Question

1.) Describe the stages of airflow from the nose to the alveoli using the guide below.

2.) Why does the Human chorionic gonadotropin (HCG) hormone stimulate the growth of the corpus luteum during early pregnancy? Explain.

Guide

Nares → Vestibule → Nasal Cavity → Nasopharynx → Oropharynx → Laryngopharynx → Larynx → Trachea → Primary Bronchus → Secondary Bronchus → Tertiary Bronchus → Bronchiole → Terminal Bronchiole → Respiratory Bronchiole → Alveolar Duct → Alveolar Sac → Alveolus

Answer 1

1.The air that we breathe in enters the nose or mouth through the external nares. It passes through nasal cavity. It then flows through the throat (pharynx) which is divided into 3 parts; nasopharynx, oropharynx and laryngopharynx and then through voice box (larynx) and enters the windpipe (trachea). The trachea divides into two hollow tubes called bronchi. The right main bronchus supplies the right lung; the left main bronchus supplies the left lung. These bronchi then go on to divide into smaller bronchi i.e, primary bronchus, secondary bronchi and tertiary bronchi .The small bronchi divide into smaller and smaller hollow tubes which are called bronchioles - the smallest air tubes in the lungs. The medical term for all the air tubes from the nose and mouth down to the bronchioles is 'the respiratory tract'. At the end of the smallest bronchioles Alveolar ducts, alveolar sacs and finally are tiny air sacs called alveoli. Alveoli are lined by a very thin layer of cells. They also have an excellent blood supply. The tiny alveoli are the place where oxygen enters the blood and where carbon dioxide (CO2) leaves the blood.

2. Human chorionic gonadotropin interacts with the HCG receptor of the ovary and promotes the maintenance of the corpus luteum during the beginning of pregnancy. This allows the corpus luteum to secrete the hormone progesterone during the first trimester.