2.2 THE RESPIRATORY SYSTEM

Function The exchange of oxygen and carbon dioxide between the Red blood cells and the lungs The circulatory system transports the oxygen and carbon dioxide to and from the rest of the body cells

Anatomy of the Respiratory System 12 Nasal passage Mouth Larynx Lung Right Bronchus Left Bronchus Diaphragm Epiglottis Pharynx Trachea Bronchiole Alveoli

Function of the Parts Nasal Passage/Mouth – warms the air as it enters the body Epiglottis: flap of tissue that divides the respiratory system digestive system Pharynx: collects the warmed air Larynx: contains the vocal chords that vibrate to make sound as air is pushed out from the lungs Diaphragm: a muscle that helps to change the pressure inside the lungs during inhalation and exhalation

Function of Parts Continued…. Trachea: smooth muscle reinforced by cartilage rings. It is the main tube that directs air into or out of the lungs. This tube branches into smaller tubes within the lungs. a) Bronchus (bronchi): one of two large branches into lungs b) Bronchioles: any of the tiny branches into which a bronchi divides Alveoli: sacs that fill with oxygen when we breath in and carbon dioxide when we breath out. They are the site of gas exchange between the lungs and the circulatory system.

Lining of the Tract The interior lining of the respiratory system is covered in cilia (hair-like structures) Cilia trap debris you breathe in Mucous secreted by cells collect the debris together (what do you think “snot” is?) so that body can get rid of it via sneezing (from your nose), coughing (from your lungs)

Are like a balloon and are composed of a membrane that is kept moist within the lung Oxygen dissolves into the thin layer of liquid that sits on the inside of the sac The sac is covered by tiny capillaries so the oxygen can move into the bloodstream Alveoli Capillary To the Pulmonary Vein of the heart From the Pulmonary Artery of the heart

“Breathing in” Oxygen enters the lungs Chest volume is large Ribs move up and out Diaphragm contracts and pushes down “Breathing out” Carbon dioxide exits the lungs Chest volume is small Ribs move down and in Diaphragm relaxes and pushes up INHALATION EXHALATION

Inhalation Exhalation Air RUSHES in * pressure is lower inside the lungs that outside Air RUSHES out *pressure is higher inside the lungs that outside

Review Questions: 1) Why are cilia important in the respiratory system? 2) People that smoke often have trouble breathing. What part of the respiratory system do you think is affected by smoking and how does it affect your ability to breathe? 3) Describe how oxygen and carbon dioxide are exchanged. 4) What is the difference between inhalation and exhalation and how does each work?