Physio HW Q's Exam 2
Which of the following is an ACCURATE description of both ionotropic and metabotropic receptors
Both affect ion channels, can be associated with second messengers, can cause EPSPs and IPSP, and are located on the postsynaptic membrane.
Which of the following neurotransmitters are biogenic amines?
Dopamine, serotonin, epinephrine
Nicotinic cholinergic receptors open channels on the plasma membrane that allow both Na+ and K+ to move across the membrane. This will lead to which type of postsynaptic potential?
EPSP, Sodium will rush into the cell at a faster rate than K+ will move out of the cell.
Once a neurotransmitter binds to a postsynaptic receptor, it remains bound until an antagonist chemical replaces it.
False, Continual binding of neurotransmitter to receptor does not occur. A number of processes quickly clear neurotransmitter from the synaptic cleft.
Which of the following statements about electrical synapses is correct?
The communication through electrical synapses could be excitatory or inhibitory. At electrical synapses, the plasma membranes of adjacent cells are linked by gap junctions. The communication through electrical signals is often bidirectional.
In some cases, neurotransmitter will bind to a receptor and activate a G protein whose function is to activate adenylate cyclase. Adenylate cyclase converts ATP to cAMP, which leaves the plasma membrane to go into the cell and activate a protein kinase A. Protein kinase A phosphorylates K+ channels, causing them to close. Based on this information, which of the following statements is correct?
The initial receptor was indirectly linked to the K+ channel.
All cells of the body require purines.
True, Purines make up the nucleic acids, such as those used in making ATP molecules. Since all cells need ATP, all cells need purines.
How does increased frequency of action potentials result in increased release of neurotransmitter?
With increased firing frequency, the voltage-gated calcium channels at the axon terminal remain open longer, allowing more calcium to enter the cell.
The mechanism by which the neurotransmitter is returned to a presynaptic neuron's axon terminal is specific for each neurotransmitter. Which of the following neurotransmitters is broken down by an enzyme before being returned?
acetylcholine, broken down by acetylcholinesterase before being returned to the presynaptic neuron's axon terminal.
Metabotropic receptors __________.
are G protein-linked receptors
Which of the following synapses function as modulatory synapses?
axoaxonic
The vast majority of synapses in the CNS are __________.
axodendritic (Most synapses occur between a presynaptic neuron and the dendrite of a postsynaptic neuron.)
A chemical synapse between an axon terminal and a cell body would be categorized as __________.
axosomatic
Which of the following are common types of synapses that occur between neurons?
axosomatic, axodendritic, axoaxonic, Not common: dendrosomatic
When an action potential reaches the axon terminal, a depolarization causes voltage-gated __________ channels to open.
calcium
Binding of a neurotransmitter to its receptors opens __________ channels on the __________ membrane.
chemically gated; postsynaptic
Opening of __________ channels leads to an __________.
chloride; IPSP
Which of the following enzymes catalyzes the synthesis of acetylcholine from acetyl CoA and choline?
choline acetyl transferase (CAT)
What is the name of the process through which one neuron receives communication from several other "upstream" neurons?
convergence
Which of the following could happen to the chemical messenger released from a pre-synaptic neuron?
degradation by enzymes in the synaptic cleft, removal by transporters on the pre-synaptic cell membrane, binding to receptors on the post-synaptic membrane
Binding of the neurotransmitter to its receptor causes the membrane to __________.
either depolarize or hyperpolarize
The activation of beta2 receptors in the bronchi causes bronchodilation (an increase in diameter of the bronchi), making it easier to breathe. Which of the following neurotransmitters would be useful for a person suffering from an episode of bronchoconstriction (a reduction in the diameter of the bronchi)?
epinephrine
The chemical messenger at a synapse is released from the pre-synaptic cell by __________.
exocytosis
Which of the following neurotransmitters can bind to N-methyl-D-aspartate receptors (NMDA)?
glutamate
Choline is needed to make acetylcholine. A diet poor in choline-rich foods would cause problems __________.
in the CNS, but more so in the PNS
When neurotransmitter molecules bind to receptors in the plasma membrane of the receiving neuron, When neurotransmitter molecules bind to receptors in the plasma membrane of the receiving neuron,
ion channels in the plasma membrane of the receiving neuron open.
The nicotinic cholinergic receptor __________.
is an ionotropic receptor, This type of receptor acts as both a ligand receptor and an ion channel.
Enkephalin is a neuropeptide that initiates a "slow" response in the postsynaptic cell; to which type of receptor does enkephalin bind?
metabotropic receptors
The summation of EPSPs and IPSPs at the axon hillock is referred to as __________.
neural integration
Which of the following types of neurotransmitters is packed in specialized vesicles called dense core vesicles?
neuropeptides, Neuropeptides are packaged into these larger types of vesicles which require higher frequency action potentials to exocytose.
The chemical messenger that carries information from a pre-synaptic neuron to a post-synaptic neuron is a(n) _____.
neurotransmitter
A molecule that carries information across a synaptic cleft is a
neurotransmitter.
At a chemical synapse, which of the following occurs first?
opening of voltage-gated calcium channels
When a neuron synapses on the axon terminal of another neuron, causing decreased neurotransmitter release from the postsynaptic neuron, it is an example of __________.
presynaptic inhibition
In a synapse, neurotransmitters are stored in vesicles located in the __________.
presynaptic neuron
The small space between the sending neuron and the receiving neuron is the
synaptic cleft.
Reflexes can be classified based on how many synapses are present in the integration center of the reflex arc (that is, how many synapses there are in the brain or spinal cord). Polysynaptic reflexes take longer to complete than monosynaptic reflexes simply because there are more synapses present and each synapse requires a certain amount of time for neurotransmitter to be released once that neuron is activated. We refer to this amount of time as __________.
synaptic delay, The synaptic delay is caused by the time needed for calcium to accumulate in the axon terminal until enough is present to initiate exocytosis.
Prior to being released by the neuron in response to an action potential, neurotransmitters are stored in the __________.
synaptic vesicles
If a signal from a sending neuron makes the receiving neuron more negative inside,
the receiving neuron is less likely to generate an action potential.
When calcium ions enter the synaptic terminal, When calcium ions enter the synaptic terminal,
they cause vesicles containing neurotransmitter molecules to fuse to the plasma membrane of the sending neuron.
An action potential releases neurotransmitter from a neuron by opening which of the following channels?
voltage-gated Ca2+ channels
The job of the axon hillock is to determine whether there are enough depolarizing potentials to reach threshold. What type of membrane channels do you think you would find at the axon hillock?
voltage-gated Na+ channels, Voltage-gated channels allow the axon hillock to sum the EPSPs and IPSPs. If there are enough EPSPs, sodium channels open and initiate an action potential.
A neuron has one axon with 10 axon collaterals. Each collateral branch synapses on __________. This is an example of __________.
10 different postsynaptic neurons; divergence
Action potential size cannot code for stimulus intensity. So, how can neurons code for stimulus intensity?
Action potentials can fire more frequently down the axon to indicate a stronger stimulus.
