Cells of Nervous System Flashcards
Be able to define peripheral and central nervous system and contrast them
CNS: brain and spinal cord; contains neurons,astrocytes, oligodendrocytes, microglia
PNS: cranial and spinal nerves; contains sensory and autonomic ganglia and schwann cells
Describe the major morphological features of neurons and their functional significance
Dendrites (recievers), Cell body (receiver/integrator, metabolic center), axon hillock (summates action potential), axon (conductor), axon terminal (transmitter) Myelin: fatty substance that contains lipids and protein, insulates the axon and prevents electrical signal from leavin
Synapses: contacts between cells; types include axon to dendritic spine, axon to just dendrite, axon to soma. Either electrical (direct contact), or chemical (more abundant than electrical) neurotransmitters are packaged in vesicles, vesicles fuse to synapse, and neurotransmitter is transported to post synaptic neuron.
Be able to recognize different neuronal types
o Unipolar cell
§ Single process
§ One branch serves as an axon that gives rise to many branches that function as dendrites
§ Mainly found in the nervous system of invertebrates and the autonomic nervous system in vertebrates
o Bipolar cell
§ Two processes that are functionally specialized
§ Dendrite and axon
§ Can be found in the retina and olfactory epithelium
o Pseudo-unipolar cell
§ Initially develop as bipolar cells, their two processes merge to form one axon, the axon splits into two (one branch to the sensory receptors the other to the spinal cord)
§ Mechanoreceptors have this variant
o Multipolar cell
§ One axon, Many Dendrites
§ Motor neuron
§ Pyramidal
· Triangular cell body
§ Purkinje cell
· Enormous synaptic input being that it has a huge amount of dendrites
Populated in the cerebellum
Describe the major morphological features of astrocytes and their functional significance
Most abundant glial cells in CNS. Provide ionic milieu for neurons to generate action potentials. Aid in detoxification. End-feet surround capillaries to help form the bbb. Provide structural matrix (tissue) in which neurons reside
§ Term: Endings of astrocytes (foot processes )
Matrix =space , astrocytes fill in those spaces between cells
§ Aid in migration of neurons during neural development along with radial glia
o Maintain homeostasis of neurons
§ Regulate ionic (K+) and molecular (glutamate) environment of neurons
§ Insulate neurons from pathologic processes
Describe the major morphological features of microglia and their functional significance
Macrophages capable of phagocytosis to protect and repair neurons. Presents antigen, will multiply and expand when the brain is damaged and secrete cytokines and growth factors
Describe the major morphological features of oligodendroglia and their functional significance
Form and maintain the myelin that surrounds neurons in the CNS. Spirally wraps around an axonal segment. Internodes: myelin absent, basis for saltatory conduction.
Describe the major morphological features of Schwann cells and their functional significance
Form and maintain the myelin in the PNS. Intraperiod line and major dense line. Wraps around axon in sheets
What are the two basic cell types in the Nervous system?
In the CNS, there are neurons. A collection of cells is a nucleus. There are glia (astrocytes, oligodendrocyte, and microglia). In the PNS, there are sensory and autonomic ganglia (collection of cells in PNS). Instead of oligodendrocytes, there are Schwann cells
What are the different types of synapses
Type 1: axon to spine (most common in CNS) Type II: directly on dendrite or shaft (axiomatic or axoaxonic)
Describe tetanus toxin
Taken up at nerve terminals and retrogradely carried to cells in spinal cord. Inhibits upstream neurons (Renshaw) which normally brake motor neurons. Uninhibited movement (spasms)
What is the difference between electrical and chemical synapses
Electrical: synchronizes electrical activity across populations of neurons through gap junctions. Bidirectional and fast
Chemical: No intercellular continuity. Current flows across postsynaptic membrane only in response to neurotransmitter release
