The Respiratory System

1. The Respiratory System

2. Functions of the Respiratory System • Gas exchanger • Air goes to blood • Blood goes to cells • Air distributor Other functions • Humidification • Filtering • Phonation • Warming • Control of pH • Olfaction

3. Respiratory System • Primary function – Gas exchange: to obtain oxygen and remove carbon dioxide. • Cells require oxygen to break down nutrients to release energy and produce ATP = Cellular Respiration • Cells must excrete carbon dioxide that results from cellular respiration.

4. Cellular Respiration - Review • C6H12O6 (aq) + 6 O2 (g) → 6 CO2 (g) + 6 H2O (l) • Without O2,a cell can only undergo fermentation, resulting in a net gain of only 2 ATP for the cell. • Why would this be a problem? • The result of cellular respiration is carbon dioxide and water. This carbon dioxide enters the blood stream and there it has various functions, including: • Regulation of blood pH • Haldane Effect • Bohr Effect • Autoregulation of blood supply to tissues

5. Cellular Respiration • Therefore it is incredibly important that cellular respiration takes place, in a timely manner, throughout the body. • When O2 levels are limited, cellular respiration activity slows down and the body reverts to fermentation. • What are the results of fermentation? • The respiratory system allows for gas exchange between the air and blood in the body to occur, resulting in an intake of oxygen from the atmosphere.

6. Introduction to Respiration • Respiration – gas exchange between atmosphere and cells. • Ventilation – movement of air into and out of lungs. • Gas exchange between blood and air in lungs = external respiration. • Gas transport in blood between lungs and body cells. • Gas exchange between blood and cells = internal respiration. • Cellular respiration – process of oxygen utilization and carbon dioxide production at the cellular level.

7. Organs Involved • Upper Respiratory Tract • Nose • Nasopharynx • Oropharynx • Laryngopharynx • Larynx • Lower Repsiratory Tract 1. Trachea 2. Bronchial Tree 3. Lungs

9. The Nose • Protrudes from face • Openings called nares • Ala are cartilage rings or flares at nares • Floor made of palatine and maxilla • Roof formed by ethmoid • Septum made of cartilage and bone (perpendicular plate of ethmoid and vomer) • Lined with mucosa • Meatuses formed cavities

10. Functions of the Nose • Passageway – filters, warms, moistens and chemically examines air • Smell • Phonation • Paranasal sinuses – air filled spaces that reduce weight of skull and affect quality of voice.

11. The Nose • Nostrils (nares) – are where air enters and leaves nasal cavity. • Nasal cavity – hollow space behind nose • Nasal conchae– bones that divide nasal passageway. • These support the nasal cavity and increase surface area. • Why is this important? • Help in nasal congestion in response to climatic changes and needs of the body. • Mucous membrane – epithelium rich in mucous-secreting goblet cells that trap dust and other particles. • How would this aid the respiratory system?

12. Pharynx (throat) • Made of muscle and mucous lining into 3 divisions • Nasopharynx – posterior nares to soft palate • Oropharynx – soft palate to hyoid bone; adenoid tonsils • Laryngopharynx – hyoid bone to esophagus; palatine and lingual tonsils

13. The Larynx • Enlargement in airway. • Houses vocal cords. • Upper end of trachea • 3-6th cervical vertebrae • Made of 9 pieces of cartilage in shape of box. • Thyroid muscle – called “Adam’s apple” • Glottis – opening between vocal cords. Triangular slit. Present during normal breathing. Muscles close glottis when eating or drinking. • Why would this be important? • Prevent food and liquid from entering trachea.

14. The Larynx • Epiglottis – lid. Muscle that allows air into larynx. • Closes during eating. Why? • Arytenoids – hold vocal cords • Vocal cords – fibroelastic bands stretched across hollow interior • Males is larger with less fat • Function to produce voice (pitch determined by length and tension in cords) • Changing the shape of the pharynx and oral cavity and using the tongue and lips transform sounds waves to words.

15. The Trachea • “Windpipe” – flexible tube lined with ciliated mucous membrane tissue. • Made of smooth muscle • Contains “C” shaped rings of cartilage • 4.5 inches long • Provides passageway to and from lungs • Splits into left and right bronchi.

16. Bronchi • Made similar to trachea but complete rings • Branched into primary, secondary bronchi, bronchioles, alveolar ducts, alveoli • Provide passageways and alveoli provide gas exchange surface

17. Bronchial tree • Branched airways leading from the trachea to the air sacs in the lungs. • Left and right bronchi, divide into primary, secondary… • Bronchioles – terminal bronchioles, smaller tubes. Lack cartilage. • Alveoli – air sacs in lungs connected to the capillary network. Provide large surface area. • Why is the large surface area important for alveoli? • O2 diffuses through cell walls into blood • Co2 diffuses through blood into cell walls.

18. Alveoli • Alveolar ducts are very thin ducts that connect the terminal bronchioles to the alveolar sacs. • Alveoli lie within the capillary network. • Two adult lungs have about 300 million alveoli, providing a surface area nearly half the size of a tennis court.

19. Lungs • 3 lobes in Rt. Lung and 2 in the left. Therefore R lung larger than the left. • Root of lung consists of primary bronchus and pulmonary arteries and veins • Function is to provide rapid exchange of gases. • Lobes connected to lymphatic system, blood vessels, air passages, nerves, and connective tissue.

20. Respiratory Mucosa • Lining of entire respiratory system • Makes mucous (sputum) • Mucous will help clean and filter • Make about 125 mL daily • Moves about 1 to 2 cm per minute from lower respiratory tract to oropharynx • Swallow or spit out

21. Quiz Time! Very short quiz over anatomy and some functions of the respiratory system.

22. Breathing Mechanisms • Inspiration – inhalation • Atmospheric pressure, due to weight of air, is the force that moves air into lungs. • At sea level, the atmospheric pressure is sufficient to support a column of mercury about 760 mm high in a tube. Therefore, normal air pressure = 760 mmHg. • Normal, resting inspiration – if pressure inside lungs and alveoli decreases, atmospheric pressure will push outside air in.

