Unit 1 - Anatomy and physiology for health and exercise - Skeletal system Flashcards
What do bones consist of?
Bone consists of a mixture of water, protein and mineral salts, the latter of which constitutes roughly 50% of its structure.
What is bone strength the rsult of?
Bone strength is the result of a combination of the hardness of the minerals combined with the tensile properties of collagen.
What is collagen derived from?
Protein.
What happens to a bone if it had too little of collagen?
The bone would shatter like an eggshell.
What happens if the bone had too little of the mineral salts?
The bone will bend like a piece of rubber.
What is the process of bone formation called?
Ossification.
What does the hardening and growth process of bones involve?
Replacing a cartilage “framework” with mineral salts.
Why are bones of young children softer than those of adults?
Because they still contain significant proportions of cartilage.
When is the hardening process of bone complete?
It may not be complete until 30 years of age.
In early life, what does the ossification emphasize on?
The emphasis of ossification is very much on bone growth and bone hardening.
In adulthood, what does the ossification emphasize on?
The emphasis of ossification is more geared towards replacing and maintaining existing bone material.
What are the primary cells involved in bone growth?
Osteoblasts.
What is the function of osteoblast?
Its function is to replace worn out or damaged bone tissue.
Their activity is coordinated with what other cells?
Osteoclasts, which remove the old bony tissue.
Does the maintenance of a healthy skeletal system happen in every bone equally with osteoblast and osteoclast?
No, it can vary according to the region of bone concerned; then end of the femur, for example, can be completely remodelled every few months, which contrast with the bone shafts, which may never be fully remodelled.
What other factors will remodelling of bone tissue tend to follow?
The lines of stress placed upon the bone, such as exercise and habitual posture.
Give an example of bad remodelling of bone tissue.
Incorrect exercise technique coupled with generally poor alignment will lead to a remodelling process that may reinforce the predominating bad posture.
What is bone formation predominantly regulated by in the pre-puberty years?
Human growth hormone (HGH), produced by the pituitary gland (located in the brain).
What is bone formation regulated by at puberty?
Testosterone produced by the male testes and oestrogen produced by the female ovaries.
In what important functions is calcium involved in?
Apart from providing the skeletal system with rigidity, it is also involved in muscular contraction, the transmission of nervous impulses and regulating fluid balance.
Why do bones have calcium reservoirs?
The calcium reservoirs in bones can either take up or release calcium depending on the body’s needs.
What happens if calcium is scarce?
It will be withdrawn from the bones, which is why diets that are chronically low in calcium tend to increase the risk of osteoporosis.
How is osteoporosis, brittle bone disease, caused?
By an imbalance in the delicate balance of the bone remodelling, whereby osteoblast activity decreases causing a drop in bone growth. This leads to a gradual loss in bone density and ultimately gives rise to a skeletal system that is unable to withstand the forces placed upon it.
What may cause an imbalance in osteoblast and osteoclast activity?
there may be a number of causes of the condition; however one of the biggest is the drop in oestrogen levels associated with the menopause.
Why are women more prone to osteoporosis than men?
The drop in oestrogen levels associated with the menopause makes woman significantly more likely to develop the condition than men. In men, a proportion of circulating testosterone is converted into oestrogen and this is thought to provide men with significant protection against loss of bone mass.
What other risk is there to develop osteoporosis in females?
Low calorific intake and/or overtraining also increase the risk of osteoporosis in females by depleting body fat stores which are one of the primary sources of oestrogen. Poor quality diets which are lacking in or have an imbalance of minerals and vitamins also increase the risks by limiting the availability of calcium
List Osteoporosis risk factors.
→ female sex - due to a drop in oestrogen levels
→ calcium deficiency - through poor diet or poor absorption
→ lack of exercise
→ smoking - causes a drop in oestrogen levels
→ family history
→ certain drugs, such as alcohol which interrupt normal hormonal and calcium regulation
→ low body fat
→ overtraining
In what two forms does bone tissue come in?
Compact and cancellous.
Describe a compact bone.
→ It has a relatively high density of bone matter.
→ It forms the external surfaces of bones, predominates in the shafts of long bones and serves to resist compressive forces.
Describe a cancellous bone.
- It is relatively more porous than a compact bone and if viewed closely has a spongy appearance.
- It predominates in the interior of bones and especially at bone ends (ephiphyses).
What are the spaces within the cancellous bone good for?
They form a vital function by housing red marrow, which is responsible for red blood cell production.
Name the four shape categories of bones.
- Long bones
- Short bones
- Flat bones
- Irregular
- Sesamoid (“seed-like”)
Describe a long bone.
- They have a greater length than width and consist of a shaft with normally two extremities.
- They contain mostly cancellous bone in their ephiphysis and more compact bone in their diaphysis.
- They act principally as levers.
Give examples for long bones.
- Humerus
- Femur
- Fibula
- Tibia
- Ulna
- Radius
- Metacarpals
- Metatarsals
- Phalanges