1. Respiratory System

2. Respiratory System – Fig. 14-1
Includes the passages that transport air to and from the lungs, and the air sacs in which gas exchange occurs. Respiration is the entire process by which gases are exchanged between the atmosphere and the body cells.
(Overview of respiratory system)
(Don’t get confused with cellular respiration which is the breakdown of food to produce chemical energy.)

3. Organs of the Respiratory System
Upper respiratory (outside thorax) – nose, larynx, & pharynx
Lower respiratory (within thorax) – trachea, bronchial tree, and lungs
Nose
Supported by bone & cartilage
Nostrils provide entrances for air

4. Organs of the Respiratory System
Nasal Cavity (space behind the nose) – Fig. 14-4
Divided medially by the nasal septum
Nasal conchae divide the cavity into passageways & help increase the surface area of the mucous membrane
Mucous membrane (Fig. 14-2) – filters, warms & moistens incoming air; particles trapped in the mucus are carried to the pharynx by ciliary action & are swallowed

5. Organs of the Respiratory System

6. Organs of the Respiratory System
Cilia
Pseudostratified
epithelium
Submucosa
Mucous gland

7. Organs of the Respiratory System
Sinuses – Fig. 14-3
Spaces in the bones of the skull that open into the nasal cavity
Lined with mucous membrane that is continuous with the lining of the nasal cavity
Function mainly to reduce weight of skull, they also serve as resonant chambers that affect the quality of the voice

8. Organs of the Respiratory System

9. Organs of the Respiratory System
Pharynx (throat)
Located behind the mouth and between the nasal cavity and the larynx
Functions as a common passage for air and food
Aids in creating vocal sounds

10. Organs of the Respiratory System

11. Organs of the Respiratory System
Larynx – Fig. 14-5
Enlargement at the top of the trachea
Serves as passageway for air & helps prevent foreign objects from entering the trachea
Composed o muscles & cartilage
Contains the vocal cords which produce sounds by vibrating as air passes over them
Pitch of sound is related to the tension of cords
Intensity is related to the force of the air passing over the cords
Glottis (space between vocal cords) & epiglottis help prevent food & liquid from entering the trachea

12. Organs of the Respiratory System

13. 1- vocal cords; 2 – vestibular fold; 3 – epiglottis; 4 – glottis; 5 – cartilage; 6 – sinus piriformis; 7 – base of the tongue

14. Organs of the Respiratory System
Larynx – Fig. 14-5
(vocal cords)

15. Organs of the Respiratory System
Trachea – Fig. 14-6
Extends into the thoracic cavity in front of the esophagus
Divides into the right and left bronchi
Mucous lining continues to filter incoming air
Wall is supported by incomplete (C shaped) cartilaginous rings; keeps trachea from collapsing

16. Organs of the Respiratory System

17. Organs of the Respiratory System
Bronchial tree –
Consists of branched air passages that lead from the trachea to the air sacs
Primary bronchi  secondary bronchi  bronchioles  alveolar ducts  alveolar sacs  alveoli
****Respiratory surface is alveoli – exchange of carbon dioxide and oxygen between alveoli & capillaries of circulatory system****

18. Organs of the Respiratory System
Bronchial tree (con’t)
Structure of the respiratory tubes
As tubes branch the amount of cartilage in the wall decreases and the muscular layer becomes more prominent
Elastic fibers in the walls aid the breathing mechanism
Epithelial lining changes from pseudostratified & ciliated to cuboidal & simple squamous as tubes decrease in size

19. Organs of the Respiratory System

20. Organs of the Respiratory System

21. Organs of the Respiratory System
Lungs
Left and right lungs are separated by the mediastinum and are enclosed by the diaphragm & the thoracic cage
Visceral pleura is attached to the surface of the lungs; parietal lines the thoracic cavity
R. lung – 3 lobes; L. lung – 2 lobes
Lobes contain – alveoli, nerves, blood vessel, and lymphatic & connective tissue (no muscle tissue)

22. Organs of the Respiratory System

23. Organs of the Respiratory System

24. Inspiration – air moves into lungs (atm. Pressure = 760 mm Hg)
Breathing/Pulmonary Ventiliation – Fig – movement of air into & out of lungs
Inspiration – air moves into lungs (atm. Pressure = 760 mm Hg)
Phrenic nerve impulses cause diaphragm to contract
As dome shaped diaphragm moves downward the size of the thoracic cavity increases
External intercostal muscles may contract causing ribs to rise which causes in increase in the size of thoracic cavity
As size of thoracic cavity increases pressure within alveoli DECREASES (758 mm Hg)
Atm. Pressure which is greater on the outside forces air into respiratory tract
Lungs inflate

