Physiology Flashcards
motor units allow what
simultaneous contraction
what is motor unit recruitment
stimulation of more motor units, stronger contraction
tension in the muscle is dependent on what? (3)
length of the muscle, thickness, frequency and summation of contraction
What is the relationship between AP and duration of resulting twitch
the AP is shorted than the resulting twitch
can cardiac muscle be tetanised?
no
why can cardiac muscle not be tetanised
the refractory period
two types of contraction exhibited by skeletal muscle
isotonic and isometric contraction
What is isotonic contraction
body movements; muscle tension remains constant
what is isotmetric contraction
support of objects in fixed positions, muscle tension develops at a constant
what is the relationship between velocity of muscle and load
as the load on muscle increases the velocity of muscle shortening decreases
4 examples of impaired skeletal muscle function
intrinsic disease of muscle, diseased NMJ, motor neurone disease, blocked input to motor units
stretch reflex is the most simple example of
Monosynaptic spinal reflex
the function of the stretch reflex
negative feedback that resists change in muscle length, this maintains optimal resting length of muscle
what is the muscle spindle
sensory receptor
when is the muscle spindle activated
by the muscle stretch reflex
what happens when the muscle spindle is stretched
increase in firing in the afferent neurones
where do afferent neurones synapse
within the spinal cord with the alpha motor neurones
how is the stretch reflex co-ordinated
relaxation of antagonist muscle
what muscle is involved in the knee jerk reflex
Quadriceps femoris
5 reflexes that can be tested with the tendon hammer
knee, ankle, biceps, triceps and brachioradialis
what spinal nerves are involved in the biceps and brachioradialis reflex
C5-6
what peripheral nerve is affected by the brachioradialis and triceps jerk
Radial
what spinal nerves are involved in the knee jerk
L3 + 4
what spinal nerves are involved in the ankle jerk
S1 + 2
what spinal nerves are involved in the triceps jerk
C6 + 7
what peripheral nerve is affected by the knee jerk
femoral nerve
what peripheral nerve is affected by the ankle jerk
tibial nerve
what peripheral nerve is affected in the biceps jerk
musculocutaneous nerve
muscle spindles can also be called
intrafusal fibres
extrafusal fibres are also called
ordinary muscle fibres
where are muscle spindles found
within the belly of muscles
sensory nerve endings on muscle spindles are called
annulospiral fibres
efferent neurones that supply muscle spindles are called
gamma motor neurones
what is the role of game motor neurones
adjust the level of tension in the muscle spindles
differences between skeletal muscle fibres
- enzymatic pathways for ATP synthesis 2. resistance to fatigue 3. activity of myosin ATPase
what are the type 1 fibres used for
prolonged low energy tasks; posture and walking
what are the type 2a fibres used for
prolonged moderate energy tasks; jogging
what are the 2x fibres used for
short term high intensity activities; jumping
Investigations in neuromuscular disease
EMG, muscle enzymes, nerve conduction
