2. Functions of the Respiratory System Provides extensive surface area for gas exchange Moves air to and from exchange sites Protects respiratory surfaces from dehydration, environmental variations, and invasion from pathogens Produces sounds involved in speaking, singing, and other forms of communication Facilitates detection of olfactory stimuli by olfactory receptors

3. Organization of the Respiratory System The respiratory system is divided into upper and lower regions Upper respiratory system Nose, nasal cavity, paranasal sinuses, pharynx Lower respiratory system Larynx (voice box), trachea, bronchi, bronchioles, alveoli

5. Respiratory Mucosa Lines conducting portion of respiratory system. Nasal cavity and superior pharynx consist of pseudostratified ciliated epithelium. Contains glands that secrete mucous. Inferior pharynx consists of stratified squamous epithleium. Trachea and Bronchii consist of pseudostratified ciliated epithelium. Bronchioles consist of cuboidal cells with scattered cilia Alveoli consist of simple squamous epithelium.

6. Respiratory System Defense

7. Mucous glands along much of the tract secrete a sticky mucous that traps particles. Cilia sweep the mucous and particles towards the pharynx. The mucous and particles are swallowed, and the microorganisms are destroyed by the acids in the stomach. Hairs in the nasal cavity trap larger particles. Macrophages in the alveolar region ingest particles that make it that far.

9. Upper Respiratory System The nose and nasal cavity Air enters through the external nares (nostrils) Nasal septum divides the nasal cavity into left and right portions. The hard palate form the floor of the nasal cavity and separates the nasal cavity from the oral cavity. The soft palate extends posterior from the hard palate.

10. Upper Respiratory System The Pharynx Chamber shared by the digestive and respiratory systems

12. The Larynx Also known as the voicebox Structures are mostly made of hyaline cartilage Contains: Glottis – opening to larynx Thyroid cartilage – largest section, protects glottis, also known as the adam’s apple Epiglottis – made of elastic cartilage, covers glottis during swallowing as thyroid cartilage moves superiorly

15. The Larynx Vestibular ligament and vocal ligaments Extend anteriorly-posteriorly within the thyroid cartilage Known as vocal cords Vibrate as air passes over them to produce sound.

16. The Larynx

17. The Trachea and Primary Bronchi Trachea Runs from the level of C6 to T5. Consists of rings of C-shaped hyaline cartilage. Open portion of the “C” is posterior and faces the esophagus This allows food to pass without problem.

18. The Trachea and Primary Bronchi Primary Bronchi Made of C-shaped rings of cartilage Where the trachea branches Left primary bronchus takes air to and from the left lung, right primary bronchus takes air to and from the right lung. Right primary bronchus is larger in diameter and is at a steeper angle. More objects find their way into the right primary bronchus.

19. The Trachea and Primary Bronchi

20. The Lungs Have lobes that are separated by fissures Right lung has 3 lobes Left lung has 2 lobes The Bronchi As the primary bronchi enter the lungs, they form secondary and tertiary bronchi. One secondary bronchus goes to each lobe of the lungs. The secondary bronchi branch to form the tertiary bronchi.

21. The Lungs

22. The Bronchi (con’t) The walls of the primary, secondary, and tertiary bronchi contain progressively less cartilage and progressively more smooth muscle. The constriction of this smooth muscle is what makes it difficult to breath is certain conditions.

23. The Lungs The Bronchioles Are formed from the multiple branching of the tertiary bronchi About 6500 bronchioles arise from each tertiary bronchus The walls of the bronchioles lack cartilage and are dominated by smooth muscle. Bronchodilation – enlargement of bronchioles Bronchoconstriction – narrowing of bronchioles Effect of asthma and anaphylaxis

24. The Lungs Alveolar ducts and alveoli Alveolar ducts connect bronchioles to alveoli Alveoli – sac-like structure Comprised of simple squamous epithelium Each lung contains approximately 150,000,000 alveoli This is where gas exchange takes place. Alveolar macrophages patrol the area to ingest any particles that eluded the other respiratory defense mechanisms.

26. The Lungs Pneumonia An infection that causes inflammation in the lungs. Fluid collects in the alveoli Bronchioles swell and constrict

27. How does air enter and exit your lungs?

28. Pulmonary Ventilation Physical movement of air into and out of the respiratory tract. The function of pulmonary ventilation is to maintain adequate alveolar ventilation Movement of air into and out of the alveoli. Assures continuous supply of oxygen and prevents build up of carbon dioxide.

29. Pulmonary Ventilation The Movement of Air To understand how air moves into and out of your lungs, it is important to understand the relationship between gas pressure and volume (Boyle’ Law) Boyle’s Law In a sealed container, at a constant temperature, if you increase the volume of the container, the pressure inside of that container will decrease. If the volume of that container is decreased, the pressure inside of that container will increase.

