Transport and Circulation

1. Transport and Circulation

2. We’ll be discussing • Cellular Transport • Plant Tissues and Transport in Plants • Trends and Various Strategies Used by Animals to Transport Materials • Transport in Man • Disorders of the Circulatory System

4. Membranes and cellular transport

5. Active vs Passive Transport

6. Transport of large molecules

7. Summary of Transport Processes

8. 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

9. Transport in Plants

11. 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

12. Transport occurs on three levels • 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

13. 1 2 3 4 Through stomata, leaves take in CO2 and expel O2. The CO2 provides carbon for photosynthesis. Some O2produced by photosynthesis is used in cellular respiration. Sugars are produced by photosynthesis in the leaves. Transpiration, the loss of water from leaves (mostly through stomata), creates a force within leaves that pulls xylem sap upward. 6 5 7 Water and minerals are transported upward from roots to shoots as xylem sap. Roots absorb water and dissolved minerals from soil. Roots exchange gases with the air spaces of soil, taking in O2 and discharging CO2. In cellular respiration, O2 supports the breakdown of sugars. A variety of physical processes are involved in the different types of transport CO2 O2 Light H2O Sugar Sugars are transported as phloem sap to roots and other parts of the plant. O2 H2O CO2 Minerals

14. 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

15. Short-distance H2O transport from the soil to the root xylem occurs through diffusion

16. Water and minerals ascend from roots to shoots through the xylemRoot pressureTranspiration–cohesion–tension theory Tension – negative pressure

17. Cuticle Upper epidermal tissue Lower epidermal tissue Trichomes (“hairs”) 100 m Stomata Stomata help regulate the rate of transpiration Leaves – broad surface areas • Increase photosynthesis • Increase water loss through stomata (transpiration) Turgid Flaccid

18. Turgid Flaccid

19. Vessel (xylem) Sieve tube (phloem) Source cell (leaf) 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. 1 H2O Sucrose 1 H2O 2 2 This uptake of water generates a positive pressure that forces the sap to flow along the tube. 3 The pressure is relieved by the unloading of sugar and the consequent loss of water from the tubeat the sink. Transpiration stream Pressure flow 4 In the case of leaf-to-root translocation, xylem recycles water from sink to source. Sink cell (storage root) 4 3 Sucrose H2O 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

20. Pressure – flow model • high solute concentration at source • increase in hydrostatic pressure • sugars in sink draw water out of phloem