Respiratory System Functions: Moves Air into and out of the Lungs This exchanges Gases between that Air and the Blood Organs: Nose Small amount of Bone, Large amount of Cartilage Forms Septum and Nasal Cavities Cavities lined with ciliated mucous membrane Functions: Filters - foreign particles caught by air Warms - Air moves through passageways (turbulence, exposure to warm) Humidifies - adds moisture from mucous Has Olfactory Receptors located in upper medial portion Has drainage pipes from the Lacrimal Glands (tears) Beyond the Nose are the Sinuses Paranasal Sinuses (ethmoidal, sphenoidal, etc.) Opens into nasal cavities Filled with Mucous Membranes Humidifies and Warms the Air Further Hard and Soft Palate Also Exist Hard palate is immoveable seperation between Oral and Nasal Cavities Soft Palate moves back to cover the Nasopharynx when swallowing Pharynx (Throat) Connects nasal and oral cavities to Larynx Consists of three parts Seems divided by what it carries Nasopharynx (opening from nasal cavities) Oropharynx (opening from mouth) Laryngopharynx (opens from the larynx) Nasopharynx Nose has connection to ears (Eustacian Tubes connect to Middle Ear) We equalize pressure by forcing air into them Adenoids (pharyngeal tonsils) located here Lymph tissue Oropharynx Middle Portion Contains Palatine (bone) tonsils and Linguinal (tongue) tonsils Laryngopharynx Inferior portion Carries both food (to esophogus) and air (to trachea) Larynx (voice box) Triangular box located in superer portion of Trachea Adam's apple at Apex (front) Top is made of the Glottis Varies in size depending upon need Covered with the Epiglottis when food is swallowed Contains vocal cords at edge of Glottis Mucous membrane folds with elastic ligaments Stretch from Adams apple to sides of Glottis Air moving past vibrates them, causing sound Trachea (windpipe) Responsible for transporting air to lungs Extends from Larynx to Thoracic Cavity there it divides into 2 bronchii Made of C-shaped cartilige rings hold it open Contains ciliated mucous membrane with Goblet Cells cilia move small particles upward Bronchi and Bronchioles Trachii divides into two Bronchi (singular = Bronchus) Bronchi enter the lungs Bronchi divide further into Bronchioles (again and again) Bronchioles terminate in Alveoli (singulur = Alveolus) Alveoli make up the Lungs Lungs Alveoli surrounded by capillaries Capillaries composed of epithelial layer and basement layer Together, make up the respiratory membrane Also composed of Surfactant-Secreting cells Surfactant is a chemical that lowers surface tension Important during exhalation as alveoli sacs may otherwise collapse Structure: Lie within the Thoracic Cavity Ribs compose the Top and the Sides of the Thoracic Cavity Large muscle (Diaphragm) comprises the Bottom Lungs are enclosed by plueral membranes Parietal Membrane outer layer near thoracic cavity and diaphragm Visceral Membrane inner layer, fused to the lungs Seperated by a low pressure fluid (less than 1 ATM) Inhalation Muscles and tissue is busy using O2 Biproduct is CO2 When CO2 levels increase excessively, Breathing Center in Medulla Oblongata is stimulated Doesn't respond to Low O2, but responds to high CO2 Certain bodies do respond to low O2 carotid bodies aortic bodies can also increase breathing rate Occurs when stimulus is sent to the Diaphragm Diaphragm is normally in dome-shaped position Stimulus causes contraction to occur Contraction causes thoracic cavity to enlarge Enlargement draws air into the lungs (Negative Pressure) Exhalation Occurs when the diaphragm relaxes As lungs fill, stretch receptors in the alveoli are stimulated Send signal to the medulla Tell it to stop contracting It quits sending signals to the diaphragm The diaphragm relaxes The size of the Thoracic Cavity Decreases Air is forced out of lungs Lung Capacities Tidal Volume air that is typically breathed in and out Inspiratory Reserve Volume air that can be breathed in beyond Tidal Volume Expiratory Reserve Volume air that can be breathed out beyond Tidal Volume Residual Volume air that cannot be breathed out remains in lungs Total lung Volume amount of air in lungs at full inspiration Vital Capacity Total Lung Volume minus residual volume is air that can be moved Respiration Mechanisms and Transport of Gases Two types of Respiration: External (exchange of gases in lungs) Internal (exchange of gases between blood and tissue cells) Exchange takes place because of pressure differentials Gases move from higher pressure to lower pressure In Venous blood CO2 pressure is higher in blood than in alveoli CO2 diffuses out of blood into alveoli O2 pressure is lower in blood than alveoli O2 diffuses into blood from alveoli In Arterial blood CO2 is higher in tissues than in artery CO2 diffuses from tissues to arteries O2 is higher in arteries than in tissues O2 diffuses from arteries to tissues Oxygen is carried in the blood by hemoglobin Hemoglobin + O2 = Oxyhemoglobin Loose binding between the two (O2 easily given up to tissues) CO2 is Harder to Understand When O2 is released by the hemoglobin molecule, Oxyhemoglobin (bright red) becomes deoxyhemoglobin (dark purple) Deoxyhemoglobin now can carry CO2 back to the lungs Still, some CO2 disolves into solution (7%) Binding occurs with the amino site on the hemoglobin This differs from where O2 binds (no competition) Carbaminohemoglobin formed Decomposes rapidly when PCO2 is low About 15-20% of CO2 carried this way Third way CO2 is transported is by Bicarbonate Ions CO2 reacts with H2O to form H2CO3 (Carbonic Acid) Occurs slowly in blood plasma Some CO2 seep into the RBC's RBC's contain enzyme (carbonic anhydrase) Speeds up the reaction Carbonic Acid disassociates immediately to H+ and bicarbonate ions These leave the RBC and enter the plasma for transport to the lungs As blood passes through the lungs Dissolved CO2 diffuses into alveoli H+ and bicarbonate ions reform carbonic acid molecules Carbonic anhydrase makes CO2 and H2O CO2 diffuese again into the alveoli Carbaminohemoglobin also releases CO2 into the alveoli CO (Carbon Monoxide) Produced by gasoline engines Also present in smokers CO binds with hemoglobin more tightly than O2 With CO present, less O2 can be transported Results in O2 deficincies and tissues suffer (die)