Support Systems Flashcards
turgor pressure
fluid within vacuole provides turgidity to help stand upright
parenchyma
in the pith, thin primary cell walls to increase size for solid structure
collencyhma
in the cortex, primary cell wall with thickening (tissue outside cell) to allow flexibility
pith/cortex relationship
parenchyma presses on collenchyma
vascular bundles
containing xylem which is hollowed via apoptosis for water transport and solidified with lignin for support
sclerencyhma
surrounds vascular bundles, thick secondary wall to make them large, flexible and elastic
tap root
provides anchorage and stability
lateral roots
involved in absorption of water and dissolved minerals
hydrostatic skeleton
made up of water, capsule of fluid surrounded by circular and longitudinal muscle which contract in order for movement
exoskeleton
external hard structure for protection of soft tissue, providing strength and stability, made of chitin which is mineralised
limitations of exoskeleton
doesn’t grow with body so animal sheds exoskeleton (ecdysis) which leaves it vulnerable until exoskeleton regrows
endoskeleton
internal structure, size limiting, provides rigid system for muscle contraction and organ protection
cartilaginous endoskeleton
made of calcified cartilage, light and flexible but must be thin because cartilage is avascular so gas exchange required via diffusion
bony endoskeleton
dynamic so respond to physiological loading
medullary cavity
centre of bone, reduces weight and increases strength to resist compression
