Tissues, Organs, and Homeostasis Flashcards
What is homeostasis?
The dynamic constancy of the internal environment
Describe Negative Feedback?
- Change in conditions (stimulus) occurs in body
- Change is detected by sensors
- Info. is then fed to an integrating center that compared conditions at a set point
- Message sent to effector to initiate a response
- Response bring internal conditions back to set point
- Once at set point, sensor no long detects any change
What are antagonistic effectors?
Increasing activity of one effector is accompanied by a decrease in another
Describe Positive Feedback?
- Do not themselves maintain homeostasis
- Response is cumulative
- Is generally part of some mechanism that does
ex. blood clotting
What does surface area and volume effect?
- Mechanical demands on support structures
- Nutrient absorption rates
- Heat gain and loss
- Gas Exchange
Describe the root system in vascular plants?
- Anchors plant
- Absorbs water and minerals
Describe the shoot system in vascular plants?
- Supporting stems
- Photosynthetic leaves
- Reproductive flowers
Describe the cell walls in plants?
- Made of mainly cellulose
- Primary cell wall: found in all cells
- Secondary cell wall: found in some cells, increase mechanical strength of wall
Explain the three different tissue systems in roots, shoots, and leaves?
- Dermal tissue: for protection, wax and bark
- Ground tissue: for storage, photosynthesis, and secretion
- Vascular tissue: for conduction, xylem (water and dissolved minerals), phloem (nutrient containing solution)
What are meristems?
- Clumps of small cells with dense cytoplasm and large nuclei
- Act as stem cells do in animals (one cell divides producing a different cell or one that remains meristematic)
What are apical meristems?
- Located at tips of stems and roots
- Give rise to primary tissues
- The three primary meristems give rise to the three major types of plant tissue
What are lateral meristems?
-Exhibit secondary growth increasing the size of stems and roots
Describe dermal tissue?
- Forms the epidermis (usually only one cell layer thick)
- Cuticle
- Contains special cells: guard cells, trichomes, and root hairs
Describe Guard cells?
- Part of dermal tissue
- Flank a stomata, which is the passageway for oxygen and carbon dioxide
Describe Trichomes?
- Part of dermal tissue
- Uni or multicellular growths of epidermis
- Keep leaf surface cool and reduce evaporation
- Some are glandular secreting substances that deter herbivores
Describe Root Hairs?
- Part of dermal tissue
- Tubular extensions of individual epidermal cells
- Increase the root’s surface area and efficiency of absorption
What three cells types are in ground tissue?
- Parenchyma
- Collenchyma
- Sclerenchyma
Describe Parenchyma cells?
- Part of ground tissue
- Most common type of plant cell
- Provides storage, photosynthesis, secretion, provide little to no support