25. Expiration – air moves out of lungs
Breathing/Pulmonary Ventilation – Fig – movement of air into & out of lungs
Expiration – air moves out of lungs
Diaphragm & external respiratory muscles relax
Elastic tissue of the lungs, thoracic cage and abdominal organs, which were stretched during inspiration suddenly recoil & surface tension causes alveolar walls to collapse
Pressure within the alveoli INCREASES (761 mm Hg) causing expiration of air out of lungs

26. Breathing/Pulmonary Ventilation – Fig
Breathing/Pulmonary Ventilation – Fig – movement of air into & out of lungs
(Boyles Law and ventilation)

27. Respiratory or Pulmonary Air Volumes & Capacities – Fig. 14-13
Breathing/Pulmonary Ventilation – Fig – movement of air into & out of lungs
Respiratory or Pulmonary Air Volumes & Capacities – Fig
Tidal volume – amount of air that normally moves into or out of lungs during quiet breathing (approx. 500 ml)
Inspiratory reserve volume – additional air that can be inhaled (approx ml)
Expiratory reserve volume – additional air that can be exhaled (approx ml)
Residual volume – amount of air that remains in lungs (approx ml)

28. Respiratory or Pulmonary Air Volumes & Capacities – Fig. 14-13
Breathing/Pulmonary Ventilation – Fig – movement of air into & out of lungs
Respiratory or Pulmonary Air Volumes & Capacities – Fig
Vital capacity – maximum amount of air a person can exhale after taking the deepest breath possible
VC = TV + IRV + ERV
Lung Capacity – TLC = VC + RV – varies with age, sex, body size, athlete vs. non athlete
Residual air mixes with new air, this prevents concentrations of oxygen and carbon dioxide from fluctuating excessively with each new breath

29. Control of Breathing – normal breathing is rhythimic & involuntary, although the respiratory muscles can be controlled voluntarily
Respiratory Center
Located in the brain stem and includes parts of the medulla oblongata & pons
Controls both inspiration & expiration & rates of breathing

30. Factors affecting breathing
Control of Breathing
Factors affecting breathing
Breathing is affected by certain chemicals, the stretching of lung tissues & the persons emotional state
Chemosensitive areas are associated with the respiratory center
CO2 combines with H2O to form H2CO3 which in turn dissociates into HCO3- & H+
Chemosensitive areas mainly influenced by [H+], this concentration determines acidity of blood
Stimulation of these areas causes the breathing rate to increase

31. Factors affecting breathing
Control of Breathing
Factors affecting breathing
Chemoreceptors in the carotid & aortic bodies
Sensitive to low [O2]
When [O2] is low  increase breathing rate
An inflation reflex is triggered by stretching the lung tissues; this reflex reduces the duration of inspiratory movements & prevents over-inflation of the lungs during forceful breathing

32. Alveolar Gas Exchange – Internal Respiration
Alveoli
Tiny sacs clustered at the distal ends of the alveolar ducts
Some alveoli have openings into adjacent air sacs that provide alternate pathways for air when passages are obstructed
Respiratory Membrane/Surface
Consists of the alveolar & capillary walls
Gas exchange occurs here
Diffusion
Gasses diffuse from regions of higher concentration to lower concentration
O2 diffuses from alveoli to capillaries;
CO2 diffuses from capillaries to lungs

33. Organs of the Respiratory System

34. Organs of the Respiratory System

35. Transport of Gases – blood transports O2 & CO2 – Fig. 14-12
O2 transport
Mainly combines with HB (hemoglobin) to produce oxyhemoglobin O2 + Hb  HbO2
HbO relatively unstable & releases O2 in areas where [O2] pressure is low
There is an increase in the release of O2 from the blood when
CO2 levels increase
pH becomes more acidic
blood temperature increases

36. Transport of Gases – blood transports O2 & CO2 – Fig. 14-12
CO2 transport
Carried in solution either bound to Hb or as HCO3-
Most CO2 transported as HCO3- (approx. 70%)
CO2 + Hb  HbNHCOOH (carbamino hemoglobin) (approx. 23%)
Some dissolved in plasma (approx. 7%)

37. Transport of Gases – blood transports O2 & CO2 – Fig. 14-12
Carbon monoxide – CO
Combines with Hb more readily than O2 & forms a stable compound
Toxic because decreases Hb available for transport of O2
Utilization of O2 – used for cellular respiration
C6H12O6 + 6O2  6CO2 + H2O + ATP