Ch16: Respiratory System

Function: To exchange gas betweenthe external environment and theblood- O2 in and CO2 out of the blood vessels in thelungs- O2 out and CO2 into the blood vesselsaround the cells- Gas exchange happens in alveoli- Other organs purify, humidify, and warm theincoming air- also act as conducting passageways

Cells, Tissues, and Membranes Cells– Surfactant secretingcells– Macrophage Connective– Hyaline cartilage inthe larynx and nose– Elastic cartilage inthe larynx Epithelial Membranes– Simple squamous –– Mediastinumalveoli– Pleural – visceral– Pseudostratifiedand parietalcolumnar – respiratorypassageway

Development Lungs are one of the last organ systems todevelop– Surfactant levels are not large until late in pregnancy– Surfactant fatty molecule that lowers the surfacetension of water in the lining of alveoli to keep themopen Fetus – lungs filled with fluid– All respiratory gas exchange made by placenta At birth – passageways are drained and alveoliinflate for the first time Lungs are not fully inflated until 2 weeks

Anatomy of the RespiratorySystem Consists of the nose, pharynx (throat),larynx (voice box), trachea (windpipe),bronchi, and lungs with alveoli.

NoseFunction warming, filtering, andmoistening inhaled air; detecting smells;and modifying the sounds of speechExternally: Framework of bone and hyaline cartilage covered withmuscle, skin, and mucosa (on the inner surface) Air enters external nares (nostrils)Internally: Divided into right and left sides by the nasal septum orvomer bone Space within nasal cavity

Nose Nasal Conchae three shelves within thenasal cavity lined with mucosa– Swirls the air through the cavity and trapsparticles, as well as warms the airnasal cavity- Cilia within the nasal cavitywave mucus to the throat,where it, along with trappedparticles, is swallowedand/or spit out.nasal conchae

Nose The nasal cavity is separated from the oralcavity below by a partition called thepalate– Hard palate – anterior part that is supported by bone– Soft palate – unsupported posterior part The nasal cavity is surrounded by a ring ofparanasal sinuses– Function: lighten skull, add resonance chambers forspeech, produce mucus which drains into the nasalcavity– Nose blowing helps clear sinuses

Pharynx Funnel-shaped tube fromthe end of the nasal cavityto the superior border ofthe larynx Function passagewayfor air, food, and liquid,provides a resonatingchamber for voice, andhouses the tonsils, whichare lymphatic organs

Pharynx Nasopharynx (uppermost portion) Air travels from thenasal cavities into the nasopharynx– Also, the auditory tubes open into the nasopharynx,allowing pressure equalization in the middle ear Oropharynx (middle portion) Has openings into themouth and nasopharynx; passage for air and food Laryngopharynx (lowermost portion) Connects withthe esophagus, oropharynx, and the larynx

Larynx Larynx (Adam’s Apple) rigidcartilage structure (hyaline andelastic) that connects the pharynxwith the trachea (windpipe)larynx Function voice boxanterior– Hyaline cartilage forms the anteriorwall of the larynx.– Present in both genders, but islarger and more pronounced inmales.anteriorposterior

Larynx Epiglottis large flap of elastic cartilagewhich attaches to the anterior rim of thethyroid cartilage and the hyoid bone– As you swallow, the larynx and pharynx rise andthe pharynx widens as it rises to accommodatethe swallowed food– As the larynx rises, the epiglottis moves downand forms a lid over the opening to the trachea,preventing food and/or liquid from getting intothe airways

Voice Production The structures that allow forvocalization are folds in the larynx– Two pairs of folds: false vocal cords andtrue vocal cords False vocal cords allow you to “holdyour breath against pressure”, aswhen you pick up something heavy True vocal cords vibrate to giveyour voice resonance and pitch.Without them, you’d be forced towhisper. The space between the cordsis called the glottissuperior view:muscles andcartilagesuperior view:as if through alaryngoscope

