Respiration & Gas Exhange
Respiration
• Two processes:
1. Release of energy from breakdown of food
molecules.
All living cells use oxygen to release energy.
This process produces waste carbon dioxide.
2.The exchange of gases between the atmosphere
and body’s cells.
We will focus on the exchange of gases.
So what are the functions of the respiratory
system?
•
•
•
•
Bring oxygen into the body
Remove carbon dioxide (CO2) from the body
Clean, moisten and warm air
Enable speech
…………………………………………………………………………………………………………………
Gas exchange supplies oxygen for cellular
respiration and removes CO2
 Gas exchange – uptake of O2 from environment
and discharge of CO2
 Mitochondria need O2 to produce more ATP, CO2
is the by-product
C6H12O6 + 6O2  6CO2 + 6H2O + 36 ATP
DIFFUSION
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
Respiratory surfaces and gas exchange
• Respiratory surface
• Simple invertebrates
– Size of organism
– Habitat
– Metabolic demands
– Sponges, cnidarians,
flatworms
– diffusion
• Unicellular organisms
– Entire surface area for
diffusion
Human Respiratory System
Our own pathway, in order:
Mouth/Nasal Cavity
Pharynx
Larynx
Trachea
Bronchi
Bronchioles
Alveoli (tiny air sacs)
Mammalian respiration
Organs of the respiratory system
• Nose and sinuses
• Q. List the advantages of breathing in from the
nose? (page 170 )
1. Cleans dust and bacteria in the air by hair
and mucus,
2. warms and moistens the air
3. Detect harmful chemicals by sensory cells
Organs of the respiratory system
• Pharynx – short tube
leading to larynx
• Epiglottis –
cartilaginous flap
covering opening to
larynx (glottis)
• Larynx – voicebox
containing vocal cords
Hyoid Bone
Epiglottis
Thyrohyoid
Membrane
Thyroid
Cartilage
Cricothyroid
Ligament
Cricothyroid
Muscles
Cricothyroid
Cartilage
Trachea
Organs of the respiratory system
mouth
trachea
bronchi
alveoli
• Trachea – tubes leading
into lungs.
• These branch into
primary bronchi then
into bronchioles
sinuses
pharynx
bronchiole
larynx
trachea
bronchial
tube
alveoli
Organs of the respiratory system
• Bronchioles end in sac
like structures called
Alveoli
• Gas exchange occurs
between the alveoli and
capillaries
Primary
bronchus
Secondary
bronchus
Tertiary
bronchus
Bronchiole
Terminal
bronchiole
Alveoli
Bronchial Tubes
Gas Exchange
• Capillaries surround the alveoli
• Gases are exchanged between the thin walls of the
alveoli and capillaries
How Does O2 Get Into the Blood?
A
i
From
heart
To
heart
r
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
How Air Moves in and Out
• Inhaling: getting air with oxygen in
• Exhaling: getting air with 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. Diaphragm & rib muscles (external
intercostal muscles) contract
2. Rib cage expands
3. Volume in lungs increases
4. Pressure in lungs decreases
5. Air pressure outside is greater
6. Air rushes into lungs
1.
2.
3.
4.
5.
6.
Can you fill in steps
1- 6 for exhaling?
Lung ventilation through breathing
• Negative pressure breathing in reptiles and mammals
• Rib muscles and diaphragm change lung volume and pressure
Lung volumes
• Factors
•
•
•
•
•
•
•
Smoking, increase due to CO
Anxiety, increase due to the effect of adrenaline
•
Drugs, some may cause an increase
Environmental factors, increased by high CO2
concentration in the atmosphere
Altitude, increased by low O2 conc. In the
•
atmosphere
Weight, can increase because fat makes lung
ventilation harder (i.e tidal volume falls),
Tidal volume
– Volume of air inhaled and
exhaled with each breath
Vital capacity
– Maximum volume inhaled and
exhaled during forced breathing
Residual volume
– Air left in alveoli after forced
exhalation
Control centers
in the brain
regulate
breathing
Gases diffuse
down pressure
gradients
concentration and
pressure drives the
movement of gases
into and out of
blood
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.
3.
4.
5.
6.
7.
8.
9.
10.
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.
What are the reactants and products of cell respiration?
Use Boyle’s Law to explain inhaling, exhaling, and why the Heimlich
Maneuver works.
Describe how gas exchange occurs in the lungs.
Why is your trachea lined with cartilage?
What is the function of your nasal cavity?
What is your epiglottis and what is it for?
Why do you have cilia inside your trachea?
Which respiratory condition can be the result of allergies?
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