Chapter 13 – Part 1

The Respiratory System

Organs of the Respiratory system

 Nose  Pharynx  Larynx  Trachea  Bronchi  Lungs – alveoli

Function of the Respiratory System

1.

Oversees gas exchanges between the blood and external environment 2.

Exchange of gasses takes place within the lungs in the alveoli 3.

Passageways to the lungs purify, warm, and humidify the incoming air

The Nose

 The only externally visible part of the respiratory system  Air enters the nose through the

external nares

(nostrils)  The interior of the nose consists of a

nasal cavity

divided by a

nasal septum

Figure 13.2

Anatomy of the Nasal Cavity

 Olfactory receptors for the sense of smell are located in the mucosa on the slitlike superior part of the nasal cavity  The rest of the cavity is lined with respiratory mucosa, which function to: 1.

Warm the air 2.

Moistens the air 3.

Traps incoming foreign particles (cleanse)

Anatomy of the Nasal Cavity

 The ciliated cells of the nasal mucosa create a gentle current that moves contaminated mucous posteriorly towards the

throat (pharynx)

 It is then swallowed and digested by stomach juices.  When it is extremely cold, these cilia become sluggish, allowing mucus to accumulate in the nasal cavity and to dribble outward through the nostrils.

 This is why you have a “runny” nose on a cold day.

Nosebleeds

 The respiratory mucosa rests on a rich network of thin-walled veins (warms the air as it flows by).

 Because of the superficial location of these blood vessels, nosebleeds are common and often profuse.

Anatomy of the Nasal Cavity

 The lateral walls of the nasal cavity have three projections or lobes called

conchae

, which function to: 1.

Increases surface area 2.

Increases air turbulence within the nasal cavity  Helps to deflect inhaled particles onto the mucus-coated surfaces, where they are trapped and prevented from entering the lungs.

Anatomy of the Nasal Cavity

 The nasal cavity is separated from the oral cavity by the

palate

 Anterior

hard palate

(bone)  Posterior

soft palate

(muscle)

Cleft Palate



Cleft Palate

– The bones forming the palate fail to fuse medially   Genetic defect Results in breathing difficulties and problems with oral cavity functions (chewing and speaking)

Paranasal Sinuses

 The nasal cavity is surrounded by a ring of

paranasal sinuses

.

 Are located in the: 1.

Frontal bone 2.

Sphenoid bone 3.

Ethmoid bone 4.

Maxillary bone

Paranasal Sinuses

 Function of the sinuses 1.

Lighten the skull 2.

Act as resonance chambers for speech 3.

Produce mucus that drains into the nasal cavity • The suctioning effect created by nose blowing helps to drain the sinuses.

• The nasolacrimal ducts, which drain tears from the eyes, also empty into the nasal cavities

Sinusitis



Sinusitis

– Sinus inflammation  Difficult to treat  Can cause marked changes in voice quality  When the passageways connecting the sinuses to the nasal cavity are blocked with mucus or infectious matter, the air in the sinus cavities is absorbed  The result is a partial vacuum and a sinus headache

Pharynx (Throat)



Pharynx

- Muscular passage from nasal cavity to larynx  About 5 inches long  Commonly called the throat  Serves as a common passageway for food and air  Is continuous with the nasal cavity anteriorly via the

internal nares

Pharynx (Throat)

 Three regions of the pharynx: 

Nasopharynx

– Superior region behind nasal cavity 

Oropharynx

– Middle region behind mouth 

Laryngopharynx

to larynx – Inferior region attached  The oropharynx and laryngopharynx are common passageways for air and food  Air then passes through the larynx, while food is directed into the esophagus posteriorly

Structures of the Pharynx

 The auditory tubes, which drain the middle ear, open into the nasopharynx  Since the mucosae of these two regions are continous, ear infections may follow a sore throat or other types of pharyngeal infections



Structures of the Pharynx

Tonsils

(clusters of lymphatic tissue) are also found in the pharynx  Their job is to trap and remove any bacteria or other foreign pathogens entering the throat 

Pharyngeal Tonsil

nasopharynx – Located high in the 

Palatine Tonsils

– Located in the oropharynx at the end of the soft palate 

Lingual Tonsils

tongue – Located at the base of the

Tonsillitis



Tonsillitis

– Inflammation and swelling of the pharyngeal tonsil  Can occur during a bacterial infection  It obstructs the nasopharnyx and forces the person to breathe through the mouth  In mouth breathing, air is not properly moistened, warmed, or filtered before entering the lungs  Years ago, the belief was that the tonsils were more trouble than they were worth and they were routinely removed.

 Now, this is no longer necessary because of the large use of antibiotics

Larynx (Voice Box)

 Functions of the Larynx: 1.

Routes air and food into proper channels 2.

Plays a role in speech (voice production) 3.

Acts as an airway  Made of eight rigid hyaline cartilages and a spoon-shaped flap of elastic cartilage (epiglottis)

Structures of the Larynx



Thyroid Cartilage

 Largest hyaline cartilage  Shield-shaped  Protrudes anteriorly  Commonly called the

Adam’s apple

Structures of the Larynx



Epiglottis

 Protects the superior opening of the larynx  Routes food to the esophagus and air toward the trachea  The epiglottis moves positions when swallowing  When we are not swallowing: The epiglottis does not restrict the passage of air into the lower respiratory passages  When we are swallowing: The larynx is pulled upward and the epiglottis tips, forming a lid over the opening of the larynx; this routes

food into the esophagus

Structures of the Larynx

 Palpate your larynx by placing your hand midway on the anterior surface of your neck. Swallow. Can you feel the larynx rising as you swallow?

Cough Reflex

 If anything other than air enters the larynx, a

cough reflex

is triggered to expel the substance and to prevent it from continuing into the lungs.

 Because this protective reflex does

not

work when we are unconscious, it is never a good idea to try to give fluids to an unconscious person when attempting to revive him or her.

Structures of the Larynx



Vocal Cords

(vocal folds)  Pair of folds  Vibrate with expelled air to create sound  Allows us to speak 

Glottis

– The slitlike passageway between the vocal cords