CHAPTER 23 THE RESPIRATORY SYSTEM

The process of gas exchange in the body called respiration is composed of 3 steps;
a)

Pulmonary ventilation or breathing is a mechanical flow of air into (inspiration) and out of the lungs
(expiration)
xternal respiration is the exchange of gases between the air spaces of the lungs and the blood in the capillaries – capillary blood gains O2 and loses CO2 nternal respiration is the exchange of gases between blood in systemic capillaries and tissue cells.
Within the cells that consume O2 and give off CO2 to produce ATP is called cellular respiration

Structure
1. upper respiratory consist of nose and pharynx,
2. lower respiratory consist of larynx, trachea, bronchi and lungs
a. conducting part ( tubes and cavities)
b. respiratory part ( alveoli sacs, ducts and alveoli) Nose
1. functions include : warming incoming air, moisten and filter receiving olfactory stimuli provide the large chambers for modifying speech sounds 2. external and internal part =
a. external part includes nares (nostrils): the bony framework is the frontal, nasal and maxilla bones; the cartilaginous framework consist of hyaline cartilages = septal, lateral and alar cartilages
b. internal part includes: choanar (internal nares) and openings of ducts = posteriorly, the internal nose merges with the pharynx thru 2 openings called the internal nares or choanar. Ducts form the paranasal sinuses (frontal, sphenoidal, maxillary and ethmosidal) and the nasolacrimal ducts open into the internal nose
c. the nasal septum divides the nasal cavity into left and right; the anterior part consist of hyaline cartilage; the remainder is formed by the vomer, perpendicular plate of the ethmoid, maxillae,a nd palatine bones
d. the anterior part of the nasal cavity , just inside the nostrils is the vestibule ; where the air 1st enters and is warmed. The nose hairs filter out dust and particles
e. 3 shelves formed by projections of the superior, middle and inferior nasal conchae extend out of each lateral wall of the cavity. These subdivide the cavity into groove­like passages – the superior, middle and inferior meatuses; mucous membranes lines the cavity and this serves to increase the surface area in the internal nose and prevents dehydration b/c the meatuses trap water droplets during expiration
f. the olfactory receptors lie in the membrane lining the superior nasal conchae and adjacent septum
– the olfactory epithelium. Inferior to the olfactory epitheliumi s a mucous membrane containing capillaries and PCCE with goblet cells. As inspiration occurs, capillaries in the epithelium of the conchea and meatuses warm the air, & mucus secreted moistens the air and traps dust particles. Drainage form the nasolacrimal ducts and from the sinuses also help to moisten the air.
The cilia move the mucus and trapped dust particles toward the pharynx where it is swallowed or spit out

Pharynx (throat)
1. funnel­shaped tube (5 in) long; lies behind the nasal cavity, and extends to the cricoid cartilage;
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connects the internal nares to the cricoid cartialge (larynx) walls are composed of skeletal muscle and lined by mucous membranes functions as a passageway for air and food, provides a resonating chamber for speech sounds, and houses the tonsils (participate in immunological reactions against foreign invaders via the tonsils) consist of 3 parts: nasopharynx, oropharynx, laryngopharynx nasopharynx = extends from the posterior nasal cavity to the soft palate; there are 5 openings including from the ears (Eustachian ); this region includes the soft palate & the tonsils. Air is exchanged with the Eustachian tube to equalize pressure with the ear. It is lined with PSCCE oropharynx = runs from the soft palate to the hyoid bone. This part is both respiratory and digestive because it is common passage of food and air and