Anatomy & Physiology of Respiratory System

1. Anatomy & Physiology
of Respiratory System
Mr. Mayur Gaikar
Assistant Professor
Department of Pharmacology
College of Pharmacy (For Women), Chincholi, Nashik.

2. Respiratory System: Oxygen Delivery System
 The respiratory system is the set of organs that allows a
person to breathe & exchange oxygen & carbon dioxide
throughout the body.
 The integrated system of organs involved in the intake &
exchange of oxygen and carbon dioxide between the body &
the environment and including the nasal passages, larynx,
trachea, bronchial tubes, & lungs.
The respiratory system performs two major tasks:
 Exchanging air between the body & the outside
environment known as external respiration.
 Bringing oxygen to the cells and removing carbon dioxide
from them referred to as internal respiration.

3. Lung
Bronchial tubes
Nose
Mouth
Trachea
Diaphragm

4. 1. Supplies the body with oxygen and disposes of carbon dioxide
2. Filters inspired air
3. Produces sound
4. Contains receptors for smell
5. Rids the body of some excess water & heat
6. Helps regulate blood pH
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.

5.  Air from the outside environment enters the nose or mouth
during inspiration (inhalation).
 Composed of the nose & nasal cavity, paranasal sinuses,
pharynx (throat), larynx.
 All part of the conducting portion of the respiratory system.
Nostril
Mouth
NasalCavity
Throat
(pharynx)
V
oicebox(Larynx)

6. The organs of the respiratory system are:
Nose
Pharynx
Larynx
Trachea
Two bronchi (one bronchus to each lung)
Bronchioles & smaller air passages
Two lungs & their coverings, the pleura
Muscles of breathing – the intercostal muscles
& the diaphragm.

8.  Also called external nares.
 Divided into two halves by the nasal septum.
 Contains the paranasal sinuses where air is warmed.
 Contains cilia which is responsible for filtering out foreign bodies.
Nose and Nasal Cavities
Nasal concha Sphenoid sinus
Internal naris
Nasopharynx
External naris
Frontal sinus
Middle nasal concha
Inferior nasal
concha
1. Nose & nasal cavity

9. •The roof is formed by the cribriform plate of the ethmoid bone &
the sphenoid bone, frontal bone & nasal bones.
•The floor is formed by the roof of the mouth & consists of the
hard palate in front & the soft palate behind.
•The hard palate is composed of the maxilla & palatine bones, &
the soft palate consists of involuntary muscle.
•The medial wall is formed by the septum.
•The lateral walls are formed by the maxilla, the ethmoid bone &
the inferior conchae

10.  Internal nares - opening to exterior
 External nares - opening to pharynx
 Nasal conchae - folds in the mucous membrane that increase
air turbulence & ensures that most air contacts the mucous
membranes
1. Respiratory function of the nose:
• Warming
• Filtering & cleaning
• Humidification
Openings into the nasal cavity

11. 2. The sense of smell:
•The nose is the organ of the sense of smell (olfaction).
•The resultant nerve signals are carried by the olfactory
nerves to the brain where the sensation of smell is perceived

12. 2. Pharynx
Position
The pharynx is a tube 12 to 14 cm long that extends
from the base of the skull to the level of the 6th cervical
vertebra.
It lies behind the nose, mouth & larynx and is wider at its
upper end.

13.  Common space used by both the respiratory & digestive
systems.
 Commonly called the throat.
 Originates posterior to the nasal & oral cavities and extends
inferiorly near the level of the bifurcation of the larynx &
esophagus.
 Common pathway for both air and food.
 Walls are lined by a mucosa & contain skeletal muscles that are
primarily used for swallowing.
 Flexible lateral walls are distensible in order to force swallowed
food into the esophagus.

14. Three Sections of the Pharynx
 Nasopharynx
 contains the pharyngeal tonsils (adenoids) which aid
in the body’s immune defense.
 Oropharynx
 back portion of the mouth that contains the palatine
tonsils which aid in the body’s immune defense.
 Laryngopharynx
 bottom section of the pharynx where the respiratory
tract divides into the esophagus and the larynx.
Oropharynx
Nasopharynx
Laryngopharynx

15. Structure of the pharynx
Mucous membrane lining:
•Nasopharynx, nose -consists of ciliated columnar epithelium.
•oropharynx & laryngopharynx - tougher stratified squamous
epithelium, which is continuous with the lining of the mouth &
oesophagus.
Submucosa:
Below the epithelium (the submucosa) is rich in mucosa-
associated lymphoid tissue (MALT), involved in protection
against infection.
Tonsils are masses of MALT that bulge through the epithelium.

16. Smooth muscle
pharyngeal muscles help to keep the pharynx permanently open so
that breathing is not interfered with. Sometimes in sleep, and
particularly if sedative drugs or alcohol have been taken, the tone
of these muscles is reduced and the opening through the pharynx
can become partially or totally obstructed. This contributes to
snoring and periodic wakenings, which disturb sleep.

