In a few words, what is the central nervous system?
The CNS is made up of the brain, spinal cord and nerves. It is responsible for controlling virtually all aspects of body functions. It helps us move, think, remember and feel emotions.
What is the Central Nervous System?
Brain: The most complex part of the CNS. It is responsible for processing information, directing activities and making decisions. Spinal Cord: A tube-like structure that connects the brain to the body. It carries messages between the brain and every other part of the body.
What is your opinion on the complexity of the Human Central Nervous System?
- It is extremely complex and hard to understand.
- It is complex but can be understood.
- It is simple and can be understood easily.
The human brain has about 100 billion neurons. The spinal cord is only about 18 inches long. The brain consumes approximately 20% of the oxygen used by the body.
When parts of the nervous system are cut open different areas appear different colours. Grey areas are called grey matter and consist of nerve cells bodies and unmyelinated fibres. White areas are called white matter and consist of only myelinated fibres (axons).
Grey & White matter
Draw / write: What are the differences between grey and white matter in the central nervous system?
Why does the CNS need a mix a grey & white matter? Why isn't it all just white matter?
Draw / write: How do the protective structures of the central nervous system help it to function?
The brain and spinal cord are very delicate and vital parts of the body and are heavily protected by: Bone Three membranes called meninges A fluid called cerebrospinal fluid (CSF)
Protection of the CNS
Bone (Cranium protects the brain and the spinal cord runs through the vertebral canal) protects from physical injury.
Three membranes called meninges Its role is to The meninges also Outer layer, called the dura mater, is tough and fibrous, sticks closely to the cranium/vertebral canal, it anchors the CNS to the bone. The middle meningeal layer, arachnoid mater, is a loose mesh of fibres, that connect with the inner layer. The inner layer, pia mater, is delicate, contains many blood vessels and sticks closely to the surface of the brain and spinal cord.
A fluid called cerebrospinal fluid (CSF) that acts as a It occupies the space between the middle and inner meningeal layers (subarachnoid space), circulates through the four cavities in the brain (ventricles) and in the centre of the spinal cord. It is a clear watery fluid containing a cells, glucose, protein, urea and salts. The CSF is formed from blood, circulates through the CNS, taking nutrients to the neurons and removing wastes and eventually re-entering the capillaries.
Cerebral spinal fluid
Functions of the CSF: Act as a shock absorber, protect from mechanical injury Deliver nutrients to the tissues of the central nervous system Remove wastes produced by the brain Regulation of the concentration of H+ and CO2, which regulates breathing Maintain fluid to bath cells of the brain (homeostatic balance) Transport chemical messengers around the CNS
Which layer of protection do you think is most important?
- All equally important
What do you think would happen if the protective structures of the central nervous system were not present?
What would you say is the most important aspect of the central nervous system?