5.1 Organisation of the Nervous System - Divisions and Main Cell Types Flashcards
Describe the function of glial cells
Nourishing and supporting cells and their surrounding environment
Which cells make up the vast majority of the nervous system?
Glial cells
What does “glia” mean?
Glue
List four kinds of glial cells
- Astrocytes
- Microglia
- Ependyma
- Oligodendrocytes
Can glial cells be replicated? How does this differ from neurons?
Glial cells can be replicated. Neurons can’t
What is the function of microglia? What response are they involved?
- Defense cells (phagocytes)
- Patrolling “macrophages” of the CNS
- Remove foreign particles via phagocytosis
- Involved in inflammatory response
What is the function of astrocytes?
- Star shaped
- Structural and chemical support, comprises the blood brain barrier
- Multiple processes extending from body
- Regulates concentrations
What is the difference in relative size between astrocytes and microglia?
Astrocytes are bigger.
What concentrations do astrocytes regulate?
- Ions
- Nutrients
- Interstitial gases
Why is it significant that astrocytes are present at synapses?
- Astrocytes absorb and recycle neurotransmitters
What are glial scars?
Scars that repair nervous tissue (but do not regenerate)
Provide a brief description of the function and location of satellite cells
Astrocytes of the PNS
What is the function of ependymal cells?
- Line ventricles of brain
- Produce and secrete CSF, and aid in its circulation
What is the function of oligodendrocytes?
Produce myelin sheath (think: Deep Work)
How many processes can an oligodendrocyte contain?
15 (basically spiderman)
What are Schwann cells?
The olgiodendrocytes of the PNS
How many processes can a Schwann cell contain?
One. Much more loyal than oligodendrocytes
Are there any fenestrations in the blood brain barrier?
No. Don’t be fucking stupid
How is it ensured that there are no gaps in the blood brain barrier?
Tight junctions between endothelial cells
What is the largest type of neuroglial cells?
Astrocytes
What is the name given to the “feet” of astrocytes?
Podocytes
Describe the different structures present within the blood brain barrier
- Endothelial cells
- Pericytes
- Podocytes of astrocytes
- Basement membrane (inherent to epithelium)
What are cranial nerves?
Nerves that come from the brainstem
What are spinal nerves?
Nerves that come from the spine
What are ganglia?
Collections of neuronal cell bodies
What are the anatomical divisions of the nervous system?
PNS and CNS
What are the two ways we can functionally divide the nervous system?
- Somatic, autonomic, enteric
- Sensory, motor, integrated
Can we control the autonomic nervous system?
No
Can we voluntarily control the somatic nervous system?
Yes
Can we voluntarily control the somatic nervous system?
Yes
What are the two divisions of the autonomic nervous system?
Parasympathetic and sympathetic
What is the axon hillock? Where/what is it?
Site of action potential initiation. It is the conical projection that connects the cell body to the axon
What are the ends of axons called?
Axon terminals
What are Nissl bodies?
Accumulations of ribosomes on the rough ER
What is meant by anterograde in terms of nervous transmission?
Toward the axon terminal
What is meant by retrograde in terms of nervous transmission?
Toward the soma
What is the name given to the three kinds of neuron connections?
Neuron-Neuron: Synapse
Neuron-Gland: Neuroglandular synapse
Neuron-Muscle: Neuromuscular junction
Why is grey matter grey?
Because it is filled with closely-packed cell bodies
Describe the location of grey/white matter in the brain vs spinal cord
Brain: Grey outside, white inside
Spine: Grey inside (butterfly), white outside
Why is white matter white?
White from myelin of axons
Neuron vs nerve
Neuron: Single cell
Nerve: Multiple neurons with connective tissue
Can electrical signals travel both ways along an axon?
Check
What are the four classifications of neuron by shape?
- Multipolar
- Bipolar
- Pesudo-Unipolar
- Unipolar
(Relates to number of cytoplasmic extensions)
Which is the most common shape of neurons in the CNS?
Multipolar cells
What types of neurons are multipolar?
Motor neurons and interneurons.
Where are unipolar/psuedo-unipolar neurons mostly present?
Sensory nervous system
