Respiratory system in detail in anatomy and physiology

1. Respiratory System
Presented by
PARIKSHA PARVEZ
Lecturer
NIHS

2. O B J E C T I V ES
 At the end of this unit learners will be able to:
 Define respiratory system.
 Define respiration.
 Describe the structure and the function of following
 The upper respiratory tract (Nose, Pharynx, Larynx)
 The lower respiratory tract (Trachea, Bronchial tree, lungs)
 Discuss the physiology of respiration by explaining
the mechanism of:
 Pulmonary Ventilation
 External Respiration
 Internal Respiration
 Discuss nervous control of respiration
 Briefly discuss the lung volumes & capacities
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3. Respiratory system consist of:
•Nose
•Pharynx (Throat)
•Larynx (Voice Box)
•Trachea (Wind Pipe)
•Bronchi
•Bronchioles
•Alveoli
Respiratory System
The Respiratory System

4. THE RESPIRATORY SYSTEM:
 The respiratory system contributes to homeostasis by
providing for the exchange of gases—oxygen and
carbon dioxide—between the atmospheric air, blood,
and tissue cells. It also helps adjust the pH of body
fluids.
 The branch of medicine that deals with the diagnosis
and treatment of diseases of the ears, nose, and throat
(ENT) is called otorhinolaryngology (oto -ear; rhino-
nose; laryngo- voice box; - logy study of).
 A pulmonologist is a specialist in the diagnosis and
treatment of diseases of the lungs. 3/20/2024
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5. RESPIRATION.
 “RESPIRATION” IS GENERALLY CONSIDERED TO BE
EXTERNAL OR INTERNAL.
 A. External respiration refers to gas exchange
between the air and blood (at the lungs).
 Includes pulmonary ventilation
 Includes blood circulation
 B. Internal respiration refers to gas exchange
between capillary blood and the tissues.
 Includes blood circulation
 Cellular respiration (metabolic reactions that consume O2
and produce CO2)
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6. RESPIRATORY SYSTEM:
COMPONENTS:
 Lungs and air
passageways such as
the Nose, pharynx
(throat), larynx (voice
box), trachea
(windpipe), and
bronchial tubes
leading into and out of
the lungs.
FUNCTIONS:
 Transfers oxygen from
inhaled air to blood and
carbon dioxide from blood
to exhaled air.
 Helps regulate acid–base
balance of body fluids.
 Air flowing out of lungs
through vocal cords
produces sounds.
 Aids in the sense of smell
(olfaction).
 pH regulation. 3/20/2024
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Nose
Nasal cavity
Oral cavity
FUNCTIONS:
1.Provides for gas
exchange—intake of
O2 for delivery to
body cells and
elimination of CO2
produced by body
cells.
2.Helps regulate blood
pH.
3.Contains receptors for
the sense of smell,
filters inspired air,
produces vocal sounds
(phonation), and
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8. Pharynx
Larynx
Trachea
Bronchioles
Nose
Alveoli
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10. Conti:
Structurally respiratory system consist of two
parts
 The upper Respiratory System
 The lower Respiratory System
The upper Respiratory System (URT).
 Nose
 Pharynx(throat).
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11. Conti:
The Lower Respiratory System (LRT).
 Larynx (Voice Box)
 Trachea (Wind Pipe)
 Bronchi
 Lungs
 Bronchioles
 Alveoli
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12. Conti
Functionally, the reparatory system is consists
of two part:
 The conducting zone
 The respiratory zone
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13. THE CONDUCTING ZONE:
The conducting zone consist on series of interconnecting
cavities and tubes both outside and within the lungs &
Includes:
 Nose
 Pharynx
 Larynx
 Trachea
 Bronchi
 Bronchioles
 Terminal Bronchioles
Function
( Filter, warm and moisten air and conduct it into the
lungs) 3/20/2024
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14. THE RESPIRATORY ZONE:
The respiratory zone consists of
tissues within the lungs where
gas exchange occurs &
Includes:
 Respiratory Bronchioles
 Alveolar ducts
 Alveolar sac
 Alveoli
Function
(Gas exchanges between air 3/20/2024
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16. Conti…
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17. NOSE AND NASAL PASSAGES
 Nose can be divided into external and internal portions.
