Respiration

Cambridge Biology

Let’s watch a video! But first…

• What is “respiration”?• NOT “breathing”!– This is the action of your lungs inhaling and

exhaling air; “ventilation.”• Respiration = the process of breaking down

glucose to use for ENERGY– If glucose were gasoline, then respiration would

be the engine running in your car.• (you can’t go anywhere if the engine’s not running!)

One more thing before video:

Aerobic Respiration

• Using O2 to break down glucose

• “with air” ~ “with oxygen”

Anaerobic Respiration

• NOT using O2

• “without air”

Aerobic Respiration

• Using O2 to break down Glucose to release Energy for cells.

• Glucose + Oxygen Carbon Dioxide + Water + Energy

• C6H12O6 + 6O2 6CO2 + 6H20 + Energy

But where did the Glucose come from?

• You ate it! • Food breaks down into glucose molecules in

the stomach (Digestion).• These glucose molecules enter your blood in

the small intestine (Absorption).• Blood carries the glucose molecules to

individual cells (Circulation).

But where did the Oxygen come from?

• You inhaled it (breathing).• In your lungs, your blood takes in O2 and lets

out CO2. • This is called Gas Exchange.– (you’re exchanging one gas for another)

• You need LOTS of surface area to exchange gasses quickly enough.– Lungs have about 70 square meters of S.A.• (about the size of a tennis court!)

How do you get so much Surface Area in the Lungs?

• Alveoli: very tiny sacs about 0.25 mm across• Alveoli are where Gas Exchange occurs– Gas can only exchange through a small distance– Blood capillary is right next to alveolus– Gas moves through capillary wall and alveolus wall• Distance of 0.001 mm

Alveolar Gas Exchange

Alveolar Gas Exchange

Alveolar Gas Exchange

Alveolar Gas Exchange

Pathway of Inhaled Air

• Mouth/nose• Trachea• R + L Bronchi• Bronchioles• Alveoli

Pathway of Oxygen• Alveoli• Pulmonary (Lung) Capillaries• Pulmonary Vein– The blood in this Vein is Oxygenated (!!)– It is moving AWAY from the Lungs, but TOWARD the

Heart.• Heart Aorta Arteries Arterioles

Capillaries Body Cells• Respiration (conversion to Energy) happens in

the Cell– Now the Cell has plenty of Energy!

Pathway of Oxygen

Pathway of Oxygen

Pathway of Oxygen

Question Time!• Where does the blood in Pulmonary Vein come

from? (Hint: it is Oxygenated)– The Lungs• Where is it going?– The Heart• Where does the blood in the Pulmonary Artery

come from? (Hint: it is Deoxygenated)– The Heart • Where is it going?– The Lung

Oxygen Content of Air

Inspired Air Expired Air

Oxygen 21.00 % 16.00 %

Carbon Dioxide 00.04 % 04.00 %

Nitrogen 78.00 % 78.00 %

Moisture Content Variable High

Temperature Variable High

How do we Breathe?

• Ventilation:– Moving fresh air into lungs– Moving “used” air out of lungs

• Ventilation happens because of changes in pressure that our body creates by contracting and relaxing muscles:– Diaphragm– Intercostals (“between ribs”)

• Pleural membranes keep everything airtight.

Pleural Cavity and Breathing Muscles

Lungs & Diaphragm

Inhalation

• Diaphragm contracts– It moves DOWN because of its unique shape

• Intercostal muscles contract– Making the ribs move UP

• Volume increases inside pleural cavity.• Pressure decreases; creates a vacuum!• Air from outside flows into the Lungs.

Diaphragm

Inspiration

Inspiration

Exhalation

• Diaphragm relaxes– Now it moves back UP

• Intercostals also relax– Ribs can move back DOWN

• Volume DECREASES• Pressure INCREASES – like a full balloon!• Air moves back out of the Lungs.

