Nervous System Flashcards
What are the branches of the nervous system?
What are the different meninges?
- dura mater: outermost layer
- arachnoid: membrane attached to dura mater
- pia mater: innermost layer, highly vascular, adherent to brain and spinal cord
- leptomeninges - arachnoid + pia mater
- subarachnoid space: contains CSF
What are the embryonic brain divisions and their derived brain structures?
- forebrain
- telencephalon: cerebrum, basal nuclei, hippocampus, + amygdala
- dincephalon: thalamus + hypothalamus
- midbrain
- mesencephalon: midbrain
- hindbrain
- metencephalon: pons + cerebellum
- myelencephalon: medulla oblongata
What are some features of the surface of the brain?
- gyrus/i + sulcus/i of main brain
- folia + sulci of cerebellar cortex
- arbor vitae “tree of life” cross-section
What are the different kinds of nervous tissue and the system they are part of?
What is white matter? Grey matter?
- white matter: formed by dense accumulations of myelinated axons. Myelin sheath is rich in lipids so has a white appearance
- grey matter: rich neuronal cell bodies , glial cells, and neuropil. Neuropil represents the axons, dendrites and cytoplasmic projections of glial cells that form the background matrix to neuronal cell bodies within the grey matter.
T/F: white matter is peripheral in the brain and central in the spinal cord
- False; white mater is peripheral in the spinal cord and central in the brain
- grey matter is peripheral in the brain and central in the spinal cord
T/F: the cells of the CNS that are sensitive to hypoxia are of mesodermal origin
- False; ectodermal origin
- ectodermal origin: neurons, astrocytes, oligodendrocytes
- mesodermal origin: microglia, vascular endothelium
What cells compose the CNS?
- neurons
- glial cells
- ependymal cells
- endothelial cells
- pericytes of blood vessels
What are neurons?
- functional cells of the nervous system in which two protoplasmic properties are highly developed
- irritability: generation of an impulse
- conductivity: ability to transmit such a impulse from one locality to another
- neurons are dispersed through the CNS and grouped in specific areas in the PNS
How are neurons distributed?
- individually
- layers (cortex)
- groups
- nuclei (CNS)
- ganglia (PNS)
Describe the structure of a neuron
- parts:
- perikaryon
- nucleus
- nucleolus
- dendrites
- axons
Describe the structure of a soma
- euchromatc nucleus w/ prominent nucleolus
- basophilic cytoplasm: nissl substance, SER, and ribosomes
- lipofuscin: “wear and tear” pigment
- cell body = perikaryon/soma: contains nucleus + organelles, axons and dendrites branch off it
What are the arrows pointing at?
- yellow: lipofuscin
- blue: nucleolus
- green: nucleus
What is shown in this image?
- neurons + glial cells
What are some features of synapses?
- specialized junctions with other cells that are along the length or at end of an axon
- act as transmission points for electrical impulses
- can trigger the generation of an action potential in the postsynaptic cells, can be excitatory or inhibitory
- synapses at end of an axon or axon branches are swollen into a club shape, called boutons terminaux
- those along the length of the axon result in varicosities (swellings) called boutons en passant
What are structures of synaptic knobs?
- 3 parts:
- presynaptic part: termination of axon (bouton terminaux)
- intersynaptic cleft
- postsynaptic cleft (dendritic thorn)
T/F: stimulatory synapse vesicles contain GABA, inhibitory synapse vesicles contain acetylcholine
-false; stimulatory = ACh, inhibitory = GABA
Neurons can synapse with:
- neurons
- muscle
- glands
What are the sense organs of the skin?
- thermoreceptor: sense heat or cold
- meissner’s corpuscle: senses touch
- nociceptor: sense pain
- pacinian corpuscle: senses pressure
What are functions of oligodendrocytes?
- myelin sheath to axons
- unlike Schwann cells (PNS), they form myelin sheaths for several axons at once (“octopus” shape)
What is shown? What are some features?
- oligodendrocyte
- small dark nuclei (between myelin sheaths or sounds neurons)
- can be destroyed by viruses/toxins resulting in primary demyelination
What are some functions of microglia?
- immunosurveillance
- immunoregulation
- reparative —> phagocytic
- gitter cells (myeophages) —> activated during necrosis/inflammation —> globular and swollen after having phagocytized debris from injured cells
What is shown? What are some features?
- microglia
- derived from blood-borne monocyte
- resident macrophage of CNS
- Gitter cells: note cytoplasmic vacuolation due to ingestion of cellular debris
What is shown?
- microglia
- activated Gitter cells (macrophages) in a area of brain tissue necrosis
What is shown?
- microglia
- activated microglia cells in a myelin sheath (“myelophages” w/ a “digestion chamber”)