23. Normal, quiet Inspiration • Diaphragm contraction (result of impulse from phrenic nerves)  diaphragm moving down. • Increase in vertical diameter of thorax • Increase in transverse diameter of thorax • Alveoli air pressure decreases about 2-3 mmHg less than atmospheric pressure. • Expansion of lungs – cohesion of visceral and parietal pleuras • Air enters lungs = inspiration.

24. Normal, quiet Expiration • Expiration – exhalation • Force comes from elastic recoil of tissues and surface tension (attraction of H2O molecules that make it difficult for alveoli to inflate) • Passive process • Relaxation of inspiratory muscles • Decrease in size of thorax – elastic recoil of lung tissue • Increase in intrathoracic pressure • Decrease in size of lungs • Increase in alveolar pressure from about -3mm of Hg to +3 or +4 mm Hg (Pressure and volume in inverse relationship) • Air moves out of lungs – expiration

25. Respiratory Volumes • Respiratory Cycle – 1 inspiration and following expiration. • Tidal Volume – volume that enters during 1 resp. cycle • Resting Tidal volume – about 500 mL of air. • Inspiratory reserve volume (IRV) – During forced inspiration, air in addition to resting tidal volume can enter lungs. This maxes out at about 3,000 mL of air. • Expiratory reserve volume (ERV) – lungs can forcefully expel about 1,100 mL more than resting tidal volume. • Residual volume – amount always in lungs = 1,200 mL.

26. Respiratory Volumes • Because of the residual volume, new air inhaled mixes with old air in the lungs. • This is very important as it prevents the concentration of O2 and CO2 in the lungs from fluctuating much during respiration. • Why would this be important? • CH3CH2OH(g) + O2(g) -> HC2H3O2(g) + H2O(l) • Ethyl alcohol and oxygen to acetic acid and water. • The breathalyzer. No way around it!

27. Respiratory Capacities • When two or more volumes are combined. • Vital Capacity – tidal volume + ERV + IRV = 4,600 mL. Maximum air during deepest breath possible. • Inspiratory Capacity – Tidal volume + IRV = 3,500 mL. Maximum amount a person can inhale after resting expiration. • Functional residual capacity – ERV + Residual volume = 2,300 mL. Volume of air in lungs after resting exp. • Total lung capacity – vital capacity + residual volume = 5,800 mL. Varies with age, sex and body size.

28. The didgeridoo • Wind instrument developed by Aborigines in Australia over 1,500 years ago. • Often considered world’s oldest wind instrument. • Termite-bored branches are often used to make these instruments. • Vibrations produced by the player’s lips and the strength of the vocal tract influence the timbre of the sound. • The technique of circular breathing can help.

29. Gas Exchange • Respiratory membrane – walls of alveoli exchange gas between blood and air. • Gases diffuse from regions of high pressure to regions of low pressure. • Air = 78% N, 21% O, 0.04% CO2 • Partial pressure – amount of pressure each gas contributes to its concentration. • O2 = 160 mmHG (21% of 760 mmHg) • Gas diffuses into liquid - O2 into blood. • Another example: CO2 into coca cola.

30. Gas Exchange • Follow partial pressure gradients. • Each gas diffuses between blood and its surroundings from areas of higher partial pressure to areas of lower partial pressure until the partial pressures in the two regions reach equilibrium. • PO2is alveoli is 105 mm of Hg while in the blood it is only 40 mmHg. Thus O2 diffuses from the alveolar air into the blood. • PCO2 is 45 mmHg in blood but only 40 mmHg in alveolar air. Therefore CO2 diffuses from the blood into the alveoli.

31. Oxygen Transport

32. Oxygen Transport • 98% of O2 binds with iron group of hemoglobin. 2% dissolves in plasma. • In lungs, combines with hemoglobin  oxyhemoglobin. • This is an unstable bond and as PO2 decreases, oxygen releases and diffuses into cell to be used in cellular respiration. • More O2 is released from oxyhemoglobin when [CO2] is high, when blood pH is low, and when blood temperature is high. • When might these conditions occur? • Exercise, when more O2 is released to the muscles.

33. Carbon Dioxide Transport • Tissues have relatively high PCO2 to blood, so CO2 rapidly diffuses into blood. • Blood transports CO2 to lungs as CO2 in plasma, bonded to hemoglobin, or as bicarbonate ion (HCO3-) • CO2 bonds with the amino group of hemoglobin forming carbaminohemoglobin, which decomposes in areas of low PCO2 releasing carbon dioxide. • Do you think it’s possible for both O2 and CO2 to be bound to hemoglobin at the same time? • Yes! CO2 binds to the amino group while O2 binds to the iron group of hemoglobin. Some exceptions…

34. Bohr Shift • At lower pH (more acidic environment), hemoglobin will bind to oxygen with less affinity = Bohr Shift • That is, oxygen is more likely to be released from oxyhemoglobin in a more acidic environment. • In RBCs carbonic acid (H2CO3) dissociates into protons (H+) and bicarbonate ions (HCO3-). • Since CO2 is in direct equilibrium with the concentration of protons in the blood, increasing CO2 levels leads to a decreases in pH  Bohr Shift.

35. Haldane Effect • Related to the Bohr Shift is the Haldane Effect, which is the phenomenon in which oxygenated blood has a reduced capacity for hemoglobin to carry carbon dioxide and vice versa.

36. Quiz Time! A short quiz over physiology and gas exchange in the respiratory system