L&B + CV&R - Non-Anatomy Lectures Flashcards
What are the 2 types of bone ?
Cortical (compact) and trabecular (spongy)
What type of bone makes up diaphyses (shafts) ?
Cortical
What type of bone makes up epiphyses (ends of bone) and vertebral bodies ?
Trabecular
Which bone type is more susceptible to conditions associated with increased bone turnover ?
Trabecular
What percentage of the human skeleton is comprised of trabecular bone ?
20%
What percentage of bone is inorganic ?
70%
What percentage of bone is organic ?
22%
What percentage of bone is water ?
5-8%
What is inorganic bone comprised of ?
95% calcium hydroxyapatite (the rest is impurities)
What is organic bone composed of ?
85% collagen type 1, 15% other collagens, proteins, glycoproteins and cells
What are the 3 types of bone cell ?
Osteoblasts
Osteoclasts
Osteocytes
(+ osteogenic)
What is the function of osteoblasts ?
Bone formation, regulation of bone turnover
What is the function of osteocytes ?
Sense mechanical strain and release signals (prostaglandins, nitric oxide) that modulate the function of neighbouring cells
Where are osteocytes found ?
Embedded in the bone matrix, each within their own lacuna
What is the function of osteoclasts ?
Bone removal (resorption)
What are osteoblasts and osteocytes derived from ?
mesenchymal stem cell precursor
What are osteoclasts derived from ?
hemopoietic mononuclear cells
What are the 4 stages of the bone remodelling cycle ?
Quiescence
Resorption
Reversal
Formation
What are osteoclasts rich in ?
Enzyme TRAP
What does the RANK-RANKL interaction do ?
Responsible for osteoclasts maturation, Stimulates bone resorptive activity of mature osteoclasts
What does osetoprotegerin (OPG) do ?
It bins to RANKL and prevents RANK activation, inhibiting osteoclasts formation
What do osteoclasts secrete ?
Hydrochloride acid and proteolytic enzymes
What can mesenchymal stem cells differentiate into ?
Osteoblasts, myocytes and chondrocytes
What molecule causes osteoblasts differentiation ?
Cbfa1
What do osteoblasts secrete ?
Cytokines/GF, enzymes and proteins
What are the 2 eventual forms of osteoblasts ?
Osteocytes or lining cells
What secretes RANKL?
Osteoblasts
What do osteoblasts secrete that creates new bone ?
Osteoid
What stimulates bone remodelling ?
IL-1,tumour necrosis factor, PTH, Vit D
What inhibits bone remodelling ?
Oestrogens, androgens and calcitonin
What changes to the spine occur during adolescence ?
Increase in size and trabecular thickness
What changes to the long bones occur during adolescence?
Increased length and diameter
What age is peak bone mass obtained ?
~30 yrs
What happens to bone mass post-menopause?
Accelerated bone loss
What do oestrogens and androgens do to bone ?
Oestrogen = bone maturation and mineralisation
Androgen = proliferate chondrocytes
Define osteoporosis
A decrease in bone mass causing compromised bone strength and an increased risk of fracture
What happens to trabecular bone in osteoporosis?
The trabecular thins and it’s continuity is disrupted
What causes post-menopausal osteoporosis (PMO)?
decided oestrogen levels, resulting in an excess of RANK-L
What percentage of BMD variability is caused by genetic factors ?
60-80%
What is Colles fracture ?
Falling onto outstretched hand , radius fractures and displaces dorsally
At what age does the risk of hip fractures massively increase ?
70 yrs
Name 3 risk factors for osteoporotic fractures
Older than 65, family history, malabsorption syndrome
Outline percentages detailing the complications of osteoporotic fractures
30% permanent disabled, 50% can’t return to full independence, 12-20% die within 1 year
What scanning method is used in the diagnosis of osteoporosis ?
DXA Scan
What are the T-score ranges for diagnosis ?
Greater or equal to -1 = normal
-1 to -2.5 = osteopenia
Less than -2.5 = osteoporosis
More than -2.5 + prescience of 1 or more fractures = established osteoporosis
What is the aim in managing osteoporosis?
Reducing Fx risk
What is absolute fracture risk ?
Age + past history + BMD
What is the calcium intake recommended for post-menopausal women ?
1000-1500 mg/day (vit D = 800 IU/day)
Name 3 drugs used as osteoporosis treatments ?
Bisphosphonates, SERMS (Raloxifene), Estradiol (semisynthetic oestrogen)
What does DENOSUMAB do ?
It targets RANK-L and inhibits bone resorption, it is a monoclonal antibody
What does ROMOSUMAB do ?
It’s inhibits sclerostin, increasing bone formation and decreasing bone resorption
How much does osteoporosis treatment reduce fracture risk by ?
Half
How man kg of Ca are there in the body ?
1
What percentage of serum calcium is free ?
47%
What is the adjusted calcium equation ?
Ca (adj) = Ca(tot) + [0.02[45-alb)]
What is a normal Ca (adj) value ?
2.2-2.6 mmol/L
What are the main organs involved in Ca homeostasis ?
