section 1 Flashcards
What does the dendrite do?
Brings the input to the cell.
What does the dendrite look like?
Like a tree’s branches or roots
What is the main role of the nervous system?
Communication—bringing information in from the outside world to the nervous system and brain to be analyzed and sending information from the brain and nervous system out to the body to interact with the outside world.
What does the axon look like?
The axon is of uniform thickness or diameter and can extend for as far as several feet in mammals, half the length of your entire body! Some axons branch, and these branches may extend to other regions of the brain or body.
What do some dendrites have?
Some have spines or small protrusions of the neuronal membrane the typically make contact with one other neuron.
What is the axon used for?
Transmitting electrical signals or releasing packets of chemical transmitters.
What does the myelin do?
Insulates the axons. Speeds up the conduction of the neuron’s electrical signals that travel down the axon.
What is the myelin?
A fatty substance made glial cells.
What does the axon do?
Transmits output signals from the neuron
What are Nodes of Ranvier?
Small gaps in the myelin.
What do the Nodes of Ranvier do?
They allow the axon inside to gain access to the fluid outside the cell, which is important for sending electrical signals.
Where is the nucleus found?
The cell body, or soma.
Where does the axon begin and end?
Axons begin at the soma, at a section of the axon called the axon hillock, and end in slightly wider sections called the axon terminals.
What happens at the axon terminal?
The neuron will release its signal in the form of a neurotransmitter, passing the information to the next neuron. Most of the time the signal is received at one of that other neurons dendritic spines.
What is a synapse?
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What is the synaptic cleft?
It’s the space between where two neurons connect.
What is a presynaptic neuron?
The first neuron in a synapse.
What is a postsynaptic neuron?
The second neuron receiving the signal.
The axon terminal of the presynaptic neuron is usually filled with what?
Spherical packets (or vesicles) of signaling chemicals called neurotransmitters.
Where are neurotransmitters produced?
Neurotransmitters are usually produced in the soma and are sent down the axon to the terminal.
How do neurotransmitters travel?
At the proper time, the neurotransmitters are then released to float across the synaptic cleft and bind to specialized receptors that receive the neurotransmitter signal on the postsynaptic neuron.This method of signaling across the synaptic cleft is highly customizable and plays a large role in neural communication.
What does a neuron’s shape depend on?
Their job in the nervous system.
What are the three types of neurons?
Motor neurons, sensory neurons, and interneurons.
What do motor neurons do and how do they look?
Motor neurons that bring movement commands to the muscles tend to have a soma at one end of the cell surrounded by a small set of dendrites and then a very large, long axon going out to the muscle.
What do sensory neurons do and how do they look?
Sensory neurons vary widely and are different from motor neurons,as their role is to bring sensory input from the body to the brain. Some sensory neurons have dendrites at both ends connected by a long axon with a cell body on a branch in the middle.
What do interneurons look like and how do they work?
They work to connect other neurons within the nervous system and are often quite small without long axons or large complex dendritic arbors
The central nervous system can generally be divided up into which two types of tissue?
Grey Matter and White Matter
What is grey matter made of?
This is made of the cell bodies and dendritic arbors of neurons.
What is white matter made of?
This is made of the myelinated axons of the neurons.
When the brain is opened, what is the color difference between the axons and the cell bodies and dendrites?
The axons are lighter in color while the cell bodies and dendrites are tan or darker grey. tan (depending on if the brain has been preserved or is fresh)
Where are the grey matter and white matter located?
In the brain, the grey matter is located mostly on the outside with the white matter tucked inside.
How is it different in the spinal cord?
The white matter axons are on the outside, and it is the cell bodies that are tucked inside the structure.
What are glia or glial cells?
The non-neuronal cells found in the nervous system.
How are new glial cells produced?
New glial cells are produced throughout the life of an organism.
What do Oligodendrocytes and Schwann cells have in common?
Both myelinating glial.
What is the difference between Oligodendrocytes and Schwann cells?
Oligodendrocytes myelinate axons in the central nervous system (the brain and the spinal cord), Schwann cells myelinate axons in the peripheral nervous system (the nerves in your tissues, skin, muscles, internal organs, etc.).
What is the most common type of glial cell?
Astrocyte.
What the roles of an astrocyte?
One critical role of astrocytes is to regulate the chemical makeup of the extracellular fluid in the space between the cells in the nervous system. Astrocytes do this by removing excess signaling molecules and maintaining the proper balance of ions. They can also react to tissue damage. Astrocytes send out long extensions that wrap around blood vessels in the brain to form part of the blood brain barrier.
What does the blood barrier do?
The blood barrier keeps infections from damaging the neurons.
What are the restrictions of the blood barrier?
The blood barrier makes it more difficult for nutrient molecules to pass from the bloodstream into the brain to nourish the cells there. The restriction of the blood brain barrier also makes it more difficult to deliver drugs to the brain that might be helpful in treating diseases or disorders of the nervous system.
What are microglia?
They are smaller than the other glial cells (micro) and they are the immune cells of the brain.
What do microglia do?
They protect the brain from toxins, diseases, invaders, bacteria, and virues.
Why does the brain need seperate immune cells?
The brain needs separate immune cells because of the blood barrier which isolates the brain.
What are the negatives of microglia?
Microglia can cause inflammation in the brain (alzheimer’s) because of hyperactive microglia.
What are the three main layers of meninges surrounding the central nervous system?
Dura matter, pia matter, and the arachnoid matter.
What is the first layer of the Central Nervous System?
The dura matter which is thick and leathery. Between the skull and the dura, there is the epidural space which is full of fat to absorb shock from sudden blows to the head
What is the second layer of the Central Nervous System?
The arachnoid membrane, which features long stringy components that look like spider webs. Between the dura and arachnoid layers, there is a very thin space called the subdural space
What is the third layer of the Central Nervous System?
Below the arachnoid space is the subarachnoid space which is filled with cerebrospinal fluid, which cushions and protects the brain.
What is the innermost layer of the Central Nervous System?
The last layer is the pia mater, which is a thin layer that protects the brain matter from the cerebrospinal fluid in the subarachnoid space.
What are the four lobes of the brain?
Frontal Lobe, Parietal Lobe, Temporal Lobe, Occipital Lobe
What does the Frontal Lobe do?
The frontal lobe is located in the front of the brain (hence its name). Its responsible thinking, decision making, problem solving, reasoning, motor control, emotion, and language.
