the nerve

neurons

have highly irregular shapes with one or more cellular processes extending from the cell body

neuronal cell body

also referred to as the soma or pericarion that contains the same organelles found in other cells

rough endoplasmic reticulum and polysomes

collectively referred to as Nissl substance that are especially abundant in perikarya

axon hillock

the area of the cell body where an axon originates

axon hillock

also referred to as the trigger zone, as action potentials are generated here

initial segment of the axon

located just distal to the axon hillock

dendrites

the remaining neural processes that resembles trees

dendrites and perikarya

primary receptive sides of impulses from other neurons

action potential

it travels along the axon at a speed that varies from 0.5 to 120 m/s

myelinated

larger axons, over one nanometer in diameter

not myelinated

axons less than 1 nm in diameter

neurons

they are contiguous and not continuous and they communicate with each other via synapses

unipolar neurons

bipolar neurons

two types of neurons

unipolar neurons

have a single stem process that bifurcates to form two processes, the peripheral and central

unipolar neurons

it innervates peripheral tissues, bringing somatic and visceral sensory information to the central nervous system

bipolar neurons

have two processes and are sensory neurons

bipolar neurons

their peripheral processes innervates sensory receptors, bringing sensory signals to the central nervous system

cilia

act as receptors detecting the chemical environment in nasal air

schwann cells

also referred to as neurolemmocytes which support actions of the peripheral nervous system depending on the size of the axon in two ways

schwann cells

associated with most axons over one nanometer in diameter form myelin sheets by concentrically wrapping their plasma membrane around the axon (up to 50 or more layers)

node of ranvier

junction between each internode

oligodendrocytes

they are the small neuroglia of the central nervous system

oligodendrocytes

they are present in both the white and gray matter and have numerous cell processes that extend to adjacent axons to form myelin sheaths

nerve fiber

formed when axon and myelin sheath or together

peripheral nerve fibers

vary in diameter, ranging from 0.3 to 22 micrometer

aa nerve fibers

innovate the skeletal muscle heavily myelinated and have the fastest conduction velocity

B nerve fiber

they are progressively smaller and poorly myelinated

C nerve fiber

they are not myelinated and have a slow conduction velocity

microglia

comprises 10 to 20% of all neuroglia

microglia

they are the macrophages of the central nervous system and act as the first line of defense against tissue injury or infection

microglia

they're also known to release nitric oxide which prevents viral replication

astrocytes

are star shaped cells with numerous long cell processes, however appear a cells with pale avoid nuclear with routine staining

astrocytes

it represents approximately 50% of the real cell population in the central nervous system

astrocytes

they provide structural and metabolic support for neurons

neurotrophic factors

the released by astrocytes which are important for neuronal survival

perivascular end feet

the astrocytic processes that cover capillaries