External Nose
 The external nose consists of a supporting framework of
bone and hyaline cartilage and lined by a mucous
membrane.
 Frontal bone, nasal bone, maxillae form bony framework
of the external nose.
 Undersurface of the external nose are two openings
called the external nares or nostrils.
 The cartilages framework of external nose consists of:
 Septal cartilages
 Lateral nasal cartilages
 Alar cartilages
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18. STRUCTURES OF THE CONDUCTIVE ZONE
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Alar cartilage
Septal nasal cartilage
Lateral nasal cartilages
Cartilaginous framework:
Bony framework:
Frontal bone
Nasal bones
Maxilla
Dense fibrous
connective and
adipose tissue
(a) Anterolateral view of external portion of
nose showing cartilaginous and bony
framework
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19. STRUCTURES OF THE CONDUCTIVE ZONE
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20. INTERNAL NOSE
 Internal nose is a large cavity in the anterior
aspects of the skull.
 It lies inferior to nasal bone and superior to
mouth.
 It lined with muscle and mucous membrane
 The space between internal nose is called
nasal cavity (which are rich with capillaries and
lined by a mucous membrane)
 Pseudostratified ciliated columnar epithelium with
many goblet cells secrete mucous that moistens the
air and traps the air particles.
 Olfactory epithelium.
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21. NOSE -- INTERNAL STRUCTURES
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22. Conti
 Interior portion of the nasal cavity just inside the
nostrils called vestibule.
 A vertical partition, the nasal septum, divides the
nasal cavity into right and left sides.
 Conchae (turbinates = 3) Divide each side of the
nasal passages into a series of groovelike
passages (superior, middle and inferior meatuses)
which ↑ surface area and retain H2O during
exhalation.
 Paranasal sinuses – four pairs of mucous
membrane lined chambers in skull bones that
drain into the nasal cavity (along with lacrimal
fluid). They lighten the skull, produce mucus, and
serve as resonating chambers for sound.
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23. OLFACTORY NERVE
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24. Nose
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25. 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.
Cilia move mucous towards pharynx.
 Paranasal sinuses open into nasal cavity.
Found in ethmoid, sphenoid, frontal &
maxillary.
Lighten skull & resonate voice. 3/20/2024
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26. PHARYNX/ THROAT.
 It is funnel shaped tube about 13cm long.
 Connects the nasal and oral openings with the
esophagus and larynx.
 It is chamber shared by digestive and
respiratory system.
 It starts at the internal nares and extends to
the level of cricoid cartilage.
 Pharynx can be divided into three anatomical
regions.
 Nasopharynx (Superior portion)
 Oropharynx (Intermediate portion)
 Laryngopharynx (Inferior portion)
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27. PHARYNX/ THROAT.
 FUNCTIONS:
Passageway for food and air.
Resonating chamber for speech
production.
Tonsil (lymphatic tissue) in the walls
protects entryway into body.
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29. PHARYNX/ THROAT.
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30. PHARYNX/ THROAT.
 Nasopharynx:
 From choanae to Soft palate.
 Auditory (Eustachian) tube opening OR
(pharyngotympanic) from middle ear cavity, adenoids or
pharyngeal tonsil in roof).
 Passageway for air only lined by pseudostratified ciliated
columnar epithelium with goblet.
 Oropharynx:
 Intermediate portion with both respiratory and digestive
system functions.
 From soft palate to epiglottis.
 Fauces is opening from mouth into oropharynx.
 Palatine tonsils found in side walls, lingual tonsil in tongue.
