even more physiology/muscle mechanics Flashcards
describe a smooth muscle fibre
30-200 micro-metres long
single nucleus
describe filaments in smooth muscle
irregular
not straited
attached to structures called dense bodies
2 types of smooth muscle fibres -
visceral/ single unit
multi unit
where would you find visceral muscle fibres
found in walls of vessels/hollow organs - stomach, veins, bladder
describe how visceral muscle fibres operate
AUTORYTHMIC
all fibres contract together, as a single unit
where would you find multi unit muscle fibres
walls of arteries, airways, iris, arrestor pili muscles in hair follicles
describe how multi unit smooth muscle fibres operate
individually - independently from each other
contractions of smooth muscles
slow long contractions (no t tubules) takes calcium longer to get in and out.
other properties of smooth muscles
short. stretch more than skeletal muscles
stress-relaxation response - can expand (bladder)
exhibit tonicity - important for blood pressure maintenance
Reasons for smooth muscle to contract:
action potential from nervous system stretching(bladder) hormones ph change 02/c02 levels temperature ion concentration
fleshy part of muscle called
belly
when fibres contract the muscle becomes - and -
thicker and shorter
the origin is
the attachment of the muscle tendon to the stationary bone
the insertion is
the attachment of the muscle tendon to the moving bone
the ends of the muscle are called the
tendons
4 groups of muscles (mechanics)
prime movers/agonists
antagonists
synergists
fixators
most skeletal muscles are arranged in -
antagonistic pairs
depending on the movement one muscle is the XX and one is the X
prime mover
antagonist
what is a synergist muscle
stabilises intermediate joints
ex synergist muscle
synergists of wrist hold it still while fingers flex
what is a fixator
helps keep an origin bone still while a prime mover contracts it.
ex of fixator
muscle holds shoulder blade still while arm muscles contract
Which muscles can undergo hypertrophy
all -
skeletal
smooth
cardiac
can muscle cells divide?
no
how can skeletal muscle regenerate
limited regeneration via satellite cells - divide slowly and fuse with existing fibres to assist muscle repair
what is hyperplasia -
how new smooth muscle cells can be regenerated from periocytes - stem cells in capillaries & veins
can cardiac muscles regenerate?
under certain circumstances, possibly via satellite cells
