Respiratory System

Respiratory System

Functions of the Respiratory System

The respiratory system handles the following functions for the body:

Analyzing the name for this system gives a clue as to its first two functions. The word respiratory (RES pur uh tore ee) comes from the combining form spir/o, which means to breathe. As a matter of fact, to breathe in is to inspire, and to breathe out is to expire. When one dies, one breathes out and no longer breathes in again—hence the expression that the patient has “expired.” Inhalation (in hull LAY shun) and exhalation (ex hull LAY shun) are alternative terms for inspiration and expiration.

The next two functions—filtering air and regulating blood pH—take place during breathing. The function of producing sound for speech and singing is accomplished by the interaction of air and the structures of the voice box, the larynx, and the hollow cavities, the sinuses, connected to the nasal passages.

Although the sense of smell, olfaction (ohl FACK shun), is not strictly a function of respiration, it is accomplished by the tissue in the nasal cavity, which receives the stimulus for smell and routes it to the brain through the nervous system.

Anatomy and Physiology

The respiratory system is anatomically divided into the upper respiratory tract—the nose, pharynx, and larynx—and the lower respiratory tract—the trachea, bronchial tree, and lungs (Fig. 11-1). Physiologically, it is divided into conduction passageways and gas exchange surfaces.

There are two forms of respiration: external respiration and internal respiration. External respiration is the process of exchanging O2 and CO2 between the external environment and the lungs. Internal respiration is the exchange of gases between the lungs and the blood.

Upper Respiratory Tract

The upper respiratory system encompasses the area from the nose to the larynx (Fig. 11-2). Air can enter the body through the mouth, but for the most part, it enters the body through the two nares (NAIR eez) (nostrils) of the nose that are separated by a partition called the nasal septum (NAY zul SEP tum). The hairs in the nose serve to filter out large particulate matter, and the mucous membrane and cilia (SEE lee uh) (small hairs) of the respiratory tract provide a further means of keeping air clean, warm, and moist as it travels to the lungs. The cilia continually move in a wavelike motion to push mucus and debris out of the respiratory tract. The air then travels up and backward, where it is filtered, warmed, and humidified by the environment in the upper portion of the nasal cavity. Fig. 11-3 illustrates the route of air into the body. The receptors for olfaction are located in the nasal cavity. The nasal cavity is connected to the paranasal sinuses (pair uh NAY zul SYE nus suhs), named for their proximity to the nose.

These sinuses, divided into the frontal, maxillary, sphenoid, and ethmoid cavities, acquire their names from the bones in which they are located. The function of sinus cavities in the skull is to warm and filter the air taken in and to assist in the production of sound. They are lined with a mucous membrane that drains into the nasal cavity and can be the site of painful inflammation.

Air continues to travel past into the nasopharynx (NAY zoh fair inks), which is the part of the throat (pharynx) behind the nasal cavity. The eustachian (yoo STAY shun) tubes from the ears connect with the throat at this point to equalize pressure between the ears and the throat. This is the site of lymphatic tissue, the pharyngeal tonsils (fur IN jee ul TAHN suls), which are also termed the adenoids (AD uh noyds). These pharyngeal tonsils help to protect against pathogens. The next structure, the oropharynx (or oh FAIR inks), is the part of the throat posterior to the oral cavity and also the location of more lymphatic tissue, the palatine tonsils (PAL ah tyne TAHN suls), so named because they are continuous with the roof of the mouth (the palate). These tonsils, just like the adenoids, are made up of protective lymphatic tissue. The lingual tonsil, located on the posterior aspect of the tongue, also serves a protective function. The oropharynx is also part of the digestive system; food and air pass through it. Below the oropharynx is the part of the throat referred to as the laryngopharynx (luh ring goh FAIR inks) because of its proximity to the adjoining structure, the larynx (LAIR inks), or voice box. As air passes back out through the opening of the larynx, the vocal cords, which are paired bands of cartilaginous tissue, vibrate to produce speech. The epiglottis (eh pee GLOT is) is a flap of cartilage at the opening to the larynx that closes access to the trachea (TRAY kee uh) during swallowing so that food is routed into the esophagus and is kept from entering the trachea. Though this is an effective protection most of the time, it can be overridden accidentally if the individual tries to talk and eat at the same time. When this happens, food can be pulled into the trachea, with possible serious consequences.

Lower Respiratory Tract

The lower respiratory tract begins with the trachea (or windpipe), which extends from the larynx into the chest cavity. The trachea lies within the space between the lungs called the mediastinum (mee dee uh STY num). Air travels into the lungs as the trachea bifurcates (branches) at the carina (kuh RIH nuh), where the right and left airways called bronchi (BRONG kee) (sing. bronchus) divide into smaller branches called bronchioles (BRONG kee ohls). These bronchioles end in microscopic ducts capped by air sacs called alveoli (al VEE oh lye) (sing. alveolus). Each alveolus is in contact with a blood capillary to provide a means of exchange of gases. It is at this point that O2 is diffused across cell membranes into the blood cells, and CO2 is diffused out to be expired. Each alveolus is coated with a substance called surfactant (sur FACK tunt) that keeps it from collapsing.

