Exam 4: Principles of Neural and Hormonal Communication
Outline the four types of signal molecules.
The most common means by which cells communicate with one another is indirectly through extracellular chemical messengers,or signal molecules,of which there are four types: paracrines/autocrines,neurotransmitters,hormones,and neurohormones.In each case,a specific chemical messenger,the signal molecule,is synthesized by specialized controlling cells to serve a designated purpose.On being released into the ECF by appropriate stimulation,these extracellular chemical messengers act on other particular cells,the messenger's target cells,in a prescribed manner.To exert its effect,an extracellular chemical messenger must bind with target cell receptors specific for it.Different cell types have distinct combinations of receptors,allowing them to react individually to various regulatory extracellular chemical messengers.The four types of extracellular chemical messengers differ in their source and the distance to and means by which they get to their site of action.
At a(n)____________________ synapse,the receptor-channels to which the neurotransmitter binds are nonspecific cation channels that permit simultaneous passage of sodium and potassium through them.
excitatory
Hormones can be classified according to their chemical structure,i.e.,____.
The dendrites and cell body are the neuron's output zone because these components send out signals.
The binding of a neurotransmitter to inhibitory synapses increases the permeability of the subsynaptic membrane to ____.
What term refers to the branching of axon terminals so that a single cell synapses with and influences many other cells?
The total grand postsynaptic potential (GPSP)is a composite of all ____________________ and IPSPs occurring around the same time.
Depolarization from the resting potential of -70 mV proceeds slowly until it reaches a critical level known as ____.
Two important relationships exist between neurons: ____________________ and ____________________.
Membrane potential is related to the uneven distribution of what two positively charged ions?
The terms action potential,spike,and firing all refer to the same phenomenon of slow reversal of membrane potential.
When a neuron terminates on a muscle or a gland,the neuron is said to innervate,or supply,the structure.
Synapses that lead to responses mediated by second messengers are known as ____________________ synapses.
____________________ is the hindrance to electrical charge movement.
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