BL. session 8. bones Flashcards
when is the patella formed? example of which bone type?
post natal
sesamoid bone
How do newly formed blood cells leave the bone marrow?
through intracellular gaps in sinusoidal vessels
what tunica layers do capillaries have?
tunica intima only.
DO NOT contain tunica media or externa
describe the layers of endothelium
tunica externa/adventitia (external elastic lamina) tunica media (smooth muscle cells) tunica intima (internal elastic lamina) endothelium (inner endothelial cell layer)
clinical treatment for patients with low neutrophils?
injection of GCSF
what is hypoxia?
when tissue is depleted of oxygen supply.
- causes kidneys to secrete erythropoietin which inc RBC count.
- inc haematocrit (ratio RBC: total blood volume)
> inc risk of clotting
which cell type increases in parasitic worm infections
eosinophils
give example of bone types and their function
long- femur = facilitate movement. support body weight
short- wrist and ankle joints. carpals. =provide stability and some movement.
irregular- vertebrae= protect spinal chord
pelvis (sacrum) = protect organs/bladder in pelvic cavity
sesamoid- patella= protect tendons from stress
flat- sternum/ribs/cranial bones (skull) = protects internal organs. provide areas of attachment for muscles
diff names for cancellous bone?
Trabecular/spongy
diff name for cortical bone
compact (/periosteal?)/lamellar
What feature of cartilage distinguishes it from most other connective tissues?
It is an avascular tissue
where is elastic cartilage found
pinna of the ear
eustachian tube
epiglottis
what type of cartilage is nasal cartilage? what collagen type?
hyaline cartilage
type 2 collagen only
what is the function of the canaliculi?
allow the movement of nutrients between osteocytes
Which component of bone impedes the free distribution of nutrients and oxygen to osteocytes?
extracellular matrix- impervious to aqueous solution
what is an osteophyte
a spur of bone produced when bone is damaged and tries to repair itself
e.g. in rheumatoid arthritis (abnormal bone formation.)
what is the endosteum
is inside (endo) the bone (osteum) lines the medullary cavity.
what is the periosteum
Composed of two layers: osteogenic and fibrous.
Continuous with the joint capsule
Attached to the bone surface by collagen bundles called Sharpey fibres
how does parathyroid hormone effect bone?
which drug is given to reverse the effects of high PTH?
PTH acts on osteoclasts to resorb bone and release calcium into the blood
Calcitonin acts on osteoblasts to re-use the released calcium to lay down new bone and so strengthen any bone weaknesses
label the section through compact bone
A= an osteon
B= Blood and lymphatic vessels in Haversian canal
C= Periosteum
D= Concentric lamellae
E= Endosteum at junction with medullary cavity
F= Volkmann’s canal
G= Haversian system
see screenshot ‘compact bone diagram’
what is the difference between osteoporosis and osteomalacia
Osteoporosis
- holes in bone
- bones broken down (reabsorption) faster than being made (build up)
Osteomalacia
- no holes
- adult form of rickets.
clinical signs/symptoms of inflamed RH arthritis joint
- loss of funtion
- redness (rubor)
- heat (calor)
- pain (dolor)
- swelling (tumor)
which cells are not found WITHIN cortical bone? found where
osteoclasts
found on the edges only (periosteum and endosteum)
What are the two steps of bone remodelling
1)osteoclast- cutting cone
wide tunnel in the bone
2)osteoblast- closing cone
smaller tunnel of cortical bone
what is osteogenesis imperfects
brittle bone disease
mutation in COL1A gene- incorrect production of collagen 1 fibres
blue sclera
what is rickets
bowed legs in children
vit D deficiency
poor calcium mobilisation
weakened bones, soft bones
what is osteomalacia
adult rickets
vit D deficiency > dec calcium absorption.
which factors can lead to vitamin D deficiency
kidney disease (kidney usually activates vit D)
lack of sunlight
drugs e.g. phenytoin (anti epileptic) prevents vit D absorption
what is secondary osteoporosis
- result of drug therapy (corticosteroids)
- processes affect bone remodelling (malnutrition/space travel)
- metabolic bone diseases (hyperparathyroidism/ metastatic cancers)
what is achondroplasia (gene?)
how is ossification affected?
FGF3 gene which promotes collagen formation from cartilage (endochondrial ossification affected, intramembranous unaffected)
which hormones are involved in type 1 and type 2 osteoporosis?
1- oestrogen only
2- oestrogen AND androgen
what factors influence fracture healing
blood supply
age
comorbidities
diet
what is Swiss cheese bone
how does it occur?
osteoporotic trabecular bone (osteoporosis structural changes)
Major risk factor for fractures in older people.
incomplete filling of osteoclast reabsorption bays
what are the modified risk factors for osteoporosis
- insufficient calcium intake (700mg/day recommend)
- exercise > immobilisation leads to accelerated bone loss
- cig smoking in women
what do people with achondroplasia look like
Short stature, normal sized head/torso
short long bones
strong cortical bones
