Endocrinology - introduction to bones

Question 1

What makes up main components of musculoskeletal system?

Answer 1

muscle, bone skeleton

Question 2

What are 3 parts of connective tissue ?

What are their function?

Answer 2

tendon - joins muscle to bone

ligaments - connect bone to bone

cartilage - structural support, protect tissues, attachment sites

Question 3

What are 2 types of bones?

Answer 3

Flat and long bones

Question 4

What are 5 functions of skeleton?

Answer 4

Support, protection, movement, storage of Ca and phosphate, produce blood cells

Question 5

How do you produce each bone type?

Answer 5

Flat - intramembranous mesenchymal cells converted into bone

long - endochondral mesenchymal to cartilage to bone

Question 6

What is the process to produce flat bones called?

Answer 6

intranmembranous ossification

Question 7

What is process of IO?

Answer 7

mesenchymal cells in connective tiusse condense and differintate into osteoblasts

they secrete oestoid that causes osteblasts to bcome oestocytes

ossification centre fuse together to form trabecular matrix (SPONGY BONE)

on outer surface mesenchyma cells fuse togehter stongly to form periosteum

then compact bone develops on outside of cancellous (spongy) bone. And crowded blood vells condense into red bone marrow

https://www.youtube.com/watch?v=gh6J2CHR_q4

Question 8

What is the process to form long bones?

Answer 8

Endochondral ossification

development of long bone from hyaline cartilage model

Question 9

1st Stepsof endochondral ossification?

Answer 9

1st - formation of collar bone by invading of blood vessles that cause osteoblast to be formed and release bone matrix

(this area of activity called primar oesification centre)

Question 10

2nd Stepsof endochondral ossification?

Answer 10

cavitation - chondryctes enlarge + send signal for cartilage to calicfy

causes matrix to become impermable to nurtients and die + central clearing

Question 11

3rd step of EO?

Answer 11

periosteal bud invasion- invades cavity and causes spongy bone to be made also delivers osteoclasts(remove cartilage) and blasts (produce spongy bone)

Question 12

4th step of EO?

Answer 12

diaphysis (primary ossification centre) - enlarging mainly spongy bone

Question 13

5th step of EO?

Answer 13

secondary ossification centres epihpyseal forms and only start to ossidify after birth

cartilage only remains at bone surface and at epiphyseal plates

Question 14

what are bones made up of?

Answer 14

matrix and cells

Question 15

What cells are bone stem cells?

Answer 15

osteogenic cell

Question 16

What are osteoblasts and where are they found?

Answer 16

bone forming cells, secrete osteoid

cause minerealisiation of oesteoid

Found in growing portions of bone such as periosteum and endosteum

Question 17

What are osteocytes and where are they found?

Answer 17

matyre bone cells, when osteoblasts imbedded in its secretions.

senses strain to direct osteoblast/clast activity

found entrappped in matrix

Question 18

What are osteoclasts and where are they found

Answer 18

bone breaking, dissolve bone by phagocytsosis, derived from bone marrow

found: bone surfaces and sires of old injured or unneeded bone

Question 19

What makes up bone matrix?

Answer 19

Organic components - T1 collagon, ground substace like proteoglycans and glycoproteins and cytokines

inorganic component - calcium hydroxyapatite, osteocalcium phosphate

Question 20

What are types of bone?

Answer 20

immature - first bone layed down and in woven manner quite weak. becomes replaced by mature

mature bone - mineralized woven bone, lamellar (layer) structure - v strong

Question 21

2 types of mature bone?

Answer 21

• cortical/lamellar, compact and strong
• cancellous/spongy - honeycomb strucutre, not suitable for weight baring activity

Question 22

How doe cortical and cancellous present in bones of body?

Answer 22

cortical - shell on outside, the unit of one is osteon

Question 23

How is cortical bone organized?

Answer 23

repeated units of ‘osteons’

lamellae around a ‘haversian central’ - contains blood, vien and nerve

lacunae - small spaces containing osteocytes, tiny canaliculi radiate from lacunae filled with EC fluid

volkmans canal - transverse perforating canals

Question 24

Label diagram

Answer 24

periosteum - connective covering

outer cortex - compact bone

medullary cavity - yellow bone marryow

articular cartilage - surface of bone at joints

Question 25

What is the growth plate in long bones?

Answer 25

physeal bone plate

Question 26

What are 2 types of bone growth?

Answer 26

insterstital - long bones only and increase in lnegth appositonal - mainly children and increase thickness and diameter

Question 27

How do long bones grow? (intersititial)

Answer 27

physeal plate, that normally has hylaine cartilage epiphyseal side - hyaline cartilage divide form hyaline cartilage matrix diaphyseal side - cartilage calcifies and dies replaced by bone

Question 28

What is mechanism of appositional growth?

Answer 28

deposition of bone beneath periosteum to increase thickness

Question 29

Steps of appositional growth?

Answer 29

1. ridges in periosteum creates groove for periosteal blood vessel 2. ridges fuse and form endosteum lined tunnel 3. osteoblasts in endosteum build new lamellae towards centre of tunnel new osten 4. bone grow outwards as osteoblasts in peristeum build new lamellae. osteon formationrepeated as new periosteal ridges.

Question 30

What are 3 types of joints?

Answer 30

**Fibrous joints** (also sutures) are joints in which bones are joined by dense connective tissue.The joints between bones of the cranium **Cartilaginous joints** are joints in which bones are joined by cartilage. (vertebrae in the spine) **Synovial joints** are characterized by a fluid-filled space, called a synovial cavity, between the bones of the joints.

Question 31

What are the joints that come under synovial joint?

Answer 31

Question 32

Which joint is most common and mobile?

Answer 32

Synovial joint

Question 33

What is structure of joint capsule?

Answer 33

articular capsule (outer) that keeps bones togehter synovial membrane(cavity) - contains synovial fuild secreted by synovial lining SF - reduce friction, high liubrication

Question 34

How are synovial joints stabilized?

Answer 34

By muscle/tendons ligaments bone surface conguirty

Question 35

How do ligaments stabilise a joint?

Answer 35

prevent excessive movement that damage to a joint the more and tighter ----\> greater stability + LESS mobility (less stability more risk of dislocation)

Question 36

What ligaments laxity? And how can it an affect

Answer 36

(usually natural) loose ligements leads to hypermobility and greater risk of injury

Question 37

Factors affecting stability?

Answer 37

joint articular joint capulse ligaments muscles moblity

Question 38

Compare Hips Vs shoulder

Answer 38