Functions:

1) moves air to and from the gas exchange surfaces where

diffusion occurs between air and circulating blood

2) provides nonspecific defenses against pathogenic invasion

3) permits vocal communication

4) helps control the pH of the body fluids

Components:

1) EXTERNAL NOSTRILS OR NARES

2) NASAL CAVITY:

a) vestibule (anterior portion) contains hairs that

protect the entrance from dust and insects and

enclosed by the cartilage of the nose

b) lateral and superior walls formed from the

following bones of the skull: maxillary, nasal, frontal,

ethmoid, and sphenoid bones

c) posterior septum formed from portions of the vomer

and ethmoid bone

d) inferiorly the nasal cavity is separated from the oral

cavity by the hard palate (formed by the palatine and

maxillary bones)

e) a fleshy soft palate extends behind the hard palate

separating the superior nasopharynx and the rest of the

pharynx

f) nasal cavity opens into the nasopharynx through the

internal nares

g) superior, middle, and inferior conchae project

toward the nasal septum from the lateral walls of the

nasal cavity***

***Air passes between conchae as it is inhaled, warming

and filtering the air(nasal cavity lined with mucous

membrane: mucous catches dust particles, turbulent

flow over the conchi allows extra time for warming and humidifying the air)

3) THE MUCOUS MEMBRANE:

a) lines nasal cavity and the rest of the respiratory tract

b) made of respiratory epithelium with goblet cells, and an

underlying loose connective tissue (lamina propia) contain-

ing mucous glands

c) Both goblet cells and mucous cells produce mucus onto

surface of epithelium

d) Cilia sweep mucous and any trapped debris or micro-

organisms toward the pharynx to be swallowed and exposed

to the acid of the stomach

e) surface is also flushed by mucus produced by the

paranasal sinuses (frontal, sphenoid, ethmoid, and maxillary sinuses)**

f) flushed also by tears through the nasolacrimal duct**

**exposure to allergens, pathogens,noxious vapors, dust...

causes a rapid increase in the production of mucus

(a "runny nose")

4) THE PHARYNX(throat)

a) location: between internal nares and entrance into the

larynx and the esophagus

b) three divisions:

---nasopharynx (from the internal nares to the edge of

the soft palate

---oropharynx (from the soft palate to the base of the

tongue (at the level of the hyoid bone)

---laryngopharynx (between the hyoid bone and the

entrance into the esophagus

5) THE LARYNX

a) Glottis---opening into the larynx (voicebox)

b) Epiglottis--flap of cartilage over the glottis (during

swallowing the larynx is lifted upward and epiglottis folds

over the glottis preventing passage of food into the larynx

c) Contains nine cartilages:

Two larger cartilages:

---thyroid cartilage: shield shaped and forms the

anterior and lateral surfaces; anterior surface has

a ridge (Adam’s apple)

---cricoid cartilage: ring shaped, found below the

thyroid cartilage; provides posterior support to the

larynx

**both thyroid and cricoid cartilages provide a point

of attachment for muscles and ligaments

Three pairs of smaller cartilages:

---arytenoid,corniculate, and cuneiform cartilages

----all supported by cricoid cartilage and posterior to

the thyroid cartilage

d) The Vocal Cords

---two pairs of ligaments extend across larynx between

thyroid cartilage and the smaller cartilages and reduces

the size of the glottis

---upper pair called the false vocal cords; inelastic and

only serve to help prevent objects from passing into the

glottis

---lower pair called the true vocal cords; elastic and

located between the thyroid and arytenoid cartilages;

muscles attach to them to change there positions and

tension for the production of different sounds

6) THE TRACHEA

---eleven cm long; diameter of 3.5 cm--

---extends between the level of the 6th cervical

vertebrate (where it attached to the cricoid cartilage)

to the 5th thoracic vertebrate

---walls of trachea consist of 20 "C" shaped tracheal

cartilages: support and protect airway, prevent collapse

or over expansion as pressure changes, open portions of

the "C" face posteriorly toward the esophagus allowing

large masses of food to pass through the esophagus

(allows trachea to easily distort in front of the

esophagus--diameter of the trachea can be adjusted by

muscles--makes it easier to move large volumes of air

7) THE BRONCHI AND THE BRONCHIOLES

1) Divisions:

TRACHEA

TWO PRIMARY BRONCHI

9-10 TERTIARY BRONCHI

(in each lung)

BRONCHIOLES

(called bronchioles when ring cartilages

disappear and diameter = 1 mm)

TERMINAL BRONCHIOLES

(.3 to .5 mm in diameter)

(located in each lung lobule: a segment of

lung tissue and supplied by a single bronchiole,

accompanied by branches of the pulmonary

artery and veins)

