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Passage of air from outside the body to the lungs and gas exchange

3 Main Functions:

• supply oxygen to the blood

• remove carbon dioxide from the blood

• regulate blood pH

Breathing vs Respiration

-getting air to the lungs 3 Types: (movement of gases)

1. External O2/CO2 exchange in lungs

2. Internal gas exchange at the tissue level

3. Cellular utilizing O2 for energy

Conductive Zone vs Respiratory Zone

Nasal cavity

Mouth

Pharynx

Larynx

Trachea

Bronchii

• warm

• humidfy

• filter

-hairs

-mucous

Bronchioles

Terminal bronchiole

Respiratory bronchiole

Alveolar sac

• gas exchange

• each sac covered by network of capillaries short diffusion

- grape like structure

-HUGE surface area

?

Pulmonary artery

Pulmonary vein

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“movement of air from outside the body to the lungs”

Diaphragm is the principle muscle in controlling breathing upon stimulation, will contract

Air outside Air inside

PRESSURE CHANGES

High pressure Low pressure

So how do we breath?

Diaphragm contracts (moves down)

Chest increases in size air space increases

Decrease in pressure in the lungs

.: Pressure outside body > inside body

Air rushes in

INHALATION (active process)

EXHALATION (passive/active)

Diaphragm relaxes

Chest decreases in size air space decreases

Increase in pressure in the lungs

.: Pressure outside body < inside body

Air rushes out Quiet breathing

Forced breathing

Ventilation (VE )

“The volume of air that is moved in 1 minute.”

VE (L/min)= VT (L) x f (breaths/min)

Air in and out

Tidal Volume

• volume of air in each breath

• rest = 0.5 L/min

max = 3-4 L/min

Respiratory frequency

• number of breaths per minute

• rest = 12 breaths/min

max = 30-40 breaths/min

Ventilation at maximum?

Graphically????

What controls ventilation?

CNS medulla oblongata (contraction/relaxation of muscles)

-O2 vs CO2 needs

Bicarbonate (HCO3)

-blood pH (buffer)

So we’ve got the air to the lungs. . .

Lung Volumes

Static

vs

Dynamic

-volumes determined by structure of lung

-volumes dependent on movement of air

TLC = VC + RV

Total Lung Capacity

• max air lungs hold

Vital Capacity

• max air exhaled following max inhale

Residual Volume

• remaining air in lungs after max exhale

Now what happens with the air in the lungs?

Gas Exchange (Alveoli)

• Respiration

• Lungs O2 blood CO2 Lungs

DIFFUSION!!

* Read pages 123-124 *

• Describe partial pressures

• Explain the 3 factors that contribute to gas exchange

•Diffusion pathway

•Barrier thickness

•Surface area

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O2 Transport• 2% dissolved in plasma

• VAST majority binds to hemoglobin (1.34 ml of O2 per molecule)

• OXYHAEMOGLOBIN DISSOCIATION CURVE

-Percent saturation of hemoglobin (SbO2%)

-Pressure of oxygen in the blood (PO2)

What does this graph illustrate?

The lower the PO2, the less O2 will bind to hemoglobin

Carbon Dioxide Transport

Read page 125: Carbon Dioxide Transport and Ventilation and the Regulation of Blood pH

Make your own brief notes on:

a) The 3 ways in which CO2 is transported in the blood

b) The role pH plays in human ventilation