 Common passageway for food & air lined by stratified
Squamous epithelium.
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31. Cont…
 Laryngopharynx:
 Begins at level of the hyoid bone and opens
posteriorly to the esophagus and anteriorly
to the larynx.
 Extends from epiglottis to cricoid cartilage
 Common passageway for food & air & ends
as esophagus inferiorly lined by stratified
squamous epithelium.
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32. Cont…
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33. COMPONENTS OF THE LOWER
RESPIRATORY SYSTEM

34. LARYNX (Voice Box)
 Larynx or voice box is a short passageway
that connects the laryngopharynx with
trachea.
 It lies on the midline of neck anterior to
esophagus and through 4th to 6th cervical
vertebrae.
 The wall of larynx is composed of nine pieces
of cartilage.
 Three cartilages occurs singly
 Thyroid cartilage
 Epiglottis
 Cricoid cartilage
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35. Conti:
 Other three occurs in pairs
 Arytenoid cartilages
 Cuneiform cartilages
 Corniculate cartilages
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36. THYROID CARTILAGE
 It is also known as Adam’s Apple
 It consists of two fused plates of hyaline
cartilage.
 It is present in both male and female
 It is usually larger in males due to male sex
hormone (testosterone) in puberty.
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37. EPIGLOTTIS
 Epiglottis (epi = over; glottis = tongue).
 It is large leaf like piece of elastic cartilage and
covered with epithelium.
 During the swallowing, the pharynx and larynx
rise. Elevation of pharynx widens it to receive
food or drink
 Elevation of larynx causes the epiglottis to move
down and form a lid over glottis, closing it off.
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38. CRICOID CARTILAGE
 It is a ring of hyaline cartilage and forms the
inferior wall of the larynx.
 It is attached to the first ring of cartilage of the
trachea.
 The cricoid cartilage is the landmark for making
an emergency airway called a tracheotomy.
ARYTENOID CARTILAGE:
 It is paired Arytenoid Cartilages.
 It is triangular pieces of hyaline cartilages.
 They attach the vocal folds and intrinsic
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39. CORNICULATE CARTILAGES
 It is paired cartilages.
 It is like small horn.
 Small horn shaped pieces are made up by
elastic cartilage.
 It is located at apex of each arytenoid cartilages.
 They are supporting structures of epiglottis.
CUNEIFORM CARTILAGES:
 It is paired Cuneiform Cartilages.
 It is composed of club shaped elastic cartilages.
 It supports the vocal cards.
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40. 3/20/2024
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41. 23-41
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42. 3/20/2024
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43. THE STRUCTURES OF VOICE PRODUCTION
 Mucous membrane of the larynx forms two pairs of
Folds a superior pair called the ventricular folds (false
vocal cords) and an inferior pair called the vocal folds
(true vocal cords).
 The space between the ventricular folds is known as
the rima vestibuli.
 Ventricular folds help to hold breath against pressure
in the thoracic cavity.
 Vocal folds, which is lined by nonkeratinized stratified
squamous epithelium, bands of elastic ligaments are
stretched between pieces of rigid cartilage like the
strings on a guitar.
 If air is directed against the vocal folds, they vibrate
and produce sounds (phonation).
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44. 3/20/2024
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Thyroid cartilage
Cricoid cartilage
Vocal ligament
Arytenoid cartilage
Posterior
cricoarytenoid
muscle
Tongue
Epiglottis
Glottis:
Vocal folds
(true vocal cords)
Rima glottidis
Ventricular folds
(false vocal cords)
Cuneiform cartilage
Corniculate cartilage
Lateral
cricoarytenoid
muscle
The glottis consists of a pair of folds of mucous membrane in the larynx
(the vocal folds) and the space between them (the rima glottidis).
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45. SPEECH AND WHISPERING
 Speech is modified sound made by the
larynx.
 Speech requires pharynx, mouth, nasal
cavity & sinuses to resonate that sound.