30. Pulmonary Ventilation

31. The Movement of Air (con’t) Pressure and air flow to the lungs Air will flow from an area of higher pressure to an area of lower pressure. 1. In the relaxed state, the diaphragm that forms the floor of the thoracic cavity is in the shape of a dome that projects into the throacic cavity. 2. When the diaphragm contracts, is tenses and moves inferiorly. 3. The volume of the thoracic cavity increases, thereby decreasing the pressure inside the thoracic cavity and lungs.

33. Pulmonary Ventilation The Movement of Air (con’t) 4. Air rushes into the lungs to equalize the pressure. 5. When the diaphragm relaxes, it moves superiorly. This decreases the volume of the throacic cavity and the lungs, which increases the pressure inside the cavity and lungs. 6. Air will then rush out to equalize the pressure.

36. Pulmonary Ventilation Respiratory Rates and Volumes Respiratory Rate (f)– number of breaths you take in one minute Average in adults is 12-18 Average in children is 18-20 Respiratory minute volume (V E )– amount of air moved each minute Calculated by multiplying rate (f) by tidal volume (V T ) V E = f x V T Average tidal volume is 500ml each normal breath

37. Pulmonary Ventilation Respiratory Rates and Volumes (con’t) Not all 500ml reaches the alveoli About 150ml remains in the conducting passageways (trachea, bronchi, bronchioles) This volume of air is called the anatomic dead space (V D ) Alveolar ventilation (V A )– amount of air reaching the alveoli each minute Less than respiratory minute volume because some air never reaches the alveoli. V A = f x (V T - V D )

38. Pulmonary Ventilation Respiratory Performance and Volume Relationships Resting tidal volume – amount of air you move during a single respiratory cycle About 500ml Residual volume – amount of air that remains in your lungs after maximum exhalation 1200ml in males; 1100ml in females

39. Pulmonary Ventilation

40. Respiratory Performance and Volume Relationships (con’t) Vital capacity – maximum amount of air that you can move into and out of your lung in a single respiratory cycle About 4800ml in males; 3400ml in females Total lung capacity – total volume of your lungs Calculated by adding vital capacity and the residual volume About 6000ml in males; 4500ml in females

41. Pulmonary Ventilation

42. How does gas enter and exit your bloodstream?

43. Gas Exchange Gases are exchanged between the alveolar air and the blood through diffusion. This diffusion is dependent on the concentration gradients and temperature of the molecules. To fully understand gas exchange, two gas laws must be understood. Dalton’s Law Henry’s Law

44. Gas Exchange Dalton’s Law and Partial Pressures Air is a mixture of nitrogen (78.6%), oxygen (20.9%), with the remaining 0.5% mostly water vapor and about 0.04% carbon dioxide This means that of the total pressure, 78.6% is due to N2 (P N2 ), 20.9% is due to O2 (P O2 ), 0.5% is due to H2O (P H2O ), and 0.04% is due to CO2 (P CO2 ). These partial pressures will help us determine in which direction the gasses will diffuse.

45. Gas Exchange Henry’s Law of Diffusion Between Gasses and Liquids At a given temperature, the amount of a particular gas in a given solution is proportional to the partial pressure of that gas. If partial pressure goes up, more gas will enter the solution. If partial pressure goes down, gas will leave the solution. Just like in a can of soda. Initial high pressure inside can, and when opened, the gas leaves the liquid. This will continue, theoretically, until equilibrium is reached.

46. Gas Exchange

47. At the level of the alveoli: When you breathe in: The partial pressure of oxygen is higher in the alveoli than in the blood, so oxygen will leave the alveoli and enter the blood. The partial pressure of carbon dioxide is greater in the blood than in the alveoli, so carbon dioxide will leave the blood and enter the alveoli. This is the same overall process that occurs at the cells of your body.

49. Hemoglobin Only about 1.5% of the oxygen in your blood is dissolved in the fluid. The rest of the oxygen is carried on hemoglobin molecules Specifically on the iron centers of the heme units in the hemoglobin Each hemoglobin can carry 4 oxygen molecules (has 4 heme units) Each red blood cell has about 280 million molecules of hemoglobin So…each red blood cell can carry over 1 billion oxygen molecules!!!

50. Hemoglobin On average though, each hemoglobin carries only 2 oxygen molecules. Hemoglobin saturation is normally at 50% As PO2 increases, more oxygen binds to the hemoglobin. The increase is not linear, because each oxygen that binds makes it easier for the next one to bind. Without hemoglobin, your blood would not be able to deliver enough oxygen to your cells.

51. Hemoglobin