Unit 4 A transport and respiraton Flashcards
What is always a consequence of the evaporation of water from mesophyll in leaves of a healthy planet?
Water moves up in the stem in the xylem
What occurs at gas exchange surfaces in the lungs of mammals?
- Gasses diffuse across a moist surface
- Concentration gradients are maintained by ventilation
- Water is lost
For what reason do large organisms need specialized gas exchange structures?
They have a relatively small surface in contact with outside
What can be seen in a plain diagram of a leaf?
Chloroplasts in palisade cells and position of waxy cuticle
What causes the expansion of the thorax during inspiration?
The contraction of the diaphragm and external intercostal muscles
Which variable must be controlled if transpiration rates are compared in different plant species?
- Total leaf surface area
- Room temp
What happens during inhalation?
External intercostal muscles? Contract
Movement of ribs? Rise
Which is a feature of phloem sieve tube cells?
No nucleus
What is the role of the Sinotrial SA node?
To stimulate the contraction of the walls of the atria
Phloem transports organic molecules from the leaves to other parts of the plant. How are phloem sieve tubes adapted for this function?
Sieve tubes have pourus endplates that allow the cytoplasm to move freely between adjacent cells
What distinguishes capillaries from other blood vessels?
They have thin permeable walls to allow exchange of materials between tissue and blood
Which characteristic of the subclavian vein distinguishes it from subclavian artery?
Larger lumen
Which structure sends messages to the Sinoatrial node of the heart to cause changes in heart rate?
medulla of brain
