1. Respiratory System

2. Nostrils & Pharynx
Nostrils trap and filter out dust and foreign particles using tiny hairs and mucus
Air is warmed up and moistened
Pharynx is where nasal and oral cavities join

3. In males, the larynx increases during puberty = deeper voice
Trachea
Also known as the windpipe
Contains:
A flap-like structure called the epiglottis
When swallowing food, it prevents it from passing into trachea
The larynx (also known as the voice box because it contains your vocal cords  air forced up from the lungs causes these vocal cords to vibrate and produce sound)
In males, the larynx increases during puberty = deeper voice

4. Bronchi Singular form: Bronchus
Two air passages that move inhaled air from the trachea to the right or left lung
Rings of cartilage surround both bronchi and trachea = increases flexibility of structures
Cilia (tiny hairs) line the inside of the trachea, bronchi and bronchioles and are coated with mucus = prevents bacteria, dust and pollen from entering further down the lungs. Cilia sweeps it upwards to mouth (cough reflex).

5. Lungs
Contains:
Bronchioles – air passageways throughout the bronchus that become smaller and smaller until they reach tiny air sacs called alveoli
Alveoli – tiny air sacs in which gas exchange occurs

6. Gas Exchange
O2-poor blood enters network of capillaries on each cluster of alveoli
O2 gas inside alveoli diffuses into the blood (and CO2 diffuses out of the blood and enters the lungs in reverse fashion)
O2-rich blood leaves capillary network

9. How We Breathe Two Steps:
Inspiration – air is forced into lungs (inhalation)
Expiration – air is forced out of lungs (exhalation)
Just as molecules diffuses from area of high concentration to areas of low concentrations, air moves from areas of high pressure to areas of low pressure!

10. Air pressure is less in lungs compared to the outside of the body  INSPIRATION (air moves into lungs)
Air pressure is greater in the lungs compared to outside of the body  EXPIRATION (air moves out of lungs)

11. Inspiration Diaphragm contracts and moves downward
Rib cage moves outward due to the contraction of the intercostal muscles
Result: increase in volume of chest cavity causes a decrease in air pressure  air moves into the lungs
(Note – when volume increases, the pressure decreases)

12. Expiration Diaphragm relaxes and moves upward
Rib cage moves inward due to the relaxation of the diaphragm
Result: Decrease in the volume of chest cavity causes an increase in air pressure  air moves out of lungs
(Note – when volume decreases, pressure increases!)

13. Diaphragm – thin sheet of muscle that separates the abdominal organs (below it) from the organs of the chest cavity (above it)
Intercostal muscles – muscles between the ribs that raises the rib cage when contracted
Pleural membranes – Thin, fluid-filled membrane that covers the outer surface of the lungs to protect it as it constantly expands and contracts

14. Homeostasis and Respiration
You are working out on a treadmill. After 15 minutes, you feel out of breath and find yourself breathing faster. Explain briefly how homeostasis is related to this. Normal breathing involves intake of O2 and removal of CO2. As you work out vigorously, you need more O2 to keep up with the energy demands. Your brain detects that there is more CO2 in the blood than O2. The brain adjusts this by making you breath faster, so you can take in more O2 to try to balance it out.