The Slides that accompany our discussion of the respiratory system.

1. Respiratory
System

2. v Major Functions
v Gas exchange (external and internal exchange)
v Cleanse/Moisten/Warm Air
v Inspiration and expiration move air in and out of the
lungs during breathing.
v Cellular respiration is the final destination where ATP is
produced in cells.
Introduction

3. The respiratory tract

4. The Nose
v The two nasal cavities are divided by a septum.
v They contain olfactory cells, receive tear ducts from
eyes, and communicate with sinuses.
v The nasal cavities empty into the nasopharynx.
v Auditory tubes lead from the middle ears to the
nasopharynx.

5. The path of air

6. The Pharynx
v The pharynx (throat) is a passageway from the nasal
cavities to oral cavities and to the larynx.
v The pharynx contains the tonsils; the respiratory tract
assists the immune system in maintaining homeostasis.
v The pharynx takes air from the nose to the larynx and
takes food from the oral cavity to the esophagus.

7. The Larynx
v The larynx is a cartilaginous structure lying between the
pharynx and the trachea.
v The larynx houses the vocal cords.
v A flap of tissue called the epiglottis covers the glottis, an
opening to the larynx.
v In young men, rapid growth of the larynx and vocal cords
changes the voice.

8. Placement of the vocal cords
15-8

9. The Trachea
v The trachea, supported by C-shaped cartilaginous rings, is
lined by ciliated cells, which sweep impurities up toward
the pharynx.
v Smoking destroys the cilia.
v The trachea takes air to the bronchial tree.
v Blockage of the trachea requires an operation called a
tracheostomy to form an opening.

10. Cilia in the trachea
15-10

12. The Bronchial Tree
v The trachea divides into right and left primary bronchi
which lead into the right and left lungs.
v The right and left primary bronchi divide into ever smaller
bronchioles to conduct air to the alveoli.
v An asthma attack occurs when smooth muscles in the
bronchioles constrict and cause wheezing.

13. The Lungs
v Lungs are paired, cone-shaped organs that lie on either
side of the heart and within the thoracic cavity.
v The right lung has three lobes, and the left lung has two
lobes, allowing for the space occupied by the heart.
v The lungs are bounded by the ribs and diaphragm.

14. The Alveoli
v Alveoli are the tiny air sacs of the lungs made up of
squamous epithelium and surrounded by blood capillaries.
v Alveoli function in gas exchange, oxygen diffusing into the
bloodstream and carbon dioxide diffusing out.
v Infant respiratory distress syndrome occurs in premature
infants where underdeveloped lungs lack surfactant (thin
film of lipoprotein) and collapse.

15. Gas exchange in the lungs

16. v During breathing, air moves into the lungs during
inspiration (inhalation) from the nose or mouth, then
moves out again during expiration (exhalation).
v A spirometer allows measurement of the components
of air during breathing.
Mechanism of Breathing

17. Respiratory Volumes
v Tidal volume (VT) the normal amount of air
moved in and out of the lungs when relaxed, is
usually 500 ml.
v Inspiratory reserve volume is the maximum
amount of forcibly inspired air.
v Expiratory reserve volume is the maximum
amount of forcibly expired air.
v Vital capacity is the maximum amount of air
moved in and out on deep breathing, and is the
sum of tidal, inspiratory reserve, and expiratory
reserve volumes.
v Air that remains in the lungs is residual volume.

18. Vital capacity

19. Inspiration and Expiration
v There is a continuous column of air from the pharynx to
the alveoli, and the lungs lie within the sealed-off thoracic
cavity.
v The thoracic cavity is bounded by the rib cage and
diaphragm.
v Pleural membranes line the thoracic cavity and lungs and
the intrapleural pressure is lower than atmospheric
pressure, keeping the lobules of the lungs from collapsing.
v Minute Ventilation – The volume of inhaled and exhaled
air in one minute.

20. Inspiration
v When we inhale (inspiration) impulses from the
respiratory center in the medulla oblongata cause the rib
cage to rise and the diaphragm to lower, causing the
thoracic cavity to expand.
v The negative pressure or partial vacuum in the alveoli
causes the air to come in.
v Changing amounts of blood of H+ and CO2 detected by
chemoreceptors in the carotid arteries and aorta increase
breathing rate.

21. O2 UPTAKE DURING
EXERCISE
v VO2 - measured in
ml/Kg/min
v VO2max - maximal
oxygen uptake
v Metabolic Cart
v Predicted VO2max
testing
v Astrand 6 min. test
v Balke Test

22. Nervous control of
breathing

23. Inspiration

24. Expiration
v When we exhale (expiration), lack of impulses from the
respiratory center allow the rib cage to lower and the
diaphragm to resume a dome shape.
v Expiration is passive, while inspiration is active.
v The elastic recoil of the lungs causes expiration (gravity).
v A deep breath causes alveoli to stretch; stretch receptors
then inhibit the respiratory center via the vagus nerve.

