1. BIOLOGY 252 Human Anatomy & Physiology
Chapter 23
The Respiratory System:
Lecture Notes

2. The Respiratory System
Cells continually use O2 & release CO2
Respiratory system designed for gas exchange
Cardiovascular system transports gases in blood
Failure of either system
rapid cell death from O2 starvation

3. Respiratory System Anatomy
Nose
Pharynx = throat
Larynx = voicebox
Trachea = windpipe
Bronchi = airways
Lungs
Locations of infections
upper respiratory tract is above vocal cords
lower respiratory tract is below vocal cords

4. Nose - Internal Structures
Large chamber within the skull
Roof is made up of ethmoid and floor is hard palate
Internal nares (choanae) are openings to pharynx
Nasal septum is composed of bone & cartilage
Bony swelling or conchae on lateral walls
See lab manual p – 1.17

5. Functions of the Nasal Structures
Olfactory epithelium for sense of smell
Pseudostratified ciliated columnar with goblet cells lines nasal cavity
warms air due to high vascularity
mucous moistens air & traps dust (cleanse)
cilia move mucous towards pharynx
Paranasal sinuses open into nasal cavity
found in ethmoid, sphenoid, frontal & maxillary
lighten skull & resonate voice

6. Pharynx Muscular tube (5 inch long) hanging from skull
skeletal muscle & mucous membrane
Extends from internal nares to cricoid cartilage
Functions
passageway for food and air
resonating chamber for speech production
tonsil (lymphatic tissue) in the walls protects entryway into body
Distinct regions -- nasopharynx, oropharynx and laryngopharynx

7. Cartilages of the Larynx
Thyroid cartilage forms Adam’s apple
Epiglottis - leaf-shaped piece of elastic cartilage
during swallowing, larynx moves upward
epiglottis bends to cover glottis
Cricoid cartilage - ring of cartilage attached to top of trachea
Pair of arytenoid cartilages sit upon cricoid
many muscles responsible for their movement
partially buried in vocal folds (true vocal cords)
See lab manual – p

8. Larynx Cartilage & connective tissue tube Anterior to C4 to C6
Constructed of 3 single & 3 paired cartilages

9. Vocal Cords
False vocal cords (ventricular folds) found above vocal folds (true vocal cords)
True vocal cords attach to arytenoid cartilages

10. Trachea Size is 12 cm (5 in) long & 2.5 cm (1in) in diameter
Extends from larynx to T5 anterior to the esophagus and then splits into bronchi
Layers
mucosa = pseudostratified columnar with cilia & goblet cells
submucosa = loose connective tissue & seromucous glands
hyaline cartilage = 16 to 20 incomplete rings
open side facing esophagus contains trachealis m. (smooth)
internal ridge on last ring called carina
adventitia binds it to other organs
See lab manual p. 2.5 – 2.7

11. Trachea and Bronchial Tree
Full extent of airways is visible starting at the larynx and trachea

12. Histology of the Trachea
Ciliated pseudostratified columnar epithelium
Hyaline cartilage as C-shaped structure closed by trachealis muscle

13. Copyright © 2014 John Wiley & Sons, Inc. All rights reserved.
Trachea
The trachea extends from the larynx to the primary bronchi
Copyright © 2014 John Wiley & Sons, Inc. All rights reserved.

14. Airway Epithelium
Ciliated pseudostratified columnar epithelium with goblet cells produce a moving mass of mucus.

15. Tracheostomy and Intubation Tracheotomy, syn. = Tracheostomy
Reestablishing airflow past an airway obstruction
crushing injury to larynx or chest
swelling that closes airway
vomit or foreign object
Tracheostomy is incision in trachea below cricoid cartilage if larynx is obstructed
Intubation is passing a tube from mouth or nose through larynx and into trachea
Tortora & Grabowski 9/e 2000 JWS

16. Bronchi and Bronchioles
Primary bronchi supply each lung
Secondary bronchi supply each lobe of the lungs (3 right + 2 left)
Tertiary bronchi supply each bronchopulmonary segment
Repeated branchings called bronchioles form a bronchial tree

17. Lung Volumes and Capacities
Tidal volume = amount air moved during quiet breathing
MVR= minute ventilation is amount of air moved in a minute
Reserve volumes ---- amount you can breathe either in or out above that amount of tidal volume
Residual volume = 1200 mL permanently trapped air in system
Vital capacity & total lung capacity are sums of the other volumes
Tortora & Grabowski 9/e 2000 JWS

18. Structures within a Lobule of Lung
Branchings of single arteriole, venule & bronchiole are wrapped by elastic CT
Respiratory bronchiole
simple squamous
Alveolar ducts surrounded by alveolar sacs & alveoli
sac is 2 or more alveoli sharing a common opening

19. Histology of Lung Tissue
Photomicrograph of lung tissue showing bronchioles, alveoli and alveolar ducts.

20. Cells Types of the Alveoli
Type I alveolar cells
simple squamous cells where gas exchange occurs
Type II alveolar cells (septal cells)
free surface has microvilli
secrete alveolar fluid containing surfactant
Alveolar dust cells
wandering macrophages remove debris

