muscular system Flashcards
Skeletal Muscle
- Consciously controlled- somatic nervous system
- They fatigue during exercise
- Contract by impulses sent by the brain- voluntary
- Skeletal muscles contract which pull on bones to create movement and maintain posture
- striated in appearance
- eg.Biceps Triceps Deltoids Gluteals
cardiac muscle
- Unconsciously controlled- involuntary, autonomic nervous system
- Does not fatigue
- Only found in the walls of the heart
- Cardiac muscles help circulate blood through and out of the heart
Smooth Muscle
- Unconsciously controlled- involuntary, autonomic nervous system- They are controlled by the nervous system
- Control body functions such as: the movement of food and blood
- walls of blood vessels, digestive tract, respiratory tract
- eg, Arteries Veins Bladder Stomach Intestines
Flexion
Bending a joint- the angle of a joint decreases.
Eg. elbow flexes when performing a biceps curl.
Extension
straightening a joint- the angle of a joint increases
eg. the elbow when putting a shot
Dorsiflexion
the foot moves towards the shin as if you are pulling your toes up. This movement occurs at the ankle
Plantar flexion
pointing the toes – movement occurs at the ankle
eg. pointing the toes in ballet.
Lateral Flexion
The movement of bending sideways- Goal keeper diving to
the side when saving the ball
Horizontal Flexion & Extension
Similar to flexion and extension but on a horizontal plane- Bending and
straightening of the elbow when it is out in front of you
HyperExtension
Involves movement beyond the normal anatomical position in a direction opposite to flexion.- Shoulder extended behind the back
Abduction
movement away from the midline of the body.
eg. at the hip and shoulder joints during a jumping jack movement
Adduction
movement towards the midline of the body.
Eg. at the hip and shoulder, returning to their original position from a jumping jack movement.
Horizontal Abduction & Adduction
the movement of bringing your arm across your body (flexion) and then back again (extension)- Shoulder action when performing a drive shot in tennis
Rotation
the limb moves in a circular movement around a fixed joint towards or away from the midline of the body.
eg. in the hip in golf while performing a drive shot.
Circumduction
limb moves in a circle.
eg. the shoulder joint during an overarm tennis serve
Trapezius
at the top of the back
used to elevate and depress the scapula. It is useful for shrugging and overhead lifting
Deltoids
at the top of the shoulder
helps you move your arms in different directions (flexion, extension and abduction).
They also protect and stabilise your shoulder joint.
Useful for sports that need arm movements (swimming, throwing)
Erector spinae
runs along the spine
helps straighten the back and provide for side-to-side rotation.
Used in extension.
Pectorals
(this includes the pectoralis major and minor)
helps with flexion and extension of the upper arm
Teres major
between humerus and scapula
helps with movement of the humerus (abduction and rotation)
Latissimus dorsi
works with the teres major and pectoralis major to adduct, medially rotate, and extend the lower arm.
Triceps brachii
outside of upper arm
helps extend the lower arm at elbow
Biceps brachii
front of upper arm
helps flexion and supination (outward rotation) of the forearm
Supinators
top and back of forearm
rotation of the forearm and hand so that the palm faces forward or upward
Pronator
top and front of forearm
a rotational movement of the forearm that results in the palm facing posteriorly
Wrist flexors
(including the flexor carpi radialis and the palmaris longus)
at the front of forearm, creates flexion at wrist/hand.
Wrist extensors
(including the extensor carpi radialis longus, extensor carpi ulnaris and extensor digitorum)
at the back of the forearm,
helps extend the wrist and straighten it
Abdominals
(these include the rectus abdominis and the transversus abdominis)
support the trunk, allow movement and hold organs in place by regulating internal abdominal pressure.
Protects the spine and allows flexion and rotation.
Obliques
(external/internal)
important stabilisers in the trunk.
The primary function of the oblique muscles is to rotate your trunk (torso)
Hip flexors
(iliopsoas and pectineus) flexing hip joint
Gluteals
(gluteus maximus and gluteus medius)
act on the hip joint, mainly to facilitate abduction and extension of the thigh but some also assist in the adduction, external rotation and internal rotation of the thigh.
Tensor fasciae latae
extension and lateral rotation of leg on knee joint.
the movements of the thigh, acting as a weak abductor and medial rotator on the hip joint.
Sartorius
it can serve as both a hip and knee flexor
Adductor longus
to adduct the thigh at the hip joint and plays a role in external/ lateral rotation and flexion of the thigh.
Gracilis
flexes the knee, adducts the thigh, and medially rotates the tibia on the femur.
Quadriceps
(including rectus femoris, vastus intermedius, vastus lateralis, vastus medialis) all work to extend (straighten) the knee.
- The rectus femoris also flexes the hip.
