1. The Respiratory System

2. The Respiratory System
Process by which O2 and CO2 are exchanged between cells, the blood, and air in the lungs = respiration
The human respiratory system has three phases of gas exchange:
breathing, the ventilation of the lungs by alternate inhalation and exhalation,
transport of oxygen from the lungs to the rest of the body via the circulatory system, and
diffusion of oxygen from the blood and release of CO2 into the blood by cells of the body.

3. The Respiratory System (continued)
Human Respiratory System
Consists of the nose, pharynx, larynx, trachea, bronchi (singular bronchus), and lungs

4. The Respiratory System
Figure 23.19a
The Respiratory System
Pharynx
Nasal cavity
Esophagus
Larynx (voice box)
Left lung
Trachea (windpipe)
Right lung
Bronchus
Bronchiole
Diaphragm
Heart
(a) Overview of the human respiratory system

5. Passageway of Air Into the Lungs
Air entering the lungs is warmed, moistened, and filtered by the nose and mouth, keeping lung tissue healthy
Air enters pharynx – passageway for food and air
Air then passes through the larynx – area containing vocal cords
Air passes through trachea – the windpipe – which is covered by the epiglottis (flap of cartilage) when you swallow

6. Passageway of Air Into the Lungs (continued)
Air then passes from the trachea into two large tubes in the chest called bronchi. Each bronchus leads to one of the lungs. The bronchi then branch out and get smaller and are called bronchioles
Bronchi and bronchioles are surrounded by smooth muscle and help regulate the size of air passageways
Bronchioles continue to get smaller and read “dead ends” – millions of tiny air sacs called alveoli. Alveoli are grouped into little clusters (like grapes) with capillaries surrounding each alveolus. This is where gas exchange takes place.

7. carbon dioxide exchange at
Movement of Oxygen and Carbon Dioxide In and Out of the Respiratory System
Nasal
cavities
Oxygen-rich
air from environment
Pharynx
Trachea
Bronchi
Oxygen and
carbon dioxide exchange at
alveoli
Bronchi
Bronchioles
Alveoli
Bronchioles
Nasal
cavities
Carbon
dioxide-rich
air to the environment
Trachea
Pharynx

8. Gas Exchange 350 million alveoli in healthy lung
O2 dissolves on wet surface of alveoli and then diffuses into capillaries
CO2 in blood, diffuses across membrane of alveolus and into the air of the lung
Alveoli
Bronchiole
Capillary

9. Gas Exchange
However, there is one problem with this simple gas delivery system.
Problem: Oxygen does not readily dissolve in blood.
Solution: Oxygen is carried in hemoglobin molecules within red blood cells.

10. Hemoglobin in Red Blood Cells
Figure 23.23
Hemoglobin in Red Blood Cells
Heme
group
Iron
atom O2
O2 loaded
in lungs O2
O2 unloaded
in tissues
Polypeptide chain

11. Breathing Movement of air into and out of lungs
Air is driven into lungs by air pressure
Bottom of chest cavity is the muscular diaphragm
When you inhale, the diaphragm contracts and expands chest cavity = less pressure inside = vacuum that brings air into lungs
When you exhale, the diaphragm relaxes and makes the chest cavity smaller = more pressure inside = air rushes out of lungs
If chest cavity punctured, probably not be able to breathe

12. Breathing Inhalation Exhalation Air exhaled Air inhaled
Rib cage descends
Rib cage rises
Diaphragm
Diaphragm
Inhalation
Exhalation

13. Breathing Inhalation Exhalation Air exhaled Air inhaled
Rib cage descends
Rib cage rises
Diaphragm
Diaphragm
Inhalation
Exhalation

14. The Respiratory System

15. How Breathing is Controlled
Breathing is NOT voluntary
Nervous system controls breathing in the medulla oblongata which “senses” when CO2 levels rise = impulses sent to diaphragm to contract = breathe

16. Tobacco and the Respiratory System
Tobacco destroys lung tissue
Carbon Monoxide (CO) in tobacco prevents O2 from getting into blood and deprives body of O2
Smokers cough due to mucus and trapped smoke particles building up in airways

17. Healthy Lung Tissue vs. Diseased Lung Tissue

18. Tobacco and the Respiratory System (continued)
Smoking causes chronic bronchitis, emphysema, cancer, and heart disease
Chronic Bronchitis – swollen bronchi = exercise difficult
Emphysema – loss of elasticity of lungs = breathing difficult
Lung cancer – can spread to other parts of the body
Heart disease – smoking causes high blood pressure = heart has to work harder