Nervous System and Nervous Tissue

Nervous System 

• master controlling and communicating system of the body

• perception, thought, memory, emotions, actions

• maintenance of homeostasis

  • info to maintain normal temp

Sensory input

monitor stimuli inside and outside the body

Integration

interpretation of sensory input

Motor output

respond to stimuli by activation effector organs

Neurons

excitable cells that transmit electrical signals

• principal cell type

Supporting cells

cells that surround and wrap neurons

Neuroglia/Glial cells

• provide a supportive scaffolding for neurons

• segregate and insulate neurons

• guide young neurons to the proper connections

• promote health and growth of neurons

Astrocytes

the most abundant CNS neuroglia

Microglial cells

defensive cells in the CNS

• immune (phagocytes)

Ependymal cells

line cerebrospinal fluid-filled CNS cavities

• circulate fluid in spinal cord

Oligodendrocytes

have processes that form myelin sheaths around CNS nerve fibers

Satellite cells & Schwann cells

form myelin sheaths that surround neurons in the PNS

Neurons (nerve cells)

• components: body, axon, and dendrites

• long-lived, amitotic, and have a high metabolic rate

• plasma membrane functions:

  • electrical signaling

  • cell-to-cell signaling during development

Cell Body (Soma)

• contains the nucleus, nucleolus, and other organelles

• is the major biosynthetic center

Dendrites

• short, tapering, and diffusely branched processes

• receptive/input regions of the neuron

Axon functions

• generate and transmit action potentials

• secrete neurotransmitters from the axonal terminals

• molecular transport

  • everything made in nucleus

Axon structure: 

• nerve fibers

• usually only one axon per neuron, unbranched or with collaterals 

• axonal terminal

Nerve fibers

long axons

Axonal terminal

branched terminus of an axon

Anterograde transport

molecular transport from the soma to terminals

Retrograde transport

molecular transport from the terminals to soma

• motor proteins

• neurotransmitter components