- The vastus medialis adducts the thigh and also extends and externally rotates the thigh
and stabilises the kneecap.
The quadriceps are primarily active in kicking, jumping, cycling and running.
Hamstrings
(adductor magnus, biceps femoris, semitendinosus, semimembranosus) to flex your knee, extend the thigh at your hip and rotate your lower leg from side -to-side when your knee is bent
Gastrocnemius
produces flexion of the leg at the knee joint and plantar flexion of the foot
Soleus
plantar flexion (foot goes downward)
Tibialis anterior
ankle dorsiflexion and inversion of the foot.
how muscles work
Muscles move body parts by contracting and then relaxing. Muscles can pull bones, but they can’t push them back to the original position.
origin (on agonist)
The bone where a muscle begins and is usually the proximal (nearest) end.
When a muscle contracts, one end remains stationary
insertion (on agonist)
The bone on which a muscle ends and is normally the distal (furthest) end
When a muscle contracts, one end moves
Antagonistic pair
The muscle that contracts is called the agonist and the muscle that relaxes is called the
antagonist.
Eg. When we bend the elbow (flexion) the biceps contract and the triceps relax
Agonist = Biceps, Antagonist = Triceps
Eg. When we straighten the elbow (extension) the triceps contract and the biceps relax
Agonist = Triceps, Antagonist = Biceps
Agonist and antagonist pairs examples
Biceps & Triceps, Hamstrings & Quadriceps, Gluteus maximus & Hip flexors, Gastrocnemius & Tibialis anterior, Pectoralis major & Latissimus dorsi.
Prime mover/agonist
The muscle primarily responsible for a movement is called the prime mover/ agonist
synergists
help prime movers by producing the same movement or by reducing undesirable movements
fixator
A synergist that makes the insertion site more stable is called a fixator. They stop any unwanted movement by stabilising the joints. This enables the agonist to achieve contractions.
Isometric
A muscular contraction in which the length of the muscle does not change, and the angle stays the same, muscle holds a static position. Is fatiguing.
EG, a plank position/ holding a squat.
in sport= archery, holding handstand before a dive, holding in a scum (still)
Isotonic
A muscular contraction in which the length of the muscle changes.
Concentric isotonic contraction
- The muscle contracts and shortens
- Known as the positive phase of muscle contraction
eg.Biceps on the upward phase of a bicep curl
eg.Triceps on the upward phase of a press-up
eg. quadriceps when kicking ball
eccentric isotonic contraction
Eccentric = extends
An isotonic contraction where the muscle lengthens, as it returns to its normal length after shortening against resistance.
Used to decelerate the body as working with gravity. Normally when still.
Known as the negative phase of muscle contraction
eg. Biceps on the downward phase of a bicep curl
eg. Triceps on the downward phase of a press-up
eg. skip in triple jump as quads try to slow body down
Type of muscle fibre: 1. Slow Oxidative
- slow twitch
- Contract Slowly
- Low force of contraction
- Aerobic
- High resistance to fatigue
- Generation of ATP aerobically
eg.Endurance events: Marathon, Triathlon, Long distance rowing
Type of muscle fibre: 2A. FAst oxidative Glycolytic
- fast twitch
- Contract fast
- Medium force of contraction
- Aerobic & Anaerobic
- Medium resistance to fatigue
eg. Middle distance events: 400m Tennis Rally Combination punches Gymnastics floor routine
Type of muscle fibre: 2X.Fast glycolytic
- fast twitch
- glycolytic
- Contract very fast
- High force of contraction
- Anaerobic
- Low resistance to fatigue
eg. Power events: 100m Shot-put Javelin Power lifting
All or none law
to make a muscle contraction:
1. impulse to motor neuron, connected to muscle fibres in muscle (motor unit)
2. all of the fibres attached to the neuron contract
= all or nothing rule- The force produced by the muscle is due to the number of motor units stimulated to contract.
Responses of the muscular system to a single sport or exercise: Increased blood supply
As you start exercising, your muscles begin to increase their demand for oxygen and there will be higher demands or other nutrients such as carbohydrates of fats. This would mean that the blood would have to get to the working muscles quicker so you are able to carry on with physical activity.
Responses of the muscular system to a single sport or exercise: Increase in muscle temperature
produce energy for exercise = creates heat.
more exercise= more energy= more heat.
