Physiology recap Flashcards
What are osteoclasts?
bone forming cells (oesteiod that mineralises into bone)
What are osteocytes and what do they do
mature bone cells
What do osteoclasts do
break down and remodel bone
constant turnover (5-7% a week)
What do osteocytes do?
maintain calcium homeostasis
where are osteoclasts found
on the surface of the bone
what are the 2 types of bone
compact ( cortical - outside of bone)
spongy (trabecular - middle of bone)
What is the orientation of muscle filament s
6 thin actin filaments surrounding 1 thick myosin filament
What are 4 ways to classify muscle fibre types
Histochemical
Biochemical
Morphological
Physologic
3 types of muscle fibre
type 1
type 2a
type 2x
what are muscle spindles?
stretch sensors
what happens when the muscle is stretched?
spindles are stretched sending a impulse to spinal coord causing motor neurones to fire contracting the muscle to prevent tearing
What are Golgi tendon organs
tension sensors
What happens when a large load is applied to a muscle (tendon)
discharge of the GTO and the muscle relaxes
what does having sarcomeres in series improve?
velocity of contraction
what does having sarcomeres in parallel improve?
force of contraction
5 shapes of parallel pennation angle
Flat Fusiform (flat with a middle bulge) Strap Convergent (triangular - pec) Circular (eg around eyes)
Where is the sarcomere located?
Between the 2 Z-lines
What are the thick filaments?
Myosin
What are the thin filaments?
Actin (G actin binding sites covered by tropomyosin)
What is titin and does it do?
An elastic filament - connects myosin to Z discs - prevents over stretching and allows for muscle recoil
What does the I band contain?
Only actin filaments
What does the A band contain?
Both action and myosin filaments (overlapping)
What does the H zone contain?
Only myosin filaments
Sliding filament theory overview Stage 1
Nerve impulse -> ACh -> Ca+ release from sarcoplasmic reticulum -> tropomyosin moves exposing actin binding sites
