Functional Anatomy Flashcards
Central Nervous sytem
Brain and spinal cord
brains role:
interpret/decides on the information and sends signals/impulses via the spinal cord
spinal cord
transmits electrical messages from the brain to the parts of the body
2 types of neurons
sensory neuron
motor neuron
Sensory neuron
receives signals from various organs or sense and they relay them to the brain and spinal cord
motor neuron
transmits electrical signals from CNS to a muscle to cause contraction of the associated muscle fibres
Motor neuron contains
dendrite
cell body/soma
axon
terminal at end of axon
Dendrite
passes information from the sensory receptors to the cell body of the motor neuron
FROM SENSORY RECEPTOR TO CELL BODY
cell body/soma
direct the neurons activity from the dendrite to the axon
FROM DENDRITE TO AXON
axon
transmits electrical information/signals away from the cell body to the muscle fibres
AWAY FROM CELL BODY TO THE MUSCLE FIBRES
axon terminal
motor end plates or axon terminal at the end of an axon
Motor unit
A single motor neuron and all of its corresponding muscle fibres it stimulates (motor neuron and muscle fibres)
larger the motor neuron, harder it I to stimulate (calf raises)
size is dependant of number of muscle fibres it stimulates
All or none principle
a motor unit is either activated completely or it is not activated at all based on it reaching its stimulation threshold
nerve impulses will not stimulate muscle fibres and make them contract unless it reaches a certain threshold level
muscles all contract at the same time with as much force as possible
more force equals more motor units
How do we vary the intensity/strength of each contraction 4 ways
- increasing the number of motor units made active
- type of muscle fibres recruited
- varying the frequency at which the impulses arrive at the motor neuron
- recruiting different sizes of motor units
increasing the number of motor units made active
amount of force applied by the muscle group varies with the number of muscle fibre recruited
stronger nerve impulses mean more neurons are activated which results in muscle fibres to contact
Example: want to increase throw, use bigger muscle groups which means more force is needed to do the throw
types of muscle fibres recruited
low intensity/force activities recruit mainly slow-twitch fibres
powerful activities mainly recruit fast-twitch muscle fibres
low distance run= slow-twitch fibres
types of muscle fibres recruited
low intensity/force activities recruit mainly slow-twitch fibres
powerful activities mainly recruit fast-twitch muscle fibres
low distance run= slow-twitch fibres
varying the frequency at which the impulses arrive at the motor neuron
Greater the frequency of the nerve impulse, greater the contraction of the muscle
recruiting different sizes of motor units
recruited in order from smallest to largest as contraction increases (slow to fast-twitch)
larger the motor unit, the larger numbers of muscle fibres it can stimulate
All or none principle
When a motor unit receives impulses potential to the threshold, all muscle fibres associated with the motor unit will contract to their max level (all at the same time)