Lesson Plan For Primary School Science

Important of skeletal system:
Provide physical support

Attachment for muscles
- function in locomotion

Protection for the bodies
- protect the limb of organism

Exoskeleton
√Skeletal system on the outside of the body.
√Chitin shell is secreted by the mantle.
√Thin sheet of epithelial tissue that extends from body wall.

1st layer: Cuticle
√Made up of very thin laminations of chitin
√Wings, hair, legs
√No cell, unable to grow
√2 parts: epicuticle & procuticle


3 layers of exoskeleton:


2^nd layer: Epidermis
Made up of a layer of living cell that secrete chitin making up the outer cuticle.

3^rd layer: Basal membrane
Separate epidermis from internal body fluids and organs.

Cockroach molt exoskeleton

√Undergo the growth process
√Exoskeleton will split down the back and force it to climb out from the old cuticle.
√Takes six or seven molts for a newly hatched cockroach to reach sexual maturity.

Molt of exoskeleton:


Attachment of muscles on exoskeleton:
√Join of muscle to part of exoskeleton
√Allow muscle contraction
√Move, fly
Example: flexor and extensor muscle


The two main muscles:
√Extensor tibiae muscle which causes the leg to extend
√Flexor tibiae muscle which causes the leg to flex.
√These tendons can be seen by removing the cuticle from one side of the leg in the joint region.