Nervous System Flashcards
Describe the nervous system.
A network of fibres which span the body, coordinating a diverse range of voluntary and involuntary actions.
The nervous system involves both _____ and ______ actions.
Voluntary and involuntary
The nervous system is divided up into 2 main regions /divisions. Name them.
- Central Nervous System (CNS)
2. Peripheral Nervous System (PNS)
What is the Central Nervous System (CNS) made up of?
The brain and spinal cord.
What is the Peripheral Nervous System (PNS) made up of?
All peripheral nerves (any nervous tissue found outside the brain and spinal cord)
What is the name given to the information being sent to the brain from the peripheral nerves?
Sensory information
The nervous system provides us with 3 key categories of functions. What are they?
- Sensory (detection)
- Integration (processing)
- Motor (responding)
Give an example of sensory information.
Touch, vision, smell
Which region of the brain processes sensory information / input?
The sensory cortex
Define proprioception
Sense of body position
A deficiency in which vitamin, can be the cause of problems with nerve impulses up the spinal cord?
Vitamin B12
List 2 things that vitamin B12 is very important for in the body.
- Producing red blood cells
2. Producing the myelin sheath around nerve fibres
Why might a vitamin B12 deficiency present clinically as a loss of balance.
Because lack of vitamin B12 leads to demyelination (a lack of myelin) around the nerves running up through the spinal cord, which means that messages get to the brain a lot slower.
This means our awareness of where our body is (proprioception) can be compromised and we can be unsteady on our feet as a result.
What is myelin needed for?
To relay electrical signals quickly. It provides an insulating sheath around nerve cells.
List 3 functions of the nervous system.
- Detects internal and external environment changes.
- Processes sensory information
- Produces responses to sensory information.
What is the nervous system made up of?
Brain, spinal cord, peripheral nerves
Name the 3 types of neurons
- Sensory neurons
- Interneurons
- Motor neurons
Which type of neuron connects sensory and motor neurons in creating an output movement?
Interneuron
What does ‘autonomic’ mean?
Involuntary
Is the somatic nervous system voluntary or involuntary?
Voluntary
What can the peripheral nervous system (PNS) be sub-divided into?
The somatic nervous system (voluntary) and autonomic nervous system (involuntary)
What is the role of the peripheral nervous system?
Carrying messages to and from the CNS
What is the CNS?
Central Nervous System
What is the PNS?
Peripheral Nervous System
What is the role of the autonomic nervous system?
Control of involuntary body functions
Which 2 systems can the Autonomic Nervous System be sub-divided into?
Sympathetic and Parasympathetic nervous systems
What is the main role of the spinal cord?
Connecting the brain and the peripheral nervous system
Which is the ‘fight or flight’ part of the autonomic nervous system?
Sympathetic nervous system
Which is the ‘rest and digest’ part of the autonomic nervous system?
Parasympathetic nervous system
Which nervous system is important to regulate homeostasis?
Autonomic nervous system
What has overall control over the autonomic nervous system (ANS)?
The hypothalamus
Which body parts does the autonomic nervous system control / regulate?
Organs, glands, cardiac and smooth muscles.
Which sub-division of the ANS contains the vagus nerve?
The parasympathetic nervous system
Which major nerve is actually a branch off of the brain stem?
The vagus nerve
Which is the biggest nerve in the Autonomic Nervous System (ANS)
The vagus nerve
List one key function of the vagus nerve within the body
- Helps to promote digestion (mechanical and chemical)
Which sub-division of the ANS prepares our body to cope with threats?
The sympathetic nervous system
Where is the nerve origin in the sympathetic nervous system?
Thoraco-lumbar
Where is the nerve origin in the parasympathetic nervous system?
Cranio-sacral
What is the enteric nervous system?
The ‘brain of the gut’. (The gut-brain connection)
How many neurons make up the enteric nervous system?
Around 100 million neurons
What is the other name for the vagus nerve, and why?
The wandering nerve.
