muscles Flashcards
what are the 3 types of muscles
- ) smooth muscle
- ) cardiac muscle
- ) skeletal muscle
skeletal muscle
attached bones via tendons
striated (light and dark protein bands)
voluntary control
cardiac muscle
wall of the heart
striated-
involuntary control
smooth muscle
wall of blood vessels and internal organs.
non striated
involuntary control
functions of the muscle
- ) motion (of muscle/body part, substances within the body)
- ) stabilizes posture- sitting, standing
- ) thermogenesis- shivering
charateristics of muscle tx
- ) excitability- respond to stimuli by producing electrical signals
- ) contractibility - can shorten or thicken to produce force
- ) extensibility- can stretch
- ) elasticity- can recoil
fascia
a sheet(s) of connective tissue that surround(s) the muscle protect, support and separate the muscle tendons are extensions of the fascia which attach muscle to bone
general blood and nervous supply
Capillaries
are linked to each individual muscle fiber
Motor neurons
linked to each muscle fiber
general structure of muscle
muscle– fascicle— muscle fiber(muscle cell)— myofibrils– filaments
a motor unit
a motor neuron plus all the muscle fibers it stimulate
Stimulation -> simultaneous contraction of all the muscle fibers of the motor unit
a single motor neuron will stimulate approx. 150 fibers through branches (average)
(For fine precision movements
e.g. larynx,
a motor unit may have only 2-3 fibers
powerful gross movements
e.g. biceps,
there may be as many as 2000 fibers)
pathways of ATP
ATP regeneration (creatine
phosphate, for short burst )
glycogen lactic acid, 30-40 sec-400)
aerobic respiration, cellular respiration in mitochondria.
Myoglobin
O2 source for muscle tx
O2 binding protein- oxygen inside muscle fibers, it gets released when required.
muscle fatigue
inability of muscle to maintain it’s contraction due to lack of ATP. may result from:
insufficiency of oxygen,
glycogen depletion or
lactic acid build-up
oxygen debt
increased Vm after exercising to payback depleted O2 levels.
recovery O2 consump.
1) liver converts lactic acid to glycogen stores
2) creatine phosphate and ATP stores resynthesized
3) replace oxygen stores in myoglobin
the all-or-none principle of muscle contraction
When muscle fibers receive a stimulus to contract, they contract fully.
(i.e. a muscle fiber never partially contracts).
*Whole muscles can have various degrees of contraction
Why - only some fibers contract.