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Respiratory System
 Every animal needs a system to take in oxygen
from the environment
 Why is oxygen needed?
 Oxygen is required for cell respiration
 Oxygen and nutrients are combined to release energy
 Remember cell respiration?
Reactants:
Glucose + O2
Products:
CO2 + H2O + Energy
How Does Oxygen Get Into Cells?
 O2 and CO2 enter and leave the cells
(gas exchange) by diffusion
 Different animals have different systems
 Some examples:
Organism:
one-celled
earthworm
insects
fish
mammals
Gas exchange between:
cell membrane and outside cell
skin and capillaries
trachea and body cells
gill filaments and capillaries
air sacs (alveoli) and capillaries
Human Respiratory System
Our own pathway, in order:
Mouth/Nasal Cavity
Pharynx
Larynx
Trachea
Bronchi
Bronchioles
Alveoli (tiny air sacs)
Respiratory System Tissues
Mouth/nasal cavity:
 Air enters the body
 Nasal hairs and mucus warm and clean the air
Pharynx and larynx:
 Pharynx is the back of your mouth (say aaaaah)
 Larynx is lower – this is your throat (voice box)
Trachea:
 Air passageway leading to lungs
 Lined with C-shaped rings of cartilage
Bronchi, bronchioles, alveoli:
 Air pathway into each lung branches down and ends in millions
of microscopic air sacs (alveoli)
 An adult human lung has several hundred million alveoli,
each one surrounded by capillaries of your circulatory system
How Air Moves in and Out
 Inhaling: getting oxygen in
 Exhaling: getting carbon dioxide out
 Air is forced into and out of your lungs.
But how?
 When you squeeze a plastic bottle, what does the air do?
Which direction does it move?
 When you let the plastic bottle spring back into shape,
what does the air do? Which direction does it move now?
 This is because of an important law of how gases work:
Boyle’s Law
Boyle’s Law
 Robert Boyle discovered that if:
 volume decreases, pressure increases
 volume increases, pressure decreases
 Pressure and volume are inversely related:
 If one increases, the other decreases
 This is called an inverse relationship
 Gases always move from:
 areas of higher pressure to areas of lower pressure
 Boyle’s Law explains how air is forced into and out of
your lungs !
1.
2.
3.
4.
5.
6.
Diaphragm & rib muscles contract
Rib cage expands
Volume in lungs increases
Pressure in lungs decreases
Air pressure outside is greater
Air rushes into lungs
1.
2.
3.
4.
5.
6.
Can you fill in
steps 1- 6 for
exhaling?
How Does O2 Get Into the Blood?
A
i
To
heart
r
From
heart
A
i
r
Alveolus
(air sac)
O2
CO2
Pulmonary capillary
How Does O2 Get Into the Blood?
 Blood needs a special chemical to “carry” the oxygen:
 Hemoglobin
 oxygen “sticks to” or binds with hemoglobin in red blood cells
 hemoglobin contains iron which binds with oxygen
 Can you follow the oxygen?
 In the lungs:
 Oxygen diffuses from the air in the alveoli into capillaries
 Oxygen passes into red blood cells and binds with hemoglobin
 In the blood, oxygen remains bound to hemoglobin until it reaches
your cells
 At your cells:
 CO2 diffuses from cells into capillaries
 Hemoglobin releases oxygen and binds with CO2
 Oxygen diffuses from red blood cells into your body cells
Respiratory System Problems
 Dirt, pollen, dust, and smoke damage the system and
interrupt the flow of oxygen to your cells
 Respiratory System Defenses:
 White blood cells
 Surround, consume, and digest bacteria
 Cannot consume asbestos
 Cilia
 Tiny hairs lining trachea
 Hairs “wave” upward to expel foreign particles
 Cigarette smoke paralyzes cilia
 Defense against choking:
 The epiglottis
 Flap of tissue that closes trachea when you swallow
 Makes certain food travels through esophagus instead
Respiratory Disorders
 Asthma
 Bronchial tubes become constricted
 Symptoms: shortness of breath, wheezing, coughing
 Causes: environmental factors: allergies, stress, certain foods
 Emphysema
 Alveoli lose ability to expand and contract when breathing
 Alveoli stretch and rupture; scar tissue develops
 Less oxygen to cells + buildup of CO2
 Lung cancer
 Caused by “tars” and other carcinogens in cigarette smoke
 Cancerous tumors destroy lung tissue
 Effects of smoking:
 Short term: carbon monoxide (CO) replaces oxygen in blood
 Long term: heart disease, emphysema, lung cancer
 Without smoking, these disorders are a minor problem in society
Review Questions
1.
Which term does not belong with the others and why not?





2.
gills, alveoli, diaphragm, trachea
asthma, respiration, emphysema, lung cancer
gills, lungs, hemoglobin
lung cancer, asthma, emphysema
alveoli, diaphragm, trachea
Explain what happens to your diaphragm and ribcage when you
inhale and exhale.
3. What are the reactants and products of cell respiration?
4. Use Boyle’s Law to explain inhaling, exhaling, and why the
Heimlich Maneuver works.
5. Describe how gas exchange occurs in the lungs.
6. Why is your trachea lined with cartilage?
7. What is the function of your nasal cavity?
8. What is your epiglottis and what is it for?
9. Why do you have cilia inside your trachea?
10. Which respiratory condition can be the result of allergies?