 Tongue & lips form words.
 Pitch is controlled by tension on vocal folds.
 Pulled tight produces higher pitch.
 Male vocal folds are thicker & longer so vibrate
more slowly producing a lower pitch.
 Whispering is forcing air through almost
closed rima glottidis -- oral cavity alone3/20/2024
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46. TRACHEA
 It is also known as wind pipe.
 It is tubular passageway for air
 It is 12cm long and 2.5cm in diameter.
 It is located anterior to esophagus.
 It is divided into right primary and left primary
bronchi
Layers of tracheal wall
 Mucosa= pseudostratified columnar with cilia &
goblet
 Submucosa= loose connective tissue.
 Hyaline cartilage = 16 to 20 incomplete rings
 Open side facing esophagus contains trachealis m.
(smooth).
 Internal ridge on last ring called carina.
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47. Tracheal histology
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48. Conti…
 Mucosa= pseudostratified columnar with cilia &
goblet
 TYPICAL RESPIRATORY MUCOSA
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49. Conti…
SUBMUCOSA:
Loose connective
tissue
Simple branched
Tubuloacinar
Glands
Mixed type
Seromucus Glands
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50. Conti…
ADVENTITIA:
 Loose
connective
tissue, with
collagen
fibers
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51. Conti:
 The walls of trachea are supported by 16–20
rings of incomplete tracheal
cartilages(hyaline).
 Tracheal cartilages are like C shaped.
 These C shaped cartilages stiffen the tracheal
wall and protects its collapse
 Adventitia of the trachea is consists of areolar
connective tissues.
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52. Conti:
 Posteriorly theses ring of C-shaped cartilage
faces toward the esophagus and is spanned
by a fibromuscular membrane.
 Within this membrane are trachealis muscle,
and elastic connective tissue that allow the
diameter of the trachea to change subtly
during inhalation and exhalation.
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53. 3/20/2024
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Esophagus Trachea
Cartilage of
trachea Right lateral lobe
of thyroid gland
Fibromuscular
membrane of
trachea (contains
trachealis muscle)
Esophagus
Left lateral lobe
of thyroid gland
Superior view of transverse section of thyroid gland, trachea, and esophagus.
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54. TRACHEOSTOMY AND INTUBATION
 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 trachea.
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55. BRONCHI
 At the superior border of the
5th thoracic vertebrae, trachea
divides into right primary
bronchi and left primary
bronchi which goes into lungs.
 The right bronchi is more
vertical, shorter, wider than
left primary bronchi.
 It is lined by pseudostratified
ciliated columnar epithelium.
 At the point where trachea
divides into right and left is
known as carina.
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56. Conti:
 The primary bronchi (supply each lungs) divides
into secondary bronchi (Lobar bronchi).
 The secondary bronchi divides into 9 or 10 tertiary
bronchi (Segmental bronchi).
 Tertiary bronchi divides successive sets of
intralobular bronchioles (IL) into
Bronchopulmonary segment ( right = 10, left = 8).
 IL bronchioles split into terminal bronchioles.
 The terminal bronchioles divides into respiratory
bronchioles (0.5mm diameter).
 RB splits into multiple alveolar ducts which end in an
alveolar sac
 This extensive branching is known as bronchial tree.
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BRANCHING OF
BRONCHIAL TREE
Trachea
Primary bronchi
Secondary bronchi
Tertiary bronchi
Bronchioles
Terminal
bronchioles
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57. Cont….
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58. 3/20/2024
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59. ALVEOLAR DUCTS
 Respiratory bronchioles open into expensive
chambers called Alveolar ducts.
 These passageway ends at alveolar sacs.
ALVEOLAR SACS:
 It is common chambers connected to individual
alveoli
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60. ALVEOLI.
 Alveoli is a cup shaped OR grape-like cluster out
pouching lined by simple squamous epithelium.
