CHAPTER 2: THE NERVOUS SYSTEM Flashcards
purpose of the CNS/ the CNS consists of…?
central nervous system
- carries messages to and from the PNS
- consists of the brain and spinal cord
- purpose of brain: responsible for virtually everything we think, feel or do
- purpose of spinal cord: connects brain and pns; initiates spinal reflexes
purpose of the PNS/ the PNS consists of…?
peripheral nervous system
- carries messages to and from the CNS
- autonomic nervous system and somatic nervous system
purpose of the autonomic nervous system
ANS
connects the CNS to internal organs and glands; self regulating and therefore occcur w/o conscious effort and are not usually under our voluntary control.
purpose of the somatic nervous system
SNS
acronym SAME - sensory afferent motor efferent
network of nerves carries sensory info to the CNS and motor information from the CNS
afferent info: sensory info entering CNS
efferent info: motor info leaving CNS
how the somatic nervous system works
- sensory neurons in your body detected from sensory receptors are carried to along sensory neural pathways
- motor info is carried along motor neural pathways by motor neurons to skeletal muscles to control their activity by causing them to contract or relax
- skeletal muscles attached to the bones respond to the CNS intiate, change or stop movement
subdivisions of the autonomic nervous system
- sympathetic division: arousing activates internal muscles, organs and glands to prepare the body for vigorous activity or deal w/ a stressful or threatening situation
- parasympathetic division: calming helps maintain the internal body environment in a steady, balanced state of normal functioning (esp. calming after a sympathetic activation)
enteric nervous system
ENS
- detect physiological condition of the gastrointestinal tract (GI)
- Integrate information about its state
- provide outputs to control gut movement
- nutrient management
- gastric acid
- blood flow
- Interact with immune and endocrine system
synapse
the site where communication occurs between adjacent neurons
- made up of two components: the terminal buttons of the presynaptic (‘sending’) neurons and the dendrites of the postsynaptic (‘receiving’) neuron
neurotransmitters
a chemical substance produced by a neuron that carries a message to other neurons or cells in musces, organs or other tissue
process of neurotransmission
in terms of neurotransmitters
- neurons transmit signals when sti mulated by sensory input or triggered by neighbouring neurons
- dendrites pick up the signal and activiate the neuron’s action potential
- presynaptic neuron receives an electrical signal (action potential)
- action potential runs down to the end of an axon and activates the chemical messengers that pass through the synaptic gap
- neurotransmitters (excited or inhibited) lock into the receptor sites of the postsynaptic neuron
- reuptake: excess neurotransmitters are reabsorbed into the neuron and recycled
types of neurotransmitters
- excitatory effect
- neurotransmitters stimulate the post-synaptic neuron and make it MORE LIKELY TO FIRE (glutamate)
- inhibitatory effect
- neurotransmitters depresses the activity of the post-synaptic neuron and make it LESS LIKELY TO FIRE (GABA)
neuromodulators
neurotransmitters that influence/modulate the effect of other neurotransmitters
* e.g: if a neurotransmitter has modulatory effects, it can change the reactivity of receptors to another type of neurotransmitter to enhance their excitatory or inhibitory response
neurotransmission vs neuromodulation
neuromodulation:
* is not restricted to the synaptic gap b/w two adjacent nuerons
* does not release their chemical messengers into a single synapse -> released into far broader areas where they can affect a large number of neurons at once
* effects take take longer to become established and last longer than NTs
* convey global control of brain states that underlie different behaviours such as sleep and wakefulness
dopamine
modulatory neurotransmitter known to have multiple functions depending on where in the brain it acts
important roles in:
* voluntary movements
* experience of pleasure
* motivation
* appetite
* reward-based learning
* memory
primarily an excitatory neurotransmitter, dopamine can have either an excitatory effect at one location or an inhibitatory effect at another, depending on the type of receptors present
mesolimbic /mesocortical (overlap)
dopamine pathway
- associated with rewarding behaviour through the experience of pleasure-dopamine reward system.
- healthy behaviours (such as eating when hungry and drinking when thirsty)
- harmful behaviours that involve a loss of impulse control and have become addictive (such as gambling and video gaming).
