14. Nervous Tissue Flashcards
What are the two divisions of the nervous system?
• Central nervous system (CNS)
- Brain and spinal cord
• Peripheral nervous system (PNS)
- Cranial nerves and spinal nerves and some of the peripheral nerves
Where is the grey matter in the brain and spinal cord?
- Peripheral in brain and in areas called ‘nuclei’
* Central in spinal cord (H- or butterfly-shaped)
What does the grey matter consist of?
Consists of: • Nerve cell bodies • Dendrites • Axon terminals • Non-myelinated axons • Neuroglia (support cells)
Where is the white matter found in the brain and spinal cord?
- Central in brain
* Peripheral in spinal cord
What des white matter consist of?
Consists of:
• Myelinated material
• axons
• no cell bodies
What is the grey matter roughly in the form of in the spinal cord?
A butterfly
What are the anterior and posterior prongs of the grey matter in spinal cord referred to as?
The anterior = ventral
horns
posterior = dorsal horns
In the grey matter in spinal cord, what connects the dorsal and ventral horns?
grey commissure
What is the direction of the ascending and descending neurones in the white matter?
- Ascending neurone - from periphery to brain
* Descending neurone - from rain to periphery
Where do the neurones from ventral and dorsal horns come out of?
Neurones in the dorsal horn come out through the dorsal root.
Neurones in the ventral horn come out through the ventral root.
What is the pia mater?
The outer connective tissue layer of the spinal cord
What is the ventral fissure?
a groove along the anterior midline of the spinal cord that incompletely divides it into symmetrical halves
Describe the location of the structures of a neurone
• The main cell body (soma), dendrites, and proximal part of
the axon are within the CNS
• Distal axon and arborisations are within PNS
In the CNS what produces the myelin?
In the CNS, the myelin for the axon is produced by, and is
part of, an oligodendrocyte
In the PNS what produces the myelin?
in the PNS, the myelin is produced by, and is part of, a Schwann cell
What are the 4 types of neurones?
- Motor
- Sensory
- Integrative
- Anaxonic
What is the location of motor neurones?
CNS to periphery
What is the function of motor neurones?
to send signals to effector tissues
What is the location of sensory neurones?
Periphery towards CNS
What is the function of sensory neurones?
to send environmental signals to integrative centre
Which motor neurones act on a secondary neurone?
Presynaptic autonomic neurone
Which motor neurone act on smooth muscle in blood vessels and in the gut?
Post-synaptic autonomic neurone
In sensory neurones, when the nerve body is sitting to one side, what is the neurone called?
pseudounipolar neuron
In sensory neurones, when the nerve body is sitting in the middle, what is the neurone called?
Bipolar neurone
What is the location of integrative neurones?
CNS
What is the function of integrative neurones?
To Collate all information
What are the 3 types of integrative neurone?
- Pyramidal cell
- Interneurones
- Purkinje cell
What is the location of anaxonic neurones?
Retina and some parts of CNS
What is the function of anaxonic neurones?
To act as relays
How are anaxonic neurones specifically different from the other neurones?
They don’t have any axons,
Which neuron cell bodies are located outside the CNS?
pseudounipolar (unipolar), bipolar, and
postsynaptic autonomic neuron cell bodies
Which cell bodies are restricted to the CNS?
Purkinje and pyramidal cells
Which type of neurones is the majority in the CNS?
Interneurones
Describe multipolar neurones(purkinje and pyramidal cell)
- one axon and multiple
- most common
- most neurones in the CNS
Describe the bipolar neurones
- one axon and one dendrite
- found in olfactory cells, retina, inner ear
Describe unipolar neurones
- Single process leading away form the soma
- sensory from skin and organs to spinal cord
Describe anaxonic neurones
- many dendrites but no axon
- help in visual processes
What are nissl bodies?
A Nissl body is a large granular body found in neurons. These granules are of rough endoplasmic reticulum (RER) with rosettes of free ribosomes, and are the site of protein synthesis.
Which organelles are abundant in neurones?
RER
Free Ribosomes
Folding apparatus
Describe axonal transport
- Empty vesicles are transported to the axon by intracellular neurofilaments
- When they reach the axon hillock, they assemble which allows them to move along a transport system in the axon
- The transport system starts with a neurofilament sitting on a microfilament
- As it forms , a new structure comes in called a microtubule which is made up of different subunits - the subunits come together and bring in a protein called kinesin which can bind empty vesicles and mitochondria and transport them along this transport system in a process called anterograde from the axon hillock to the end of the axon - proximal end of axon to distal.
- Retrograde movement of material - empty vesicle that have not been used or have been reprocessed at the synapse are brought back to the body . They use dynein which only bring back empty vesicles not mitochondria
What are the 5 different types of synapses?
- Axodendritic
- axosomatic
- Axoaxonic
- Dendrodendritic
- Axo-axonal
What are axodendritic synapses?
Axon connecting directly to the dendrite of another neurone
Or
Axon terminal synapses connecting with a dendritic spine. Axon bouton change shape to envelope the spine