Respiratory System
It’s a gas!
Respiratory System
Pathway of Air:
• Nose/mouth
• Nasal/oral
cavities
• Pharynx
• *Epiglottis
• Larynx
• Trachea
• Bronchi
• Bronchioles
• Alveoli
Oral & Nasal Cavities & Pharynx
• Warm & moisten air to
protect delicate lung
tissue.
• Sticky mucous lining &
mucous-covered hairs in
nasal cavity filter
particles from air.
Larynx &
Voice
• Sound produced as 2 ligaments (vocal cords) vibrate when air
passes through them.
• Pitch varies with tension of vocal cords – more tension =
higher pitch
• Volume depends on amount of air forced past them – more
air = greater volume.
• Laryngitis – inflammation of vocal cords due to overuse.
Lungs
• Right is larger (3 lobes) than
left (2 lobes).
• In thoracic cavity, lined w/
pleura (membranes that
reduce friction.
• LARGE surface area.
Trachea/bronchi
• Made of rings of cartilage
(keeps airway open).
• Lined with mucous membranes
(trap particles) and cilia
(sweep particles up and out
of airway).
• Epiglottis closes trachea when
swallowing.
• Bronchi branch into bronchioles
Airway
Alveoli & Capillaries
Bronchioles terminate in dead-end sacs –
alveoli – surrounded by a net of capillaries.
Gas Exchange
• External Respiration Exchange of gases between
atmosphere and blood by
diffusion.
• Internal Respiration –
Exchange of gases between
blood and cells by diffusion.
• Diffusion happens when
there is a concentration
gradient (difference) in a
fluid (gas or liquid).
• *The Respiratory System
• Respiratory System
97% of oxygen
transported on
hemoglobin in
RBCs.
67% of CO2
reacts w/ water
to form carbonic
acid,
disassociates
into bicarbonate
ions (HCO3-)
Oxygen & CO2 Transport
In Blood
Mechanism of
Breathing
• Diaphragm
• Mechanism of Breathing
• Mechanics of Breathing 2
Boyle’s Law – pressure
exerted by a gas varies
inversely with the
volume of the gas.
Inspiration & Expiration
Respiratory System Review - Kahn Academy
Regulation of
Breathing
Brain monitors the
concentration of CO2 in the
blood. Why not O2?
A: O2 is carried by
hemoglobin inside RBCs,
while CO2 is mostly carried
in the plasma.
Disorders
• Asthma –
inflammation of
the lining of
bronchioles
causes reduced
air flow.
• Emphysema –
alveoli lose
elasticity and
rupture, reducing
surface area and
lung capacity.
Smoking
• Tar and particles clog up lungs & paralyze cilia
so they can’t clear debris.
• If a smoker quits, damage may be reversible.