Respiratory System Lecture Outline
Unicellular organisms – only organisms
without resp. system – gasses exchange
through membrane.
Oxygen in atmosphere: 21% oxygen –
anything below 15% humans can’t survive
Diagram of Resp. Syst.: Mouth\nose – nasal
cavity – pharynx – larynx – trachea – bronchi
– bronchioles – alveoli (gas exchanges here)
Purpose of respiratory system
a. supply cells with oxygen
b. remove carbon dioxide from cells
Upper Resp. Stem: (Nose, Pharynx, Larnyx)
Air enters external nares (nostrils) into nasal
Nasal Conchae bones: increase surface area
by being folded into 3 ridges
Conchae and entire lining of nose covered by
mucus membrane – clean dust and debris
from air.
Three functions of nasal cavity:
a. Clean out dirt and dust (mucus and
nose hairs)
b. Warm the air you breathe (blood
vessels in nasal cavity raise air temp.)
c. Moisten incoming air.
Four pairs of sinuses – drain into nose
 Lightens the skull and acts as a
resonance chamber for sound.
Nasal Cavity – Pharynx – back of mouth;
food and air.
 Pharynx ends at the glottis (opening
to the larynx)
 Glottis is a narrow slit: males 23 mm,
females 17 mm
 Around the rim of the glottis are vocal
chords – vibrations produce sound.
 Epiglottis is a cartilage flap that
covers the glottis when you are
Larynx = voice box
 Aka adam’s apple
 Made of thyroid cartilage (upper part)
and cricoid cartilage (lower part)
Lower respiratory Tract – trachea, bronchi
Trachea: 11 cm long and 2 – 2.5 cm wide.
 Made of alternating bands of cartilage
and membrane
 Rings of cartilage are open at the back
 Esophagus is just behind the trachea
 Trachea is lined with ciliated epithelium
and mucus.
 Trachea divides into 2 primary bronchi
 Bronchi – Bronchioles - Alveolar ducts –
alveolar sacs – alveoli (300,000,000)
 Surface area is the size of a tennis court
Ducts, sacs, and alveoli are made of thin
squamous epithelial tissue (for better gas
Left Lung – superior and inferior lobes
Right lung – superior, middle and inferior
Visceral pleura – membrane covering lungs
Parietal pleura – membrane lining thoracic
Pleural cavity – between the two membranes
and is filled with fluid to reduce friction when
Size and shape of nose, mouth, pharynx, and
sinuses determine sound quality.
Large flat muscle that allows the lungs to
inflate and deflate
Inhale: diaphragm pushes down
Exhale: diaphragm pushes up
Lung capacity: total capacity is 6 Liters, but
we only exchange .6 liters under normal
breathing conditions.
Vital Capacity: max amount of air that can
be moved in and out of resp. system
Hemglobin: red colored protein that is found
in blood that has attachment site for oxygen
Sensory Receptors
Responsible for sending signals to the brain
about oxygen and Carbon Dioxide levels
Carotoid artery in neck
Aorta in heart
More concerned about Carbon Dioxide levels
being too high.
CO2 + O2 -> H2CO3 Carbonic Acid
Changes blood pH which is what receptors
respond to.
Asphyxiation: suffocation from blockage
Heimlich (abdominal thrusts) – procedure to
remove blockage.
Tracheotomy: puncture a hole in the trachea

Alveolar ducts – alveolar sacs – alveoli (300,000,000)