Topic 4

Question 1

Lable the diagram of a motor unit

Answer 1

• Dendrite
• Cell body
• Nucleus
• Axon
• Motor end plate
• Synaspse
• Muscle

Question 2

Expalin the role of neurotransmitters in stimulating skeletal muscle contraction

Answer 2

Neurotransmitters-chemicals that are used communication between hevron at the end of the synapse and another cell
Acetylcholue -transfers the action potential from the motor unit to muscles cells vin a chemical transfer to contract the muscle
· At the end of the motor endplate acetylcholine changes electrical impulse into a chemical stimulus
· it increases membrane permeability to sodium ions
↳ causing calcium to be released into the muscle tell
cholinesterase -an enzyme which breaks down acetylcholine
· breaking down acetylcholine will depolarize the membrane which will stop the muscle from contracting

Question 3

Explain how skeletal muscles contracts by the sliding filament theory

Answer 3

· A. P travels along sarcolemma and through +-tubules
· A. P stimulates Sarcoplasmic-reticulum release (22t Into muscle cells
· Ca’t binds to troponin which then moves tropomyosin and opens the binding sites on actin
· myosin binds to actin forming In cross-bridge
myosin head undergoes a power stroke sliding actin across If pulling 2 lines closer together
· Cross-bridge is broken from the breakdown of energy released from ATP to ADP
myosin head is re-excited from energy released from the breakdown ATP to ADP + P
· The cross-bridge cycle continues until muscle is no longer stimulated

Question 4

Explain how fast and slow twitch fiber types differ in structure and function

Answer 4

Fiber Types Type I fibers Type II A fibers Type II B Fibers
· contraction speed · Slow · fast · very high
- Size of motor neuron. Small · large · very large
- Resistance to fatigue high · intermediate · low
· Activity used for · nerobic · large term anaerobic · short terp anaerobic
· Force production · low · high · very high
· Efficiency · highly · Intermediate · low
· Number of Mitochondria high · high · low
· Capillary density high · Intermediate · low
· oxidative capacity high · intermediate · low

Question 5

Outline the types of movement of synovial joints

Question 6

Outline the types of muscle contractions

Answer 6

sotonic -the muscle contract changing size and causes body movement
There are two types of Isotonic contractions
· Concentric= muscle shortens
· Eccentric muscle lengthens
sometric -no change in length when muscle contracts ex: carrying an object
Isokinetic-contractions that produce movements at a constant speed ex: rehealing Injury/dynamometer

Question 7

Explain the concept of reciprocal inhibition

Question 8

Analyse movements in relation to joint action and muscle contraction

Question 9

Explain delayed onset muscle soreness in relation to eccentric and concentric muscle contractions

Question 10

Define the terms force, speed, velocity, displacement, acceleration, momentum, impulse

Answer 10

velocity -The rate at which a body moves from one location to another in a specific direction
impulse -The effect of force over time
acceleration -The rate at which velocity changes over time
distance -The length of a path a body follows
force -A pushing or pulling action that causes a change of state (rest/motion)of a body
Scalar -A quantity that only has magnitude
displacement -The length of a straight line joining the start and finish points
Vector -A quantity that has magnitude and direction
momentum-A vector describing a ‘quantity of motion’and is the product of mass and velocity mass x velocity
↳ heavier object = heavier momentum

Question 11

Anaylse velocity-time, distance-time, and force-time graphs of sporting actions

Question 12

Define the term centre of mass

Answer 12

The point at which the body is balanced in all directions

Question 13

Explain that a change in body position during sporting activities can change the position of the centre of mass

Answer 13

The centre of mass can change when the body is moving dynamically. The centre of mass is not always Inside the body, it can be
outside of the body depending on positions
Why is it important to know where center of mass Is? Determines the stability of static position. 2. it provides the
axis of rotation.
CofM remains in body CofM outside body
erunning -> Diving
-walking · high Jump
swimming -> Long Jump
-> Somersalt

Question 14

Distinguish between first, second and third class levers

Answer 14

Fulcrum -> The joint
Resistance -body part to be moved 123 FRE >What is In the middle
Effort muscle pull at the muscle insertion
f First class lever -fulcrum in middle EX: Nodding head
L second class lever -Load Is In the middle EX: Heel up and down
= Third class Lever -Effort In middle EX: blcep curl

Question 15

Label anatomical representations of levers

Question 16

Define newtons three laws of motion/ Explain how newtons three laws of motion apply to sporting activities

Answer 16

Newtons first law
an object will remain at rest or constant velocity unless acted upon by an external force
Ex: An athlete at a starting block will not move unless a force acts upon them. The external force comes from the blocks and this propels the sprinter
out of the blocks when exert a downward and backward force against the blocks
Newtons Second law
The rate of change of acceleration of an object is proportional to the force applied and acts in the direction of the force
Example: two athletes at starting block, one is lighter-accelerate faster. Two athletes same mass, the one who applied more force = accel fast
Newtons third law
For every action there is an equal and opposite reaction
Ex: Sprinter applied downwards/backwards force on Immorable block, they exert back with a forward/upward reaction force on the sprinter, pushing
the sprinter forwards. The harder the sprinter pushes, the greater the reaction force will be

Question 17

State the relationship between angular momentum, moment of inertia and angular velocity

Answer 17

angular momentum: The product of the body’s moment of interfa, and its angular velocity. M = IxV
moment of Inertia: its determines the torque (force that causes rotation)needed for a desired angular acceleration about a
rotational axis. It depends on the mass of the object, its shape, and its relative point of rotation
-
Example -> ⑳ · The first object the mass is evenly distribution high moment of Inertim
e
The second object the d moment of Inertice
Center point
Angular Velocity: Is a ratio of a change of angular displacement and the time during which the change occured. The rate at
which a body spins/rotates/turns through an angle.
Angular Velocity = angular displacement time [ 96

Question 18

Explain the concept of angular moment in relation to sporting activities

Answer 18

High moment of Inertia small moment of Inertia
⑳ open arms = > Pulling arms and legs together
O
O
—(high)moment of Inertia · · decrease (low)moment of Inertia
I -> Decrease In angular velocity I · increase in angular velocity
L ↳ = decrease speed L ↳ = Increases speed

Question 19

Explain the factors that affect projectile motion at take-off or release

Answer 19

Projectiles -are objects or athletes that are propelled in the air
Influences
-> height of release
1. the higher the release = the greater distance covered
2. The higher the release = the longer spent In the air
3. The higher the release: the longer the horizontal component will be acting
-angle of release
1. Ideal angle of release Is 45 degrees
2. the angle changes the relationship between the horizontal and vertical components of projectile
-> speed of release (most influential
1. Speed is directly related to the distance
2. greater the speed-greater the distance
3. Initial vertical velocity increases the height of the trajectory, creating a longer flight path
4. Initial horizontal velocity will increase the length of flight time and distance

Question 20

Outline the Bernoulli principle with respect to projectile motion in sporting examples