Kidney , gut, bone , parathyroid glands
What are the main hormones involves with metabolic control of calcium ?
PTH, vit D (active 1.25DHCC form)
What’s are the WHOs 6 Domains of QOL ?
Physical, environment, social relationships, psychological, level of dependence, spiritual
Name the 3 common musculoskeletal ageing syndromes
Joints = osteoarthritis
Bone = osteoporosis
Muscles = Sarcopenia
What makes healing of articulation cartilage slow ?
No innervation, vascularisation or macrophages
What cells are in articulate cartilage ?
Chondrocytes
What percentage of chondrocytes are lost between 40-80 years old ?
50%
What maintains swelling pressure of proteoglycans ?
ECM contains hydrophilic proteoglycans
Define osteoarthritis
A disorder of synovial joints which occurs when damage triggers repair processes leading to structural damage within a joint
Name 3 features of osteoarthritis
Localised loss of cartilage
Osteophyte formation
Mild synovitis
How long does morning stiffness last for osteoarthritis?
Wither no morning stiffness or less than 30 minutes
What growth hormone is responsible for differentiating osteoblasts ?
IGF-1
What is the rate of rapid bone loss in the first 5 years after menopause ?
2-3%
What are the most common fragility fractures ?
Spine , hip and wrist
Outline the SARC-F screening tool for sarcopenia
Strength
Assistance walking
Rise from chair
Climb stairs
Falls
What is subluxation?
Dislocation if a joint where contact to some of the articulating surfaces remains
What is grade 1 ligament injury ?
Fibres stretched but normal range on stressing
What is grade 2 ligament injury ?
More fibres involved, laxity on stressing but definite end point
What is grade 3 ligament injury ?
Complete tear, excessive laxity and no end point. May be pain free as nerve fibres torn
Outline management of grade 1 and 2 ligament injury
Promote tissue healing, prevent joint stiffness, protect against further damage, strengthen muscles
Outline management of grade 3 ligament injury ?
Protective bracing or surgical repair/ reconstruction
What e muscles are most commonly affected by strains and tears ?
Hamstrings, quadriceps femora’s and gastrocnemius
What tendon is most likely to rupture ?
The quadriceps tendon
What is the treatment for hamstrings rupture ?
NSAIDs, electrotherapy, strength and stretching (physio), surgery ??
What happens in muscles contusion ?
Local damage and bleeding, due to direct blow
What is myositis ossificans ?
Ossification due to severe contritions, haematoma calcification
What are the 2 most common tendon injury sites ?
Achilles tendon and supraspinatus
What are the 2 common nerves injured in sport ?
Ulnar nerve at elbow, common fibular/personal nerve at the neck of the fibula
Outline tendon composition
20% = cellular-tenocytes
70% = water
30% solids = collagen 1, ground substance, elastin, other collagen (collagen 3)
What is tendinopathy ?
Painful conditions that arise in and around tendons, in response to overuse
What are the 3 phases of tendon healing ?
Inflammation (day 0-7), repair (day 3-60), organisation and remodelling (day 28-180)
What is the function of a tendon ?
To transmit force
What happens in the inflammation step of tendon healing ? (Day 0-7)
Inflammatory cells migrate
Defect filled with granulation tissue, haematoma and tissue debris
Matrix proteins laid down as scaffolding for collagen synthesis
What happens during the repair step of tendon healing? (Day 3-60)
By day 5 = fibroblast/tenocyte migrate and begin to synthesise collagen 3 (laid in random orientation)
During 4th week = fibroblasts proliferate synthesising and reabsorbing collagen, collagen switched to type 1, vascular ingrowth via fibronectin scaffolding
What happens during the remodelling phase of tendon healing ? (Day 28-180)
Cross linking between fibrils increases tendon tensile strength, final stability reached
What is the composition of ECM ?
50% water, proteins, glycoproteins, proteoglycans, glucosaminoglycans, collagen
Where is type 1 collagen found ?
Skin, bone, tendons, ligaments, cornea, internal organs
Where is type 2 collagen found ?
Cartilage, IVD, notochord
Where is type 3 collagen found ?
Skin, blood vessels, internal organs
Where is type 4 collagen found ?
Basal lamina
What is collagen structure described as ?
Triple helix , 3 polypeptide chains
What is osteogenesis imperfecta ?
Brittle bone disease, collagen type 1
What are the 5 derivatives of the mesoderm ?
Notochord, paraxial mesoderm, intermediate mesoderm, lateral plate mesoderm, extraembryonic mesoderm
What mesoderm forms somites ?
Paraxial mesoderm
What does the intermediate mesoderm form ?
Genitourinary system
What does the lateral plate mesoderm form ?
The parietal and visceral layers of mesoderm
What muscles aren’t formed by the mesoderm ?
Pupil, mammary and sweat gland smooth muscles, there’s are from the ectoderm
What can you use somite numbers for ?
To determine the age of an embryo
What regulates somitogenesis?
Clock and wave mechanism - FGF family, Wnt, Notch act as alarms (clocks)