ALVEOLAR CELLS:
 Type I alveolar cells:
 It is simple squamous epithelial cells.
 It is forms about 95% of the cells.
 It is main sites of gas exchange.
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61. TYPE II ALVEOLAR CELLS:
 It is also known as septal cells.
 It is form about 5% of the cells, and Cuboidal in nature.
 It secretes the alveolar fluid, which moist the air.
 It produces the SURFACTANT.
 Surfactant is complex mixture of phospholipids and
lipoprotein.
 Surfactant lowers the surface tension of alveolar fluid, which
reduces the tendency of alveoli to collapse.
ALVEOLAR MACROPHAGES (DUCT CELLS):
It removes the fine dust or other debris from the alveolar sacs
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Respiratory Zone of Lower Respiratory Tract

63. LUNGS
 Lungs are paired, cone-shaped organs in the thoracic
cavity.
 They are separated from each other by the heart and
other structures in the mediastinum.
 The outer covering of lungs is called pleura.
 Pleura is composed of pleural membrane.
 Pleural membrane has two layers.
 Partial pleura.
 Visceral pleura.
 Pleural fluid lubricates the both membranes and prevents
from friction.
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64. PLEURAL MEMBRANES & PLEURAL CAVITY
 Visceral pleura covers lungs --- parietal pleura
lines ribcage & covers upper surface of
diaphragm.
 Pleural cavity is potential space between ribs &
lung.
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65. Conti:
 Lungs extend from the diaphragm to just slightly
superior to the clavicles and lie against the ribs
anteriorly and posteriorly.
 Broad inferior portion is base which is concave.
 Narrow superior portion is called apex.
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66. GROSS ANATOMY OF LUNGS
 Base, apex (cupula), costal surface, cardiac notch
 Oblique & horizontal fissure in right lung results in 3
lobes
 Oblique fissure only in left lung produces 2 lobes
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67. BLOOD SUPPLY TO LUNGS
 Pulmonary arteries (The only arteries in the
body that carry deoxygenated blood).
 Pulmonary vein(Venous drainage returns all
blood to heart).
 Bronchial arteries (it the branch of aorta which
deliver the blood to the lungs).
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68. MEDIASTINAL SURFACE OF
LUNGS
 Blood vessels & airways
enter lungs at hilus.
 Forms root of lungs.
 Covered with pleura
(parietal becomes
visceral).
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69. 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
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70. ALVEOLAR-CAPILLARY MEMBRANE
 Respiratory membrane = ½ OR (0.5 µm) micron
thick.
 Exchange of gas from alveoli to blood.
 4 Layers of membrane to cross.
 Alveolar epithelial wall of type I cells and type II
alveolar cells.
 Alveolar epithelial basement membrane.
 Capillary basement membrane.
 Endothelial cells of capillary.
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71. DETAILS OF RESPIRATORY MEMBRANE
 Find the 4 layers that comprise the respiratory
membrane.
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72. Respiratory membrane
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73. DOUBLE BLOOD SUPPLY TO THE LUNGS
 Deoxygenated blood arrives through pulmonary trunk
from the right ventricle.
 Bronchial arteries branch of the aorta to supply
oxygenated blood to lung tissue.
 Venous drainage returns all blood to heart.
 Less pressure in venous system.
 Pulmonary blood vessels constrict in response to low
O2 levels so as not to pick up CO2 on there way
through the lungs.
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74. Respiratory System Functions
 Transfer of O2 (Oxygen) from atmosphere to
tissues.
 Transfer the CO2 ( Carbon Dioxide) from the
tissues to the air.
 Produces sound.
 Contains receptors for smell.
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75. Breathing
 Breathing (pulmonary ventilation). consists of two
cyclic phases:
 Inhalation, also called inspiration - draws gases
into the lungs.
 Exhalation, also called expiration - forces gases
out of the lungs
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76. 3/20/2024
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77.  Pulmonary ventilation: “Exchange of gases between
alveoli of lungs and atmosphere”.
