content: Types of skeletons, Tissues that make up the skeleton, Bone injuries, Human skeleton, Axial skeleton, Appendicular skeleton, Diseases of the skeletal system.
source of information from the Mind Action Series Life Sciences grade 11 textbook
THE SKELETON
- Supports
- Protects
- Enables movement
Types of skeletons:
HYDROSTATIC:
- Fluid-filled, closed chambers within an organism.
- Made of water.
Advantages:
- Changes shape – this allows movement.
o Muscles contract & push against water
▪ Creates pressure
Disadvantages:
- No protection (skeletal defence mechanism)
- Restricted movement.
- Confined to water.
- Remain small.
Examples:
- Soft-bodied invertebrates.
- Coelenterates
o Jellyfish
o Anemones
- Annelids
o Earthworms
- Nematodes
o Roundworms
How they move:
- Contracting muscles surrounding fluid-filled cavity creates pressure
causing change in shape
- Causes movement
o Jellyfish
▪ Contract bell-shaped form, forcing water out
▪ This propels them forward
o Earthworm
▪ Change shape to move forward by peristalsis
▪ Circular + longitudinal muscles produce waves of contraction +
relaxation.
, EXOSKELETONS:
- Surround the body of an organism
- Made of chitin outside of the body
o Chitin – substance found in cell walls of plants – it is light and strong
Advantages:
- Support + protection.
- Muscle attachment – allows movement.
- Joints – move easily.
- Waxy cuticle – reduces loss of water loss.
Disadvantages:
- Rigid – limits movement.
- Heavy – limits growth so remains small.
- Vulnerable while moulting.
How disadvantages are overcome:
- Moult / ecdysis (shed skeleton) – grow bigger.
- Jointed limbs – range of movements.
Examples:
- Arthropods
o Insects
o Crustaceans
ENDOSKELETON:
- Made of bone within the body.
Advantages:
- Support.
- Shape.
- Can grow – in living tissue.
- Protects internal organs.
- Muscle attachment allows movement.
Disadvantages:
- Not all soft tissues protected.
Examples:
- Mammals
o Humans.
Tissues that make up the skeleton:
- CARTILAGE
- BONE
The benefits of buying summaries with Stuvia:
Guaranteed quality through customer reviews
Stuvia customers have reviewed more than 700,000 summaries. This how you know that you are buying the best documents.
Quick and easy check-out
You can quickly pay through EFT, credit card or Stuvia-credit for the summaries. There is no membership needed.
Focus on what matters
Your fellow students write the study notes themselves, which is why the documents are always reliable and up-to-date. This ensures you quickly get to the core!
Frequently asked questions
What do I get when I buy this document?
You get a PDF, available immediately after your purchase. The purchased document is accessible anytime, anywhere and indefinitely through your profile.
Satisfaction guarantee: how does it work?
Our satisfaction guarantee ensures that you always find a study document that suits you well. You fill out a form, and our customer service team takes care of the rest.
Who am I buying this summary from?
Stuvia is a marketplace, so you are not buying this document from us, but from seller ambermcluckie. Stuvia facilitates payment to the seller.
Will I be stuck with a subscription?
No, you only buy this summary for R80,00. You're not tied to anything after your purchase.