Stem cells

Although the stem cells could be considered a tissue, they are treated separately due to their importance to animal growth and development.
[Animal] stem cells are analogous to [plant] meristem cells.
Stem cells retain the ability to divide throughout the life of the animal.
The daughter cells from meristem may remain meristematic, or may differentiate to other tissues.
The ultimate stem cell is the zygote.

body plans

• symmetry
• radial
• bilateral
  cephalization
• head
• thorax
• abdomen
• tail
• skeletal support
• exoskeleton (invertebrate)
• endoskeleton (vertebrate)
• body cavity
• aceolomate
• pseudoceolomate
• ceolomate

tissues

• tissues are groups of contiguous cells
• differentiated to provide the same function

epithelial tissue

• simple
• cuboidal
• squamous
• columnar
• stratified
• squamous
• pseudostratified columnar

connective tissue

• loose
• adipose
• dense
• cartilage
• bone
• blood

muscle tissue

• skeletal
• cardiac
• smooth

nerve tissue

• cell [neuron]: dendrite→body→axon
• reflex arc
• sensory neuron
• interneuron(s)
• motor
• synapse & neurotransmitters

organs

Tissues (usually several types) are assembled into larger [macroscopic] structures each of which provides a function(s) at the whole animal level.

organ systems

integumentary

reproductive

respiratory

circulatory

excretory

digestive

musculature

skeletal

nervous

endocrine

immune

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© 2004-2005 TwoOldGuys ™

revised 19 aug 2006