Gas Exchange/Respiration

Gas Exchange =Exchange CO 2 for O 2 =Need Respiratory Surface –Needs to be thin for diffusion –Needs to be moist for diffusion –Needs to be in contact with gases

Gas Exchange/Protists CO 2 O2O2 Respiratory surface is the cell membrane What drives the diffusion?

Gas Exchange/Hydra Diffusion through cell membranes (respiratory surface) O2O2 CO 2

Gas Exchange/Worm Worms live in moist soil Oxygen from air goes into soil Thin, mucus-coated, skin is their respiratory surface (Gas exchange across skin) If skin dries, they suffocate (Worms can also drown in water- Low O 2 levels in water compared to air!) Oxygen in Air CO 2

But how do the gases get transported to the center of the worm?

Need a transport system Need vessels Need blood with an oxygen-carrying molecule, a respiratory pigment (ex. Hemoglobin) 100ml of water can carry 0.2ml of O 2 100ml of blood can carry 20.0ml of O 2

Gas Exchange/Grasshopper Spiracles= 5 pairs of openings Allow O 2 in and CO 2 out

Spiracle opening Tracheal Tubes

Gas Exchange/Grasshopper Tracheal tubes branch through body They end with a moist, thin membrane that butts up against body cells (respiratory surface) Body movements allow for air to come in and out of tracheal system No Hemoglobin in blood and blood not used for gas transport

Gas Exchange/Aquatic Gills –layers of tissue rich in blood –Large surface area –O 2 gas is dissolved in H 2 O –H 2 0 with O 2 gas washes over gills –Exchange gases –Need constant flow of water over gills or they suffocate –Gills covered by operculum flap

Gas Exchange/Humans Respiratory Surface= Lungs

Lungs Bronchi part of respiratory system but not part of lung

Air Inhaled (Breath In): –79% Nitrogen Gas –20.9% Oxygen –0.04% CO 2 –water Exhaled (Breath out): –79% Nitrogen Gas –16.3% Oxygen (CPR) –4.5% CO 2 –water

Route of Air 1.Nose (Nasal passages) Hair for filtration Mucus to moisten air Blood vessels to warm air Don’t get this with mouth breathing 2.Pharynx 3.Larynx (Voice Box with vocal cords made of cartilage) Tyler Vid

Route of Air 4. Trachea (Windpipe) –Get open by rings of cartilage –Lined with a ciliated mucus membrane –Coughing reflex Tobacco smoke paralyzes cilia (1 cigarette=20min of paralysis) Also increase mucus production

Route of air 5. Bronchi –Ringed –2 –ciliated

Route of air 6. Bronchial Tubes 7. Bronchioles –No rings –Tiny tubes –Open into the… 8. Alveoli

Lung Volume Tidal Volume=500ml of air in and out during rest (3500ml- exercise ) 12 breaths/min(6L/min)Rest 40 breaths/min(42L/min)Exercise Functional Residual Capacity=always left with 2300ml air after breathing out

Alveoli Like cluster of grapes 300 million alveoli 70 sq meter surface area Walls of air sacs are one cell thick Site of gas exchange

Problems Emphysema –Destruction of alveoli walls –Scar tissue from macrophage attack –Reduced breathing ability Asthma –Allergic reaction in bronchioles with their subsequent closing –Treat with Epinephrine mist Lung Cancer Pneumonia –Fluid in alveoli Tuberculosis –Immune attack leaves scars that thicken alveoli and affect diffusion Bronchitis –Inflammation of bronchial tubes

Process of Inhalation (Active) 1.Rib muscles pull ribs up and out 2.Diaphragm muscle pulled down 3.Now low air pressure in chest 4.Air sucked into chest 5.Alveoli expand

Process of Exhalation (Passive) Diaphragm relaxes and goes back up Rib muscles relax Ribs go down and in Increase pressure in chest Air squeezed out of lungs

Lung Model

Air pressure and altitude High altitudes have lower air pressure than at sea level High altitudes have lower concentration of O 2 compared to sea level

Planes are pressurized and pump oxygen into the plane

Air pressure and altitude What happens to our blood when we go suddenly from high pressure to low pressure environments?

Nitrogen gas in blood bubbles out The “Bends”

The Bends

Andes Mountains in Peru Have a high red blood cell count More red bone marrow More developed lungs

Breathing Regulation Involuntary Have Chemoreceptors in walls of arteries that detect CO 2 levels High CO 2 levels in blood detected and send message to respiratory center of brain (Medulla) Medulla send message to diaphragm and rib muscles to increase rate and depth of breath Low pH of blood also stimulates medulla

External vs. Internal Respiration External –Gas exchange in alveoli with capillaries Internal –Gas exchange in capillaries with body cells

Oxygen transport In lungs oxygen combines with Hemoglobin to form oxyhemoglobin

Oxygen Transport Oxygen released in locations of low O 2 concentration Carbon monoxide has greater binding ability to hemoglobin than oxygen

Carbon Dioxide Transport 70% as Bicarbonate in plasma CO 2 + H 2 0 H 2 CO 3 H + + HCO 3 -

Carbon Dioxide Transport 20% as carbaminohemoglobin CO 2 + Hb HbCO 2 (HbCO is carboxyhemoglobin)

Carbon Dioxide Transport 10% as free CO 2 in plasma

Carbon Dioxide Transport

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