3Respiration Includes Pulmonary ventilation External respiration Air moves in and out of lungsContinuous replacement of gases in alveoli (air sacs)External respirationGas exchange between blood and air at alveoliO2 (oxygen) in air diffuses into bloodCO2 (carbon dioxide) in blood diffuses into airTransport of respiratory gasesBetween the lungs and the cells of the bodyPerformed by the cardiovascular systemBlood is the transporting fluidInternal respirationGas exchange in capillaries between blood and tissue cellsO2 in blood diffuses into tissuesCO2 waste in tissues diffuses into blood
4Functions of the Respiratory System: Overview Exchange O2Air to bloodBlood to cellsExchange CO2Cells to bloodBlood to airFigure 17-1: Overview of external and cellular respiration
5The Airways: Conduction of Air from Outside to Alveoli Filter, warm & moisten airNose, (mouth), pharynx, larynx, trachea, bronchi & bronchiolesHuge increase in cross sectional areaFigure 17-4: Branching of the airways
6NoseProvides airwayMoistens and warms airFilters airExternal nose
7* * The Pharynx (throat) Houses tonsils (they respond to inhaled antigens)Uvula closes off nasopharynx during swallowing so food doesn’t go into noseEpiglottis posterior to the tongue: keeps food out of airwayserve as common passageway for food and air**
8The Larynx (voicebox) Three functions: Produces vocalizations (speech) Provides an open airway (breathing)Switching mechanism to route air and food into proper channelsClosed during swallowingOpen during breathing
9Trachea (the windpipe) Descends: larynx through neckDivides in thorax into two main (primary) bronchi16-20 C-shaped ringsof hyaline cartilagejoined by fibroelasticconnective tissueFlexible for bendingbut stays open despitepressure changesduring breathing
10Wider, shorter, and more vertical than the left tracheaRight Primary BronchusLeft primary bronchusBoth primary bronchi have the same anatomic structure as the trachea.
11Bronchi The primary bronchi divide to form SECONDARY BRONCHI There is one secondary bronchus for each lobe of the lungs.There are 2 lobes on the left lung.There are 3 lobes on the right lung.These also have the same anatomy as the trachea.
12Bronchi, continuedThe secondary bronchi branch to form TERTIARY BRONCHI.They continue to branch.As they get smaller, they lose their cartilage.When they lose their cartilage, they are called BRONCHIOLES which are microscopic.
13Lungs and PleuraAround each lung is a flattened sac of serous membrane called pleuraParietal pleura – outer layerVisceral pleura – directly on lungPleural cavity – slit-like potential space filled with pleural fluidLungs can slide but separation from pleura is resisted (like film between 2 plates of glass)Lungs cling to thoracic wall and are forced to expand and recoil as volume of thoracic cavity changes during breathing
14Right lung: 3 lobes Left lung: 2 lobes Upper lobe Middle lobe Lower lobeLeft lung: 2 lobesAbbreviations in medicine:e.g.” RLL pneumonia”Horizontal fissureOblique fissureOblique fissureEach lobe is served by a lobar (secondary) bronchus