Major Systems of Nervous System
Central Nervous System and Peripheral Nervous System
Subsets of PNS
Somatic and Autonomic (Sympathetic and Parasympathetic)
Sympathetic Division
Fight or flight
Parasympathetic Division
Restorative
Blood in Brain
Delivers glucose and oxygen to neurons in brain
Cerebrospinal Fluid (CSF)
circulates through ventricular system and is replaced every 3 hours
Astrocytes
energy supply, regulation of neural activity
Oligodendricytes
myelin (CNS)
Microglia
immune response, housekeeping
Schwann Cells
myelin (PNS)
Cerebrum
cortex, contains frontal, parietal, occipital, and temporal lobe
Frontal Lobe
associated with reasoning, planning, parts of speech, movement, emotions, and problem solving
Parietal Lobe
associated with movement, orientation, recognition, perception of stimuli
Occipital Lobe
Associated with visual processing
Temporal Lobe
associated with perception and recognition of auditory stimuli, memory, and speech
Cerebellum
regulation and coordination of movement, posture and balance
Limbic System
contains thalamus, hypothalamus, amygdala, and hippocampus
Thalamus
sensory and motor functions
Hypothalamus
homeostasis, emotion, thirst, hunger, circadian rhytms, and control of autonomic nervous system
amygdala
memory, emotion, and fear
Hippocampus
learning and memory, short term memory to permanent memory, recalling spatial relationships
Brain Stem
Midbrain, pons, and medulla
Midbrain
vision, hearing, eye movement, and body movement
Pons
motor control and sensory analysis
Medulla
maintaining vital body functions (breathing and heart rate)
How is the resting potential maintained?
due to force of diffusion and electrostatic pressure
How is the action potential initiated?
At the axon hillock, EPSPs and IPSPs are summed and if large enough voltage-gated ion channels react
How is the action potential propagated?
Starts at 70; Na channels open and Na enters raising voltage; K channels open and K slowly leaves cell, raising voltage; Na channels become refractory (no more can enter) lowering voltage; K continues to leave cell causing membrane potential to return to resting level but due to slowness hyper polarization; K channels close and Na channels reset bring cell to resting level
How does optogenetics allow neuroscientists control neuronal firing?
Control action potentials by inserting ion channels that are receptive to light; they activate channels causing open/close and potential being generated
How are vesicles transported to axon terminal?
Anterograde-kinesin protein walks vesicle down microtubule;
Retrograde-dynein protein takes what is not needed back
How are neurotransmitters released?
action potential causes opening of Ca2+ channels which allow vesicle docking on presynaptic membrane
How are neurotransmitters detected?
Neurotransmitter attaches to binding site on receptors and cause ionotropic or metabotropic responses
How are neurotransmitters cleared from the synapse?
By diffusion away from the cleft, reuptake by presynaptic cell, degraded in cleft by enzyme, or uptake by astrocytes
How does chemical transmission lead to electrical transmission?
Neurotransmitters cause ions to enter/leave cell causing a potential that meets at axon hillock, the type of ion determines if IPSP or EPSP
How is chemical transmission regulated?
Autoreceptors-regulate syntesis and release of neurotransmitters
What are the factors that determine the action of a drug?
Route of administration, passage across membranes, non-target binding, target binding kinetics, dose, and elimination
Direct agonist
drug that binds with and activates a receptor
Indirect agonist
drug that attaches to a binding site on a receptor and facilitates the action of the receptor
Cross-tolerance
tolerance to drug A also diminishes response to drug B
Drug disposition tolerance
drug A causes effects that reduce its own concentration (such as increasing enzyme presence)
Pharmacodynamics tolerance
drug A effectiveness is reduced through action at the receptor or downstream of the receptor (such as # of receptors decrease or intracellular signaling become less sensitive)
Behavior Tolerance
drug A effectiveness is reduced through learned association of environmental or internal cues with drug effects (alcohol at a bar)
Sensitization
effects of drug A increase over repeated doses
Four Criteria for a Neurotransmitter
- Synthesized in the neuron
- present in the presynaptic terminal and released in amounts sufficient to exert action on postsynaptic neuron or organ
- same effect when injected as when released by the body
- specific mechanism exists for removing it from its site of action