Biology 103 - Main points/Questions

1. Biology 103 - Main points/Questions Remember the heart? What tissue lines your vessels? How do plants circulate fluids?

2. This side of the heart gets blood from the and ships it to the . This side of the heart gets blood from the and ships it to the .

3. Arteries • Blood leaving the heart • Deal with high pressure • Very little exchange with surrounding tissue

4. Capillaries • Lower pressure • Major location of exchange • Very “leaky” Three kinds of capillaries: 1 – continuous 2 – fenestrated 3 – sinusoids (most leaky)

5. Veins • Return blood to the heart • Lowest pressure .

6. Fig. 29.7 • Low pressure in veins means: • Valves • “muscle assist”

7. Why does exchange happen in capillaries? Speed of blood in capillaries is much lower • Like a wide spot in a river… Capillary bed leaks fluid into interstitial fluid • This “stirs” the interstitial fluid • Makes diffusion even more efficient • But more fluid leaves than returns…

8. Fig. 29.9 What type of tissue?

9. Tissue of the Day - Epithelial • Has one surface open to space • Other side is attached to connective tissue • Build linings and membranes of your body • Line blood vessels • Line mouth • Outer layer of skin

10. Tissue of the Day - Epithelial Named based on 2 properties How many layers • 1layer = simple, multiple layers = stratified Type of cells

11. Several types of epithelial tissue are found including thin flattened cells good for diffusion and thicker cells specialized for secreting or absorbing.

12. Tab. 28.2 • Columnar • Taller than they are wide • Squamous • Look like pancakes • Cuboidal • Look like cubes

13. Tissue of the Day - Epithelial Named based on 2 properties How many layers • 1layer = simple, multiple layers = stratified Type of cells Squamous, cuboidal, columnar

14. Capillaries • Lined with simple squamous epithelial • Near all your body cells • Can be opened and closed

15. Fig. 29.3.a

16. Fig. 29.3.b

17. Your circulatory system keeps all your cells constantly supplied with nutrients But what happens in plants? (remember they don’t have muscle)

18. Plants must move water to leaves and sugars to roots! How do they do this? Lets look at a plant…

19. Do you think this section is through a root or a shoot? The next slide is a blow up of this region! }

20. Notice this ring of cells – endodermis!What type of cells do you think these are?These are sugar transporting cells! }

21. Circulation in Plants • Plants have two systems for moving fluids • Phloem for sugar transport • Xylem – 2 cell types (?)

22. Figure 23.6 Comparison of vessel elements and tracheids

23. Circulation in Plants • Plants have two systems for moving fluids • Xylem – 2 cell types (?) • Phloem for sugar transport • These systems work in very different ways • Xylem transports using negative pressure • Phloem transports using positive pressure • First look at xylem

24. Xylem function • Xylem cells form a continuous tube • Stretches from root to leaf • Water attractions keep water from falling • Power for xylem sap movement • Driven by evaporation from leaf pours • Ultimately energy comes from heat/sunlight

25. Watch water transport video… http://www.dnatube.com/video/1873/Cohesion-Transport

26. 1 Water evaporates through pores of leaves water molecules

27. 2 Cohesion of water molecules to one another and adhesion to xylem wall by hydrogen bonds creates a "water chain."

28. heartwood (xylem) sapwood (xylem) vascular cambium secondary phloem bark cork and cork cambium

29. 3 Water enters the vascular cylinder of root. flow of water

30. Phloem cells • Two main types - both alive at maturity • Sieve tube element - lack a nucleus • Companion cells provide for both cells

31. Figure 23.7 Sieve tubes & Companion cells

32. Phloem cells • Two main types - both alive at maturity • Sieve tube element - lack a nucleus • Companion cells provide for both cells • Transports sugar • Moves under high pressure • Moves from source to sink (direction of movement can change!)

33. Phloem transport • To generate pressure • Actively load sugar (sucrose) into sieve tube cells • Water “follows” the sugar (osmosis!) • Sugar is actively unloaded where it is needed • Transport is from loading (source) to unloading (sink) • Direction of flow changes

34. Figure 23.23 How translocation works

35. Figure 23.23 How translocation works

36. Source cell(leaf) Vessel(xylem) Sieve tube(phloem) Loading of sugar (source!) 1 H2O Sucrose 1 Uptake of water 2 H2O 2 Sap Flow… 3 Bulk flow by positive pressure Bulk flow by negative pressure Sink cell(storageroot) Unloading of sugar (sink!) 4 3 4 Sucrose H2O

37. EXPERIMENT How can you test contents of phloem? Aphids pierce the pholoem but don’t cause it to stop flow… 25 µm Sieve-tubeelement Sapdroplet Sap droplet Stylet Stylet in sieve-tubeelement Separated styletexuding sap Aphid feeding

38. honeydew droplet

39. stylet of aphid

40. Storage roots • Store sugar (or starch) in the fall so phloem flows towards root in fall • These sugars fuel early spring growth so in spring flow is from root to shoot!

41. Circulation across the kingdoms • Plants and animals push extracellular fluids • Plants generate flow w/o muscle tissue • Animals generate flow with pumping muscles • Fungi move intracellular fluids • Use cytoplasmic streaming - Proteins inside the cytoplasm (actin mainly) “stir” the cytoplasm moving nutrients etc. to rapidly growing hyphae. • Protists use mainly diffusion and streaming