The amount of heat your muscles produce = the amount of work they perform.
used in warm ups to warm up muscles
Responses of the muscular system to a single sport or exercise: Increased muscle pliability
exercise= muscles warm and become more pliable and flexible
good as less likely to be injured as improved joint flexibility and can stretch further
Responses of the muscular system to a single sport or exercise: Lactate accumulation
build-up of lactic acid is a waste product of anaerobic exercise. This build-up of acid in the muscle tissue = rapid fatigue and will impede muscular contractions if it is not removed quickly
Responses of the muscular system to a single sport or exercise: Micro Tears
resistance training= muscles are put under stress = tiny tears occur in the muscle fibres = micro tears= swelling in the muscle tissue = pressure on the nerve endings and pain
need to rest and recover
Responses of the muscular system to a single sport or exercise: Delayed onset of muscle soreness (DOMS)
pain 4–48 hours after taking part in strenuous exercise= caused by micro tears = normally at eccentric muscle contraction
Adaptations of the muscular system to exercise: Hypertrophy
muscles larger due to larger muscle fibres due to increased protein in muscle cells due to overloading muscles in training= muscles contract with greater force. Type IIX and IIA show larger muscles than Type I muscle.
Adaptations of the muscular system to exercise: Myoglobin levels rise
myoglobin is a haemoglobin found in muscles- can increase amount of myoglobin= more oxygen to mitochondria= releases energy to muscles aerobic/endurance events
Adaptations of the muscular system to exercise: Increased mitochondria
increased muscle fibres = many mitochondria/ larger and denser = aerobic energy production = type 1 fibres= last longer in aerobic.
Adaptations of the muscular system to exercise: Glycogen Storage Increase
muscle glycogen does not require oxygen to produce energy = rain at higher intensities for longer periods = muscles can store more glycogen as your body adapts to long-term exercise
The ATP-PC system uses a stored molecule in the muscle called creatine phosphate (CP) to resynthesise ATP. It is the breakdown of this molecule that releases the energy needed to rejoin the ADP and free phosphate to form ATP. This system is anaerobic as it works without oxygen, and does not produce any waste products.
Adaptations of the muscular system to exercise: Tendon Strengthening
Tendons (fibrous connective tissue bands that are designed to withstand tension, connecting muscle to bone) = adapt to overload of exercise = regular exercise = increase the flexibility and strength of tendons/ ligaments
Adaptations of the muscular system to exercise: Increase Lactate Tolerance
Anaerobic training =muscles more tolerant of lactic acid and get rid of it better = work harder for longer = increased blood vessel (capillary bed) = increase body’s max 02 consumption = type 2x muscles = anaerobic
Adaptations of the muscular system to exercise: Improved use of energy sources
athletes use fats more efficiently to break them down into fatty acids and energy using oxygen = can use fats as energy source when carbohydrates become scarse
Additional factors affecting the muscular system: Age
older = muscle mass shrinks (Sarcopenia) = loss muscle strength and power
Additional factors affecting the muscular system: Cramp
cramp is an involuntary muscle contraction that occurs suddenly due to factors like dehydration (insufficient supply of blood to the muscles, reducing the supply of oxygen and essential minerals). To help, drink fluids and stretch to lengthen muscle fibres = increased flexibility.
safety and effectiveness of muscles: levers
longer lever= harder exercise
safety and effectiveness of muscles- momentum
when exercise with speed/ lack of control= joints under strain= antagonist muscle severely stretched
safety and effectiveness of muscles- stability
exercises should be performed with stable base
safety and effectiveness of muscles- alignment
forces and stresses of an exercise can be minimised by keeping skeleton aligned
State two characteristics of cardiac muscle.
Non-fatiguing (1)
Involuntary (contractions) (1)
Found only in the heart (1)
(a) Give the meaning of the term ‘isometric contraction’.
A muscle contraction where no
movement takes place/remains the same
length under tension (1)
Give one example of a sporting action that requires an isometric contraction.
Gymnasts body when on the rings
(crucifix position) (1)
Skiers’ legs when holding the crouched
position (1)
A rock climber when holding a position
on the wall/rock (1)
Jane is an 800m runner. One of the adaptations of her training is an increase in the size
and number of her mitochondria.
6 (a) (i) State the function of mitochondria.
To produce energy (1)
Explain why an increase in the number of mitochondria is beneficial to Jane’s
800m performance.
More energy can be produced
aerobically (1)
+any three from
which reduces the requirement for
anaerobic energy production (1)
therefore less lactic acid would be
produced/delayed OBLA (1)
Jane can work at a higher
intensity/maintain faster speed for longer
in the 800 m (1)
therefore finishing the race in a quicker
time/delaying fatigue until later in the
race (1)
One reason Type IIa muscle fibres are important to an 800m runner’s performance is
that they are more resistant to fatigue than Type IIx muscle fibres.
(b) Explain one other reason that Type IIa muscle fibres are important to an 800m
runner’s performance.
Type IIa are used because they are fast
contracting/they can produce great force (1)
so enabling Jane to work at a high intensity (1) so
Jane can keep running fast/maintain her pace to
the end of the race/run race quicker (1)
