SKELETAL TISSUE Flashcards by humaira afzal

what does the skeletal system include?

bones of skeleton
cartilage
ligaments 
tendons 
CT

How well did you know this?

Not at all

Perfectly

what is the function of skeletal system?

Structural support
Levers:change direction of forces generated by skeletal muscle
protection, storage, blood cell production

How well did you know this?

Not at all

Perfectly

what is cartilage?

supporting CT

How well did you know this?

Not at all

Perfectly

what does cartilage contain?

gelatinous matrix: ground substance and fibres

How well did you know this?

Not at all

Perfectly

what are cartilage cells?

chondrocytes occupy lacunae

How well did you know this?

Not at all

Perfectly

what are the characteristic of cartilage?

Poorly vascularised
Exchange nutrients/waste occurs by diffusion
heals slowly

How well did you know this?

Not at all

Perfectly

what is cartilage derived from?

embryonic mesoderm

How well did you know this?

Not at all

Perfectly

what is mesoderm made of?

mesenchyme

How well did you know this?

Not at all

Perfectly

how is cartilage separated from surrounding tissue?

by perichondrium

How well did you know this?

Not at all

Perfectly

how many layers does perichondrium have?

2 layers
Outer fibrous irregular CT layer
Inner cellular layer

How well did you know this?

Not at all

Perfectly

what are the 3 types of cartilage?

hyaline, elastic, fibrocartilage

How well did you know this?

Not at all

Perfectly

what does hyaline cartilage contain?

translucent matrix

covered by dense perichondrium

How well did you know this?

Not at all

Perfectly

what does the matrix contain?

closely packed collagen fibres

How well did you know this?

Not at all

Perfectly

what does the matrix provide?

Provides tough but flexible support

How well did you know this?

Not at all

Perfectly

give examples of hyaline cartilage

Connect ribs & sternum

Nasal cartilages & resp tract

How well did you know this?

Not at all

Perfectly

what is articular cartilage?

cover opposing bone surfaces joints e.g. knee & elbow

How well did you know this?

Not at all

Perfectly

what is elastic cartilage?

Contains many elastic fibres: resilient & flexible

Tolerates distortion - returns back to shape

How well did you know this?

Not at all

Perfectly

give examples of elastic cartilage?

External flap outer ear, epiglottis, larynx

How well did you know this?

Not at all

Perfectly

what does fibrocartilage contain?

little ground substance

matrix dominated by large collagen fibres which are densely interwoven

How well did you know this?

Not at all

Perfectly

what is a characteristic of fibrocartilage?

Tough & durable:
resists compression
absorbs shocks
prevents damaging bone to bone contact

How well did you know this?

Not at all

Perfectly

give examples of fibrocartilage

Pads between spinal vertebrae
Between pubic bones in pelvis
Around/within some joints & tendons

How well did you know this?

Not at all

Perfectly

what are the 2 mechanism of cartilage growth?

interstitial

appositional

How well did you know this?

Not at all

Perfectly

what happens in interstitial growth?

Chondrocytes: undergo cell division -additional matrix

Enlarges cartilage from within

How well did you know this?

Not at all

Perfectly

what is interstitial growth important in?

Important during embryonic development

How well did you know this?

Not at all

Perfectly

what happens in appositional growth?

New layers added to surface | Inner layer of perichondrium divides

what happens to cells in appositional growth?

cells - immature chondrocytes - cartilage matrix - differentiate mature chondrocytes

what is the source of new cartilage cells?

fibroblasts

why is appositional growth important?

increases size of cartilage by adding to outer surface

what is the role of hyaline cartilage in growing bone?

Initial skeleton of foetus | Each cartilage is miniature bone model

what is the precursor of bone developed by?

endochrondral ossification

what is osteogenesis?

Bone formation & growth

when does osteogenesis take place?

begins 6 wks after fertilisation, continues through fertilisation

what is ossification?

replacement of cartilage & CT by bone

what are the 2 forms of ossification?

Endochondral | Intramembranous

what is endochondral ossification?

Bone replaces existing cartilage | 6 wk embryo cartilaginous models of limb bone replaced by bone

what happens in endochondral ossification?

