Respiratory System Respiration processes Pulmonary ventilation (air in/out, gas exchanged in lungs) External respiration (gas exchanged between blood and alveoli in lungs) Transport of respiratory gases (transport of oxygen and carbon dioxide) Internal respiration (gas exchange between blood and tissues) Two zones of respiratory system: Respiratory zone - actual site of gas exchange (bronchioles, alveolar ducts, alveoli) Conducting zones - all other respiratory passageways Upper respiratory tract Nose and nasal cavity Provides airways for respiration Moistens and warms entering air Filters inspired air and cleanses it Serves as resonating chamber forspeech Houses the olfactory (smell) receptors Parts of the nose: External nose,internal nasal cavity Pharynx: Connects nasal cavity andmouth to larynx and esophagus (throat) Three regions:- Nasopharynx - lined withpseudostratified epithelium andhouses the pharyngeal tonsil(adenoids)- Oropharynx - lined with stratifiedsquamous epithelium, locatedposterior to oral cavity, includearchway (fauces) between uvula and epiglottis, and contain palantine and lingual tonsils- Laryngopharynx - lined with stratified squamous epithelium, commonpassageway for food and air, posterior to epiglottis Larynx: Voice box attached to hyoid superiorly and inferiorly with trachea Composed of corniculate, arytenoid, cricoid, and thyroid cartilage Functions:- Provide open airway- Act as switching mechanism (epiglottis) to route air and food- Voice production (vestibular fold or false vocal chord and vocal fold ortrue vocal cord) Trachea: Windpipe Descends from larynx through neck into mediastinum and ends by dividing (at carina) into two primary bronchi Walls (mucosa, submucosa, hyaline cartilage and adventitia) lined with pseudostratified epithelium Branching of bronchial tree: Tracheaprimary bronchisecondary bronchitertiary bronchibronchiolesterminalbronchioles Trachea: conduct air to andfrom the lungs, filter air, andtrap particles in mucus Bronchi: air passages in thelungs. Site of conducting zonestructures Right and left primary bronchi: carry oxygen to lungs Secondary bronchi: aka lobar,3 branches from right primarybronchus and 2 branches fromleft primary bronchus. - Oxygen within lobe Tertiary bronchioles: akasegmental, suppliesbronchopulmonary segment. Usually 10 in right and 8 in left Bronchioles: smaller tube divisions of bronchi. Walls contain smooth muscle and no cartilage which allows for contraction and relaxation Microscopic airways Terminal bronchiolesRespiratory bronchiolesalveolar ductsalveolar sacsalveoli Terminal bronchioles: most distal segment of the conducting zone that branches off the lesser bronchioles Respiratory bronchioles: narrowest airways of the lungs that deliver air to the exchange surfaces of the lungs Alveolar duct: tiny ducts that connect the respiratory bronchioles to the alveolar sacs Alveolar sacs: transport vital elements to your lungs and out of your lungssuch as blood, carbon dioxide, and oxygen Alveoli: tiny air sacs that are at the end of the smallest airways; oxygen exchange occurs here. 300 million Conducting zone: bronchi Function is to for a continuous passageway for air to move in and out of the lungs Air that reaches the bronchi is warmed/cleansed of impurities and saturated with water vapor The conducting zone is made up of the nose, pharynx, larynx, trachea, bronchi, bronchioles, and terminal bronchioles right and left primary (principle) bronchi branch into: Secondary bronchi (3 on right 2 on left) which branch into Tertiary (segmental) bronchi which branch into 4th, 5th, etc... 23 orders Until bronchioles then terminal bronchioles Tissue composition of walls of primary bronchi is same as trachea but decreases in size of conducting tubes, then increase in change in compositionwith each subsequent subdivision: Cartilage rings replaced by irregular plates of cartilage Epithelium: Pseudostratified, then columnar, then cuboidal; cilia and mucus producing cells only in upper bronchioles Smooth muscle increases with decreasing size of bronchioles Respiratory zone Site of 02 and CO2 exchange with the blood Respiratory bronchioles and alveolar ducts are responsible for 10% of gas exchange and the alveoli are responsible for the other 90% terminal bronchioles divide into respiratory bronchioles with scattered air sac outpocketing from walls, branch into Alveolar ducts with sacs called alveoli (chambers where bulk gas exchange occurs) Alveolar sacs open into a common chamber called an atrium Air sacs (alveoli) provide surface area for gas exchange Respiratory membrane - single layer of squamous epithelium (Type I pneumocytes) with pulmonary capillaries Respiratory membrane (air-blood barrier) site of gas exchange (by diffusion) Diffusion requires moist membrane, therefore there are cuboidal epithelium (Type II pneumocytes) that secretes surfactant, coating gas-exposed alveolar surfaces Alveoli contain alveolar macrophages that provide an immunologic defense. The respiratory membrane’s function is to preventeach alveolus from collapsing as air moves in and outduring respiration Used as a barrier across which gases areexchanged between alveolar air and the blood - The barrier is made of alveolar and capillarywalls - The alveolar walls Respiratory gases must diffuse in order tobe exchanged between the air in the alveoliand the blood; this consists primarily of thetype I alveolar cells Permit gas exchange by simple diffusionand secrete angiotensin converting enzyme(ACE) Angiotensin converting enzyme: help relax blood vessels by preventing an enzyme in your body from producing angiotensin II Breathing Pulmonary ventilation Mechanical process that depends on thevolume changes in the thoracic cavity Consists of inspiration and expiration - Inspiration: air flows into the lungs - Expiration: gases exit the lungs Since gases always fill the container, thelarger container will have the moleculesmore spread out and pressure will belower than a container that is smaller Pressure relationships Respiratory pressure is relative toatmospheric pressure (Patm)- Atmospheric pressure is the
View Full Document
Unlocking...