Nerve And The Brain Flashcards
What are the main functions of the Nervous System?
Master controlling and communicating
Monitors internal and external environments
Integrates sensory inputs and motor commands
Coordinates involuntary and voluntary responses
What are the two divisions of the Nervous system?
Central nervous system
Peripheral nervous system
What is the central nervous system?
Command centre
Composed of the brain and spinal cord
What is the peripheral nervous system?
Composed of all nerves that extend from the CNS
made of motor and sensory nerves
Further subdivided into cranial and spinal nerves
Produces the information, then processed by the CNS and a response indicated by the peripheral
What are Lower motor neurons?
Neurones with cell bodies in the spinal cord or brain stem whose axons directly innervate skeletal muscle
- peripheral nerves
What are Upper motor neurones?
Neurones that transmit information from brain to lower motor neurones and interneurons in the brain stem and spinal cord
- central nerves
Describe peripheral nerves
Take information from the spinal cord to the muscles
Sensory info goes into the spinal cord and motor comes out
These nerves have the ability to mend and repair them selves
What are the two types of peripheral nerves?
Cranial
Spinal
Describe cranial nerves
Carry info to and from the brain
12 pairs serving the head and neck
Number 10 however supplies the heart lungs and gastrointestinal - known as the Vagus nerves
Number 7 supplies the face
Describe spinal nerves
Information to and from the spinal cord
31 pairs named according to the point at which they leave the spinal cord
Some can form plexi - which are areas where certain nerves combine at the spinal canal
What is the autonomic nervous system? What are the 2 systems within it?
An unconscious system
Sympathetic- emerges from the thoracic and lumbar spine. Involves the flight or fight response. Causes increase in HR, BR, Blood pressure etc.
Parasympathetic- emerges from the cranial and sacral parts of the spinal cord. Slows all responses and rates down.
What is the structure of a nerve?
Carry both sensory and motor fibres
Whole nerves are surrounded by a connective tissue membrane called the Epineurium.
Bundles of afferent and efferent neurones are surrounded by Perineurium.
Each individual neurone is covered by Endoneurium.
What structures do highly specialised nerve cells contain?
Dendrites Cell body Axon Axis Hillock Synapse
Describe dendrites
Can contain 1000s Extend from the cell body’s Extensions of plasma membranes Receive incoming impulses from sensory receptors Bring info to the cell body
Describe the cell body
Contain the nucleus and the cell organelles needed for the neurone to carry out its function.
Such as Golgi apparatus, mitochondria
Describe the axon
Long cytoplasmic process Capable of conduction action potentials Only one, but have collateral branches and many terminal branches May be covered in a myalin sheath Can be meters long and very thick
What is a myelin sheath?
A fatty substance produced by Schwann cells in the PNS and oligodendrocytes in the CNS.
Describe axon hillocks
Only place where an action potential can be initiated
Describe a synapse
The axons end in a synapse
There terminals contain 1000s of vesicles contain neurotransmitters
When an AP reaches the synapse, these vesicles fuse with the membrane and empty the contents into the synaptic cleft.
These then diffuse across and bind to receptors on the post synaptic membrane, passing the impulse on to the next neurone or muscle.
What is Neuroglia and where is it found?
Found in the CNS and PNS
It’s a nerve glue
Provides support, insulation and protection
It’s cells lie around and between the neurones
Provides solidity
Contribute to 50% of the Nervous system weight
What are 3 other cells located in the CNS?
Astrocytes
Microglia
Oligocendrocytes
What are astrocytes?
Connect neurones to blood vessels
Filter blood, preventing damaging substances from entering the neurones of the brain.
What are mircoglia?
Additional immune cells
Like phagocytes, to remove debris
What are oligodendrocytes?
Produce myelination in the CNS
Can supply multiple segments of axon for multiple neurones
Protect them