21. Details of Respiratory Membrane
Find the 4 layers that comprise the respiratory membrane

22. Alveolar-Capillary Membrane
Respiratory membrane = 1/2 micron thick
Exchange of gas from alveoli to blood
4 Layers of membrane to cross
alveolar epithelial wall of type I cells
alveolar epithelial basement membrane
capillary basement membrane
endothelial cells of capillary
Vast surface area = handball court

23. Double Blood Supply to the Lungs
Deoxygenated blood arrives through pulmonary trunk from the right ventricle
Bronchial arteries branch off of the aorta to supply oxygenated blood to lung tissue
Venous drainage returns all blood to heart

24. Breathing or Pulmonary Ventilation
Air moves into lungs when pressure inside lungs is less than atmospheric pressure
How is this accomplished?
Air moves out of the lungs when pressure inside lungs is greater than atmospheric pressure
Atmospheric pressure = 1 atm or 760mm Hg

25. Boyle’s Law
As the size of closed container decreases, pressure inside is increased
The molecules have less wall area to strike so the pressure on each inch of area increases.

26. Dimensions of the Chest Cavity
Breathing in requires muscular activity & chest size changes
Contraction of the diaphragm flattens the dome and increases the vertical dimension of the chest

27. Quiet Inspiration
Diaphragm moves 1 cm & ribs lifted by external intercostal muscles and we inhale 500 ml of air
If Diaphragm moves 10 cm & ribs are lifted accordingly Intrathoracic pressure falls and we inhale 2-3 liter of air.

28. Quiet Expiration Passive process with no muscle action
Elastic recoil & surface tension in alveoli pulls inward
Alveolar pressure increases & air is pushed out

29. Labored Breathing Forced expiration Forced inspiration
abdominal mm force diaphragm up
internal intercostals depress ribs
Forced inspiration
sternocleidomastoid, scalenes & pectoralis minor lift chest upwards as you gasp for air

30. Intrapleural pressures or Intrathoracic pressures (see text p
Intrapleural pressures or Intrathoracic pressures (see text p. 859) & Alevolar or Intrapulmponary pressures
Always subatmospheric (756 mm Hg)
As diaphragm contracts intrathoracic pressure decreases even more (754 mm Hg)

31. Alveolar Surface Tension
Thin layer of fluid in alveoli causes inwardly directed force = surface tension
water molecules strongly attracted to each other
Causes alveoli to remain as small as possible
Detergent-like substance called surfactant produced by Type II alveolar cells
lowers alveolar surface tension
insufficient in premature babies so that alveoli collapse at end of each exhalation

32. Pneumothorax
Pleural cavities are sealed cavities not open to the outside
Injuries to the chest wall that let air enter the intrapleural space
causes a pneumothorax
collapsed lung on same side as injury
surface tension and recoil of elastic fibers causes the lung to collapse
Tortora & Grabowski 9/e 2000 JWS

33. Compliance of the Lungs
Ease with which lungs & chest wall expand depends upon elasticity of lungs & surface tension
Some diseases reduce compliance
tuberculosis forms scar tissue
pulmonary edema - fluid in lungs & reduced surfactant
paralysis
Tortora & Grabowski 9/e 2000 JWS

34. Airway Resistance Resistance to airflow depends upon airway size
increase size of chest
airways increase in diameter
contract smooth muscles in airways
decreases in diameter

35. Breathing Patterns Eupnea = normal quiet breathing (yu-p-ne a)
Apnea = temporary cessation of breathing (ap ne a)
Dyspnea =difficult or labored breathing (disp-ne a)
Tachypnea = rapid breathing (tak-ip-ne a)
Diaphragmatic breathing = descent of diaphragm causes stomach to bulge during inspiration
Costal breathing = just rib activity involved

36. Modified Respiratory Movements
Coughing
deep inspiration, closure of glottis & strong expiration blasts air out to clear respiratory passages
Hiccuping
spasmodic contraction of diaphragm & quick closure of glottis produce sharp inspiratory sound
Valsalva maneuver
- forced exhalation against a closed glottis as may occur when lifting a heavy weight
Chart of others on page 868

37. The Gas Laws
Boyle’s Law – the pressure of a gas varies inversely with its volume (if temperature remains constant).
Gay-Lussac’s Law – the pressure of a gas increases directly in proportion to its (absolute) temperature.
Tortora & Grabowski 9/e 2000 JWS

38. The Gas Laws
Dalton’s Law – in a mixture of gasses, each gas exerts a partial pressure, proportional to its concentration.
Henry’s Law – the quantity of a gas that will dissolve in a liquid is directly proportional to its partial pressure, if temperature remains constant.
Tortora & Grabowski 9/e 2000 JWS

39. What is the Composition of Air?
Air = 20.93% O2, 79.04% N2 and 0.03% CO2
Alveolar air = 14% O2, 79% N2 and 5.2% CO2
Expired air = 16% O2, 79% N2 and 4.5% CO2
Anatomic dead space = 150 ml of 500 ml of tidal volume
Tortora & Grabowski 9/e 2000 JWS

40. Dalton’s Law
In a mixture of gasses, each gas exerts a partial pressure, proportional to its concentration.
Each gas in a mixture of gases exerts its own pressure
as if all other gases were not present
partial pressures denoted as p
Total pressure is sum of all partial pressures
atmospheric pressure (760 mm Hg) = pO2 + pCO2 + pN2 + pH2O
Thus in atmospheric air with a total pressure of
760 mm Hg, O2 which makes up 20.93% - has a
partial pressure of 20.93/100 x 760 = mm Hg.

