4. The Nervous system and its relative to exercise

Question 1

What are the three main functions performed by the nervous system?

Answer 1

• Sensation
• Analysis
• Response

Question 2

What are the two main divisions of the nervous system?

Answer 2

Central nervous system (CNS) & peripheral nervous system (PNS).

Question 3

What structures makes up the CNS?

Answer 3

The central nervous system consists of the brain and spinal cord.

Question 4

Describe the functions and divisions of the autonomic nervous system.

Answer 4

The autonomic system is subdivided into sympathetic and parasympathetic systems. These systems either speed up internal processes and increase levels of activation in preparation for activity (sympathetic) or slow down internal processes and decrease levels of activation during rest and recovery (parasympathetic).

Question 5

Identify the three main structures that make up a neuron.

Answer 5

• Cell body
• Axon
• Dendrites

Question 6

What are the two main types of neurons making up the PNS?

Answer 6

Sensory neurons and motor neurons.

Question 7

What is the insulating sheath around a neuron called?

Answer 7

Myelin sheath.

Question 8

Name the neurotransmitter that transfers the action potential from the end of a neuron to an adjoining cell.

Answer 8

Acetylcholine (ACh).

Question 9

Describe the structure of a motor unit.

Answer 9

A motor unit is made up of one motor neuron (nerve) and all of the muscle fibres that it connects to and innervates (or stimulates) to create a desired contraction response.

Question 10

What is the ‘all or none law’ of motor unit recruitment?

Answer 10

The ‘all or none law’ – all the muscles fibres of a motor unit contract and relax together.

Question 11

With reference to motor units, describe how muscular force can be controlled.

Answer 11

Control of muscular force is achieved through a combination of adjusting the number of motor units recruited and increasing the frequency of their discharge.

Question 12

What are proprioceptors?

Answer 12

Proprioceptors act as sensors in the muscles and connective tissue of the limbs.

Question 13

Muscles spindles provide what information in relation to muscles?

Answer 13

Muscles spindles sense changes in muscle length as well as the rate that change occurs.

Question 14

Golgi tendons organs provide what information in relation to muscles?

Answer 14

Golgi tendons organs (GTO) measures the amount of tension created by the muscle.

Question 15

What is stretch reflex?

Answer 15

The stretch reflex (myotatic reflex) is a muscle contraction in response to stretching within the muscle.

Question 16

What mechanism ensures that the antagonist relaxes as the agonist muscle contracts?

Answer 16

Reciprocal inhibition (RI) describes the reflex inhibition of an antagonist muscle when the agonist contracts.

Question 17

Identify neuromuscular adaptations from training that relate directly to improvements in the nervous system.

Answer 17

• Improved reaction times
• Greater force production
• Improved timing of movements
• Enhanced stability and balance
• Better exercise technique

Question 18

What are the subdivisions of the PNS?

Answer 18

Somatic and autonomic.

Question 19

What are the subdivisions of the autonomic nervous system?

Answer 19

Sympathetic and parasympathetic.

Question 20

What does acetylcholine (ACh) enable?

Answer 20

Acetylcholine (ACh) enables the transfer of an action potential from the end of a neuron to an adjoining cell.

Question 21

Describe the neuromuscular system?

Answer 21

The neuromuscular system is the interaction between the nervous system and the muscular system.

Question 22

The nervous system

Answer 22

• Central nervous system (CNS).
• Peripheral nervous system (PNS).

Question 23

The role of the nervous system

Answer 23

• Sensation – gather information from environment.
• Analysis – decipher received sensory information.
• Response – initiate desired reaction.

Question 24

Divisions of the nervous system

Answer 24

Central nervous system: At the lower part of the brain is the cerebellum; this is responsible for controlling the group action of muscles and is the hub of the CMS. The spinal cord communicates between the brain and PNS; it integrates incoming info and produces responses via reflex mechanisms.

Peripheral nervous system: All nerves (bundles of neurons) outside of the spinal cord are categorised within the PNS. The peripheral nerves connecting with the spinal cord are divided into sensory and motor neurons.

Question 25

Sensory and motor neurons

Answer 25

Sensory neurons: feed into the spinal cord, connect with sensory receptors and relay information to the CNS.

Motor neurons: exit the spinal cord and transmit pulses from the CNS to the organs, muscles and glands; causing them to react with a contraction or secretion.

Question 26

Action potentials, axon terminals and neurotransmitters

Answer 26

Action potential: the wave of electrical activity that passes along electrically excitable cells.

Acetylcholine enables the transfer of an action potential from the end of a neuron to an adjoining cell.

Question 27

Structure and function of a neuron

Answer 27

Question 28

Motor units

Answer 28

Motor unit: The motor neuron and all the fibres it innervates (stimulates).

Motor units vary in size and some innervate only a few muscle fibres whereas others innervate many muscle fibres.

Question 29

Recruitment and the ‘all or none law’

Answer 29

According to the ‘all or none law’ the impulse sent down the neuron can’t gauge the intensity of the contraction it will stimulate. It will either activate a contraction or not.

To vary the intensity of a muscle contraction, different numbers of motor units must be stimulated at varying frequencies.

Question 30

Proprioceptors

Answer 30

Act as sensors in the muscles and connective tissue of the limbs.

Provide feedback on the impact of the immediate environment on our musculoskeletal system:

• Joint angle
• Muscle length
• Muscle tension

Question 31

Stretch reflex

Answer 31

Golgi tendon organs: tell us about muscle tension.

Muscle spindles: tell us about muscle length.

Question 32

Reciprocal inhibition

Answer 32

When a muscle contraction is activated the antagonist muscle group must be inhibited to allow for the contraction.

Question 33

Neuromuscular adaptations to exercise

Answer 33

Cardiovascular training type 1 muscle fibres:

• Increased size and number of mitochondria.
• Increased oxygen delivery to the muscle fibres.
• Increased aerobic enzymes in the muscle tissue.
• Greater supply of glycogen and triglycerides for energy.
• Improved tissue tolerance and resistance to fatigue.

Resistance training and weighted workouts type 2 fibres:

• Increased thickness of recruited muscle fibres.
• Increased force production capacity of the muscle fibres.
• Decreased nervous inhibition.
• Increased tissue tolerance and resistance to fatigue (high-stress, anaerobic conditions).