Inspiration / Expiration

Air Pressure in Model Lung

How do Other Animals Breathe?• Diffusion:

– Small animals with no ventilation structure• Gills:

– Fish• Lungs:

– Mammals– Birds– Herpetiles (Reptiles + Amphibians)

• Skin:– Amphibians

• Tracheae:– Insects

Diffusion

• O2 and CO2 diffuse in and out of the organism without a specialized organ

• Small size• Large surface area

Gills• Structures on fish that allow gas exchange

with water.• Fish “pump” water over and through gills.

Gills in Respiration

Gills in Respiration

Lungs

• Allow gas exchange with air.• Bird lungs are structured to allow maximum

gas exchange– Air moves through the lungs, not in-and-out like in

mammals

Bird Respiratory System

Bird Respiration

Lungs + Skin

Tracheae

• Network of branching tubes in insects.• Gas exchange occurs directly between

tracheae and respiring cells.– No blood involved!

• Insects breathe in and out through spiracles.

Insect Anatomy

Insect Tracheae

Respiration WITHOUT Oxygen

• “Anaerobic Respiration”• Many organisms respire anaerobically.– Even humans! (sometimes)

• But Aerobic Respiration is more efficient– It yields about 19 times as much energy from one

glucose molecule as Anaer. Resp.

Anaerobic Respiration in Yeast

• Yeast is a single-celled fungus.• Breaks down Glucose into Ethanol and CO2

• Can be used to make alcoholic drinks and bread– Ethanol = alcohol– CO2 bubbles = bread rises

Yeast: Anaerobic Respiration

Anaerobic Respiration in Humans

• Only when our muscles run out of O2

– During strenuous exercise

• We break down glucose into lactic acid to release useable energy.• Lactic acid is toxic!

• So, we can’t do this very long.

How do your Lungs stay Clean?

• The air we inhale contains dust and bacteria.• Lung passages are lined with goblet cells and

cilia, which keep unwanted particles from getting to the alveoli.

Goblet Cells + Cilia

• Goblet cells secrete mucus that traps dust and bacteria.

• Cilia are tiny hairs that sweep the mucus up toward the back of your throat.

• Then you swallow the mucus, along with everything else!– Bacteria die in your stomach’s acid and enzymes.

Goblet Cells and Cilia

Cigarette Smoke: Tar

• Damages DNA in lung cells• This can result in lung cancer– Lung cells divide uncontrollably into a mass called

a tumor.

• If Tar (or other harmful chemicals) get into the blood, they can be carried to other parts of the body and cause other types of cancer.

Cigarette Smoke: Tar

• Tar can paralyze or destroy Cilia– Now they can’t sweep mucus out of the bronchial

tubes!• Tar makes Goblet Cells excrete more mucus– Mucus slides down into lungs, creating a breeding

ground for bacteria• Excessive coughing damages lining of tubes– Bronchitis: inflammation of bronchi

• Damage to alveolar walls hinders gas exchange– Emphysema: difficulty getting enough O2

Cigarette Smoke

• Also contains Carbon Monoxide (CO)• CO binds to hemoglobin in blood (just like O2)– But it never comes off!– So that means less places in the blood for O2

• Smokers often run short of O2 during energetic activity.

Air Pollution: Particles

• Coarse– 1-10 μm across– Filtered out in airways and bronchial tubes

• Fine– 0.1 to 1 μm across– Not filtered out; can deposit in alveoli

• Ultrafine– 0 to 0.1 μm across– Can penetrate cell walls, enter bloodstream, and

travel to your brain!

Particles

Air Pollution: Sulfur Dioxide

• Gas produced from burning fossil fuels– (industry + automobiles)

• Mixes with water and becomes sulfuric acid (acid rain):– SO2 + H2O H2SO4

• SO2 turns to acid when enters your lungs and can damage the lining and alveoli.

So… what should you do to protect your Lungs?

• Don’t smoke!• Try not to breathe polluted air.