summary of Transport Processes Diffusion Direction Osmosis Facilitated Diffusion Pumps High to Low to High Endocytosis /exocytosis N/A Transport Mechanism Pores Channels Pumps Membrane Energy Required? No No No Yes Type of particle Small, nonpolar Water Smallmedium Ions Small-large Examples of particles CO 2, O 2 H 2 O 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 TISSUES: XYLEM AND PHLOEM Xylem Tracheids* Vessel elements* Parenchyma cells Fiber Phloem Sieve-tube members Companion cells Sclerenchyma fibers Parenchyma cells Both are continuous throughout the plant body

TRANSPORT OCCURS ON THREE LEVELS 1. 2. 3. Uptake and release of water and solutes by individual cells Short-distance transport of substances by tissues and organs Long-distance transport of minerals in water and sap within xylem and phloem by the whole plant body

A VARIETY OF PHYSICAL PROCESSES ARE INVOLVED IN THE DIFFERENT TYPES OF TRANSPORT 4 Through stomata, leaves take in CO 2 and expel O 2. The CO 2 provides carbon for photosynthesis. Some O 2 produced by photosynthesis is used in cellular respiration. CO 2 H 2 O O 2 5 Sugars are produced by photosynthesis in the leaves. Light Sugar 3 Transpiration, the loss of water from leaves (mostly through stomata), creates a force within leaves that pulls xylem sap upward. 6 Sugars are transported as phloem sap to roots and other parts of the plant. 2 Water and minerals are transported upward from roots to shoots as xylem sap. 1 Roots absorb water and dissolved minerals from soil. O 2 H 2 O Minerals CO 2 7 Roots exchange gases with the air spaces of soil, taking in O 2 and discharging CO 2. In cellular respiration, O 2 supports the breakdown of sugars.

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 surroundings

SHORT-DISTANCE H 2 O TRANSPORT FROM THE SOIL TO THE ROOT XYLEM OCCURS THROUGH DIFFUSION

WATER AND MINERALS ASCEND FROM ROOTS TO SHOOTS THROUGH THE XYLEM ROOT PRESSURE TRANSPIRATION–COHESION– TENSION THEORY Tension – negative pressure

STOMATA HELP REGULATE THE RATE OF TRANSPIRATION Cuticle Upper epidermal tissue Leaves – broad surface areas Increase photosynthesis Increase water loss through stomata (transpiration) Turgid Lower epidermal Trichomes tissue (“hairs”) Flaccid Stomata 100 m

Flaccid Turgid

ORGANIC NUTRIENTS ARE TRANSLOCATED THROUGH THE PHLOEM Vessel (xylem) Sieve tube (phloem) H 2 O (PRESSURE – FLOW MODEL) Source cell (leaf) 1 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 This uptake of water generates a positive pressure that forces the sap to flow along the tube. Sucrose 1 H 2 O Translocation – transport of organic molecules in the plant Phloem sap Pressure flow sucrose Sugar source sugar sink Source is a producer of sugar Sink is a consumer/storage facility for sugar Transpiration stream Mostly 2 4 3 H 2 O 3 4 Sink cell (storage root) Sucrose The pressure is relieved by the unloading of sugar and the consequent loss of water from the tube at the sink. In the case of leaf-to-root translocation, xylem recycles water from sink to source.

PRESSURE – FLOW MODEL 1. 2. 3. high solute concentration at source increase in hydrostatic pressure sugars in sink draw water out of phloem