Skeletal Muscle Physiology 2 Flashcards
Dr S Khogali
skeletal muscle tension is dependant on 2 factors. what are they?
number of muscle fibres contracting and tension developed by each fibre
in skeletal muscle, the duration of twitch is much shorter than the duration of reaction potential
true or false?
false
the duration of action potential is much shorter than the duration of resulting twitch
what is evoked when the motor nerve that innervates a skeletal muscle emits action potentials at a very high rate?
tetanus
what muscle type cannot be tetanised?
cardiac muscle due to refractory period
what is produced if skeletal muscle is stimulated once?
a twitch
The tension developed by skeletal muscle increases with increasing frequency of stimulation
true or false?
true
Maximal tetanic contraction can be achieved when the muscle is at its _______ ______ before the onset of contraction
optimal length
name the 2 types of muscle contraction
isotonic contraction
isometric contraction
what is isotonic contraction used for?
body movements and moving objects
what is isometric contraction used for?
supporting objects in fixed position and posture
in which type of contraction does the muscle length change?
isotonic contraction
outline 3 ways metabolic pathways supply ATP in muscle fibre
from creatine
oxidative phosphorylation
glycolysis
when do we get ATP from glycolysis?
when O2 is not present
name the 3 types of muscle fibres
type I
type IIa
type IIx
what are type I fibres aka?
slow oxidative
slow twitch
what are type IIa fibres aka?
fast oxidative
intermediate twitch fibres
what are type IIx fibres aka?
fast glycolytic
fast twitch
list what each muscle fibre is used for
type I - low work aerobic
type IIa - moderate work
type IIx - short term high intensity
what is the simplest monosynaptic spinal reflex?
stretch reflex
what feedback is seen in the stretch reflex?
negative feedback
stretching the muscle spindle increases firing in which type of neurone?
afferent neurone
what is another name for muscle spindles?
intramural fibres
ordinary muscle is extrafusal fibres
what are annulospiral fibres?
the sensory endings to muscle spindles
what are the efferent neurones that supply muscle spindles called?
gamma motor neurones
name some genetically determined myopathies
muscular dystrophy
myotonia
name an acquired inflammatory myopathy
polymyositis
name an acquired non-inflammatory myopathy
fibromyalgia
name an endocrine myopathy
Cushing syndrome
list some useful investigations in neuromuscular disease
ECG
enzymes - CK
inflammatory markers - CRP and PV
muscle biopsy
whats the fastest way to a mans heart if your clara white?
through his ribcage
