HUMAN RESPIRATORY STRUCTURES• Nose/mouth: filters,

moistens, warms

• Pharynx• Larynx• Trachea – mucus, cilia• 2 lungs– 2 bronchi – Bronchioles– Alveoli

• Site of exchange• Thin walls, lots-o-capillaries• Large # S.A.

• A thin layer of mucus is produced on the lining of the tubes of the respiratory systemThis thin layer traps

particles of dust or smoke

These tubes are lined with CILIA that sweep away particles

• These tubes are made of cartilage and are surrounded by smooth muscle

CILIA

ALVEOLI• Small structures at the end of each bronchiole• Occur in clusters• Place where gas exchange occurs– Oxygen into blood, carbon dioxide into lung– Each is surrounded by capillaries

• 300 million alveoli are in each healthy lung– Provides a large surface area for gas exchange

• Oxygen dissolves in the moisture – It can then diffuse into the capillaries– CO2 diffuses in the opposite direction– Coated in surfactant

HEMOGLOBIN binds with so much oxygen that it increases the oxygen carrying- capacity of the

blood more than 60 times

RECAP

• Name the structures of the respiratory system• Where does gas exchange occur?• http://www.airinfonow.org/html/lungattack/

lungplay.htm• Next: What is the difference between

respiration and breathing?

Breathing• Breathing is the movement of air

into and out of the lungs• Lungs sit in two sacs = pleural

membranes• At the bottom of the chest cavity is

the diaphragm• Between ribs are intercostal

muscles

Force that drives breathing is air pressure– No muscles are directly

connected to the lungs

VolumeIf you have a container of gas, how will the pressure change if you make the

container smaller?

Make it larger?

Inhaling• When you inhale, the diaphragm contracts and expands the volume of the chest cavity

• Because the chest cavity is tightly sealed, this creates a partial vacuum inside the cavity

• Air rushes into the lungs as a result

Exhaling• Exhaling is a passive event• Diaphragm relaxes and lungs return to normal

size, placing pressure on the lungs– Air rushes out of the lungs

78% Nitrogen21% Oxygen

0.03% Carbon Dioxide

Partial Pressure: “Concentration of Gas”1) Volume: If you have a container of gas, how will

the pressure change if you make the container smaller? Make it larger? – Bulk Flow ~ Breathing

2) Total atmospheric pressure = 760mmHg– Oxygen is 21% of this, therefore = 159mmHg

• O2 air > O2 alveoli > O2 blood > O2 cells• 159mmHg 100mmHg 40mmHg 40mmHg

(exchange to 100mmHg)

– Diffusion

RECAP

• What causes breathing?• What muscles are involved with breathing?– Are they attached to the lungs?

• What controls your breathing?

Breathing Control• Breathing is voluntary to a point, then it

becomes involuntary• Nervous system will take over– Sensory receptors in major blood vessels detect

amount of carbon dioxide in blood • b/c pH will change

– Message goes to medulla oblongata in the brain

– If the level of carbon dioxide gets too high, the diaphragm will contract

Hb + 4O2 “HbO”

Oxygen in Blood• 98.5% is bound to Hb• 1.5% dissolved in plasmaCarbon Dioxide in Blood• 60% dissolves in H2O (as H2CO3)

• 30% binds to Hb• 10% dissolves in plasma

Carbon Monoxide• Hb affinity 200 X’s stronger• irreversible

REGULATION of pH

• Normal plasma pH = 7.4 (Range: 7.35 - 7.45) CO2 + H20 H2CO3 H+ + HCO3

-

Waste product Always Converted to Waste product Bufferof metabolism Present Products on of metabolism

LEFT by Carbonic Anhydrase

____________________________________________________________________________________________________ Expelled by Adjusted in kidney Lung Or Rxts w/Bicarb. R. Or Rxts w/H+ on L.

The exchange• http://www.airinfonow.org/html/lungattack/

lungplay.htm

• What can go wrong?• http://www.hisdbenefits.org/hisd/living/animations/• List of animations for respiratory disorders• http://in.truveo.com/Human-Atlas-Emphysema/id/

1459776665• Similar animations, better quality

Breathing Quiz: Is it inhalation or exhalation?

• Diaphragm Contracts• Intercostal Muscles

relax• Chest Cavity increases

in size• Pressure in cavity

decreases• Air rushes out of

lungs

• Diaphragm relaxes• Intercostal muscles

contract• Volume of chest

cavity decreased• Pressure inside

greater• Air rushes in and

inflates lungs