Lecture 19 - Nervous System Structure & Function Flashcards
What 2 parts can the nervous system be divided into?
1) CNS - Brain & SC
2) PNS - Cranial & Spinal Nerves
Where can white & grey matter be found?
What do they consist of?
Grey = peripheral in brain, central in SC (H shape) - make sure you can recognise on a picture. Consists of nerve cell bodies, dendrites, axon terminals and neuroglia.
White = central in brains, peripheral in SC. Consists of myelinated material
Describe the structure of a section of spinal cord
- Grey matter in middle in H shape
- Top is dorsal horns and bottom in ventral horns. White matter contains nerve fibres which form ascending and descending tracts.
What is myelin on axons composed of in the CNS and PNS?
In CNS - Oligodendrocytes
In PNS - Schwann cells
What is the location & function of the 4 types of axon? (motor, sensory, integrative and anaxonic)
1) Motor - CNS to periphery. Sends signals to effector tissues.
2) Sensory - Periphery to CNS. Sends signals to integrative center.
3) Integrative - In CNS, collates all information
4) Anaxonic - retina, acts as a relay
Which direction is anterograde and retrograde in regards to an axon?
How to vesicles move in these directions from the soma to synapse and back?
- Anterograde is towards the synapse, retrograde towards the soma (cell body).
- Along a microtubule “shuttle” system.
What are the different kinds of synapse?
1) Axodendritic - axon to plasma membrane of nerve or cell
2) Dendro-dendritic - axon terminal synpases with dendritic spine
3) Axoaxonic - axon synpases with another axon
4) Axo-axonal
What are the 4 connective tissue layers that surround nerves?
1) Endoneurium - loose connective tissue surrounding single nerve cells.
2) Perineurium - loose connective tissue surrounding clusters of axons (fascicles)
3) Epineurium - dense irregular connective tissue filling space between fascicles
4) Paraneurium - separates nerves from surrounding structures.
What 2 things makes conduction in a nerve faster?
1) Larger diameter of the axon
2) Presence of myelin
Compare and constrast the size, speed, location, function, myelination and internodal distance of A, B and C fibres.
Size = thickest, medium, thinnest
Speed = Fastest, medium, slowest
Location = CNS, viscera, periphery
Function = Motor, sensory, sensory
Myelination = Myelinated, myelinated, unmyelinated
Internodal distance = Largest, smallest, NONE.
What are the 4 main support cells found in the CNS?
1) Oligodendrocytes
2) Astrocytes
3) Microglial cells
4) Ependymal cells
What is the role of oligodendrocytes in the CNS?
Same as Schwann cells in the PNS, wrap around axons to myelinate them. Difference to Schwann cells is that they wrap around more then 1 axon simultaneously.
What is the structure and role of astrocytes in the CNS?
Star like shape with perineurial feet that contain gap junctions.
They regulate nerve impulses but releasing GABA , and contribute to the BBB.
Where are satellite cells found and what is their function?
Only found in sensory neurone cell bodies (specifically dorsal root ganglion), and have functions similar to an astrocytes.
Describe the structure and function of microglial cells in the CNS.
- Large cells with elongates (flattened) nucleus
- Resident macrophage of the CNS, removes damaged nerve cells. Also thought to digest protein tangles associated with dementia and Alzheimers.