41. Henry’s Law
The quantity of a gas that will dissolve in a liquid is directly proportional to its partial pressure, if temperature remains constant. OR
The quantity of a gas that will dissolve in a liquid depends upon the amount of gas present and its solubility coefficient

42. Partial Pressures of Respiratory Gases at Sea Level
Total
H2O O CO N
Partial pressure (mmHg)
% in Dry Alveolar Arterial Venous Diffusion Gas dry air air air blood blood gradient
Tortora & Grabowski 9/e 2000 JWS

43. The Processes of Respiration
Pulmonary ventilation – or breathing, is the mechanical flow of air into (inhalation) and or out of (exhalation) the lungs
External respiration – is the exchange of gases between the alveoli of the lungs and the blood in the pulmonary capillaries. In this process, pulmonary capillary blood gains O2 and loses CO2
Internal respiration – is the exchange of gases between blood in systemic capillaries and tissue cells. The blood loses O2 and gains CO2. Within cells, the metabolic reactions that consume O2 and give off CO2 during the production of ATP termed cellular respiration
___________________________________________________
Gas transport – is the transport of O2 from the lungs to the systemic tissues and the transport of CO2 from the systemic tissues to the lungs.
Tortora & Grabowski 9/e 2000 JWS

44. External Respiration
Gases diffuse from areas of high partial pressure to areas of low partial pressure
Exchange of gas between alveolar air & blood
Deoxygenated blood becomes 100% saturated with O2
Compare gas movements in pulmonary capillaries to tissue capillaries

45. Rate of Diffusion of Gases
Depends upon partial pressure of gases in air
pO2 at sea level is mm Hg
10,000 feet (~3000 m) is 110 mm Hg / 50,000 feet is
18 mm Hg
Large surface area of our alveoli
Diffusion distance is very small (0.5 µm)
Solubility & molecular weight of gases
O2 smaller molecule diffuses somewhat faster
CO2 dissolves 24x more easily in water so net outward diffusion of CO2 is much faster

46. Internal Respiration Exchange of gases between blood & tissues
Conversion of oxygenated
blood into deoxygenated
Observe diffusion of O2 inward
at rest 25% of available O2 enters cells
during exercise more O2 is absorbed
Observe diffusion of CO2
outward

47. Oxygen Transport in the Blood
Oxyhemoglobin contains 98.5% chemically combined oxygen and hemoglobin
inside red blood cells
Does not dissolve easily in water
only 1.5% transported dissolved in blood (plasma)

48. Carbon Monoxide Poisoning
CO from car exhaust & tobacco smoke
Binds to the Hb heme group more successfully than O2
CO poisoning
Treat by administering pure O2
Tortora & Grabowski 9/e 2000 JWS

49. Carbon Dioxide Transport
Is carried by the blood in 3 ways
dissolved in plasma
combined with the globin part of Hb molecule forming carbaminohemoglobin
as part of bicarbonate ion
CO2 + H2O combine to form carbonic acid (H2CO3) that dissociates into hydrogen ions (H+) and bicarbonate ions (HCO3-)
Tortora & Grabowski 9/e 2000 JWS

50. Oxyhemoglobin Dissociation Curve (Hemoglobin saturation and oxygen partial pressure)
Blood is almost fully saturated at pO2 of 60mm
people OK at high altitudes & with some diseases
Between 40 & 20 mm Hg, large amounts of O2 are released as in areas of need like contracting muscle

51. Acidity & Oxygen Affinity for Hb
As acidity increases, O2 affinity for Hb decreases
Bohr effect
H+ binds to hemoglobin & alters it
O2 left behind in needy tissues

52. pCO2 & Oxygen Release
As pCO2 rises with exercise, O2 is released more easily
CO2 converts to carbonic acid & becomes H+ and bicarbonate ions & lowers pH.

53. Temperature & Oxygen Release
Metabolic activity
& heat
As temperature increases, more
O2 is released

54. Role of the Respiratory Center
Respiration controlled by neurons in pons & medulla
3 groups of neurons
medullary rhythmicity
pneumotaxic
apneustic centers

55. CONDITIONS AT VARIOUS ALTITUDES
Tortora & Grabowski 9/e 2000 JWS

56. Partial Pressures of Respiratory Gases at Sea Level
Total
H2O O2
CO2 N
Partial pressure (mmHg)
% in Dry Alveolar Arterial Venous Diffusion Gas dry air air air blood blood gradient
Tortora & Grabowski 9/e 2000 JWS