muscular skeletal all

Mitochondrial density

Moderate:

Respires both aerobically and anaerobically

Used for both strength and endurance

Neuron size

Large:

Medium force production

Recruited for more powerful movements

Large size allows for control of more muscle fibres creating a larger motor unit

Fibres per neuron

Many:

Fast contraction time

Increase force production for short, powerful bursts of movement

Capillary density

Moderate:

Provides oxygen for aerobic respiration

Also respires anaerobically so does not require as much oxygen as T1

Phosphocreatine store = a high-energy compound stored in the muscles that rapidly regenerates ATP for explosive, high-intensity activities lasting up to 10 seconds

High:

Used in anaerobic respiration

Fuels explosive movement as energy is provided immediately

Crucial for first seconds of intense activity

Myoglobin content =

an oxygen-storing protein in muscle cells

Moderate:

Respires aerobically sometimes

So requires oxygen but not as much as T1

Medium resistance to fatigue

Mitochondrial density

Low:

Respires anaerobically

Low resistance to fatigue

Neuron size

Large:

High force production

Fastest speed of reaction

Large size allows for control of more muscle fibres creating a larger motor unit

Fibres per neuron

Many:

Fastest contraction time

Large motor unit allows for powerful, explosive movements

Capillary density

Low:

Oxygen is not needed for respiration

Waste products build up quickly

Easily fatigued

Phosphocreatine store = a high-energy compound stored in the muscles that rapidly regenerates ATP for explosive, high-intensity activities lasting up to 10 seconds

High:

Used in anaerobic respiration

Fuels explosive movement as energy is provided immediately

Crucial for first seconds of intense activity

Myoglobin content =

an oxygen-storing protein in muscle cells

Low:

Respires anaerobically so does not require oxygen

Hinge joint

A cylindrical bone articulates with a trough shaped bone held tightly by ligaments which limit sideways movement

Motion restricted to one plane

E.g. Elbow, knee and ankle joints

Pivot joint

A rounded bone articulates with a ring-shaped bone which restricts motion to one plane

E.g. the atlantoaxial joint in the neck that allow you to rotate your head

Condyloid joint

Similar to ball and socket joint

With flatter bone surfaces to allow motion in two planes

E.g. the wrist joint

Ball and socket joint

A ball shaped head articulates with a cup shaped socket

A large range of motion in all three planes

E.g. hip and shoulder joints

Gliding joint

Between two flat or nearly flat bones

Allows for sliding or gliding

E.g. between the small carpal bones of the wrist

Slow-twitch - type 1

Small and red; Produces small amount of force; High amount of mitochondria in cells; Use oxygen as source of energy; Highly fatigue resistant; Used during low intensity activities with steady oxygen consumption.

Moderate fast-twitch - type 2a

Moderate size and red; Use a combination of glucose and oxygen as source of energy; Quicker contracting speed and higher force output; Lower fatigue resistant; Used during anaerobic activities that are moderate in duration.

Fast-twitch - type 2x

Large and white; Large stores of glycogen meaning extremely high levels of glucose; Fastest contraction speed and most force; Fatigues quickly (15-30 secs); High impact, heaving resistance activities use them.

Recruitment order

Type 1, type 2a, type 2x; This order is known as the Henneman's size principal; Helps minimize muscle fatigue; Allows precise motor control by using no more than the force necessary to complete the movement.

Axial

Central skeleton

Appendicular

Extremities

Long

Create leverage

Help generate speed, force and power

E.g. the femur helps generate speed when running

Short

Used for fine movements

E.g. the carpals when putting spin on a ball in cricket

Flat

Protect vital organs

E.g. the cranium protects the brain when a footballer carries out a header

Irregular

Protects the body

E.g. the patella stops hyperextension at the knee and provides movement based stability

Sesamoid

A small bone commonly found embedded within a muscle or tendon near joint surfaces

Protect the tendon from excessive stress and wear

Reduce friction

Alter the tendon's angle to improve muscle force and leverage

E.g. the patella

What are the key structures of the Central Nervous System (CNS)?

The key structures include the cell body, axons, and motor end plate.

Where is the cell body of a motor neuron located?

In the spinal cord.

What is the function of axons in motor neurons?

Axons branch off the cell body and send impulses to the motor end plate.

What is the motor end plate?

The motor end plate is where the action potential travels to stimulate a muscle.

What is a motor neuron?

A specialized cell that transmits nerve impulses from the CNS to muscle fibers.

What is the difference between a motor unit and a motor neuron?

A motor unit includes the muscle, while a motor neuron does not.

How does the number of muscle fibers in a motor unit relate to movement control?

The number of muscle fibers within a motor unit depends on the control a movement requires.

What determines the number of motor units recruited?

The size of the contraction required determines the number of motor units recruited.

What is an action potential?

An electrical impulse that acts as a signal.

How is a nerve impulse conducted in a motor neuron?

It is initiated in the motor neuron cell body and conducted down the axon to the synaptic cleft.

What neurotransmitter is secreted into the synaptic cleft during a nerve impulse?

Acetylcholine (Ach) is secreted to conduct the nerve impulse across the gap.

What happens if the electrical charge in a muscle fiber exceeds a threshold?

The muscle fiber will contract in an 'all or none' fashion.

What is the All or None Law in muscle contraction?

An individual muscle fibre will either contract completely and to its maximum extent, or not at all, once a stimulus exceeds its threshold potential.

How can we increase the strength of muscle contraction?

By recruiting more motor units, which involves the stimulation of additional motor units.

What is the advantage of having fewer muscle cells per motor unit?

It allows for the generation of precise movements.

What characterizes large motor units in muscles that generate gross movements?

A single neuron is connected to a large number of muscle cells.

How is muscle tone maintained?

By asynchronous stimulation of random motor units.

Type 1 at sub-maximal intensity

Around 90 seconds

Type 2A at sub-maximal intensity

Seconds / minutes

Type 2B at sub-maximal intensity

Minutes / hours

Type 1 at maximal

Days

Type 2A at maximal

Hours / days

Type 2B at maximal

4-10 days

Quadriceps

Rectus femoris

Sartorius

Vastus intermedius

Vastus medialis

Hamstrings

Bicep femoris

Semitendinosus

Semimembranosus

Rotator cuff

Supraspinatus

Infraspinatus

Teres minor

Subscapularis

Official name of hip flexor

Iliopsoas

What are the three planes of movement?

Sagittal, frontal and transverse

What are the three axes of movement?

Transverse sagital and longitudinal

What movements are carried out in the sagittal plane and transverse axes?

Flexion and extension

What movements are carried out in the frontal plane and sagittal axes?

Adduction and abduction

What movements are carried out in the transverse plane and longitudinal axes?

Rotation

Mitochondrial density

High: Respires aerobically to release energy, High resistance to fatigue.

Neuron size

Small: Lowest force of contraction, Slowest speed of reaction.

Fibres per neuron

Few: Lowest force contraction, Slowest speed of reaction. Few fibres per neuron means a small motor unit which cannot carry out more powerful contractions.

Capillary density

High: Supplies oxygen for aerobic respiration, Removes waste products from cells, High resistance to fatigue.

Phosphocreatine

A high-energy compound stored in the muscles that rapidly regenerates ATP for explosive, high-intensity activities lasting up to 10 seconds.

Phosphocreatine store

Low. Rely on aerobic respiration so do not require phosphocreatine in order to release energy.

Myoglobin

An oxygen-storing protein in muscle cells.

Myoglobin content

High. Supplies oxygen to mitochondria for aerobic respiration, High resistance to fatigue.