Nervous System General Flashcards
Name the 3 functions of the nervous system
Sensory - detection and input - what gives you info
Integrative - processing, storing, analyzing of sensory info
- decision making
- what to do once you get the information
Motor - output portion
Name the Types of nervous tissue
Neurons
Neurolglia
What are neuralgia and what is their function?
Non neuronal cells that:
Nourish, support and protect neurons in CNS and PNS
Maintain homeostasis
Form myelin
What are the parts to a nerve cell?
Dendrite
Cell body
Axon
What is the structure and function of dendrite?
Structure: single or multiple tree like extensions off of cell body
contain lots of receptor sites to receive chemical information from other cells
Function: input potion of neuron
What is the structure and function of an axon?
Structure:
One single thin cylindrical extension off cell body
Axon terminals:end of axon that divides into many fine processes
Synaptic end bulb: swollen end of some axon terminals
Some axon are myelinated
Function: output portion of the neuron
What is myelin?
A multilayered protein and fat covering that speeds up AP conduction.
Actions coated in myelin are called ‘myelinated’ axons
What is a stimulus?
Any change in the environment (internal or external) that is strong enough to stimulate an action potential (AP)
What is an Action Potential?
An electrical signal that travels along the cell membrane of a neuron.
APs can travel at various speeds
How do neurons respond to a stimulus?
They convert it to an action potential (AP)
Nervous system can be organised into what? And what do they consist of?
Central nervous system : brain and spinal cord
Peripheral nervous system: all nervous tissue outside of CNS
What is the structure and function of cell body?
aka soma
contain nucleus and organelles,
Function: Where cell processes take place ie. Protein synthesis
What is the size and shape of neurons?
Neurons vary in size and shape
What are the three structural classifications of neurons? And how are they distinguished?
Unipolar: one process off cell body
bipolar: 2 processes off cell body
multipolar: multiple processes off cell body
What is the structure of a multipolar neuron?
Where is it found?
One axon, multiple dendrites
Most in the brain and spinal cord, all motor neurons
What is the structure of a bipolar neuron?
Where is it found?
One main dendrite, one main axon (not many)
For special senses, ie sight, hearing
What is the structure of a unipolar neuron?
Where is it found?
Single axon. Cell body divides the axon into two parts: periphery process and central process
Peripheral axon has sensory receptors
Central axon has axon terminals
So… Peripheral process conducts AP from dendrites towards cell body, where it is passed to central process and then move away from cell body and enter CNS
All sensory neurons in the PNS
What is the most common type of sensory neuron?
Pain, touch, temperature, taste, proprioception, visceral organ activity
What are the three functional classifications of neurons?
And what is this classification referring to?
Sensory
Integrative
Motor
Referring to which direction the AP is conducted with respect to the CNS
What are sensory neurons also known as? How would you structurally classify sensory neurons?
Afferent neurons.
Unipolar
Describe sensory neurons structure and their role
Contain either sensory receptors at the dendritic ends OR are located just after sensory receptors on other cells
Once activated by stimulus, AP forms and propagates (continues, keeps going) along the axon and is conveyed into CNS via sensory neurons
Sensory neurons travel together in spinal and cranial nerves on a sensory pathway
What are motor neurons also know as?
What are they structurally classified as?
Efferent neurons
Multipolar
Describe motor neurons role
Action potential propagates away from CNS to effectors via motor neurons (efferent)
What are the effectors?
The cells and organs being effected (ie muscle fibres, glands)
What are interneurons also known as?
Where are they located?
What are they structurally classified as?
Association neurons
Located Primarily in CNS between sensory and motor neurons
Most are multipolar
Describe interneurons role
Process/ integrate information from sensory neurons. If a motor response is necessary they decide on the specific response,many relevant motor neurons are activated
What is a synapse?
The site of communication between two neurons or a neuron and another type of cell
What are the types of synapses?
Electrical
Chemical
What is an electrical synapse?
APs conduct directly between plasma membrane of two adjacent cells, through gap junctions
What is faster: Electrical synapse or chemical synapse?
Electrical synapse
In a chemical synapse what is the pre-synaptic and post-synaptic neuron?
The neuron that is sending the signal
The neuron that is receiving the signal
What is the synaptic cleft?
The space between the communicating neurons
What is a neurotransmitter (NT)?
A chemical released by the pre-synaptic neuron to affect (excite or inhibit) the post-synaptic neurons or effector
NT receptors are specific to the NT released (lock and key)
What is the relationship between electrical signals and chemical synapse?
Electrical —> Chemical —> Electrical
At a chemical synapse, a pre-synaptic neuron converts an electrical signal (nerve impulse) into a chemical signal (NT), the post-synaptic neuron converts the chemical signal back to an electrical signal (post-synaptic potential)
What are 4 common Neurotransmitters?
Dopamine
Serotonin
Acetylcholine
Gamma- amino uterus acid
What happens to neuralgia with injury or disease?
Neuralgia will multiply to fill the spaces formerly occupied by neurons
What are the 4 types of Neuroglia in the CNS?
Astrocytes
Oligodendrocytes
Microglia
Ependymal cells
What are the two main functions of astrocytes
Provide nutrients to neurons
Help for the blood brain barrier
What is the blood brain barrier? Name 3 components.
A specialised barrier between the brain and blood vessels that prevents the passage of materials
1) astrocytes and astrocytes end feet that encircle capillary
2) capillary basement membrane
3) tight junctions that join the overlapping capillary epithelial cells
What is the function of oligodendrocytes?
Form/ maintain myelin sheath of CNS neurons
What is the function of Microglia?
What type of cells are they?
Remove debris.
They are phagocytic cells (eating cells) - similar to tissue microbes
Where are ependymal cells found?
They line the cavities of brain and spinal cord
What is the function of ependymal cells?
Produce and help distribute cerebral spinal fluid
What is cerebral spinal fluid (CSF)?
What is its function?
Clear, colourless fluid that circulates brain and spinal cord.
Will: provide nutrients, help protect brain and spinal cord from injury
What are ventricles?
Cavities within the brain that are filled with CSF
Name the neurolglia of the PNS, and their function.
Schwann cells. Function: Circle around axons in PNS Form myelin sheath of PNS axons Involved in regeneration of PNS axons
What is a nucleus? Where is it found?
A cluster of neuronal cell bodies in the CNS
They travel together on similar pathways
What is Ganglion? Where are they found?
Cluster of neuronal cell bodies found in the PNS
What is a tract? Where is it found?
Bundle of axons in the CNS.
Aka the ‘info highway’ for sensory or motor neurons.
tracts interconnect neurons in spinal cord and brain
What is a nerve? Where is it found? Name two types.
Bundle of axons in the PNS
Peripheral nerves - connect spinal cord to periphery
Cranial nerves - connect brain to periphery
