Respiratory System

Parts of the Respiratory System

Nasal Cavity • The beginning.• Oxygen first enters your

body and Carbon Dioxide leaves

• Air enters the nose and is filtered by tiny hairs called cilia, it is moistened by the mucus that lines the nasal passage.

• The cilia and the mucus filter dust and pathogens from the air.

The Mouth

• Air can also get into your body through your mouth or the oral cavity but air is not filtered as much when it enters in through your mouth

Pharynx• Pharynx or throat • This is where the air

passes from your nose to your bronchi tubes and lungs

• Your pharynx (throat) gathers air after it passes through your nose and then the air is passed down to your trachea (windpipe).

Trachea• Long structure made up

of soft tissue that connects the mouth and nose to the lungs

• The trachea is held open by partial (or incomplete) rings of cartilage

• Without these rings your trachea might close off and air would not be able to get to and from your lungs.

Bronchi & Bronchiole• Your trachea splits up

into two bronchi tubes.• Each branch going to a

lung• The bronchi tubes are

like tree branches that get smaller and smaller, till they become the bronchiole

• At the end of the bronchiole are tiny air sacs called Alveoli

Alveoli• There are 300 – 600

million alveoli in the lungs.

• They are tiny air sacs that are highly folded and fill up with air/oxygen when you breathe in

• Your alveoli are surrounded by many tiny blood vessels called capillaries

Respiratory System• Respiratory system is the system that helps you

breathe in and out• Oxygen (O2) can be pumped through your body

• Carbon dioxide (CO2) can be removed from the blood stream.

Lungs• An internal structure to avoid water loss by

evaporation• Flow of air: Nose /mouth – Larynx – Trachea –

Bronchi – Bronchiole – Alveoli – Closed Blood Vessels

• System of tubes is restricted to one body area (the Thoracic Cavity)

• Gas exchange surface is the wall of the alveolar sac because it is wet, thin and highly folded.

Respiratory Surfaces

• Requirements of a successful respiratory surface:

• Large surface area• Very thin (one-cell

thick)• Moist or wet

surface

Gas Exchange• The walls of your alveoli (and capillaries) are so

thin that the oxygen or carbon dioxide can pass through them, traveling right into, or out of your blood stream

Exchange of Respiratory Gases

• Diffusion of O2 and CO2 is driven by pressure gradient (gases move from areas of higher partial pressure to lower partial pressure.)• Direction of O2: lungs to cells

• Direction of CO2: cells to lungs

• Primary Transport forms• Oxygen: as O2 bound to hemoglobin

• Carbon Dioxide: As HCO3- (bicarbonate in plasma)

Transport of Carbon Dioxide

• CO2 is produced at the tissue level• Red Blood Cells convert CO2 to HCO3-

• HCO3- dissolved travels to lungs

• Tissue-Level reactions are reversed within the lung• CO2 is produced, then exhaled

Negative Pressure Breathing

INHALATIONDiaphragm contracts

(moves down)

EXHALATIONDiaphragm relaxes

(moves up)

Ventilation: rates, volumes, and changes with exercise

Rest• Ventilation rate• 12 breaths per minute

• Tidal Volume • 0.5 L

• Total Ventilation• 6.0 L per minute of air

Exercise• Ventilation rate• 48 breaths per minute

• Tidal Volume • 4.0 L

• Total Ventilation• 192 L per minute of air