AS Anatomy and Physiology - Neuromuscular System

Question 1

Describe the Sympathetic Nervous System

Answer 1

Prepares body for exercise - ‘fight or flight response’

Question 2

Describe the Parasympathetic Nervous System

Answer 2

Relaxes body and slows down high energy functions - ‘rest and relax’

Question 3

Characteristics of Slow Twitch (Type 1) Muscle fibres (Name 4)

Answer 3

• Slow contraction speed
• Slow motor neurone size
• Slow motor neurone conduction capacity
• Low fatigability
• High mitochondrial density
• High Capillary density
• Very high aerobic capacity
• Low anaerobic capacity
• Low force produced

Question 4

Characteristics of Fast Oxidative Glycolytic (Type 2a) Muscle Fibres (Name 4)

Answer 4

• Fast conduction speed
• Large motor neurone size
• Fast motor neurone conduction capacity
• Medium fatigability
• Medium mitochondrial density
• Medium Capillary density
• Medium aerobic capacity
• High anaerobic capacity
• High force produced

Question 5

Characteristics of Fast Glycolytic (Type 2b) Muscle Fibres (Name 4)

Answer 5

• Fast conduction speed
• Large motor neurone size
• Fast motor neurone conduction capacity
• High fatigability
• Low mitochondrial density
• Low Capillary density
• Low aerobic capacity
• Very high anaerobic capacity
• High force produced

Question 6

Define Motor Neurone

Answer 6

Nerve cells which transmit the brain’s instructions as electrical impulses to the muscles

Question 7

Define Motor Unit

Answer 7

A motor neurone and its muscle fibres

Question 8

Explain the All or None Law

Answer 8

Minimum stimulation (threshold) required to start contraction. If sequence of impulses is equal to or more than threshold, all muscle fibres in a motor unit will contract, if not, no muscle action will occur

Question 9

Explain Wave Summation

Answer 9

Repeated nerve impulse with no time to relax, so a smooth, sustained contraction occurs, rather than twitches - sustained contraction called a tetanic contraction

Question 10

Explain Spatial Summation

Answer 10

When the strength of a contraction changes by altering the number and size of the muscle’s motor units - recruiting additional and bigger motor units within a muscle

Question 11

Describe the Role of Muscle Spindles

Answer 11

They detect how far and how fast a muscle is being stretched and produce a stretch reflex, causing the muscle to contract to prevent over-stretching and reduces the risk of injury

Question 12

Describe the Role of Golgi Tendon Organs

Answer 12

They detect levels of tension in the muscle. When the muscle is contracted isometrically in PNF, they sense an increase in muscle tension - send inhibitory signals to brain, allows antagonist muscle to relax and lengthen - called autogenic inhibition