Respiratory System

Gas exchange (oxygen & carbon dioxide)

Nose/Nasal Cavity

• Air is warmed, filtered and moisturized

• Smell receptors are located at the top of the nasal cavity

• Sinuses are mucus-lined cavities in the skull bones that communicate with the nasal cavity

Pharynx

• Air then passes to your throat or pharynx which is a common opening for digestion and respiration

Larynx

• Air then passes into your larynx

• You might have called this your “Adam’s apple” or “voice box”

• Made of cartilage

• Epiglottis is a triangular flap of the larynx that closes the larynx when you swallow food

Larynx

• Also houses your vocal cords that vibrate as air moves past them

Trachea

• Windpipe

• Supported by cartilaginous rings

• Lined with cilia to keep debris out of the lower respiratory structures

Bronchi & Bronchioles

• The trachea branches into two large branches called bronchi

• These bronchi enter the lungs and subsequently branch into smaller and smaller branch,

• Until they become the smallest bronchi, termed bronchioles

Bronchi

• Large bronchi have cartilage in their walls for support

• Small bronchioles do not have cartilage in their walls

Lungs

• The two lungs are elastic sacs filled with the bronchi, bronchioles, and blood vessels.

• Lungs also have millions of tiny air sacs called alveoli.

Alveoli

• Alveoli have a very thin wall

• Alveoli are surrounded by numerous blood capillaries

• This is the site of gas (oxygen & carbon dioxide) exchange

Respiratory Physiology

• Ventilation, or breathing, has two components:

• Inhalation = Inspiration

• Exhalation = Expiration

Inhalation

• This brings air into the airways and lungs

• The diaphragm contracts and the ribcage moves up and out

• The chest cavity enlarges, as do the lungs

• This lowers the air pressure in the lungs so that air moves from high to low pressure into the lungs

Exhalation

• Air moves out of the lungs and airways• The diaphragm raises and the ribcage

moves in and down• This decreases the size of the chest cavity

and the lungs, thus increasing the pressure in the airways

• Air naturally moves from an area of high pressure to an area of lower pressure, outside to the atmosphere.

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Diffusion

• Diffusion of oxygen and carbon dioxide occurs between the alveoli and the pulmonary capillaries

• Oxygen moves from alveoli to capillaries

• Carbon dioxide moves from capillaries to alveoli to be exhaled

Gas transport in body

• Oxygen is carried by hemoglobin in the RBCs

Respiratory Control Centers

• Brainstem

Respiratory Pathology

• Carbon Monoxide Poisoning– From combustible fuel– Carbon monoxide binds to hemoglobin much

faster than does oxygen– Death is due to lack of oxygen

Respiratory Pathology

• Laryngitis is inflammation of larynx

• Bronchitis is inflammation of bronchi – most chronic cases are due to smoking

• Emphysema involves the alveoli– Alveoli become nonfunctional and are

eventually destroyed– Irreversible change in alveoli– 80% of the cases are due to smoking

Respiratory Pathology

• Cancer – 83% of cases are due to smoking

• See normal & abnormal lungs:

Respiratory Physiology

• Asthma– Usually due to allergies– Smooth muscle in smaller airways go into a

spasm, thus closing smaller airways– Wheezing sound while breathing– Life-threatening condition– Treatment includes drugs that open airways

Respiratory Pathology

• Pneumonia– Fluid-filled alveoli– Alveoli normally are filled with air– Mostly due to infection