Begins near middle of shaft 1o centre of ossification Centre of epiphyses (head) calcify: 2o ossification centre Epiphyses: filled with spongy bone

what bones are affected by endochondral ossification?

extremities & axial weight bearing | e.g. Femur, vertebrae

what is intramembranous ossification?

Bone develops from mesenchyme / CT | Stem cells within connective tissue differentiate osteoblasts

what happens in intramembranous ossification?

Mesenchymal cells cluster & secrete matrix Calcification occurs mesenchymal cells osteoblasts Ossification begins = Ossification Centre 1st forms spongy bone: remodelling: compact bone

what bones are affected by intramembranous ossification?

flat bones: skull, mandible, clavicle

what are the components of bone?

supporting CT, specialised cells, extracellular fibres, ground substance, calcium phosphate, collagen fibres, cells

how is blood supplied to bone?

Nutrient artery Metaphyseal vessels Periosteal vessels

what are long bones?

long & slender

give examples of long bone

thigh (femur) | arm (humerous)

what are short bones?

small & boxy

give examples of short bone

carpals (wrist) | tarsals (ankles)

what are flat bones?

thin & parallel surfaces

give examples of flat bones

parietal, ribs & scapula

what are irregular bones?

complex, notched/ridged surfaces

give examples of irregular bones

vertebrae, pelvis

what are sesamoid bones?

Small & flat

give examples of sesamoid bones

develop inside tendons near joints eg kneecap

what are sutural bones?

Small, flat / irregular

give examples of sutural bones

Between flat bones of skull

what does a long bone contain?

``` Central shaft (diaphysis) Expanded ends (epiphyses) Central: marrow cavity epiphyses of adjacent bones - articulate & covered by articular cartilage: hyaline ```

what are compact/dense bones?

relatively solid located on surface of bone forms diaphysis

what is spongy/cancellous bone?

forms open network interior of bone forms epiphysis

what does the outer surface periosteum contain?

Fibrous outer layer & cellular inner layer

what are osteocytes?

mature bone cells cannot divide, occupy a lacuna

what is a lacuna?

pocket / layers of matrix = Lamellae

what is a canuliculi?

passageways – link osteocytes

what is the function of osteocytes?

maintain normal function by recycling Ca2+ salts repair damaged bone released from lacunae- less specialised cell type

what are osteoblasts?

precursor cells | production of new bone: osteogenesis

what is the function of osteoblasts?

make & release proteins / organic components of matrix | increase local conc of Ca2+ phosphate

what do osteoblasts form?

Form osteocytes / develop from osteoblasts- surrounded by bone matrix

what are osteoprogenitor cells?

mesenchymal cells = | stem cells which divide daughter cells  -osteoblasts

what do osteoprogenitor cells do?

maintain populations of osteoblasts

what are osteoclasts?

giant cells remove bone matrix derived from monocytes

what do osteoclasts do?

Secrete acids & proteolytic enzymes dissolve bone matrix: osteolysis

what is the importance of osteoclasts?

regulation of Ca2+ & phosphate conc of body

what is the functional unit in compact bone?

osteon / Haversian system

how are osteocytes arranged in compact bone?

in concentric layers around central canal with blood vessels

how are the lamellae arranged in compact bone?

form cylinders around central canal

what are the perforating canals?

passageways | Blood vessels in canals supply blood to osteons

what is compact bone surrounded by?

periosteum

how is lamellae arranged in spongy bone?

form rods - trabeculae

how is an open network created in spongy bone?

Frequent branching thin trabeculae

what are the characteristics of spongy bone?

No capillaries or venules Nutrients reach by diffusion along - cannuliculi red marrow found between trabeculae

what is the structure of compact bone?

stresses come from limited range of directions | osteons aligned in same way

what is the structure of spongy bone?

bones not heavily stressed / stresses arrive in many directions lighter than compact

what is the effect of aging on bones?

become thinner & weaker =osteopenia

what is the effect of reduction in bone mass?

Osteoblast activity decreases

what is osteoporosis?

Function of bone compromised

what else is important in bone maintenance?

hormones