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- Circuit from sensory neuron to muscle response.
- In reflex arc there are more nerve sand therefor more synapses to travel across.
Repeated stimuli within a brief time have a cumulative effect
cell that receives the message.
excitatory postsynaptic potential (EPSP)
- graded depolarization
- occurs when sodium ions enter the cell.
- if it doesn’t cause an action potential, it decays quickly.
spatial summation (summation over space)
- synatptic inputs from separate locations combine their effects on a neuron.
- neither pinch alone produces a reflex but both together do.
inhibitory postsynaptic potential IPSP
- when synaptic input selectively opens the gates for potassium ions to leave the cell.
- temporary hyperpolarization of a membrane.
- decreases probability of an action potential.
spontaneous firing rate
periodic production of action potentials even without synaptic input.
- chemicals that affect a second neuron.
- no single neuron uses all transmitters.
- one transmitter interacts with several receptors.
- gas released by many small local neurons considered a neurotransmitter.
- poisonous in large quantities and hard to create in a lab.
release of neurotransmitter in burst from the presynaptic neuron in to the synaptic cleft.
- very fast effect on the postsynaptic neuron which opens channels for some type of ion.
- 10ms and very localized effects.
- sequence of metabolic reactions that are slower and longer lasting than ionotropic effects.
- emerge 30ms or more after release of transmitter and can last seconds to days.
- widespread effects.
- neuropeptides that have several properties that set them apart from other transmitters.
- released by cell bodies, sides of axons, and dendrites.
- requires repeated stimulation.
- diffuse widely and use metabotripic receptors.
- chemical secreted usu. from a gland but also by other kinds of cells conveyed in blood to other organs.
- conveys a message from the sender to receiver.
- long lasting changes in multiple parts of body.
- many chemicals are hormones and neurotransmitters.
glands that are hormone producing.
- presynaptic neuron takes up most of the released neurotransmitter molecules intact and reuses them.
- occurs through special membrane proteins called transporters.
- receptors that detect the amount of transmitter released and inhibit further synthesizing and release after it reaches a certain level.
- located on the presynaptic terminal to tell it to stop making more.
anatomy of the nervous system.
central nervous system
brain and spinal cord (segmented)
peripheral nervous system
- nerves outside brain and spinal cord
- somatic nervous system
- autonomic nervous system
somatic nervous system
axons conveying messages from sense organs (skin, eyes) to CNS and from CNS to muscles.
autonomic nervous system
controls heart, intestines, other organs.
entering dorsal roots (axon bundles) carry sensory information and exiting ventral roots carry motor information.
dorsal root ganglia
cell bodies of sensory neurons in a cluster of neurons outside spinal cord
- densely packed with cell bodies and dendrites
- H shaped center of spinal cord
- mostly mylinated axons; surrounds gray matter in spinal cord.
- sympathetic nervous system
- prepares the organs for vigorous activity, excites
parasympathetic nervous system
- facilitates vegetative nonemergency responses, relaxes.
- increases digestive activity
medulla, pons, cerebellum.
controls vital reflexes, breathing, heart rate, throwing up, salivation, coughing and sneezing.
“bridge”; many axons in the pons cross from one side of the brain to the other.
- within the medulla and pons
- controls motor areas of spinal cord;
- increases arousal and attention in the cerebral cortex.
modifies the brain’s readiness to respond to stimuli
- control of movement/ balance/ coordination;
- attention to stimuli/ timing.
roof of the midbrain
- within the midbrain
- sensory processing - vision mainly
- part of midbrain
- sensory processing – mainly hearing
- part of midbrain
- intermediate level
- border around brainstem;
- motivations and emotions: eating, drinking, sexual activity, anxiety, aggression.
- in center of forebrain
- most sensory info goes to forebrain
- conveys messages to the pituitary gland;
- damage leads to abnormalities in motivated behaviors.
synthesizes and releases hormones into the bloodstream.
connections to other parts of brain
critical for storing certain kinds of memories.
four fluid filled cavities within the brain.
fills the ventricles and canal of the spinal cord, and thin spaces b/t between the brain and thin meninges.
- membranes that surround the brain and spinal cord.
- migraine headaches = swelling of blood vessels in meninges.
- gray matter = cells of the cortex
- white matter = axons extending inward
ventral to the corpus callosum
cell perpendicular to laminae of cortex.
layers of the cortex.
monitors all info about eye, head, and body positions and passes it to brain areas that control movement.
primary motor cortex and prefrontal cortex
very deep coronal groove in brain
main target for touch sensations and info from muscle-stretch and joint receptors.
not primary target for any sensory system but receives info from all systems in diff parts of the cortex.
- occurs if you perceive two sensations as happening at the same time in the same place.
- e.g. see mouth moving on tv, hear sound coming out of tv at same time, match them by binding.
- part of frontal lobe
- control of fine movements (one finger at a time)
Effects of adrenaline on organs same effects as nervous system.
Demonstrates for first time chemical nature of nerve transmission between neurons.
- Production of neurotransmitter
- Production of smaller neurotransmitters
- Transport of neurotransmitter
- Action potential causes calcium to enter releasing neurotransmitter
- Neurotransmitter binds to receptor
- Separation from receptors
- Reuptake of neurotransmitter by transporter protein
- Retrograde transmitter – transmitter released by the postsynaptic membrane and acts on the presynaptic terminal
Two locations of synthesis of neurotransmitters
- Presynaptic terminal, close to point of release; smaller neurotransmitters (acetylcholine)
- Cell body; larger neurotransmitters
a drug that mimics a neurotransmitter, or increases its effect.
a drug that blocks or decreases effects of the neurotransmitter.
Affinity: ability of a drug to bind to a receptor.
Efficacy: the degree to which the drug activates the receptor once bound.
constricts blood vessels, raises blood pressure; decreases urine volume
controls uterine contractions milk release, parental behavior
- Critical for memory, formation of new memory
- Korsakoff’s syndrome affect hippocampus
Enteric NS “third autonomic system”
- In walls of GI tract
- Separate nervous system just to regulate digestion