Vertebrates 6 - Skeletal system

Question 2

Cartilage

Answer 2

Rigid, flexibility, tensile strength.

Question 3

Structure of cartilage

Answer 3

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

Question 4

Hyaline cartilage

Answer 4

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

Question 5

Elastic cartilage

Answer 5

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

Question 6

Fibrocartilage

Answer 6

Pretty rigid. Intervertebral disks (shock absorber)

Question 7

Cellular cartilage

Answer 7

Agnathan internal skeleton. Less matrix, more cells.

Question 8

Calcified cartilage

Answer 8

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

Question 9

Bone

Answer 9

More vascular; mineralized, dense, hard.

Question 10

Cells in bones

Answer 10

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

Question 11

Bone structure

Answer 11

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

Question 12

Membrane/Dermal Bone

Answer 12

Skull. Near body surface/beneath dermis

Question 13

Endochondral

Answer 13

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

Question 14

Functions of bone

Answer 14

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

Question 15

Fibrous joints

Answer 15

aka sutures. Immovable. example: in skulls.

Question 16

Cartilaginous joints

Answer 16

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

Question 17

Snake jaws

Answer 17

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

Question 18

Synovial joints

Answer 18

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

Question 19

Synovial fluid

Answer 19

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

Question 20

Reading: Cortical and cancellous bone

Answer 20

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

Question 21

Reading: Birds bones vs mammal bones

Answer 21

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

Question 22

Reading: Bone turnover

Answer 22

Rate of bone reuptake and formation. Constantly in flux

Question 23

Reading: what is osteoporosis? What are risk factors?

Answer 23

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

Question 24

Reading: Four experiments with rat osteoporosis

Answer 24

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.

Question 25

Reading: What part of femur had most bone loss?

Answer 25

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

Question 26

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

Answer 26

Decrease in metaphysis and epiphysis because no strain from gravity.

Question 27

Reading: OVX and treadmill rats

Answer 27

More stress prevented loss of bone compared to non-exercise

Question 28

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

Answer 28

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.

Question 29

Reading: how does estrogen work?

Answer 29

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

Question 30

Reading: what conclusions does this study of osteoporosis have?

Answer 30

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