Neurons and Glia Flashcards
What two things are composed of neurons and glia?
The brain and the spinal chord
What is the function of neurons?
Processing information and conducting electrical impusles
What is function of glia?
Mechanical and metabolic support
What 3 things makes up the neuron?
- Dendrites
- Cell body (soma)
- Axon
What are dendrites?
Recieve information from other neurons (the input part of the neuron)
What is the axon?
Conveys information to other nerve cells (the output part of the neuron)
How many axons do neurons normally have?
Just one that emerges from the cell body
What are the dendrites and axons sometimes collectively known?
Neurites
What two things make up the cell body?
The nucleus and the cytoplasm (perikaryon)
What is different between the nucleus in a neuron as compared to another cell?
Adult neurons do not replicate and the DNA is only involved in protein synthesis (it a blueprint for construction of neuronal components)
What manufactures the ribosomes of the neurons?
The nucleolus
The combination of ER and ribosomes is called the rough ER; what else can they be called?
Nissl bodies (seen by nissl staining)
Where are microtubules found in the neruon and what are they responsible for?
The dendrites, cell body and axon and are responsible for transporting packaged proteins
What else are the microtubules involved in that provides support for the neruon?
The form the cytoskeleton
What are lipofucin bodies in neurons?
The scrap yard of the neuron which contains the waste products of the old cells
What cellular components have a similar function in neurons as they do in normal cells?
Ribosomes, the golgi apparatus, mitochondria and lysosomes
What do the dendrites mainly contain in terms of cellular components?
Mitochondria and free ribosomes
What the connections with other neurons formed in the dendrites known as?
Synapses
What specialised structures of the dendrites and the synapses usually made on?
Spines
What are the four parts of the axon?
- The axon hillock
- The axon proper
- Axon collaterals
- The axon terminals
What the axon hillock?
The part of the axon that emerges from the cell body and contains lots of voltage gated ion channels to generate action potentials
What is the axon proper?
The main part of the axon
What is the axon collaterals?
The branches of the axon that go off to numerous locations
What is the axon terminals?
Swellings (boutons) that form synpases
Why is important that axons have a transport for proteins?
Because they dont contain ribosomes to make their own proteins
How does transport to the axon occur and what is this known as?
Along microtubules in axoplasmic transport
How fast is axoplasmic transport?
Very fast - 1000mm/day
What is axoplasmic transport towards the cell body called?
Retrograde transport
What is axoplasmic transport away from the cell body called?
Anterograde transport
Why would retrograde transport be useful?
To get rid of waste products back to the soma for them to be broken down
What are the 5 ways to classify neurons?
- Number of neurites
- Shape
- Connections
- Axons
- Neurotransmitters
What are the three types of neurons classified under number of neurites?
Unipolar, bipolar and multipolar
What is an example of a unipolar neuron?
Sensory neurons
What is an example of a bipolar neuron?
That ones connecting the rods and cones in the eyes to the brain
What kind of shapes can neurons have?
Pyramidal, stellate
What 3 types of neurons are there in the classification based on connections?
- Primary sensory neurons
- Motoneurons
- Interneurons
What are primary sensory neurons?
Neurons that form connection with sensory surfaces (skin, retina etc)
What are the motoneurons?
Neurons that form connections with muscles
What are interneurons?
Neurons that form connections with other neurons
What are the two types of neurons classified under axons?
- Golgi type 1 (long axons)
2. Golgi type 2 (local axons)
What are examples of three neurons classified under neurotransmitters?
- Cholinergic neurons (release acetylcholine)
- Glutamergic neurons (glutamide)
- Peptitergic neurons (peptides)
How much of the brain is composed of glia?
90%
What are the three classes of glia?
- Astrocytes
- Oligodendrocytes
- Microglia
What are astrocytes and oligodendrocytes sometimes collectively known?
Macroglia
What is the most numerous type of glial cells?
Astrocytes
Name two functions of the astrocytes:
- Repair in damaged neurons
2. Regulate flow of ions and molecules in the extracellular fluid
How many organelles do astrocytes contain?
Very few
How many organelles do oligodendrocytes contain?
Lots
What is the main function of oligodendrocytes?
They make myelin that forms a sheath around the axons of neurons?
What is myelin composed of?
Lipids
The myelin sheath around the axon is not continuous; what are the gaps in it called?
The nodes of ranvier
What do the Node of Ranvier do?
Increase the speed of electrical conduction of the axon
In what part of the nervous system do oligodendrocytes make myelin?
The central nervous system
What makes myelin in the peripheral nervous system?
Schwann Cells
What are microglia?
Phagocytes that remove waste
How many neurons in the CNS nie every day that need to be removed by microglia?
100,000
