1. Respiratory System

2. Main Function
The exchange of oxygen and carbon dioxide between the body and the outside world.
Breathing allows oxygen to enter the body and carbon dioxide to leave.

3. Cellular Respiration Takes place in mitochondria:
Nutrients + Oxygen energy + carbon dioxide + water
(food) (inhaled) (exhaled)

4. Respiratory System

5. Structures
Nasal Passages(cavity) : open to outside through nostrils to pharynx
Function: - filters air with hairs that line cavities
- warm & moisten air with mucus(secreted by glands)
Pharynx (throat): common between respiration and digestion
Function: - air toward trachea, food to esophagus
- epiglottis seals trachea
Larynx: upper trachea, cartilages, vocal cords
Function: - carries air, produces sound (voice)

6. Trachea: cartilaginous rings hold open passage, in front
Function: - filters air with cilia (hair-like)
- warms and moistens with mucus
- brings air to bronchi
Bronchi: division of trachea to left and right lung, cartilaginous
rings to hold open, branching into bronchioles
Function: carry air to lungs

7. Lungs: Spongy, elastic, enclosed in rib cage
millions of air sacs called alveoli for gas exchange
Function: gas exchange between body and outside

8. Gas Exchanges
Extract oxygen from the air and expel carbon dioxide

10. Inhalation Intercostal muscles and diaphragm contract
Ribs rise and diaphragm descends (increase size ribcage)
Lung volume increases
Air pressure inside lungs decreases (lower than outside)
Oxygen rich air from outside flows in lungs until pressure equal (inside-outside)

11. Exhalation 1. Intercostal muscles and diaphragm relax
Ribs descend and diaphragm rises, decrease size of ribcage
Lung volume decreases
Air pressure in lungs increases, greater than outside air pressure
Carbon-dioxide rich air from lungs flows out, until pressure equal (inside-outside).

12. Gas Exchange with Lungs
Oxygen absorbed by lungs must reach cells of body
Carbon dioxide waste from cellular respiration must be expelled by lungs
Both gases transported by blood through small blood vessels called capillaries
Gas exchange takes place in alveoli of lungs

15. Diffusion
Transport of molecules of a solute from region of higher concentration to one of lower concentration
Remember cells?

16. Concentration of O2 is higher in alveolar air than in the capillary blood, so it diffuses from alveoli to blood.
Concentration of CO2 is higher in the capillary blood than in alveolar air, so it diffuses from blood to alveoli.