skeletal muscle

Question 1

what is the function of skeletal system?

Answer 1

• suppport
• storage minerals
• blood cell production
• protection
• leverage

includes: skeleton, cartilage, tendons

Question 2

what is bone matrix?

Answer 2

• reinforced concrete
• rebar COLLAGEN fibers
• cement HYDROXYAPETITE
• mineral removed too bendy
• collagen removed, too brittle

Question 3

what are osteoblasts? what is ossification and osteocytes

Answer 3

• formation bone through OSSIFICATION or OSTEOGENESIS
• ossification: formation bone by osteoblasts.
  osteocytes: mature bone cells.
  lacunae: spaces occupied by osteocyte in body

Canaliculi: canals occupied cell processes
-nutrients diffuse through tiny amount liquid surrounding cell filling lacunae and canaliculi. transfer nutrients one cell to next through gap junctions.

Question 4

What do osteoclasts do?

Answer 4

• release enzymes that digest bone.
• multinucleated
• stem cells. mesenchyme(osteochondral progenitor cells) become chondroblasts or osteoblasts

Question 5

what are the shapes of bones?

Answer 5

long-upper and lower limbs
short- carpals and tarsals
flat- ribs, sternum, skull, scapulae
irregular- vertebrae, facial

Question 6

what is the ground matrix?

Answer 6

calcium and phosphate make hydroxyapatite. protein collagen fiber.

Question 7

what is the diaphysis of bone?

Answer 7

• shaft

- compact bone

Question 8

what s the epiphysis of bone?

Answer 8

• end of bone

- cancellous

Question 9

what is the epiphyseal growth plate?

Answer 9

-hyaline cartilage, present until growth stops

Question 10

what does the epiphyseal line do ?

Answer 10

-bone strops growing length

Question 11

what is the function of medullary cavity?

Answer 11

• in children red. medullary cavity red marrow. changes to yellow.

Question 12

what is significant about flat bones?

Answer 12

• no diaphysis, epiphysies

- sandwich cancellous between compact

Question 13

what is significant about short and irregular bones?

Answer 13

• compact bone surrounds cancellous centre

- no diaphysis not elongated

Question 14

what is the function of periosteum?

Answer 14

• isolates and protects bone from surrounding tissue
• provides routes and place attachment for circulatory and nervous supply. participates bone growth and repair. attaches bone to ct network of deep fascia
• superficial layer ct over compact bone

Question 15

what is the function of endosteum?

Answer 15

• superficial layer ct over compact bone

- active during growth bone and when repair or remodeling underway

Question 16

what are the two types of osseous bone?

Answer 16

cancellous bone- made trabecular, network struts and plates

compact bone-forms walls

*compact and osseous bone are two types osseous bone

Question 17

what is the structure of compact bone?

Answer 17

central or haversian canals: contain blood vessels supply osteon

perforating or volkmanns canal: blood vessels deliver blood to osteons service medullary cavity. directs flow nutrients from vessels through cell processes of osteoblasts and one cell to next

Lamellae ( 3 kinds)

concentric lamellae-series concentric rings around canal

interstitial lamellae- fill in spaces between osteons and compact bone

circumferential lamellae- form outer and inner surfaces of shaft

osteon or haversian system: associated concentric lamellae and osteocytes

Question 18

what is the function of spongy bone?

Answer 18

arranged plates called TRABECULAE.
-osteons present if thick.

• open framework lighter than compact one
• consdierable strength. easier for muscles to move bones
• found where bones NOT stressed heavily or where stresses arrive from multiple directions
• structural bone

Question 19

what is osteogenesis?

Answer 19

• bone development and growth
• bony skeleton forms about 6 weeks after fertilization
• bone growth continues until age 25.

Question 20

what is intramembranous ossification?

Answer 20

• forms skull bones, part mandible, diaphysis of clavicles
  stages:
  1: differentiation of osteoblasts within mesenchyme: Osteoblasts cluster together start secrete organic components of matrix. location where ossification begins ossification centre

2 formation of bony spicules: osteoblasts differentiate into osteocytes. remained trapped in lacunae

3. bone growth active process and osteoblasts require o2 and reliable supply nutrients. blood vessels branch within region grow between spicules, rate bone growth accelerates.

4 formation spongy bone: deposition of bone plate perforated by blood vessels. adjacent plates fuse together, bone structure becomes complex

Question 21

What is Endochondral Ossification

Answer 21

• bone development and growth
• bones base of skull, part mandible, epiphyses of clavicles, most of remaining bones of skeletal system
• catrilage formation begins at end of 4th week
  stages: begins with formation of hyaline cartilage model. cartilage models grow by expansion cartilage matrix-INTERSTITAL GROWTH and by production of more cartilage at outer surface -APPOSITIONAL GROWTH
  1. cartilage enlarges chondrocytes near centre shaft which increases greatly in size. surrounding matrix calcify. chondrocytes die
  2. blood vessels grow around edges cartilage, cells perichondrium differentiate into osteoblasts. perichondrium now converted into periosteum. inner osteogenic layer produces bone collar; thin layer compact bone around shaft cartilage
  3. changes under way; blood supply to periosteum increases, capillaries and osteoblasts migrate to heart cartilage invading spaces left by disintegrating chondrocytes. calcified cartilaginous matrix breaks down, osteoblasts replace with spongy bone.
  4. diameter is small entire shaft is filled with spongy bone. but as enlarges, osteoclast erode central portion and creates medullary cavity. bone of shaft becomes thicker, cartilage metaphysics invaded by osteoblasts that produce columns of bone.
  5. capillaries and osteoblast migrate into centre of epiphyses, creating secondary ossification enters.