Each lung is composed of sections called lobes. The right lung is made up of three sections, whereas the left has only two. The abbreviations for the lobes of the lungs are RUL (right upper lobe), RML (right middle lobe), RLL (right lower lobe), LUL (left upper lobe), and LLL (left lower lobe).

Each lung is also enclosed by a double-folded, serous membrane called the pleura (PLOOR uh) (pl. pleurae). The side of the membrane that coats the lungs is the visceral pleura (VIH sur ul PLOOR ah); the side that lines the inner surface of the rib cage is the parietal pleura (puh RYE uh tul PLOOR ah). The two sides of the pleural membrane contain fluid that facilitates the expansion and contraction of the lungs with each breath.

The muscles responsible for normal, quiet respiration are the diaphragm (DYE uh fram), the large dome-shaped muscle between the thoracic and abdominal cavities, and the intercostal (in tur KOS tul) muscles, which are located between the ribs. On inspiration, the diaphragm is pulled down as it contracts and the intercostal muscles expand, pulling air into the lungs (see Fig. 11-1, B).

image Exercise 1: Anatomy and Physiology of the Respiratory System

Match the respiratory structure with its combining form or prefix. More than one letter may be correct.

  1. pleura

  2. lobe

  3. tonsil

  4. mucus

  5. diaphragm

  6. windpipe

  7. adenoids

  8. eustachian tube

  9. bronchiole

 10. rib

 11. breathe

 12. throat

 13. alveolus

 14. lung

 15. sinus

 16. bronchus

 17. voice box

 18. mouth

 19. nose

 20. mediastinum

 21. in

 22. air

 23. out

 24. epiglottis

 25. wall

 26. carbon dioxide

 27. oxygen


bronch/o, bronchi/o


pneum/o, pneumon/o


hal/o, spir/o





pneum/o, aer/o



lob/o, lobul/o

diaphragm/o, diaphragmat/o






sin/o, sinus/o






AA cost/o

BB mediastin/o

CC ex-

DD or/o

Decode the terms.

image Exercise 2: Respiratory System

Label the drawing below with the correct anatomic terms and combining forms where appropriate.




Terms Related to Respiratory Symptoms

Term Word Origin Definition
aphonia a- without
phon/o sound
-ia condition
Loss of ability to produce sounds. Dysphonia is difficulty making sounds.
ah FOH nee ah
Cheyne-Stokes respiration   Deep, rapid breathing followed by a period of apnea.
chayne stokes
clubbing   Abnormal enlargement of the distal phalanges as a result of diminished O2 in the blood (Fig. 11-4).
KLUH bing
cyanosis cyan/o blue
-osis abnormal condition
Lack of oxygen in blood seen as bluish or grayish discoloration of the skin, nailbeds, and/or lips.
sye uh NOH sis
dyspnea dys- difficult
-pnea breathing
Difficult, and/or painful breathing. Eupnea is good, normal breathing (Eu- means healthy, normal).
DISP nee ah
apnea a- without
-pnea breathing
Abnormal, periodic cessation of breathing.
AP nee ah
bradypnea brady- slow
-pnea breathing
Abnormally slow breathing.
brad IP nee ah
hyperpnea hyper- excessive
-pnea breathing
Excessively deep breathing. Hypopnea is extremely shallow breathing.
hye PURP nee ah
orthopnea orth/o straight
-pnea breathing
Condition of difficult breathing unless in an upright position.
or THOP nee ah
tachypnea tachy- fast
-pnea breathing
Rapid, shallow breathing.
tack ip NEE ah
epistaxis   Nosebleed. Also called rhinorrhagia.
ep ih STACK sis
hemoptysis hem/o blood
-ptysis spitting
Coughing up blood or blood-stained sputum.
heh MOP tih sis
hypercapnia hyper- excessive
capn/o carbon dioxide
-ia condition
Condition of excessive CO2 in the blood.
hye pur KAP nee ah
hyperventilation hyper- excessive Abnormally increased breathing.
hye pur ven tih LAY shun
hypoxemia hypo- deficient
ox/o oxygen
-emia blood condition
Condition of deficient O2 in the blood. Hypoxia is the condition of deficient oxygen in the tissues.
hye pock SEE mee ah
pleurodynia pleur/o pleura
-dynia pain
Pain in the chest caused by inflammation of the intercostal muscles.
ploor oh DIN ee ah
pyrexia pyr/o fire
-exia condition
pye RECK see ah
rhinorrhea rhin/o nose
-rrhea discharge
Discharge from the nose.
rye noh REE ah
shortness of breath (SOB)   Breathlessness; air hunger.
sputum   Mucus coughed up from the lungs and expectorated through the mouth. If abnormal, may be described as to its amount, color, or odor.
thoracodynia thorac/o chest
-dynia pain
Chest pain.
thor uh koh DIN ee ah

Oct 6, 2017 | Posted by in GENERAL SURGERY | Comments Off on Respiratory System
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