The system that coordinates the body's activities and responses to internal and external stimuli
Components of the nervous system
Central Nervous System (CNS)
Peripheral Nervous System (PNS)
Central Nervous System (CNS)
The brain and spinal cord
Peripheral Nervous System (PNS)
Afferent division (inputs)
Efferent division (outputs)
Somatic
Autonomic
Enteric (inputs and outputs from the gut)
Neurons
Specialised cells that are long-lived, have a high metabolic rate, and cannot divide (missing centrioles)
Structure of a neuron
Cell body
Dendrites
Axons
Telodendria
Axon terminals
Types of neuroglia
Maintain the Blood brain barrier
Repair damaged neural tissue
Provide 3D framework
Guide neuron development
Provide myelin sheath (insulation)
Regulate environment
Resting membrane potential
Difference of ionic composition of ECF versus cytosol, maintained by the active Na+/K+ pump and differing membrane permeability
Altering the membrane potential
Activation leads to changes in the membrane, giving rise to a local or graded potential
Excitation potential
Depolarisation leads to action potentials, which have several phases and are all the same size
Synapse
Connections between neurons, found at the end of the axon, where neurotransmitters are released into the synaptic cleft to activate the post-synaptic cell
neurons and nervous tissue supporting cells are neuroglia
Central nervous system function
It is responsible for integrating, processing, and coordinating sensory data and motor commands.
peripheral nervous system function
The PNS delivers sensory information to the CNS and carries motor commands to peripheral tissues and systems, except those of the enteric nervous system
Somatic nervous system
Controls skeletal muscle contractions. Voluntary contractions are under conscious control.
autonomic nervous system
visceral motor system, automatically regulates smooth muscle, cardiac muscle, glandular secretions, and adipose tissue at the sub-conscious level
Two subdivisions of ANS
The ANS includes a parasympathetic division and a sympathetic division, which commonly have antagonistic (opposite) effects.
Enteric nervous system
The enteric nervous system is an extensive network of neurons and nerve networks in the walls of the digestive tract.
Functional characteristics of neuron
Neurons lack centrioles and therefore typical CNS neurons cannot divide.
Cell body, dendrite, axon and telodendria
Cell body
Has a large nucleus with nucleolus and cytoplasm called perikaryon.
Neurofibrils extend into dendrite and axon to provide support.
Perikaryon
Cytoskeleton of perikaryon contain neurofilament and neurotubules. Contain organelles that provide energy and synthesize organic matieral like neurotransmitters.
Dendrites
Dendrite have dendritic spines that participate in synapses.
They represent 80-90% of neuron total surface area