25. Expiration

26. Expiration: active
v Under extreme conditions, exhalation becomes
dynamic.
v Internal intercostal muscles contract forcing the ribs
down and inward.
v Tightening of the abdominal walls also pushes on the
viscera which pushes the diaphragm and forces out
even more air.
v FEV1 – the amount of air forcibly expired in one
second. Reduced in patients with COPD

27. Spirometry

28. v External Respiration
v Individual gases exert pressure proportional to their
portion of the total in a mixture of gases; this is called
“partial pressure” (PO2). (Air - 21% O2, 0.04% CO2)
v External respiration is the diffusion of CO2 from
pulmonary capillaries into alveolar sacs and O2 from
alveolar sacs into pulmonary capillaries.
v Most CO2 is carried as bicarbonate ions.
v The enzyme carbonic anhydrase, in red blood cells,
speeds up the conversion of bicarbonate and H+ to
H2O and CO2; CO2 enters alveoli and is exhaled.
Gas Exchange

29. Partial
Pressures

30. Hemoglobin Structure
v Hemoglobin (Hb)
takes up oxygen
from alveoli and
becomes
oxyhemoglobin
(HbO2).
v 4 globular proteins
(globin) & 4 heme
units.
v (64 000 daltons)

31. Internal Respiration
v Internal respiration is the diffusion of O2 from systemic
capillaries into tissues and CO2 from tissue fluid into
systemic capillaries.
v Oxyhemoglobin gives up O2, which diffuses out of the
blood and into the tissues because the partial pressure of
O2 of tissues fluid is lower than that of the blood.
v After CO2 diffuses from tissue cells into the blood, it enters
red blood cells where a small amount is taken up by
hemoglobin, forming carbaminohemoglobin.

32. Internal Respiration Cont.
v Most of the CO2 combines with water to form
carbonic acid (H2CO3), which dissociates to release
hydrogen ions (H+) and bicarbonate ions (HCO3
-);
the enzyme carbonic anhydrase speeds this reaction.
v The globin portion of hemoglobin combines with
excess hydrogen ions to become reduced hemoglobin
or HHb; this helps maintain a normal blood pH.
v Blood leaving capillaries is a dark maroon color
because red blood cells contain reduced hemoglobin.

33. External and Internal Respiration

34. External and Internal Respiration
External
v Hb + O2 à HbO2
v HbCO2 à Hb + CO2
v H+ + HCO3
- à H2CO3
à CO2 + H2O
Internal
v HbO2 à Hb + O2
v CO2 + H2O à H2CO3
à H+ + HCO3
-
v Hb + CO2 à HbCO2
v H+ + Hb à HHb
v HCO3
- dissolves in
plasma
Chemical Equation Summary

36. Respiratory Centre
• located in the medulla oblongata
• stimulated by the presence of CO2 and H+ ions.
• neurons send automatic rhythmic discharge that
triggers breathing
• the signals travel to the diaphragm and the intercostal
muscles via the phrenic nerve.

37. v Low O2 in blood
registered by carotid
and aortic bodies
v Communication with
respiratory centre
v Increase in minute
ventilation occurs
v Hemoglobin has 200X
affinity for CO than O2
Respiratory Centre Cont.

38. Hemoglobin Saturation (SO2)
v Lungs: 98-100% saturated
v Tissues: 60-70% saturated
v Conditions affecting Saturation:
v Partial Pressure of O2 – incr. é SO2
v pH – incr. pH é SO2
v Temperature – incr. temp ê SO2
v Exercise – increases temperature and decreases pH
causing a decrease in arterial oxygen saturation (SaO2)

39. Oxyhaemoglobin Dissociation Curve

40. v Common Respiratory System Diseases:
v Asthma
v COPD
v Chronic Bronchitis
v Emphysema
v Pleurisy
v Cancer
v Influenza
v Sinusitis
Respiration and Health

41. Sites of upper respiratory infections

42. Sinusitis
v Sinusitis is infection of the cranial sinuses within the
facial skeleton that drain into nasal cavities.
v It occurs when nasal congestion blocks the sinus
openings and is relieved when drainage is restored.
v Pain and tenderness over the lower forehead and
cheeks, and toothache, accompany this condition.

43. Lower respiratory tract disorders

44. COPD
Chronic Bronchitis
v Long-term cough with
mucus
Emphysema
v A breakdown of the
alveoli walls.
Causes, Risk Factors, Symptoms
v Smoking
v Exposure to gases and fumes, cooking fire
v Cough, Fatigue, many R.T.I, Wheezing

45. Asthma
v Muscle lining small airways becomes irritated
v Causes a narrowing of airway passages
v Steroids or bronchodilators can be used to prevent
constriction

46. Lung Cancer
v Lung cancer follows this sequence of events: thickening of
airway cells, loss of cilia on the lining, cells with atypical
nuclei, tumor development, and finally metastasis.
v Removal of a lobe or lung, called pneumonectomy, may
remove the cancer.
v Smoking, whether active or passive, is a major cause of
lung cancer.

47. Normal lung versus cancerous
lung
15-47

48. Chapter Summary
v Air passes through a series of tubes before gas exchange
takes place across an extensive moist surface in the alveoli
of the lungs.
v Respiration comprises breathing, external and internal
respiration, and cellular respiration.
v During inspiration, the pressure in the lungs decreases and
air comes rushing in; during expiration, increased pressure
in the thoracic cavity causes air to leave the lungs.

49. Chapter Summary Cont.
v External respiration occurs in the lungs where oxygen
diffuses into the blood and carbon dioxide diffuses out
of the blood.
v Internal respiration occurs in the tissues where oxygen
diffuses out of the blood into tissue cells and carbon
dioxide diffuses into the blood.
v Spirometry is the measurement of lung capacities and
can be used to diagnose certain respiratory conditions
such as COPD.

50. Chapter Summary Cont.
v The respiratory pigment hemoglobin transports
oxygen from the lungs to the tissues and aids in the
transport of carbon dioxide from the tissues to the
lungs.
v Hemoglobin’s oxygen affinity is affected by pH, temp
and PO2
v The respiratory tract is especially subject to disease
because it is exposed to infectious agents; also,
cigarette smoking contributes to two major lung
disorders—emphysema and cancer.