lecture 18 - muscles and skeletons

Question 1

What are exoskeletons?

Answer 1

Covers the outer surface of the body

For protection, support and a site for muscles to attach (from the inside)

Exoskeleton composition differs in different invertebrates

Frame for the body - gives it shape and form

important for movement

Question 2

Describe the mollusc shell exoskeleton

Answer 2

Mollusc shells are made of a composite material (calcium carbonate & protein)

Secreted by the mantle

Calcium carbonate hard but brittle - protein makes shell less brittle

Diameter of shell can be extended to allow growth - growth of animal limited by how fast material can be added to shell

Question 3

Describe the arthropod exoskeleton

Answer 3

Arthropod exoskeleton made of a cuticle containing chitin (polysaccharide fibrils) embedded in a protein matrix

Shell hardened by addition of calcium carbonate

Shell needs to be shed during growth

Question 4

What is the endoskeleton?

Answer 4

For protection of internal organs (ribcage protects heart and lungs, skull protects brain)

Muscle attached (via tendons) to enable movement

Divided into axial (trunk of body) & appendicular skeletons

Question 5

Describe bone structure

Answer 5

Bone comprises 1/3rd collagen and 2/3rds calcium phosphate crystals (hydroxyapatite)

Bones rigid, connected by joints which allow movement (e.g. hinge joint)

Diaphysis is shaft of bone and epiphysis is ends where joints form

2 types of bone tissue: compact (surrounds bone marrow cavity in diaphysis) & spongey (in the ends)

Question 6

What are osteoblasts?

Answer 6

bone forming cells

Question 7

What are osteocytes?

Answer 7

mature bone cells

Question 8

What are osteoclasts?

Answer 8

involved in breakdown and repair

Question 9

What are hydrostatic skeletons?

Answer 9

Fluid filled cavity for support

Muscles exert pressure on the cavity to produce movement

Uniform volume

not as much support as other types of skeleton but still cushions

made up of circular and longitudinal antagonistic muscle

Question 10

What are the functions of skeletons?

Answer 10

Movement

Protection

Support