Nerve cells Flashcards
What are the different types of cell?
Nerve cells (neurones) and glial cells (neuroglia)
Basic structure of neurones
Cell body (Soma)
Diameter= 4-100μm
Bounded by plasma membrane
What are the organelles in neurones?
Nucleus (DNA)
Lots of mitochondria
Ribosomes
Rough endoplasmic reticulum (ER)
Smooth ER
Golgi complex
Lysosomes
What are dendrites?
High branched complex to increase surface area and receive incoming signals but some can output signals too. Branches are proximal and spines are distal.
Axons
Only one
1μm to 25μm in diameter
μm to meters in length
Intracellular information transfer
Axon hillock
At the base of axon
Action potential generation
Takes up first 50-100μm of axon
Axon terminals
At the end of the axon
Many branches
Myelin sheath
Around the axon
Increases insulation
Role of glial cells
Neurones can be non-myelinated but signal is transported slower
Synapse
Point of inter-cellular communication
Sends chemical signals in one direction
What are the 3 different synapses
Axodendritic (axon to dendrite)
Axosomatic (axon to cell body)
Axoaxonic (axon to axon)
What is the synaptic cleft?
The gap between the axon and the dendrite. Is around 20-50nm wide.
What are the 3 neurotransmitters?
Amino acids, amines and peptides
Action potentials
Causes a signal to be sent down an axon from the cell body which causes the release of neurotransmitters across the synaptic cleft. The more action potentials, the more neurotransmitters released.
Convergence vs Divergence
Convergence: multiple input onto an individual neurone
Divergence: individual neurone outputs onto many other neurones
What are ‘Nodes of Ranvier’?
The gap between the myelin sheath and the axon
