Lec 25 skeletal system diversity exam 3

What is the skeletal system do?

• rigid support for the muscles to pull on

• can create movem

Three types of skeletal systems

• hydrostatic skeletons

• Exoskeletons

• endoskeletons

hydrostatic skeletons

• soft bodied invertebrates

• depend on pressure differences

• fluid enclosed in cavity surrounded by muscle

a hydrostatic animal

worm

even human have hydrostatic parts like discs inbetween vertebr

Exoskeleton

• insectcs/ anthropods

• rigid outer structures

• muscles causes segmented strucutres to move

• muscle attachment on inner surfaces

• mollusks

• anthropods

mollusks have which type of skeleton

exo

• protein filaments

• calcium carbonate crystallization

Anthropods have which type of skelton

• Exo

• chitin

• cuticle (of chitin)

• secreted by layer of cell under exoskelton

• hardens except at joints

Molting

• parts of growth of animals with exoskeleton

• shedding old exoskelton

• expansion to larger size

• depositing new exo

• bugs crabs

Vertebrate Endoskeleton

• mamals, bird, fish

• Bones

• cartilage

Bones are made of what?

• rods, tubes, plates

• joint

• inorganic component - hydroxyapatite

• organic component - fibers (collagen)

Cartilage

• is cell produces tough matrix

  • polysaccharides

  • protein- mainly collagen fibers

• joint surfaces

• stiff, flexible structures

  • larynx

  • nose

• cartilaginois fishes

• embryonic precursor for bone

Bones can serve as a ____

Bank

What can bones do ?

• regulate calcium homeostasis

• endocrine/ hormonal regulation

  • withdraw or deposir calcium

____ composition can lead to issues

ireegular

You want a good ration of calcium phosphate to

collagen

too much calcum phosphate means

brittle bones

too much collagen means

bones too flexible (rickets)

Types of bone cells

• osteoblasts

• osteocytes

• osteoclasts

osteoblasts

• deposit new bone matric

• grows bone tissues

osteocytes

• osteoblasts when they are surrounded by bone matrix

osteoclasts

• dissolve bone matric

• release calcium unto ECF

Types of bones

• Membranous bone

• cartilage bones

Membranous bones do what?

• forms on a scaffold of connective tissue membrane.

What is an example of membranous bone ?

• out bones of skull

Cartilage bone does what

• first forms as a cartilaginous structure that looks like future mature bone, then slowly harden/oddifies into bone

examples of carilage bones

• bones of limbs

• can grow thro ossification process

long bones growth

• endochondral ossification

• pits created in center of shaft (bone marrow)

• secondary centers created

• epiphyseal cartilage maintained throughout development

Where is the site of bone elongation during growth?

epiphyseal cartilage

• maintained throughout development

the second step of long bone growth

pits created in center of shaft

• blood vessels enter

• osteocyte activity

• osteoblasts then deposit bone matric

The third step of long bone growth

• secondary centers created

  • epiphysis

compact bone

• solid and hard

cancellous bone

• is rigid but having interbal cavities and looking spongy

  • ends of long bones

spongy bones

• trabeculae

• no haversian canals -

• density sepends on stress load

why do spongy bones have no haversian canals

Muscle work ____

unidirectionally

• need antaonist muscle to move in the opposite direction

synergists

• muscles working in same direction