Neurons and the Nervous System Flashcards
What’s a neuron?
Cells in the nervous system that communicate with one another through electrochemical signals to perform information-processing tasks.
What are neurons composed of?
The cell body (soma), dendrites and axons
What’s the purpose of the cell body?
To coordinate the information processing tasks and keep the cell alive
What’s the purpose of the dendrite?
To receive information from other neurons and relay it to the cell body
What’s the purpose of the axon?
To transmit information to other neurons, muscles or glands
What’s the myelin sheath?
An insulating layer of fatty material that covers the axon that allows signals to be transmitted more effectively
What are glial cells?
Support cells found in the nervous system that make up the myelin sheath. Glial cells can digest dead neurons, provide physical and nutritional support for neurons or form more myelin.
Why are demyelinating diseases (e.g. multiple sclerosis) so debilitating?
When the myelin sheath degenerates, transmission is slowed.
What are the different types of neurons (by function)?
- Sensory
- Motor
- Interneuron
What is the purpose of the sensory neuron?
Receive information from the external world through specialized endings on their dendrites and convey this information to the brain via the spinal cord
What is the purpose of the motor neuron?
Carry signals from the spinal cord to the muscles to produce movement
What is the purpose of the interneuron?
Connect sensory neurons, motor neurons or other interneurons
Where are mirror neurons found in many animals?
Frontal and parietal lobes
When are mirror neurons activated?
When an animal performs a behaviour (e.g. grasping) or when it observes another animal performing a behavior
When is the mirror neuron response the strongest?
When observing actions that were embedded in a context (e.g., grasping a cup to take a drink), as you can recognize the other person’s intentions
Why are mirror neurons important?
Facilitates smooth social interaction and suggests inborn neural basis for empathy
What are the different neurons by location?
- Purkinje
- Pyramidal
- Bipolar
What are purkinje cells?
Type of interneuron that carries information from the cerebellum to the rest of the brain and spinal cord
What are pyramidal cells?
Found in the cerebral cortex have a triangular cell body and a single long dendrite among many smaller dendrites
What are bipolar cells?
Type of sensory neuron found in the retinas of the eye and have a single axon and a single dendrite
2 stages of neural communication
- Conduction of electric signals within neuron
- Transmission of chemical signals between neurons
What’s resting potential?
The difference in electrical charge between the inside and outside of a neuron’s cell membrane
How does resting potential arise?
From the difference in the concentrations of ions inside and outside the neuron’s cell membrane
In a resting state, what is the ion concentration?
High concentration of positively charged sodium ions and negatively charged chloride ions outside the neuron’s cell membrane, negatively charged protein ions inside
What is ion concentration controlled by?
Channels in the axon membrane that allow molecules to flow in and out of the neuron
Which channels are open and which ones are closed during resting potential?
Potassium ions are open, sodium ions are closed
What is action potential?
An electrical signal that is conducted along the length of a neuron’s axon to the synapse
Why is an action potential an all or nothing phenomenon?
When the action potential occurs it always occurs with exactly the same characteristics and the same magnitude. Electric stimulation must also be above the threshold or the action potential won’t happen at all.