Why does the bronchioles get smaller and smaller before they reach the alveoli?

Parasympathetic stimulation causes bronchoconstriction while sympathetic stimulation causes bronchodilation. During an asthma attack, the muscles that encircle the airway tighten or constrict, limiting the flow of air to and from the lungs.

Explanation: i hope this answers your question and i have a awesome marvelous day.

In your lungs, the main airways (bronchi) branch off into smaller and smaller passageways -the smallest, called bronchioles lead to tiny air sacs (alveoli)

the bronchiole end in tiny air sacs called alveoli, where oxygen is transferred from the inhaled air to the blood, after absorbing oxygen, the blood leaves the lungs and is carried to the heart, the blood then is pumped through your body to provide oxygen to the cells of your tissues and organs.

c

explanation:

the relative atomic mass of an element is the mass of one atom of that element, relative to 1/12th of the mass of a  1212c atom. to convert to an absolute mass in kg, it is necessary to multiply by  1.661×10−271.661×10−27.

the relative atomic mass is roughly equal to the number of neutrons, plus the number of protons, in the nucleus of the atom.

for elements with more than one stable isotope (different types of nucleus with different numbers of neutrons but the same number of protons), the quoted mass is usually the average mass, weighted by the relative abundance of the different isotopes.