Ch 6: Bones

Question 1

How many bones are in the human body?

Answer 1

There are 206 bones.

Question 2

What is hematopoiesis?

Answer 2

It is the formation of blood cells in the bone marrow.

Question 3

What are the 5 functions of bones?

Answer 3

1. Support
2. Store minerals (calcium ions, phosphate ions)
3. Hematopoiesis
4. Movement
5. Protection

Question 4

Describe the axial vs appendicular bones.

Answer 4

1. Axial: head, neck, back, chest.
2. Appendicular: shoulders, arms, hands, legs, feet, pelvic bones.

Question 5

What kind of fibres is the bone made of?

Answer 5

Collagen fibres.

Question 6

What is the main component of the bone?

Answer 6

Calcium phosphate (mineral salt)+ calcium hydroxide + calcium carbonate.

Question 7

What is hydroxiapetite? What is its main component?

Answer 7

It is the thing that gives bone its flexibility, main component is calcium ions.

Question 8

What are osteoblasts?

Answer 8

Bone forming cells.

Question 9

What are their 6 types of bones? Give some egs for each.

Answer 9

1. Flat: made of 2 layers of compact bone, and middle layer of cancellous (spongy/trabecular) bone. Eg shoulder, brain, pelvis etc
2. Short: cubic shaped, handles weight, eg carpals + tarsals.
3. Irregular: various bone shapes, eg vertebrae
4. Long: has 1 epiphysis and 2 diaphysis, acts as a lever (pârghie)
5. Sesamoid: patella/kneecaps
6. Wormien: sutures in brain

Question 10

What is the articular cartilage?

Answer 10

It is a type of frictionless hyalin cartilage that is found in each epiphysis.

Question 11

What is the periosteum?

Answer 11

It is the outer layer of the diaphysis made of connective tissue.

Question 12

What types of bone are on the inside and outside of epiphysis?

Answer 12

On inside => spongy bone, on outside => compact bone.

Question 13

What is the traveae?

Answer 13

Spaces with red bone marrow in spongy tissue.

Question 14

What is the endosteum?

Answer 14

It is a layer that lines the medullary cavity, it has the osteoblasts and osteoclasts.

Question 15

What are osteons?

Answer 15

They are compact rings made of lamella.

Question 16

When does bone formation start, what is it marked by?

Answer 16

Bone formation starts at 6th week marked by the appearance of rods (tije) of hyalin that present long bone form.

Question 17

What is intermembranous ossification?

Answer 17

In flat bones of skull, osteoblasts go to membranes to form OSSIFICATION CENTRES that secrete matrix (collagen, CacO3, Ca3PO4), that causes OSSIFICATION to occur, red marrow deposits at level of trabecula.

Question 18

Describe endochondral ossification.

Answer 18

It is in long bones.
Blood vessels are formed inside the cartilaginous rods, medullary cavity forms + bone elongates + thickens => increase length.

Question 19

What happens to long bones after puberty?

Answer 19

After puberty the EPIPHYSAL PLATE of long bone forms meaning it no longer elongates.

Question 20

Does bone remodelling ever stop throughout life.

Answer 20

No, cz of osteoblasts and osteoclasts.

Question 21

What is osteoporosis? How to prevent it?

Answer 21

It is when the Ca in the body decreases causing bones to become weaker so they break easier. Prevention is through exercise/calcium supplements.

Question 22

What are menisce?

Answer 22

Knee joints in shape of crescents.

Question 23

What are bursae?

Answer 23

A type of fluid filled sacs diarthrosis. On inside of synovial mbs.

Question 24

What do osteoblasts become?

Answer 24

Osteocytes.

Question 25

What are the 17 types of joint movements, explain them.

Answer 25

Flexion: bending joint to reduce space between 2 bones.
Extension: increase angle between 2 bones.
Abduction: removing something away from midline of body.
Adduction: bringing something towards the midline of the body.
Medial rotation: rotating a bone along its own axis.
lateral rotation: rotating a bone away from the midline.
circumduction: movement of joint in circles.
supination: palm up.
Pronation: palm down.
elevation: lifting part.
Depression: lowering part.
Protraction: pushing part of body forward.
retraction: withdrawing part of body eg. Chin tuck.
Dorsal flexion: moving upwards towards body.
plantar flexion:moving foot downwards.
Inversion: turning sole of foot inwards.
Eversion: turning sole of foot outwards.

Question 26

What are the 6 types of synovial joints (diarthrosis) describe where they can be found and if they’re biaxial uni axial or no axial.

Answer 26

1. Trohlear: found in elbow (ulna + humerus) and knee (between femur and tibia)
2. Sferoidal: at shoulder, at hips.
3. Pivotal: in neck ( between axis and atlas)
4. Condyloid/ellipsoidal: biaxial, joint between radius and carpals
5. Selara (saddle): biaxial, thumbs (between 1st metacarpal and trapezium bone)
6. Planar: no axial, between certain carpal and tarsal bones.