Nervous System Flashcards
Nervous system
-Senses, interprets, and issues commands as a response to conditions in the body’s environment
-this process is made possible by very complex communication system organized as a grid of neurons
-messages are sent across the plasma membrane of neurons through a process called action potential
-these messages occur when a neuron is stimulated past a necessary threshold
-the stimulations occur in a sequence from the stimulation point of one neuron to its contact with another neuron
-at the point of contact, called a chemical synapse, a substance is released that stimulates or inhibits the action of the adjoining cell
-this network fans out across the body and forms the framework for the nervous system
-the direction of the information flows depends on the specific organizations of nerve circuits and pathways
Three functional types of neurons
Sensory neurons
Motor neurons
Interneurons
Sensory neurons
Transmit signals to the central nervous system (CNS) from the sensory receptors associated with touch, pain, temperature, hearing, sight, smell, and taste
Motor neurons
Transmit signals from the CNS to the rest of the body such as by signaling muscles or glands to respond
Interneurons
Transmit signals between neurons
-ex. Interneurons receive transmitted signals between sensory neurons and motor neurons
In general, a neuron consists of three basic parts
Cell body
axon
dendrites
Cell body (soma)
Contains the nucleus of the neuron
Axon
-Transmits the impulses away from the cell body
-the axon is insulated by oligodendrocytes and the myelin sheath with gaps known as the nodes of Ranvier
-the axon terminates at the synapse
CNS
Consists of brain and spinal cord
[CNS]
Spinal cord
-Spinal cord is encases in the bony structure of the vertebrae, which protects and supports it
-it’s nervous tissue functions mainly with respect to limb movement and internal organ activity
-major nerve tracts ascend and descend from the spinal cord to the brain
[CNS]
Brain
Brain consists of the hindbrain, midbrain, and forebrain
[CNS]
Brain: HINDBRAIN
The hindbrain includes the medulla oblongata, cerebellum, and pons
[CNS]
Brain: MIDBRAIN
-The midbrain integrates sensory signals and orchestrates responses to these signals
-The midbrain is associated with vision, hearing, motor control, sleep/wake, arousal (alertness), and temperature regulation, acting as a sort of relay station for auditory and visual information.
[CNS]
Brain: FOREBRAIN
The forebrain includes the cerebrum, thalamus, and hypothalamus