Musculoskeletal System 2 Flashcards by Angharad Jones

What is hypertrophy?

Increase in cell size
No change in cell number

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What is hyperplasia?

No change in cell size
Increase in cell number

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What is the initial stage of longitudinal bone growth?

bone growth starts as the formation of a bony collar around the cartilage template

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What is the second stage of longitudinal bone growth?

Blood vessels invade the tissue

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What is the third (middle) stage of longitudinal bone growth?

Osteoblasts enter the cartilage shaft and lay down bone matrix

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What is the fourth (2nd to last) stage of longitudinal bone growth?

Osteoblasts enter epiphysis and lay down bone matrix.

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What is the last (5th) stage of longitudinal bone growth?

Cartilage is retained between the epiphysis and the shaft.

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What are the two types of bone growth?

Interstitial Growth

Appositional Growth

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What is interstitial bone growth?

Largening of the bone longitudinally
Growth from within the cartilage
Division of chondroblasts
Replicate and enlarge - allowing lengthening of the cartilage template

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What is Appositional growth?

Thickening of the bone
Surface cells differentiate - growing into perichondrium –> dense fibrous connective tissue

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What is longitudinal bone growth?

Indirect growth via interstitial cartilage growth at the growth plate and ossification

Ends at skeletal maturity

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What is circumferential bone growth?

Occurs directly via appositional growth at the bone surface
Continues throughout life

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What are the steps in the process of longitudinal bone growth?

Bone growth starts at formation of bony collar around cartilage template
Blood vessels invade tissue
Osteoblasts enter cartilage shaft, lay down bone matrix
Osteoblasts enter epiphysis and lay down bone matrix
Cartilage is retained between epiphysis and shaft

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What is the epiphyseal growth plate?

Site of indirect bone growth via interstitial cartilage growth

Increase in bone length complete at skeletal maturity when the growth plate “closes” and interstitial cartilage growth stops

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What does endochondral (bone formation) mean?

Within cartilage

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What does intramembranous (bone growth) mean?

Inside a membrane

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How does skeletal muscle growth occur?

Achieved through upregulation of protein synthesis within muscle cells

Result of hypertrophy rather than hyperplasia

= Increase in muscle mass

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What is the main hormone involved in growth in the musculoskeletal system?

Growth Hormone (GH)

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What are the functions of growth hormone?

Acts on liver to release insulin like growth factor 1 (IGF-1)

Where is growth factor produced?

Produced at anterior pituitary gland

What does IGF-1 act on and do?

Acts on:
- bone and cartilage –> increasing longitudinal growth

muscle –> increasing muscle mass
Increases conversion of carbohydrates into proteins
Increases uptake of amino acids to be used in protein synthesis

What happens when there is a deficiency in growth hormone?

Leads to a shortened stature and decrease in growth.

What happens when there is excess growth hormone?

= gigantism

When is gigantism caused and what are the impacts?

= Onset of excess GH. Before closure of epiphysis

Tall stature
Long extremities
Delayed puberty

When is acromegaly caused and what are the impacts?

= Onset of excess GH. After closure of epiphysis - Height unaffected - Gonads unaffected - Altered facial characteristics

What is the function of Parathyroid Hormone (PTH) ?

Regulates the distribution of calcium and phosphorus in the body. Increasing osteoclast activity - cells that break down bone Decreasing osteoblast activity

What happens when there is too much parathyroid hormone in the body?

Increased Ca and P loss from bone = weakening bone Increase chance of kidney stones and osteoporosis.

What happens when there is too little parathyroid hormone in the body?

Decreased Ca in the plasma Muscular rigidity Muscular spasm

What is the function of vitamin D in the body?

Works with parathyroid hormone to release calcium from the bone Stimulates absorption of Ca and P in the GI tract Deficiency = rickets

What is the function of calcitonin in the body?

Opposes parathyroid hormone - reduces calcium in the plasma Inhibits osteoclast activity - calcium can be absorbed into the skeleton

What is the function of vitamin C in the body?

Important co-factor for many enzymatic reactions Involved in collagen synthesis Collagen = vital component of muscle, bone and cartilage Deficiency = scurvy

What is the function of oestrogen in the body?

Reduces bone resorption Stimulated bone development

What is the function of testosterone in the body?

Reduced bone resorption Stimulates bone development Stimulates muscle mass increase

Impacts of osteoblasts on bone loss?

Decreased apoptosis Decreased oxidative stress Increased maintenance of bone formation --> Bone loss

Impacts of osteoclast on bone loss?

Increased apoptosis Decreased bone resorption - bone loss

What are 5 performance enhancing drugs?

- Erythropoietins (EPO) and agents affecting erythropoiesis - Anabolic androgenic steroids (AAS) - Testosterone - Peptide hormones and releasing factors - GH - Growth factors and growth factor modulators - (IGF-1, VEGF) - Hormone and metabolic modulator - anti-oestrogens

How does exercise affect bone?

Exercise changes the mechanical environment of the skeleton Triggers cellular response and changes in bone architecture Bones adjust size and shape in response

What is wolfs law?

*Optimisation of bone strength with respect to bone mass * Alignment of trabeculae with principle stress direction * Self regulation of bone cells responding to mechanical stimulus

How does increased mechanical loading result in increased bone strength?

- increased mineralisation - decreased porosity - increased bone mass e.g. athletes

How does decreased mechanical loading result in decreased bone strength?

- decreased mineralisation - increased porosity - increased bone mass e.g astronaughts e.g teeth removed = lack of loading = bone restrictions

What are all synovial joints made up of?

- Articular cartilage - Fluid filled synovial cavity - Joint capsule --> outer fibrous membrane --> inner synovial membrane

What are some synovial joints made up of?

Articular discs or menisci Articular fat pads Tendons Accessory ligaments (extracapsular and intracapsular) Bursae

What is the structure of articular cartilage?

Has a smooth, slippery surface Transmission of loads with little friction Devoid of blood vessels, lymphatics and nerves.

What is osteoarthritis?

Progressive joint degeneration of articular cartilage and bone Joint pain only present when bone is damaged

What is sarcopenia?

Age related loss of skeletal muscle mass and a decline in strength. A decrease in size and quality of muscle. More than twice as fast in the lower limb than the upper limb Presence >50% in >80 yr olds

What impact can posture have on bone degeneration?

The vertebral column adjusts throughout development. Its shape is influenced by supporting the head and bipedal walking. In old age Kyphosis can occur --> degeneration of intervertebral disks, osteoporosis in vertebrae, lengthening of extensor muscles