Question

What is typically the role of an inhibitory synapse?

to open Na+ channels in the post-synaptic membrane

to depolarize the post-synaptic membrane

to generate an EPSP

to hyperpolarize the post-synaptic membrane

If a post-synaptic nerve cell receives a large number of EPSPs from synapses on different dendrites, what is the most likely result?

A hyperpolarization

Mechanical summation

Spatial summation

An IPSP

Why might natural selection have favored cephalization?

It allows animals to better detect stimuli behind them, if they are moving forward

It allows animals to interact with the environment equally from all sides of the body at the same time

It allows animals to better detect and capture prey

It is advantageous for animals that have very simple nervous systems, because it allows for ganglia to be spread evenly throughout an animal's body

What is most likely to happen to action potentials if the myelin sheath around an axon were damaged?

They would fail to be generated at all

They would travel in the opposite direction

They would no longer have a refractory period

Their propagation could slow down

It takes very few molecules of a hormone to cause changes in a target cell. This may be explained by the fact that:

the mechanism of hormonal action involves memory cells that have had prior contact with the hormone and immediately respond to its presence

the mechanism of hormonal action involves the replication of the hormone within the target cell to quickly magnify the hormone’s effect

hormones are large molecules that persist for years and can repeatedly stimulate the same cell

the mechanism of hormonal action may involve an enzyme cascade that amplifies the response to a hormone

Answer 1

1. To hyper polarize the post synaptic membrane.

When Na channels open, post synaptic membrane gets depolarized and nerve impulse gets generated. Depolarized membrane will have action potential. Which spreads through the nerve membrane causing action potential. EPSP is excitatory pre synaptic potentials.

2. Spatial summation.

When many dendrites receive impulses on to one neuron, spatial summation occurs.

IPSP is inhibitory presynaptic potential.

Hyperpolarization occurs when K ions go out during repolarization.

3. It allows animals to interact with environment from all sides at the same time.

4. If the myelin sheath is damaged, conduction of action potential will slow down. Myelin sheath helps in faster conduction by saltatory conduction method.

5. The mechanism of hormonal action involves an enzyme cascade that amplifies the response to a hormone.

In case of extracellular hormones, it binds to the receptor bringing some conformational changes int he receptor. This brings certain chemical changes leading to physiological effects in the body. The response is shown as long as the hormone is bound to the receptor.