The Nervous System

SYLLABUS CONTENT

How do the systems of the body influence and respond to movement?

Explain the interrelationship between the nervous system and movement, including structure and function

The Nervous System: Structure and Function

The nervous system may be considered the most important of all body systems, due to its direct influence and control over all other systems. It is the control centre of our body, using electrical signals and chemicals to coordinate all our activities. It's like a vast communication network with a central office (brain and spinal cord) and a network of cables (nerves) reaching throughout the body.

The basic unit of the nervous system is the neuron, a specialised cell with long fibres for transmitting messages. Neurons connect with each other at junctions called synapses, where chemical messengers (neurotransmitters) bridge the gap.

There are two main parts of the nervous system; the central nervous system (CNS), which includes the brain and spinal cord; and the peripheral nervous system (PNS), which includes all nerves outside of the CNS that extend to all organs and tissues.

Central Nervous System (CNS)

The CNS is made up of the brain and spinal cord.

The brain is the main control centre for the whole nervous system.

Fun facts:

it is the size of two fists
it contains about 100 billion neurons
it is made up of 75% water
it weighs only 2% of the body’s weight, yet uses 20% of its energy and oxygen intake
60% of the non-water parts are made of fat (cholesterol)
every minute about 1 litre of blood flows through the brain.

Structure:

The structure of the brain is complex. Being surrounded by a few layers of protective tissue including the skull and cerebrospinal fluid, the brain is encased by a layer of grey matter that contains the body of nerve cells, and the inner white matter is made up of the long axon bodies that conduct the electrical signal. The brain is made up of 6 parts. See the image for the functions of each part.

The Spinal Cord is a this thick piece of neural tissue with many branches that provide a connection point between the nerves of the body and the brain.

Fun facts:

it is protected by the vertebral bones
it is divided into various sections, depending on the nerves that protrude from it
there are 12 cranial nerves that control the head and neck
along the spinal cord between each vertebra, 31 pairs of spinal nerves protrude and branch off into various parts of the body from five different sections (cervical, thoracic, lumbar, sacral and coccygeal)
different nerves send electrical signals in different directions.

Peripheral Nervous System (PNS)

The Peripheral Nervous System (PNS) is made up of nerves branching out from the brain and spinal cord.

It has two parts: The Somatic Nervous System (SNS) and the Autonomic nervous system (ANS).

Somatic Nervous System (SNS)

Controls voluntary movements. It carries sensory information from the body (touch, sight, sound) to the brain and relays instructions back to the muscles for movement.

There are both sensory nerves and motor (action) nerves. The sensory nerves detect and gather external information and stimulus from the outside world using all the senses of the body. These are then processed in the CNS and a response follows if required using the motor nerves.

For example, touching a hot plate sends a signal of danger to the brain to process, and the signal is sent for the muscle to contract and pull the arm away (often before the person is even aware, which is called a reflexive action).

The Autonomic Nervous System (ANS)

Controls involuntary actions of the body (without conscious control) required to sustain life, such as respiration, ventilation, blood pressure, body temperature, heart rate and digestion.

It has two branches:

Sympathetic Nervous System: Responds to stress, preparing the body for action (fight-or-flight response).
Parasympathetic Nervous System: Promotes relaxation and restores the body at rest.

So, as an example; the sympathetic nerves of the heart increase heart rate, whereas the parasympathetic nerves of the heart reduce heart rate.

Activity

Create and draw a diagram labelling the major components and pathways of the nervous system.

Then expand the image below to check you have included all of the components.

Practical Activity 1: Hand Slaps

Play a game of hand slaps. In pairs, each person places their palms together, pointing their fingers to towards their opponent, fingertips touching. One person (the "slapper") tries to slap the back of their opponent's hand before they react and remove it. If it is slapped, they remain in control and try to slap again. If they miss, it becomes the opponent's turn. If the opponent tries to avoid a slap without the "slapper" removing their fingertips from the starting position, they lose control and the opponent becomes the "slapper".

QUESTIONS:

What concepts are being applied through this practical activity? How can you explain this simply?
What if we were to play this game blindfolded? Would you explain it in the same way? Why/why not?

Practical Activity 2: Reaction Time Test

Use the link to play the Reaction Time Game.

Reaction Time Game

Activity: Video and questions

Watch the video and answer the two questions in your books.

What is the primary function of the nervous system?
Explain the link between ‘sensory input’, ‘integration’ and ‘motor output’.

Activity

After watching the video above, complete this worksheet on the Central Nervous System and movement.

Lesson 7: Central Nervous System and movement.docx

Interaction with other systems - in brief

How does the Nervous System interact with other body systems?

Muscular System - The nervous system plays a crucial role in movement. Sensory information from the body (like feeling the ground beneath your feet) travels through nerves to the brain. The brain interprets this information and sends signals back to the muscles, instructing them to contract or relax, allowing you to walk, run, or maintain balance. This constant communication between the brain, spinal cord, and nerves throughout the body is essential for all our actions, both conscious and unconscious.

Endocrine System - The nervous system communicates with the endocrine system by triggering the release of hormones. For example, the nervous system can stimulate the adrenal glands to release adrenaline during stress. Hormones, in turn, can influence nervous system activity. The nervous system plays a crucial role in sexual arousal and response by sending signals to the reproductive organs.

Circulatory System - The nervous system regulates blood pressure and heart rate based on various factors like physical activity and emotional state.

Respiratory System -The nervous system regulates the rate and depth of breathing by sending signals to the diaphragm and muscles involved in respiration.

Digestive System - The nervous system stimulates the release of digestive juices and muscle contractions in the digestive tract, ensuring efficient food breakdown and movement.

Immune System - The nervous system can influence the immune system's response to inflammation and infection.

How does the nervous system influence and respond to movement?

Read page 227 of the Cambridge textbook. Then using that information and your own research, complete the writing task below:

WRITING TASK - RESPONSE WRITING

CUBE the following question. Then use your verb sheet and ALARM matrix to formulate a response.

Describe the relationship between the nervous system and movement.

4 marks

WRITING TASK - GLUE

Assess your response by applying the GLUE method. Highlight the following:

Green - Specific verb requirements/language
Pink - Links to the question
Orange - Syllabus-specific content
Yellow - Examples

Award yourself a mark out of 5.

Annotate what you did well and areas for improvement.

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