1- Cell biology of the nervous system Flashcards
What is the nervous system?
System of individual cells that communicate
What is the common pathway for the nervous system?
- Information collected from the environment (PNS)
- sensory neurones take information to the CNS to be processed
- Motor neurons sends information to create response from the muscle/glands
what are the building blocks of the nervous system and what are their functions?
- Neurons
- Important functioning units which allow communication between separate cells that communicate by secretion
what cell is a neurone similar to?
A neurone is an elongated secretory cell that can communicate at both ends of the cell
What effects the amount of communication a neurone makes?
The number of dendrites
What makes up a neurone?
- dendrites
- cell body
- axon
what does the nerve cell body contain?
Contains rough endoplasmic reticulum (rER) and ribosomes to create proteins and membrane.
Creates cell processes and vesicles
What are the 3 neurone types and how are they classified?
- Classified according to the number of processes
- Unipolar or pseudounipolar
- Bipolar
- Multipolar
Describe the structure of a unipolar neurone.
A single process but no dendrites
• If a single dendrite and the axon fuse during development = pseudounipolar (now often called unipolar)
Describe the structure of a bipolar neurone.
- an axon and one dendrite
- often special senses (ear, eye,nose)
Describe the structure of the multipolar neurone.
- many dendrites and one axon
- most common neurone
What are synapses?
Specialised intercellular gaps
What is a neuromuscular junction?
Numerous boutons (synaptic knobs) from presynaptic neurons may terminate on a motor neuron and its dendrites
Where is the site of chemical neurotransmitter release?
Axon end bulb
what structure provides vesicular transport for a synapse?
Microtubules
What provides energy for synaptic movement?
mitochondria
How do synapse vesicles release their content?
exocytosis
Describe exocytosis of synapse vesicle.
Vesicle docks with the pre synaptic membrane by a tether and releases neurotransmitter into the synapse
- the membrane of vesicle is added to presynpatic membrane as it no longer holds its contents
What are the 2 ways of recovering a ‘fused’ membrane?
- membrane recycling
- conserve vesicles and their membranes
Describe membrane recycling?
Clathrin baskets recover membrane in endocytic vesicles
Describe conserving vesicles and their membranes.
Rather than releasing full contents of the vesicle, it releases less products and moves back into the cell
What are the functions of the dendrite?
The dendrite tree and dendrite spines roll is the reception of signals
What happens if a dendrite is under repeated stimulation?
Modification of dendritic spines (long term potentiation)
What is the support cell (glial cell) in the PNS and what is its function?
Schwann cells – myelination, trophic support, contribute to growth and repair
What is the support cell (glial cell) in the CNS and what is it function?
Oligodendrocytes -wrap a myelin sheath around axons
Describe the features of myelination.
- Facilitate conduction of impulses using insulating coat
- Myelin sheath is discontinuous – periodic gaps
What is the difference between PNS and CNS myelination?
In PNS, one Schwann cell builds one internode whereas in the CNS, one oligodendrocyte builds a number of internodes
What is the function of astrocytes (support cell)?
- structural isolation of neurons, metabolic and mechanical support (CNS scar tissue)
- Endfoot processes help transfer important metabolites from blood to neurons at blood brain barrier
What is the function of a satellite cell (support cell)?
play a similar role to astrocytes but for the PNS
What is the function of a activated T-lymphocyte (support cell)?
enter CNS for immune surveillance
What is the function of a microglia/macrophage (support cell)?
scavenger cells for phagocytosis, inflammatory
responses
What is the function of a perivascular cell (support cell)?
similar to microglial function but near blood vessels
What is the function of a ependymal cell (support cell)?
line cavities (CSF secretion in brain ventricles)