Voice Production Tiny muscles within the larynx move the cords closertogether, farther apart.– There are also muscles that adjust the tension on the vocalcords– These adjustments, coupled with the airflow from the lungs,allow you to control the pitch and volume of your voice. Males tend to have deeper voices because their vocalcords are usually thicker and longer than those offemales. Thus, they naturally vibrate more slowly

Trachea Also known as the Windpipe Tubular air passage that runsabout 12 cm from the bottomof the larynx downward toabout T5 vertebrae, at whichpoint it splits in to right andleft bronchi.– Wall is lined with mucosa(pseudostratified columnarepithelium with cilia)– Cilia in the trachea move mucusupward to the throat to removethe trapped particles from therespiratory tractcartilage “C”esophagustrachea

Trachae Supported by C-shaped rings of cartilageto keep trachea from collapsing The gap in the C faces the esophagus,which is posterior to the trachea.– This accommodates the expansion of theesophagus as food is swallowed and sentdown to the stomach

Which part of the respiratory systemshares a passageway with thedigestive system?A.B.C.D.Nasal cavityPharynxLarynxTrachea

Bronchi and Bronchioles Trachea divides into the right and leftprimary bronchus entryways into eachlung– Right primary bronchus is wider, shorter, andstraighter than the left more common site for an inhaled object to becomelodged– By the time air gets to bronchi, it is warmed,cleansed, and well humidified

Bronchi and Bronchioles Once in the lung, the primary bronchi split intosecondary bronchi – one for each lobe of thelung (two on the left, three on the right) Secondary bronchi divide into tertiary bronchi,which continue to “divide” into smaller andsmaller tubes known as bronchioles

Bronchi and Bronchioles As branching increases:– Cartilage rings decreases, then ultimately vanish– Smooth muscle increases – this can dilate or constrictairways due to demand Asthma attacks involve spasms of this smooth muscle,constricting the airways.primary bronchidiaphragm

Lungs Spongy, cone shaped organin the thoracic cavity that isseparated by the heart andother structures in themediastinum Surrounded by the pleuralmembrane which has avisceral side and a parietalside. In between the layersis filled with fluid to easefriction.oblique fissurehorizontalfissureoblique fissure

Lungs The smallest organizational unit of the lung is alobule.– A lobule consists of a lymphatic vessel, arteriole,capillary, venule, and a branch from a terminalbronchiole.– All wrapped in connective tissue Terminal bronchioles subdivide into respiratorybronchioles, which are capable of gasexchange. These further subdivide into alveolar ducts andeventually into alveoli.

Alveoli Cup-shaped section of an alveolar sac which isthe main site of gas exchange by diffusionbetween the lungs and the bloodstream– Walls are extremely thin simple squamous tissue– The lungs contain about 300 million alveoli. Ultimately, this provides asurface area for gas exchange about 35 times the surface area of yourown skin. About half the size of a tennis court. The Respiratory Membrane: combination ofcapillary and alveolar walls that separate gas inthe lungs from the bloodstream.– Consists of five layers, but is still only 0.5 micrometers thick(significantly thinner than tissue paper) – thus gases can exchange veryquickly

Alveoli Within the alveoli are cells called surfactant secretingcells, which keep the inner surface of the alveoli moistby secreting a fluid known as alveolar fluid. Contained within alveolar fluid is surfactant – a fattysubstance that helps prevent the alveoli from collapsing. Also have alveolar macrophages that are present tohelp remove particulates and other debris in the alveolarspaces.

Close view of an Alveolus:

What type of transport is used tomove oxygen and carbon dioxideacross the alveoli membrane?A.B.C.D.ActiveOsmosisDiffusionEndocytosis and Exocytosis

List the correct order of air movement throughthe entire respiratory passageway.A. Nasal/Oral Cavity, Pharynx, Larynx, Trachea,Bronchi, LungsB. Nasal/Oral Cavity, Larynx, Pharynx, Trachea,Bronchi, LungsC. Larynx, Trachea, Bronchi, LungsD. Nasal/Oral Cavity, Larynx, Trachea, Lungs