 External respiration: “Exchange of gases between
alveoli of lungs and pulmonary capillaries across the
respiratory membrane”.
 Internal respiration:“Exchange of gases between
systemic capillaries and tissue cells”.
RESPIRATORY EVENTS
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78. BREATHING OR PULMONARY VENTILATION.
 Air moves into lungs when pressure inside
lungs is less than atmospheric pressure.
 Air moves out of the lungs when pressure
inside lungs is greater than atmospheric
pressure.
 Atmospheric pressure = 1 atm or 760mm
Hg.
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79. 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.
The pressure
of a gas varies
inversely with
volume.
•
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80. DIMENSIONS OF THE CHEST CAVITY
 Breathing in requires muscular activity & chest size
changes.
 Contraction of the diaphragm flattens the dome and
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81.  During normal quiet inhalation involves contraction of
the main muscles of inhalation, the diaphragm and
external intercostals.
 Diaphragm moves 1 cm descends & ribs lifted by
muscles(500 mL).
QUIET INSPIRATION
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82.  Passive process with no muscle action
 Elastic recoil of chest wall and lungs.
 Elastic fibers.
 Surface tension in alveoli pulls inward.
 Alveolar pressure increases & air is pushed out.
QUIET EXPIRATION
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83. LABORED BREATHING
 Forced expiration
 Abdominal muscle
move force
diaphragm up.
 Internal intercostals
depress ribs.
 Forced inspiration
 Sternocleidomastoid,
scalenes & pectoralis
minor lift chest
upwards as you gasp
for air.
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84. INTRATHORACIC PRESSURES.
 PRESSURE CHANGES IN PULMONARY
VENTILATION.
 During inhalation, the diaphragm contracts, the
chest expands, the lungs are pulled outward,
and alveolar pressure decreases.
 During exhalation, the diaphragm relaxes, the
lungs recoil inward, and alveolar pressure
increases, forcing air out of the lungs.
 Always subatmospheric (756 mm Hg).
 As diaphragm contracts intrathoracic pressure
decreases even more (754 mm Hg).
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85. Cont…
• Air moves into the lungs when alveolar pressure is less
than atmospheric pressure, and out of the lungs when
alveolar pressure is greater than atmospheric pressure.
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86. SUMMARY OF BREATHING
 Alveolar pressure decreases & air rushes in.
 Alveolar pressure increases & air rushes out.
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87. 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 causes
respiratory distress syndrome so that alveoli
collapse at end of each exhalation.
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88. BREATHING PATTERNS
 Eupnea = Normal quiet breathing.
 Apnea = Temporary cessation of breathing.
 Dyspnea =Difficult or labored breathing.
 Tachypnea = Rapid breathing.
 Bradypnea = Slow breathing rate.
 Diaphragmatic breathing = Descent of
diaphragm causes stomach to bulge during
inspiration.
 Costal breathing = Just rib activity involved.
 Kussmaul breathing= Very deep and labored
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89. Summary of Gas Exchange & Transport.
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90. ROLE OF THE RESPIRATORY CENTER
 Respiratory muscle
controlled by neurons in
pons & medulla.
 3 groups of neurons
basis of their functions:
1.Medullary rhythmicity.
1. Inspiratory Area(In tractus
Solitaris Nucleus).
2. Expiratory Area(In
Ambiguus & Retroambiguus
nucleus).
2.Pneumotaxic.(In
Parabrachilais Nucleus).
3.Apneustic centers.
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91. MEDULLARY RHYTHMICITY AREA
 Controls basic rhythm of respiration.
 Inspiration for 2 seconds, expiration for 3.
 Autorhythmic cells active for 2 seconds then
inactive.
 Expiratory neurons inactive during most quiet
breathing only active during high ventilation rates.
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92. PNEUMOTAXIC & APNEUSTIC AREAS
 Pneumotaxic Area:
Constant inhibitory impulses to
inspiratory area.
