Question

1) The transfer of heat from arterial to venous blood is seen in dolphins. This type of thermoregulation is called

A) thermogenesis.

B) evaporation.
C) vasoconstriction.

D) vasodilation.

E) countercurrent exchange.

2) Neural transmission across a mammalian synaptic gap is accomplished by

A) the movement of sodium and potassium ions from the presynaptic neuron into the postsynaptic neuron.

B) impulses travelling as electrical currents across the gap.

C) impulses causing the release of a chemical signal and its diffusion across the gap.

D) impulses ricocheting back and forth across the gap.

E) the movement of calcium ions from the presynaptic into the postsynaptic neuron.

3) When two presynaptic neurons stimulate a single postsynaptic neuron with two excitatory neurotransmitter releases, this will likely result in _______.

A) temporal summation
B) spatial summation
C) hyperpolarization of the postsynaptic cell
D) neurotransmitters entering the postsynaptic cell
E) an inhibitory postsynaptic potential in the postsynaptic cell

Answer 1

Answer:

1) E) countercurrent exchange.

Explanation: In the countercurrent exchage, The warm arterial blood transfers most of its heat to the cool venous blood coming in from the outside.

2) C) impulses causing the release of a chemical signal and its diffusion across the gap.

Explanation: neural transmission at the synaptic gaps occur via the release of neurotransmitter from the presynaptic neuron which are the chemical signals that bind to the postsynaptic membrane.

3) B) spatial summation

Explanation: Spatial summation is the effect of triggering an action potential in a neuron from one or more presynaptic neurons

Temporal summation occurs when multiple subthreshold EPSPs from one neuron occur close enough in time to combine and trigger an action potential