Lecture 1 (Revised) Flashcards
Central Nervous System (CNS)?
Brain, Spinal Cord and neural portions of the eye
Peripheral Nervous System (PNS)?
Peripheral nerves, nerve endings and peripheral nerve ganglia
CNS and PNS both include same 2 basic cell types?
Neurons and Glia/supporting cells
General Organization of Nervous System?
1) Neurons
2) Neuroglia
3) Endothelial and Epithelial Cells
Neuronal Function (Unique Properties of Neurons)?
1) Conduct electrochemical signals after impulse are received on dendrites or cell body
2) Neurons possess unique connections between cells (which are synapses)
Neuronal Function Pathway?
Dendrites > Soma > Axon > Synapse
3 Types of Neurons?
1) Bipolar
2) Pseudo-unipolar
3) Multipolar
Bipolar Neuron?
-Single axon emerges from either side of body
-Found in sensory structures such as the retina, olfactory epithelium, and the vestibular and auditory systems
Pseudounipolar Neuron?
-Single axon divides a short distance from body
-Divides into 2 branches: Peripheral Branch (carries information from periphery) and Central Branch (ends in spinal cord or brainstem)
-These cells found in sensory ganglia of cranial and spinal nerves
Multipolar Neuron?
-Many dendrites and a single long axon emerge from cell body
-Ex: pyramidal cell of cerebral cortex and Purkinje cell of cerebellar cortex
Neuronal Cell Body (Soma)?
1) Nissl bodies
2) Lipofuscin pigment- “age pigment”
1) (Neuronal Cell Body (Soma)) Nissl bodies?
Ribosomes and rER
2) (Neuronal Cell Body (Soma)) Lipofuscin pigment- “age pigment”?
Lysosomes with degradation products (residual body)
Neuronal Dendrites and Axons?
-Dendrites
-Axons
Dendrites?
-Ramified, spiny, branches extending off the cell soma
-Increase SA of neuron for reception
-Contains proteins/organelles
-NOT myelinated
Axons?
-Singular, straight segment, with no spines
-Responsible for conducting AP
-No Nissl bodies
-Can be myelinated
Neuronal Cytoskeleton is a ?
Non-membranous organelle made up of 3 types of protein filaments:
1) Microtubules
2) Intermediate Filaments
3) Microfilaments
1) (Neuronal Cytoskeleton) Microtubules?
Composed of tubulin
2) (Neuronal Cytoskeleton) Intermediate Filaments?
Composed of neurofilament (light, medium and heavy)
3) (Neuronal Cytoskeleton)
Microfilaments?
Composed of actin
1) (Neuronal Cytoskeleton) Microtubules and Motor Proteins
-Kinesin
-Dynein
Kinesin mediates?
Anterograde transport (movement of organelles, vesicles, and neurotransmitters from soma (minus end) to synapse (plus end))
Dynein mediates?
Retrograde transport (movement of organelles, vesicles, and neurotransmitters from synapse (plus end) to soma (minus end))
(Also plays a role in ciliary and flagellar movement)
(Potential entry of harmful substances)
Kinesin and Dynen are?
Axonal cytoskeleton motor proteins responsible for bidirectional transport of molecules along the axon
(both use ATP to move along microtubule)
2) (Neuronal Cytoskeleton)
Intermediate Filaments (3 types)?
(Neurofilaments (NF)- neurofilament triplet proteins (L, M, H proteins) in axons and dendrites of nerve cells)
1) Nestin
2) GFAP
3) Peripheral
1) (Neuronal Cytoskeleton (IF)) Nestin?
Neuronal stem cells (nerve cells)
2) (Neuronal Cytoskeleton (IF))
GFAP?
Astrocytes
3) (Neuronal Cytoskeleton (IF)) Peripherin?
Peripheral nerve cells
Changes in neurofilaments within brain are characteristics of?
Alzheimer’s disease, which produces neurofibrillary tangles
3) (Neuronal Cytoskeleton (IF))
Microfilaments?
Composed of protein actin
1) G Actin (Globular)
2) F Actin (Filamentous)
(Neuronal Cytoskeleton (IF) (Microfilaments))
G Actin?
(Globular)
Free actin in cytoplasm
(Neuronal Cytoskeleton (IF) (Microfilaments))
F Actin?
(Filamentous)
Polymerized actin
-“Plus-barbed” end = fast growing
-“Minus-pointed” end = slow growing
The Synapse steps?
(Membrane depolarization > Influx of Ca2+ ions > Release of a neurotransmitter)
-Release neurotransmitters
Membrane depolarization is?
Changing the charge of the synapse leading to influx of calcium ions then that makes it release neurotransmitter
Neuroglia?
(“Supporting cells” of Nervous System) (nonconductive)
Types of Peripheral (PNS) Neuroglia?
1) Schwann cells
2) Satellite cells
Types of Central (CNS) Neuroglia?
1) Astrocytes
2) Microglia
3) Oligodendrocytes
Central (CNS) Neuroglia?
-Only half the volume of brain is occupied by neurons. Other half of brain volume are Neuroglia/Glia
-Radial Glia (“scaffolding” during development)
1) CNS Neuroglia - Astrocytes?
(Found in gray and white matter)
-Interconnect and “outline” CNS
-Form desmosomal (tight) junctions and gap junctions
Functions of Astrocytes?
1) Nourishment, maintenance and protection
2) Contribute to BBB
3) Glycogen stores
4) Index of CNS toxicity
React to injury by increasing concentrations of GFAP fibrils at site of injury forming a “glial scar”?
Astrocytes
React to injury by increasing concentrations of GFAP fibrils at site of injury forming a “glial scar”?
Astrocytes
2) CNS Neuroglia - Microglia?
-Phagocytic cell of CNS: Primary responders to injury of Brain, ex. multiple sclerosis and trauma
-Severe activation leads to rounding of cells to form macrophages
Primary responders to injury of Brain?
Microglia (come in and clean up mess)
Microglial cells and astrocytes interact with each other to?
Modulate immune responses
3) CNS Neuroglia - Oligodendrocytes?
-Oligodendrocytes are found in white matter (fascicular) of CNS
1) Synthesize myelin sheaths
2) Insulates axons and enhances speed
3) Wraps around axons of several CNS axons
3) CNS Neuroglia - Oligodendrocytes?
-Oligodendrocytes are found in white matter (fascicular) of CNS
1) Synthesize myelin sheaths
2) Insulates axons and enhances speed
3) Wraps around axons of several CNS axons
1) PNS Neuroglia - Schwann cells?
-Schwann cells are found in PNS
1) Synthesize myelin sheaths
2) Insulates axons and enhances speed of conduction of electrochemical impulses
3) Wraps around a single PNS axon
Endothelial cells are specific to?
Blood vessel inner surface
Epithelial cells are specific to?
Lining of organs and body
Non-Brain Fenestrated Capillaries?
Have small gaps in plasma membrane of endothelial cells
Brain Non-Fenestrated Capillaries?
Have tight junctions between endothelial cells
Endothelial Cells and BBB?
-BBB is formed by endothelial cells with tight junctions and glial foot processes of astrocytes
-Astrocytes induce capillaries to form zonula occludes (tight junctions) limiting diffusion of small molecules
Epithelial Cells of Ependyma?
-Movement and absorption of CSF (via cilia and microvilli)
-Line inner surface of brain ventricles (produce CSF)