RESPIRATORY BRONCHIOLES

(open into many alveolar ducts which divide to

form alveolar sacs which in turn open into the

ALVEOLI

2) Varying diameter of the bronchioles control the

amount of air entering and leaving the lungs(controlled

by smooth muscle)

8) THE ALVEOLI

----gas exchange surfaces of the lungs, 150 million

alveoli in each lung---

---surface of alveoli must equal 140 square meters(size

of a tennis court) to meet our metabolic needs---

---lined with simple squamous epithelium---

---contain phagocyte cells called DUST DEVILS

alveolar macrophages which patrol and phagocytes

dust and debris----

---contain SURFACTANT CELLS: produce surfactant

an oily secretion which reduces the surface tension

within the alveolus (surface tension results from the

attraction between water molecules and an air-water

boundary----without surfactant surface tension would

collapse the alveoli

***inadequate surfactant levels, from injury or

genetics results in RESPIRATORY DISTRESS

SYNDROME: each inhalation must be forceful

enough to "pop" open the alveoli (patients become

quickly exhausted inflating and deflating the lungs)

9) THE RESPIRATORY MEMBRANE(of the alveoli)

----consists of three components

1) the squamous epithelium lining the alveoli 2) the endothelial cells lining an adjacent

capillary

3) the fused basement membranes that lie

between the alveolar and endothelial cells

-----site of "rapid diffusion" due to:

small distance between alveolar air and the blood

(about .1 micron)

both O₂ and CO₂ are lipid soluble

10) THE LUNGS

a) found in right and left pleural cavities (thoracic

cavity divided into pleural cavities by the mediastinum)

(lined by a serous membrane called the pleura; parietal

pleura covers the inner surface of the body wall

extending over the diaphragm and mediastinum and the

visceral pleura covering the outer surface of the lungs

extending into the fissures between the lungs.

---parietal and visceral pleura separated by a small

(pleural cavity) filled with fluid for lubrication and

to reduce irritation----thoracentesis: examination of

pleural fluid for bacteria, blood....

b) right lung has three lobes (superior, middle and

inferior lobes)

c) left lung has two lobes (superior and inferior)

d) top of lungs called the apex; bottom of lungs called

base(concave shaped)

e) lungs have two surfaces: costal surface (curves,

following contour of the ribs; mediastinal surface

facing mediastinum, more irregularly shaped, contains

the CARDIAC NOTCH in only the left lung

11) THE DIAPHRAGM

----large dome shaped muscle separating the

abdominal and thoracic cavity used in breathing--

12) EXTERNAL AND INTERNAL INTERCOSTALS of

the ribs and used in the breathing process

Inhalation

-----Diaphragm and external intercostals contract:

volume of lungs increases resulting in a decrease in

pressure inside the lungs, so air rushes in from outside

Exhalation

-----Diaphragm relaxes and internal intercostals

contract decreasing the volume of the lungs and

increasing the pressure in the lungs, so air rushes

out of the lungs

****When the liquid bond is broken between the visceral and parietal pleura allows air to pass into the pleural cavity the result is a collapsed lung: ATELECTASIS (from injury to pleura and alveoli or from opening up the chest cavity during an operation)

1) TIDAL VOLUME (TV) : amount of air moving into and out of the lungs during a single respiratory cycle (one single, quiet respiratory cycle)

*average TV = 500 ml

* can be greater than 500 ml during more rigorous breathing such as during exercise

2) EXPIRATORY RESERVE VOLUME (ERV): amount of air EXHALED above tidal volume (when you forcefully breathe out more air)

*average ERV = 1000 ml

3) INSPIRATORY RESERVE VOLUME (IRV):

amount INHALED above TV

*average IRV for males = 3300 ml (larger lungs)

*average IRV for females= 1900 ml

4) VITAL CAPACITY (VC): maximum amount of air moved into and out of the lungs during a single respiratory cycle

***VC = TV + ERV + IRV

**males: VC = 500ml + 1000 ml + 3300 ml = 4800 ml

**females: VC = 500ml + 1000ml + 1900 ml = 3400 ml

******VC varies with age and size of body

5) RESIDUAL VOLUME (RV): air that remains even after ERV has been exhausted (air that is held back by the thoracic wall)

average RV = 1200 ml

6) MINIMAL VOLUME (MV): amount of air that remains after the

thoracic cavity is open (surfactant coating prevents their collapse)

7) DEAD SPACE OF THE LUNGS: not all of the air reaches the

alveoli, some remains in the conducting passageways:

average DS = 150 ml

example: TV = 500 ml

only 350 ml reaches alveoli

150 ml remains in the conducting passageways