1. The Respiratory System
Accelerated Biology

2. Function of the Respiratory System
The job of the respiratory system is to obtain oxygen and eliminate carbon dioxide
CO2 is a waste product of cellular respiration and is toxic to cells
Then, the circulatory system transports the oxygen and carbon dioxide throughout the body

3. Structures of the Respiratory System
Nasal cavity – lined with cilia to trap inhaled particles and moisten and warm the air
mucus – traps inhaled particles
cilia – sweeps mucus up to throat to be swallowed
Pharynx – where oral and nasal cavities meet.
Passageway for air and food
Larynx – voice box

4. Structures of the Respiratory System
Ciliated epithelium of the respiratory system.
SEM X5000

5. Structures of the Respiratory System
Epiglottis – flap of cartilage that covers the trachea when swallowing to prevent food and liquids from entering your lungs

6. Structures of the Respiratory System
Trachea – wind pipe with cartilaginous rings
Bronchi – two branches of the trachea that lead to each lung

7. Structures of the Respiratory System
Bronchiole – smaller branches of the two bronchi that end in tiny air sacs called alveoli

8. Structures of the Respiratory System
Alveoli – You have 300,000,000 air sacs in your lungs where gas exchange occurs
Increase the surface area of your lungs to 42x the surface area of your body
Their membranes are one cell thick and are surrounded with capillaries.

9. Aveoli In the lungs

10. Structures of the Respiratory System
Diaphragm – thin sheet of smooth muscle spanning the rib cage that moves up and down to bring air into and out of the lungs

11. Breathing
Breathing occurs because of air pressure differences between the lungs and the atmosphere
Lungs have no muscles, so the work is done by the diaphragm and intercostal muscles
Intercostals – muscles between the ribs

12. Inhalation Gain O2 by inhaling Intercostals and diaphragm contract
Diaphragm flattens and pulls downward
Rib cage is pushed up and out causing a decrease in the air pressure in the lungs (air pressure in lungs is now lower than atmospheric pressure)
Air is sucked into lungs

13. Exhalation Rid body of CO2 by exhaling
Passive - also due to change in lung air pressure
Intercostals and diaphragm relax, decreasing the volume in the chest cavity
Increases the air pressure in the lungs (higher than atmospheric pressure)
Air is forced out

14. Inhalation and Exhalation

15. Gas Exchange
The exchange of CO2 and O2 in both the body tissues and the lungs. Occurs as a result of diffusion
O2 from alveoli diffuses into the blood in the capillaries, in turn CO2 in the blood diffuses into the alveoli
Body tissues – CO2 levels high, O2 levels low
RBC in lungs – O2 levels high, CO2 levels low

16. How is breathing regulated?
Receptors in the brain and the cardiovascular system continually monitor the levels of O2 and CO2 in the blood
As CO2 levels increase, the pH decreases (blood becomes more acidic) causing a person’s breathing rate to increase. Thus, they will expel more CO2 and take in more O2

17. How is breathing regulated?
CO2 combines with H2O to form carbonic acid (H2CO3)
Carbonic acid breaks up to form bicarbonate ions (HCO3) and Hydrogen ions (H+)
Most CO2 travels to the lungs as bicarbonate ions (HCO3)
The H+ ions is what makes the blood acidic, causing an increase in breathing.
The Equation:
H2O + CO2 H2CO3 HCO3- + H+

18. Carbon Monoxide poisoning
Carbon Monoxide binds more readily to hemoglobin than oxygen and carbon dioxide
If present, it will prevent oxygen from being delivered and lead to hypoxia, an inadequate oxygen supply

20. Asthma
Asthma – Chronic condition where the bronchioles of the lungs become inflamed due to sensitivity of stimuli in the air
Bronchial walls tighten and extra mucus is produced causing airways to narrow
Strenuous exercise and stressful situations can trigger an asthma attack

21. The effects of smoking
Emphysema – Elastic fibers in the lungs are destroyed
Begins with the destruction of the alveoli
Results in fatigue and breathlessness
Smoking causes 90% of emphysema cases

22. The effects of smoking Lung Cancer – abnormal cell growth
One of the leading of causes of death in the world
Accounts for 28% of all cancer deaths
Smoking is the major cause of lung cancer