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)
Producing max force summary
A greater number of motor units are used
activating larger motor units
recruit appropriate muscle type (type II fast-twitch)
muscle structure
epimysium perimysium endomysium fascicle myofibrils sarcomere myofilaments
epimysium
covers the whole muscle
the layer of connective tissue that surrounds the skeletal muscle
thickens as it reaches the ends of the muscle to form tendons to connect to the bone
perimysium
covers the fascicle
a layer of connective tissue that surrounds the fascicle
helps bind muscle fibres together
gives the muscle the ability to stretch and return back to its normal size
fascicle
bunch of muscle fibres
myofibrils
inside each muscle fibre
long standards which make up the muscle fibres
made up by sarcomeres that are separated my z lines
sarcomere
individual units of myofibrils that are responsible for contracting the muscle
link together and creates actin and myosin potentials
myofilaments
actin and myosin
actin
thin protein filament attached to the z line
myosin
thick protein filament attached to cross bridges
cross bridges
thin projections on myosin filaments that reach towards the actin filaments
Z line
end point of a sarcomere
H zone
space between the actin filaments (contraction= shortens as actin overlaps)
A band
beginning of myosin to end of adjacent myosin held together by the M line
cycle rate
the rate at which the myosin cross-bridges uncouple and couple
types of muscle fibres
Type 1= slow-twitch (red) endurance
Type 2= fast-twitch (white) IIA=800m IIB=100 sprinter
Type 1 slow twitch fibre (red) small
fatigue rate= low oxidative capacity=high speed of contraction=slow energy system=aerobic available ATP=high force generated=low endurance
Type 2 fast twitch IIA
everything moderate
anaerobic LAS system
800 m
Type 2 fast twitch IIB
capillary density: low fatigue rate= high available ATOP=low speed of contraction= high fibre diameter= large energy system= anaerobic LAS 100 m sprinter
different types of muscle contractions
isotonic
isometric
isotonic
the muscle length changes over a range of movement as force is produced
eccentric or concentric
concentric
occurs when a muscle length shortens as it contracts
eccentric
occurs when a muscle length lengthens as a muscle contracts
isometric
when a muscle contracts against a force but stays in a fixed position
neither lengthening or shortening
force velocity
the amount of force produced by a muscle depends on the velocity of the muscle contraction
muscle contracts at a high velocity, the force will decrease
more force requires slower movements meaning decrease in velocity and increase in force produced
heavy lifting= slower velocity, more force
light lifting=less force so increase in velcoity
force velocity concentric contractions
myosin cross-bridges can uncouple quickly (cycle rate) producing a lower level of force or tension
uncouple slowly equals more force kept in the sarcomere
high velocity= low force
low force=high velocity
Max force is achieved when the velocity of the concentric contraction is slow as this allows more motor units to be recruited to produce more force, therefore force can be applied for a longer period of time
isometric contraction producing the most amount of produce
no movement is occuring, but all cross-bridges are attached
with all cross-bridges attached creates greater force than when some are attached when contraction of movement occurs (eccentric and concentric)
force length
relates to the amount of force that can be produced as varying muscle lengthen 3 levels fully contracted resting overstretched
point A= contracted (bend)
less force is generated by a muscle that has a starting length that is contracted
why: there is too much cross-bridge overlap
Point B= resting (slightly bent)
the optimal amount of force is generated at midrange/resting
why: optimal overlap of actin and myosin overlap and cross-bridge attachment
Point C= overstretched (Straight)
the least force generated by muscle with starting length as stretched
why: smallest and most inefficient overlap of actin and myosin filaments occurs inefficient cross-bridge activation