Because it has such an extensive anatomical course (it travels all around the thorax and abdomen)
Which key chemical is shared by the brain and the enteric nervous system?
Serotonin
Where is serotonin predominantly found?
In the digestive tract
95% of serotonin is found in the enteric nervous system
Nervous tissue contains 2 types of cells. What are they?
- Neurons
2. Neuroglia (glial cells)
What are neurons?
Electrically excitable cells that transmit electrical currents (information) up and down our nervous system.
What name is given to the structural and functional units of the nervous system?
Neurons
What is unique about neurons from a cell perspective?
They are electrically excitable
What % of our brain volume is made up of neurons?
Only 10%
Which type of cells make up 90% of brain volume?
Neuroglia (glial cells)
What is the role of neuroglia / glial cells?
They nourish, support and protect neurons, and form a mesh/framework that sticks all the neurons together.
“glial” = glue
How many types of glial cells are there?
6 types
How many types of glial cells are found in the CNS?
4
How many types of glial cells are found in the PNS?
2
What is a nerve?
A bundle of one or more neuron axons (in the peripheral nervous system).
List the parts of a neuron
Cell body Dendrites Axon Myelin sheath Nodes of Ranvier Terminal endings
For size perspective, how many neurons (individual cells) could fit on a pinhead?
30,000
What is the name given to the insulating covering that enables nerve impulses to travel quicker?
Myelin sheath
The myelin sheath only covers which part of the neuron?
The axon
What is the name given to the spaces between sections of myelin sheath covering the axon of neurons?
Nodes of Ranvier
What is a stimulus?
Anything able to generate an action potential
What is an ‘action potential’?
The electrical current that travels down the axon of a neuron, towards the terminal endings
Which part of a neuron contains the nucleus and cell organelles?
The cell body
What are dendrites?
The receiving part of the neuron.
The look like little tree branches coming out of the cell body. They communicate with other dendrites/neurons.
What is ‘grey matter’?
‘Grey matter’ describes the appearance of some of the tissue within the Central Nervous System. Grey matter is essentially lots of neuron cell bodies and dendrites, all bundled together.
What makes ‘white matter’ appear white?
The myelin sheath around axons.
What is ‘white matter’?
‘White matter’ describes the appearance of some of the tissue within the Central Nervous System. White matter is essentially lots of neuron axons, all bundled together.
What are ‘ganglia’?
Collections of neuron cell bodies clustered together in the Peripheral Nervous System.
Collections of neuron cell bodies clustered together in the CNS are known as _______.
Nuclei
What is the name given to the thin cylindrical projections within a neuron, which carry nerve impulses away from the cell body, towards another neuron?
Axons
Which part of the neuron carries the action potential?
The axon
Where might we find an axon of more than 1 metre in length (in the PNS)?
Sciatic nerve
What is the biggest nerve in the body?
The sciatic nerve
What is the name given to the membrane that covers axons?
The axolemma
What are axon bundles called in the central nervous system (CNS)?
Tracts
What are axon bundles called in the peripheral nervous system (PNS)?
Nerves
How many sensory tracts do we have going up the CNS to the brain?
2
How many motor tracts do we have going down the CNS from the brain?
1
If the tissue is healthy, at what rate can damaged axons regenerate?
1 - 2mm per day.
Which cells are non-excitable - neurons or neuroglia (glial cells)?
Neuroglia (glial cells)
Which cells in the nervous system are far smaller than neurons but 50x more prevalent?
Glial cells (neuroglia)
Which cells in the nervous system cannot undergo division and are set at birth?
Neurons
Which cells in the nervous system can undergo division?
Glial cells
List 3 functions of neuroglia
- Surround neurons & hold them in place.
- Supply neurons with oxygen & nutrients
- Destroy pathogens
- Remove dead neurons
How many types of neuroglia are there?
6
4 in the CNS, 2 in the PNS
Name the 4 types of glial cells in the CNS
Astrocytes
Oligodendrocytes
Microglia
Ependymal Cells