lecture 30 Flashcards
3 mechanical functions of our bones
structural framework
stable foundation for posture and movement
protection of important organs
4 non mechanical functions of the bones
reservoir for mineral deposition, blood regulation pf calcium and phosphorus.
supports heamatopiesis
defends against acidosis
absorbs/captures potentially toxic materials (lead, things we might accidently take in from food)
whoose skeleton accounts for the mots weight of their body?
Young adults - weight is a force and mass is multiplied by gravity.
prenatal changes to bone systems
week 5 = formation of bones begin
when is peak heigh velocity?
~12.5 yrs (males) ~13,5 yrs (females)
when does epiphydeal plates close?
~25 years
when is max bone mass ?
~30 years
when is our rapid bone growth
1-4 years, puberty.
elderly - osteopenia
components of bone fail to develop, loss of bone mineral density = weaker bones.
osteomalacia
elderly - related to calcium and phosphate deficiencies
osteoporosis
decreased formation of new bone = brittle bones.
when do myotubes form?
5 weeks prenatal.
how much of body mass is muscles at birth?
25%
when are your first muscle fibres?
around 20 weeks. first ones that have the components of muscle such as actin and myosin.
what percent of fibres are type 1 at birth?
28-41%
infancy and adolesence changes ot the muscular system.
development proceeds from head to muscles.
differentiation of muscles fibres continues after birth.
adult-like distribution of fibres