For survival a hummingbird uses a considerable amount of energy . this energy most directly results from the life activity of ?

This energy most directly results from the life activity of  respiration.

The hummingbirds have very high energy expenditure (have the highest oxygen requirements of all vertebrae) with a fast heart rate, very fast wing beats and sustained hovering. So the hummingbird is nearly always on the edge of starvation, needing to take in more nectar than its body weight each day.

The respiratory system of these birds is highly adapted for the high oxygen needs. So, the muscles of the hummingbird cause pressure changes within the air sacs. As a result, more oxygen can enter the respiratory system. Also, they have the highest density of red blood cells which allows them to rise heart beat to around 500 breaths per minute during flight.

endo:

regulates body hormones, aldosterone, vasopressin

neural:

signal, regulates body using electric signals, reflex

endo has to do with hormones; aldosterone and vasopressin are both hormones. i also had this question and got it right : d

when you breathe in, or inhale, your diaphragm contracts (tightens) and moves downward. this increases the space in your chest cavity, into which your lungs expand. the intercostal muscles between your ribs also enlarge the chest cavity. they contract to pull your rib cage both upward and outward when you inhale.