Central Nervous System (CNS)
- Brain and spinal cord
- Communicates with the rest of the body through nerves attached to the brain and spinal cord
Peripheral Nervous System (PNS)
Nerves and most of the sensory organs (incl. the nerves attached to the brain and to the spinal cord)
Nerves
- Bundles of individual neurons contained within a protective membrane
- Relays sensory to the CNS from the body, and relays motor information from the CNS to the rest of the body
Sensory Neuron
A neuron that detects changes in the external or internal environment and sends information about these changes to the central nervous system
Motor Neuron
A neuron located within the CNS that controls the contraction of a muscle or the secretion of a gland
Structure of a Neuron (+ their general function)
- Cell body or Soma – contains nucleus and much of the machinery involved in the life processes of the cell
- Dendrites – antennas to receive a neural messages that are transmitted across the synapse
- Axon – a long, thin tube; outer surface carries information (i.e. action potential) from the cell body to terminal buttons
*Myelin Sheath – cover the axon to provide insulation for the electrical message carried along the axon membrane (prevents spreading between adjacent axons) - Terminal Buttons – the bud at the end of an axon’s branch which forms the synapse; sends information to consecutive neuron
Axoplasmic Transport
An active process by which substances are propelled along microtubules that run the length of the axon
Anterograde vs Retrograde
- Antero: In a direction along an axon from the soma toward the terminal buttons
- Retro: In a direction along an axon from the terminal buttons toward the soma
Neurotransmitter
A chemical that is released by a terminal button; has an excitatory or inhibitory effect on another neuron
Membrane
A structure consisting of lipid molecules that defines the outer boundaries of a cell and also constitutes many of the cell organelles
Cytoskeleton
- Formed of microtubules and other protein fibres
- It is linked to each other and forms a cohesive mass that gives a cell its shape
Microtubule
- A long strand of bundles of protein filaments arranged around a hollow core
- Part of the cytoskeleton and involved in transporting substances from place to place within a cell
Nucleus and Chromosome
- Nucleus: A structure in the central region of a cell, containing the cell’s chromosomes
- Chromosome: A strand of DNA (w associated proteins) that carries genetic information
