neurotransmitters and reflexes (4c) Flashcards
types of neurotransmitters and what they do
excitatory: when it binds to a receptor more positive ions enter (depolarization of postsynaptic cell)
inhibitory: when it binds to a receptor more negative ions enter (hyperpolarization of postsynaptic cell)
how are synapses categorized regarding neurotransmitters
classified (named after) based on the neurotransmitter released from the presynaptic axon terminal
what are the two types of neurotransmitter action and what are the steps
direct: neurotransmitter binds to receptor and an ion channel opens
indirect: neurotransmitter binds to a receptor which triggers reactions to open an ion channel
what are the common neurotransmitters
acetylcholine
norepinephrine
dopamine
serotonin
gaba
glutamate
characteristics of acetylcholine
mostly excitatory but inhibitory at neuromuscular synapses with the heart
found in the CNS (brain) and PNS (voluntary muscles (neuromuscular junctions) sympathetic and parasympathetic nervous systems)
characteristics of norepinephrine as a neurotransmitter
excitatory
involved in attention, temperature control and pituitary gland secretion
found in CNS and PNS (neuromuscular and neuroglandular junctions of sympathetic nervous system)
characteristics of dopamine
excitatory and inhibitory (precise movement control)
found in CNS (hypothalamus, midbrain, limbic system, etc)
characteristics of serotonin
excitatory and inhibitory
attention and emotional states
found in CNS (hypothalamus, cerebellum, spinal cord, etc)
characteristics of gaba
inhibitory
anti-anxiety effects
found in CNS (cerebral cortex, cerebellum, interneurons in spinal cord)
characteristics of glutamate
main excitatory in brain
memory and learning
found in CNS (cerebral cortex and brainstem)
why can a neurotransmitter be both inhibitory and excitatory
receptor structure is different between inhibitory and excitatory receptors
what is an agonist versus and antagonist
agonist: drug that does the same thing as the neurotransmitter (same shape)
antagonist: drug that is close enough in shape to bind to the receptor but not enough to produce an effect (there are reversible and irreversible antagonists)
examples of agonist and antagonist of acetylcholine
nicotinic receptor: nicotine and acetylcholine activate muscle contraction, curare prevents contraction
muscarinic receptor: muscarine and acetylcholine slow down your HR, atropine speeds it up
what diseases are caused by decreased levels in neurotransmitters
alzheimers: acetylcholine
clinical depression: serotonin, dopamine and norepinephrine
parkinsons: dopamine
how do reflexes occur
neural pathways called reflex arcs
what are the two types of reflexes and explain them
somatic: stimulate skeletal muscles, involuntary
autonomic: regulate activity of smooth muscles, heart and glands
steps of a reflex arc
sensory receptor reacts to stimulus
sensory neuron carries information to integration center
CNS processes information and directs motor output
motor neuron carries message to effector
effector is stimulated
types of reflex arcs
two neuron: simplest and fastest (patellar reflex)
three neuron: slower (withdrawal/flexor reflex)
