Can you have a heart attack and not know it?

How might expectations or rules at a job differ from those at your home?

Write a paragraph about why the respiratory system is important and we need to breathe easily. (guys i really need ) x(

Astructural difference between the trachea and esophagus that prevents the trachea from collapsing is the presence of: a) smooth muscle b) skeletal muscle c) respiratory cilia d) rings of cartilage