The Respiratory System

Function of the Respiratory System 2 Functions: To move oxygen from the outside environment into the body To remove carbon dioxide and water from the body Q: Why do we need oxygen? Answer: because every cell in your body needs oxygen for cellular respiration Q: Why do we need to get rid of carbon dioxide? Answer: If carbon dioxide builds up in cells, they can’t perform their functions

The Path of Air - Organs Involved Mouth & Nose Pharynx larynx Vocal cords trachea

The Path of Air - Organs Involved (continued) bronchi bronchioles alveoli

“Respiration” vs. “Breathing” Refers to the movement of air into and out of the lungs RESPIRATION Refers to the chemical reactions inside the cells. Also known as “cellular respiration”

The Nose Air enters through nostrils where the following functions are performed: Air is warmed- blood vessels line the nasal cavities and the warm blood warms the air. Air is filtered - hairs and sticky mucus trap dirt and dust Mucus is then swept by the CILIA into the throat so you can swallow it. Air is moistened – mucus also adds moisture to the air along with goblet cells

The Pharynx Air enters here from nasal cavities ONLY part of respiratory system that is shared with another system…the digestive system. Epiglottis – prevents food from entering trachea

The Larynx Houses the VOCAL CORDS – flaps of tissue that vibrate and produce sound https://www.youtube.com/watch?v= D6mLc9gOgVA

The Trachea Also called the “windpipe” Can feel it if you run your fingers gently down center of neck Lined with mucus which continues to moisten the air Lined with cilia which sweep the mucus up into the trachea where it goes to stomach When trachea is irritated, you cough which sends particles out of body Sealed by epiglottis when you swallow food

How do the cilia and goblet cells function? They they line the respiratory tract and move in waves to sweep particles up and out of the respiratory tract. https://www.youtube.com/watch?v=Uvs5cOJYw7U &list=PL-A8SZnIEPDFp32rDpgrriYP1u08miZJH Goblet cells also line the respiratory tract along with the cilia. Goblet cells secret mucus to moisten the air. https://www.youtube.com/watch?v=miEEluVlemQ

Bronchi and Lungs Lungs – main organs of the respiratory system Bronchi are the passages that direct air into the lungs (single: bronchus) Inside lungs, bronchi divide into smaller and smaller tubes like branches of a tree Alveoli – at the end of the smallest tubes. Specialized lung tissue for movement of gases between air and blood. Each alveolus is surrounded by capillaries where gas exchange takes place.

Gas Exchange After air enters an alveolus, oxygen passes through the wall of the alveolus and then through the capillary wall into the blood. Carbon dioxide and water pass from the blood into the alveoli

Page 561, Fig. 2 Q: What do the red and blue lines surrounding the alveoli in the second picture represent? A: Those are capillaries – tiny blood vessels that carry oxygen AWAY from the lungs and carbon dioxide TO the lungs How thick are the walls of the alveoli and the capillaries? A: They are only one cell thick Q: What is leaving the alveoli and entering the blood? A: oxygen

Page 561, Fig. 2 (continued) Q: What is leaving the blood and entering the alveoli? A: carbon dioxide Q: Through what process are these gasses “exchanging?” A: Diffusion – The gases are moving from areas where they are highly concentrated to areas where they have low concentrations.

How does gas exchange work? https://www.youtube.com/watch?v=AJpur6XUiq4 https://www.youtube.com/watch?v=5LjLFrmKTSA

Understand inhalation and exhalation To understand how these two things happen, you must understand 2 things: 1. Because air is a GAS, it behaves according to Boyle’s law of gases 2. Gases always move from areas of high pressure to areas of low pressure

BOYLE’S LAW OF GASES With GASES, there is an INVERSE RELATIONSHIP between VOLUME AND PRESSURE (as one goes up, the other goes down) As VOLUME INCREASES gas PRESSURE DECREASES As VOLUME DECREASES gas PRESSURE INCREASES Q: When the volume inside the chest cavity INCREASES what happens to air pressure inside the chest cavity? A: Because VOLUME INCREASES, PRESSURE DECREASES Q: When the volume inside the chest cavity DECREASES, what happens to air pressure inside the chest cavity? A: Because VOLUME DECREASES, PRESSURE INCREASES

How does the volume of the chest cavity increase or decrease? VOLUME INCREASES: 1. diaphragm contracts and MOVES DOWN 2. Intercostal muscles contract and move rib cage up and out (this increase in volume causes the air pressure in the chest cavity to decrease so higher pressure in the outside environment moves into the lungs) VOLUME DECREASES: 1. diaphragm relaxes and MOVES BACK UP 2. intercostal muscles relax and rib cage moves down and back in (this decrease in volume causes the air pressure in the chest cavity to increase so higher pressure air in the lungs moves out into the outside environment)