Lecture 2 - Communication within the Nervous System Flashcards
Does the human brain have more neurons or glial cells?
glial cells (10-50 x more than neurons)
T/F: It is always one-on-one communication between neurons.
False: 1 neuron can communicate with multiple neurons
List the 4 main functions of neurons.
- receive and integrate incoming information from sensory receptors or other neurons
- generate a nerve impulse (action potential)
- conduct the action potential
- transmit information to target cell (other neurons, muscles, glands)
How does information get passed along within the nervous system?
Action Potential
What is the basic functional unit of the nervous system?
Neuron cells
What are the 3 main features of a typical neuron?
cell body, dendrites, axons
Differentiate between dendrites and axons.
Dendrites carry signals towards the cell body, axons carry signals away from the cell body.
What are neurites?
axons and dendrites
What 2 ways are neurons classified?
structure and function
How are neurons structurally classified?
by number of a neuron’s processes extending from cell body
What are the 4 types of structural neuron classifications?
unipolar neurons
pseudo-unipolar neurons
bipolar neurons
multipolar neurons
Describe a unipolar neuron.
single process from cell body, characteristic of invertebrates
Describe a pseudo-unipolar neuron and list an example.
Short single process from cell body that splits into two processes (like a “T‟)
•Example: sensory neurons within dorsal root ganglion
Describe a bipolar neuron and list an example.
2 processes:one dendrite, one axon
•Examples: some sensory
neurons, including those of retina of eye and olfactory epithelium
Describe a mulitpolar neuron Where are they abundant? List an example of one.
a single axon and one or more dendritic branches emerge from all parts of the cell body
•characteristic of most neurons in brain and spinal cord
•Examples: motor neurons in spinal cord, Purkinje neurons of cerebellum, pyramidal neurons of motor cortex
Of the 4 structural classifications of neurons, which are the most abundant in the human nervous system?
multipolar
What are the 4 morphological characteristics of a multipolar neuron?
dendrites, cell body, axon, pre-synaptic terminal
Describe the nerve cell body.
Contains mitochondria, nucleus, neurofibrils and nissl substances; metabolic centre of the nerve.
Describe dendrites.
main apparatus for receiving information from other nerve cells; relatively short processes
often branch extensively (resemble branches of a tree)
What can you devise when you come across a neuron that has an extensive dendrite branching?
That the nerve is capable of receiving more information and is able to perform more complex tasks.
What is the main conducting unit of a neuron?
axons
Describe axons.
Can vary in length (1mm -> 1m), branch extensively before terminating, ends of the branches are enlarged and called the pre-synaptic terminals
Describe presynaptic axon terminals.
where axons make contact to transmit information, point of contact is the synpase.
What are the 3 components of a synpase?
presynaptic membrane + synaptic cleft + post synaptic membrane
How are neurons functionally classified?
based on connections to different tissue types