Nervous System, Neurons, and Neurotransmitters Flashcards
Nervous system breakdown
Nervous system:
1. Central nervous system (CNS)
2. Peripheral nervous system (PNS)
PNS:
1. Somatic nervous system (SNS)
2. Autonomic nervous system (ANS)
ANS:
1. Sympathetic nervous system
2. Parasympathetic nervous system
Central nervous system (CNS)
Brain and spinal cord
Peripheral nervous system (PNS)
Signals between the CNS and rest of the body
Somatic nervous system (SNS)
- Signals between CNS and skeletal muscles
- Voluntary actions
Autonomic nervous system (ANS)
- Signals between CNS and smooth muscles, organs
- Involuntary actions (unless learned to control through biofeedback)
Sympathetic nervous system
- Prepares body for action (fight-or-flight)
- Can cause rapid physiological changes
Fight-or-flight physiological changes
- Pupil dilation
- Sweating
- Increased heart rate
- Increased respiration rate
- Inhibited digestion
- Inhibited sexual activity
Parasympathetic nervous system
- Returns body to resting state (after fight-or-flight)
Two types of cells in nervous system
- Neurons
- Glia
Neurons function
Communicates information within nervous system
Glia function
Provides neurons with structural support, insulation, and nutrients
Neuron structural components
- Dendrites - receives information
- Soma (cell body) - contains classic cell parts (nucleus, mitochondria, etc.)
- Axon - transmits information
Myelin
- Produced by glia
- Insulates some neuron axons
- Speeds up conduction between neurons
Two processes driving communication in CNS
- Conduction
- Transmission
Conduction in the CNS
Electrochemical process:
Cell rests (negatively charged)
>
Dendrites stimulated
>
Cell membrane channels open
>
Sodium ions enter
>
Cell depolarized (less negative)
>
Action potential triggered
Action potential
- Electrical impulse
- All-or-none responses (intensity of a stimulus not based on action potential intensity but number of action potentials)
Transmission in the CNS
Typically chemical process (AKA synaptic transmission):
Action potential reaches axon terminal >
Neurotransmitter released to synaptic cleft
>
Neurotransmitter produces effect on postsynaptic neuron
>
Neurotransmitter inactivated
Neurotransmitter inactivation
- Can be reabsorbed into presynaptic neuron
- Can be broken down by enzymes
Neuroplasticity
The brain’s ability to change in structure and function throughout development and in response to life experiences
Four types of neuroplasticity
- Homologous area adaptation
- Cross-modal reassignment
- Map expansion
- Compensatory masquerade
Homologous area adaptation
If brain area damaged early, functions shift to corresponding area in opposite hemisphere, can lead to less function in corresponding area
e.g., left parietal lobe takes over for damaged right parietal lobe
Cross-modal reassignment
If sensory brain area deprived of stimuli, function in that area changes
e.g., blindness leads to “somatosensory input” (visualizing mentally) in that area
Map expansion
Temporary or permanent enlargement of a cortical area, usually when learning a new skill
e.g., practicing an instrument
Compensatory masquerade
If brain area damaged, person will use another brain area with function that compensates for lost function
e.g., using memory of landmarks to compensate for loss of visuospatial ability