 Neurons trying to turn off inspiration before
lungs too expanded.
 Apneustic Area:
Stimulatory signals to inspiratory area to
prolong inspiration.
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93. REGULATION OF RESPIRATORY CENTER.
 Cortical Influences:
Voluntarily alter breathing patterns.
Limitations are buildup of CO2 & H+ in
blood.
Inspiratory center is stimulated by
increase in either.
If you hold breathe until you faint----
breathing will resume.
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94. Physiological Conditions And Pulmonary
Volumes / Capacities
All pulmonary volumes and capacities are about 20to 25% less in women than in men, and they are greater in
large and athleticpeople than in small and asthenicpeople
The values areimportant
LungVolumes
1. Tidal volume:[TV]
2. Inspiratory reservevolume [IRV]
3. Expiratory reserve volume [ERV]
4. Residual volume[RV]
lungcapacities
1. Vital Capacity[FVC]
2. Inspiratory capacity(IC)
3. Functional Residual Capacity[FRC]
4. Total lung capacity[TLC]
Volume is a single value whilecapacity is a
sum of two or morevolumes
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95. Pulmonary Volumes
Note that the ERV& the IRVare the values
inspired/expired beyondthe tidal volume and do not
includeit.
ResidualV
olume(RV):volume of air still remaining in the
lungs after aforceful expiration (1200ml)
The residual volume maintains the structure of the lung and is crucial to
the function of thelung.
It onlyleaves the lung in case of drowning or puncture of the lung.
(This volume keeps the lung fromcollapsing)
We cannot measure it by electronic spirometer soit’s measured by Helium
dilutionmethod
The following 4 volumes when added equal the maximum volume
to which the lung canexpand
tidal volume (1100ml)
Tidalvolume (TV):Volume of air inspired or expired in each normal breath (500ml)
Inspiratoryreservevolume(IRV):extra volume of air, that can be inspired forcefully, beyond the normal tidal
volume value (3000ml)
Volume of air inspired by maximal inspiratory effort after normal tidal inspiration
Expiratoryreservevolume(ERV):extra volume of air, that can be expired forcefully, beyond thenormal
Volume of air expired by maximal expiratory effort after normal tidal expiration.
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96. Volume is a single value whilecapacity is a sum of two or morevolumes
Pulmonary Capacities
1Functional ResidualCapacity(FRC):is the amount of air that remains in the lungs at the end of
normal expiration =
expiratory reserve volume (1100)+
residual volume (1200)=
2300ml. Note the difference
between FRCand RVis RVin maximal expiration and FCRin normalexpiration
2InspiratoryCapacity(IC):is the volume of air inspired by a maximal inspiratory effort after
normal expiration =
inspiratory reserve volume (3000)+
tidal volume (500)=
3500ml.
3ForcedVitalCapacity(FVC):is the maximum amount of air that a person can expel forcefully from
the lungs after taking a deep inspiration. The vital capacity=
tidal volume +
inspiratory reserve volume +
expiratory reserve volume =
500+
3000+
1100=
4600ml. Clinically it’sthe most importance “diagnosis the diseases”
4Total lungcapacity(TLC):is the maximum volume to which the lungs can be expanded with the
greatest possible inspiratory effort. It is the sum of all pulmonary volumes. Tidal volume +
Inspiratory +
Expiratory reserve volume +
Residual volume =
500+
3000+
1100+
1200=
5800ml.
The capacity comprises of more than onevolume.
All lung capacities and volumes in females are 20%- 25%less than inmales.
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98. References
 Tortora, J. G., Derrichson, B. (2006).Principles of
Anatomy and Physiology. (11th ed). USA: New
York. John Willey 7 sons , Inc.
 Martini, H. F. (200). Essentials of Anatomy and
Physiology. (2nd ed). USA: New Jersey. Prentice
Hall.
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