Concept List: Transition to Land Flashcards
What skeletal and anatomical changes are necessary for the transition to land?
- Thickening of bones, fusing skull
- Increased musculature
- Higher metabolic rate
What are the basic physical differences between the aquatic and land environments?
Water: less O2, buoyancy, constant motion (suction), high density, water abundant.
Land: More O2, no buoyancy to support, variable temperature, low density, water limited.
What are the different types of vertebrae and where are they found?
Cervical: neck
Thoracic: midback
Lumbar: low back
Sacral: fused at the base of spine
Coccygeal: tailbone
List the advantages and disadvantages to moving to land
ADVANTAGE
1. New food sources (need more food on land tho)
2. Avoidance of aquatic predators and competitors
3. Oxygen abundant (easier to obtain)
DISADVANTAGE
1. Water is a limiting factor in distribution (desiccation, respiration, reproduction)
2. No buoyancy to counteract gravity – necessitates morphological changes and greater energetic costs
3. Extreme temperature variation
Understand the formation of the different types of bone
Intramembranous:
1. Increased vascularity of tissue
2. Proliferation of mesenchymal cells
3. Osteoblasts lay down osteoid (matrix)
4. Osteoblasts retreat or become trapped as osteocytes
5. Osteoid calcifies to form spongy bone
6. Bone remodeling (growth)
Endochondral:
1. Form cartilage
2. Primary center of ossification forms in cartilage, then same steps as intramembranous ossification
