unit 2: the airways the upper airways

Unit 2: The AirwaysThe Upper Airways

RSPT 1207 Cardio Pulmonary Anatomy &

Physiology

The Airways• Respiratory tract : combination of

organs and tissues that have one function – the transfer of gas to be used by the body.

• This process exposes the respiratory tract to many environmental extremes

The Upper Airways• Consists of:

– The nose– Oral cavities– The pharynx– The larynx

The Upper Airways• Function: There are 4 Functions

– Direct respiratory gases to and from the lung– Defense mechanism– Humidify inspired air– Heat inspired air

• Also involved with:– Speech– Eating, drinking– Smell

The Nose• Midline, external

and internal structure

• Upper third is bone and covered by skin

• Lower 2/3 is cartilage

Functions of the Nose• Filters particles prior to entering lower

airways• Humidify and heat inspired air• Provides a location for sensory

receptors used in the sense of smell• Provides resonance for speech

Major Structures of the Nose

Major Structures of the Nose

Major Structures of the Nose

Nasal Cavity• Separated by the septum making it

into a symmetric bilateral structure• Anterior portion formed by the septal

cartilage• Posterior septum formed ethmoid and

vomer bones

Nasal Cavity• External nares – (nostrils) the

openings of the nasal passageway• Internally protected from particles by

Vibrissae (nose hairs)• Immediately behind vibrissae is an

open chamber called the vestibule

Turbinates/Conchae• As incoming gas flow enter posterior to

the vestibule it is separated by the turbinates or conchae

• By having the turbinates, surface area is increased for heat/moisture exchange

Turbinates/Conchae• Lines the nasal cavity

like three walls

• Twisted to allow particles to be filtered and air to be heated and humidified

• Mucous membranes line turbinates, Mucous glands line

Choandae• Lumen – the space (hole) in a vessel,

tube, or intestine

• In the nasal passage this is call the Choandae

• Choanal atresia is a common birth defect found in infants

Paranasal Sinuses• Consists of the: frontal, maxillary,

ethmoid and posterior sphenoid Sinuses

• Openings are along the nasal passage• Paired sinuses contain mucous glands

and membranes• Helps strengthen the skull

Oral Cavity• Simply known as the mouth• Functions:

– Alternate passageway for breathing– Start of the alimentary canal– Contains major speech structures– Facial expressions

Oral Cavity• Anteriorly begins

with lips and mouth• Follows with oral

vestibule and teeth and gums

• Oral cavity begins after the teeth

The Palate• The palate is the roof of the oral cavity• Consists of:• Hard palate – anterior 2/3 of the palate

and is bony• Soft palate – posterior 1/3 and is made

of soft tissue.

The Palate• Protects the nasal passage from food• Aids in swallowing • Hard palate and tongue are used in

speech• Uvula helps protect the airway from

occlusion

The Soft Palate• Made of soft tissue• This allows for food to be passed out

of the oral cavity to the pharynx• Two structures form the soft palate:

– Palatoglossal arch (anterior)– Palato-pharyngeal arch (posterior)

The Uvula• As the arches of the soft palate come

together they form the uvula• Protects the lower airways by being

extremely sensitive to tactile stimulation

• Can cause violent gagging and possibly vomiting

Palatine Tonsils• Lies in palato-glossal arch

• Lympathic tissue that is part of the immune system

The Pharynx• Generally known as the throat

• Divided into three areas:– Nasopharynyx– Oropharynx– Laryngopharynx

Nasopharynx• Located behind the nasal cavities• Contains:

– Adenoids or Pharyngeal tonsils– Eustachian tube:

• Runs between the back of the throat and middle ear

• Equilibrates pressure in the middle ear• Acts like a pop-ff valve to release excess gas

behind eardrum

Oropharynx• Located below soft palate down to

base of tongue• Only portion that can be seen without

exam tools• Contains:

– Lingual tonsils: at base of the tongue, tactile stimulation will cause gagging

Laryngopharynx• Also called the hypopharynx• Located from base of the tongue to

entrance of the esophagus• Contains: Epiglottis

– structure that protects the opening to the lower airways which is the glottis

– Strong but flexible fibro-cartilage flap that comes out of the larynx into the laryngopharynx

Swallowing• The most critical moment is when the food

enters the laryngopharynx.• Any mishap in coordination can lead to the

food being aspirated into the lower airway• There are more than 20 muscles that are

involved in the act of swallowing• The interaction of the tongue, palate and

epiglottis in moving the food from the oral cavity to the oropharynx to the laryngopharynx and the esophagus

Swallowing• Food is broken down and lubricated in

the oral cavity• As one swallows the muscles of the

tongue and mouth move food up and back

• Soft palate protects the nasopharynx • Gravity moves food into oropharynx

Swallowing• When the tongue moves up & forward the epiglottis

moves down and backward• Results in the glottis is covered as the food moves

into esophagus• Once food is in esophagus, the epiglottis moves

back in place to allow gas to enter trachea• http://www.hopkins-gi.org/multimedia/database/intro

_250_Swallow.swf

The Larynx• Located immediately below the pharynx• Formed by:

– Three large external cartilages• Epiglottis• Thyroid cartilage• Cricoid cartilage

– Three pairs of internal cartilages• Arytenoid cartilage• Corniculate cartilage• Cuneiform cartilage

The Larynx

Epiglottis

External Cartilages• All protect the airway• Thyroid cartilage is open in the

posterior but it is solid in the anterior to protect the vocal cords inside them

• Cricoid cartilage is rigid ring and is the only structure that encircles the airway

Internal Cartilages• Form a three sided pyramid of

ligaments and muscles to control the movement of the vocal cords

• Pitch of the voice is controlled by tightening and loosening the cords

• Volume or loudness is controlled by the amount of air forced through the cords

Interior of Larynx• Viewing the glottis from above a

clinician will see the base of the tongue on top

• Below the tongue will be the epiglottis & between these two will stretch the 3 ligaments of the vallecula

• Egan’s page 173, figure 7-35

Interior of Larynx• The base of the glottal

triangle is opposite from the base of the tongue

• Surrounding the true vocal cords are tissue folds that are called the vestibular fold or the false cords

• Vallecula – space betweent the tongue & epiglottis Important landmark in

intubation

Vocal Cords• The vocal cords come together and

separate during quiet breathing so that the glottis is always slightly open.

• A Valsalva maneuver or laryngospasm are the only time the glottis closed completely

• To close the glottis completely, not only requires bringing the vocal cords together but the person tightens all laryngeal muscles at the same time

Valsalva Maneuver• Purpose: When the body requires positive

pressure for expulsion• Examples: urination, defecation, birth,

vomiting, coughing, sneezing• Person must exhale forcefully against a

closed glottis, building pressure in the abdomen and thorax

• Side effects: – Increase thoracic pressure decreases output of

heart– Increased pressure in head

Coughing• Cough reflex is triggered when there is an

irritant in the tracheal bronchial tree• Deep breath: 12-15 mL/kg IBW, • Inspiratory hold: 3 seconds for air to get

behind irritant• Compression: Valsalva maneuver. True

cords close for 0.2 seconds, resulting intrathoracic pressure is 1001-200 cm H2O pressure

• Expulsion: Glottis opens and velocity can reach 300-500 LPM