The Nervous System
Neurons and Glial Cells
Neurons and glia coordinate actions and transmit signals in the CNS and PNS.
Four major types of neurons transmit signals through the body via specialized structures such as dendrites, axons, and synapses.
The seven types of glia have specific functions that play a role in supporting neuron function.
How Neurons Communicate
Nerve Impulse Transmission within a Neuron: Resting Potential
The resting potential of a neuron is controlled by the difference in total charge between the inside and outside of the cell.
Nerve Impulse Transmission within a Neuron: Action Potential
Signals are transmitted from neuron to neuron via an action potential, when the axon membrane rapidly depolarizes and repolarizes.
Signals are transmitted from one neuron to the next across either a chemical synapse or an electrical synapse.
Signal summation occurs when impulses add together to reach the threshold of excitation to fire a neuron.
Synapses experience plasticity by strengthening or weakening over time.
The Nervous System
The nervous system is composed of the central nervous system (brain and spinal cord) and the peripheral nervous system (nerves).
The Central Nervous System
Brain: Cerebral Cortex and Brain Lobes
The cerebral cortex of the brain is divided into four lobes responsible for distinct functions: frontal, parietal, temporal, and occipital.
Brain: Midbrain and Brain Stem
Regions of the brain other than the cerebral cortex include those involved in sleep, memory, attention, motor coordination, and motivation.
The spinal cord is a bundle of nerves that is connected to the brain and relays information from the brain to the body and vice versa.
The Peripheral Nervous System
Autonomic Nervous System
The autonomic nervous system, the relay between the CNS and internal organs, is divided into the sympathetic and parasympathetic systems.
Sensory-Somatic Nervous System
The sensory-somatic nervous system transmits sensory information from the body to the brain and motor movements from the brain to the body.
Nervous System Disorders
Alzheimer's disease and Parkinson's disease are both neurodegenerative disorders characterized by loss of nervous system functioning.
Neurodevelopmental Disorders: Autism and ADHD
Autism and ADHD are neurodevelopmental disorders that arise when nervous system development is disrupted.
Neurodevelopmental Disorders: Mental Illnesses
Schizophrenia and depression are just two examples of mental illnesses caused by a disorder of the nervous system.
Other Neurological Disorders
Epilepsy and stroke are examples of neurological disorders that arise from malfunctions in the nervous system.