Vertebrates 6 - Skeletal system Flashcards Preview

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Flashcards in Vertebrates 6 - Skeletal system Deck (29)
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2

Cartilage

Rigid, flexibility, tensile strength.

3

Structure of cartilage

Living chondrocytes secrete ECM (high in collagens and glycoproteins). Chondrocytes are in lacunae. Chondroblasts are precursors

4

Hyaline cartilage

in ends of bones/ribs, larynx, trachea. Pretty rigid

5

Elastic cartilage

Less rigid. Has more elastin. Pinna of ear, epiglottis.

6

Fibrocartilage

Pretty rigid. Intervertebral disks (shock absorber)

7

Cellular cartilage

Agnathan internal skeleton. Less matrix, more cells.

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Calcified cartilage

Internal skeleton of Chondrichthyes. Rigid, almost as rigid as bone.

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Bone

More vascular; mineralized, dense, hard.

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Cells in bones

Osteoblasts: precursors; Osteocytes: secretory; osteoclasts: bone reuptake

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Bone structure

Osteocytes secrete matrix and collagen, organized. Mineral deposit there, esp. Ca2PO4.

12

Membrane/Dermal Bone

Skull. Near body surface/beneath dermis

13

Endochondral

Long bones; form from cartilage; spongy and/or compact; have bone marrow

14

Functions of bone

support and shape of body. Locomotion. Ion reservoir. Marrow (RBC)

15

Fibrous joints

aka sutures. Immovable. example: in skulls.

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Cartilaginous joints

aka symphyses. Some flexibilty. Eg. in b/w pubic bones (becomes more loose with prostaglandins at birth), mandibular (two halves - no flexibility in humans)

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Snake jaws

No mandibular symphysis, rather an elastic ligament. Helps swallow large prey. Also have double joint at quadrate bone.

18

Synovial joints

Mobility. Knees, etc. Contain synovial membranes b/w joints to seal it and secrete synovial fluid. Cartilage (hyalin) protects ends of bone.

19

Synovial fluid

Contains glycoproteins, lipids. Acts as lubricant in a synovial joint

20

Reading: Cortical and cancellous bone

aka compact and spongy bone, respectively. Both are important in strength of bone.

21

Reading: Birds bones vs mammal bones

Less compact bone to spongy bone. Less weight, but a bit less strong.

22

Reading: Bone turnover

Rate of bone reuptake and formation. Constantly in flux

23

Reading: what is osteoporosis? What are risk factors?

Decrease in bone density. Postmenopausal women or post ovariectomy, women have generally lower density (less weight and muscle), lifestyle, nutrition

24

Reading: Four experiments with rat osteoporosis

1. OVX or sham - measure bone loss. 2. OVX, then 2 weeks in space or earth. 3. OVX or sham, treadmill. 4. OVX or sham, cut sciatic nerve + estrogen replacement.

25

Reading: What part of femur had most bone loss?

Metaphysis spongy bone, middle is nearly hollow. Epiphysis had little change.

26

Reading: What happened to the rats on the space shuttle?

Decrease in metaphysis and epiphysis because no strain from gravity.

27

Reading: OVX and treadmill rats

More stress prevented loss of bone compared to non-exercise

28

Reading: what happened to the rats with sciatic nerve cut?

Loss bone in epiphysis and more in metaphysis. Less loss if leg was stressed (can’t move on own), and less loss with estrogen replacement.

29

Reading: how does estrogen work?

Estrogen stimulates apoptosis in osteoclasts so less reuptake, and stimulates a bit of bone formation.

30

Reading: what conclusions does this study of osteoporosis have?

Exercise is important to maintain bone density; nutrition is important; some drugs (bisphosphonates) slow osteoclasts