17. Functions of pharynx
•Passageway for air and food
•Warming and humidifying
•Taste
•Hearing
•Protection
•Speech

18.  Voice box is a short, somewhat cylindrical airway ends in
the trachea.
 Prevents swallowed materials from entering the lower
respiratory tract.
 Conducts air into the lower respiratory tract.
 Produces sounds.
 Supported by a framework of nine pieces of cartilage
(three individual pieces an three cartilage pairs) that are
held in place by ligaments and muscles.
3. Larynx

19. Larynx – viewed from behind.
Larynx – viewed from the front

20. Structure of larynx:
Cartilages:
larynx is composed of several irregularly shaped
cartilages attached to each other by ligaments and membranes.
1 thyroid cartilage
1 cricoid cartilage
2 arytenoid cartilages
Hyaline cartilage
1epiglottis Elastic
fibrocartilage

21. The thyroid cartilage
Made of hyaline cartilage, it lies to the front of the neck. Its
anterior wall projects into the soft tissues of the front of the throat,
forming the laryngeal prominence or Adam’s apple, which is easily
felt and often visible in adult males. The anterior wall is partially
divided by the thyroid notch.
upper part -stratified squamous epithelium like the larynx, and
lower part - ciliated columnar epithelium like the trachea

22. The cricoid cartilage
•Below the thyroid cartilage and
is also composed of hyaline
cartilage.
•Shaped like a signet (Mudra)
ring, narrow part anteriorly and
the broad part posteriorly.
•Lined with ciliated columnar
epithelium.

23. The arytenoid cartilages
Two roughly pyramid-shaped hyaline cartilages situated
on top of the broad part of the cricoid cartilage forming part of
the posterior wall of the larynx.
They give attachment to the vocal cords & to muscles
and are lined with ciliated columnar epithelium.

24. Diagram of the vocal cords

25. The epiglottis
•Leaf-shaped fibroelastic cartilage attached on a flexible
stalk of cartilage to the inner surface of the anterior wall of
the thyroid cartilage immediately below the thyroid notch.
•Covered with stratified squamous epithelium.
•If the larynx is likened to a box then the epiglottis acts as
the lid; it closes off the larynx during swallowing,
protecting the lungs from accidental inhalation of foreign
objects.

26. Functions of larynx
•Production of sound
•Speech
•Protection of the lower respiratory tract
•Passageway for air
•Humidifying, filtering and warming

27.  A flexible tube also called windpipe.
 Extends through the mediastinum
and lies anterior to the esophagus
and inferior to the larynx.
 Cartilage rings reinforce and
provide rigidity to the tracheal wall
to ensure that the trachea remains
open at all times.
 At the level of the sternal angle, the
trachea bifurcates into two smaller
tubes, called the right and left
primary bronchi.
 Each primary bronchus projects
laterally toward each lung.
Trachea
Bronchi
Larynx
4. Trachea

29. Structure of the trachea
Composed of three layers of tissue, and held open by
between 16 and 20 incomplete (posteriorly, C-shaped) rings of
hyaline cartilage lying one above the other.
The cartilages are embedded in a sleeve of smooth
muscle and connective tissue, which also forms the posterior
wall where the rings are incomplete.
The soft tissue posterior wall is in contact with the
oesophagus

30. The relationship of the trachea to the oesophagus.

31. Three layers of tissue ‘clothe’ the cartilages of the trachea.
The outer layer-fibrous & elastic tissue and encloses the
cartilages.
The middle layer-cartilages & bands of smooth muscle that
wind round the trachea in a helical arrangement.
The lining is ciliated columnar epithelium, containing mucus-
secreting goblet cells

32. Ciliated mucous
membrane Coloured scanning electron micrograph
of bronchial cilia.

33. Functions of trachea
Support and patency (permanently open)
Mucociliary escalator
Cough reflex
Warming, humidifying and filtering

34. There are two lungs, one lying on each side of the midline
in the thoracic cavity. They are cone shaped & have an apex, a
base, a tip, costal surface & medial surface.
5. Lungs
The apex
This is rounded & rises into the root of the neck, about 25 mm
above the level of the middle third of the clavicle. It lies close to the
first rib & the blood vessels & nerves in the root of the neck.
The base
This is concave & semilunar in shape, & lies on the upper (thoracic)
surface of the diaphragm.

36. The costal surface
This surface is convex & lies directly against the costal cartilages, the
ribs & the intercostal muscles.
The medial surface
This surface is concave & has a roughly triangular-shaped area, called
the hilum, at the level of the 5th, 6th and 7th thoracic vertebrae.

37. The area between the lungs is the mediastinum. It is
occupied by the heart, great vessels, trachea, right and left
bronchi, oesophagus, lymph nodes, lymph vessels and nerves.
The right lung is divided into three distinct lobes:
superior, middle and inferior.
The left lung is smaller because the heart occupies space
left of the midline.
It is divided into only two lobes: superior and inferior.
The divisions between the lobes are called fissures.

38. Pleura and pleural cavity
The pleura consists of a closed sac of serous
membrane (one for each lung) which contains a small
amount of serous fluid. The lung is invaginated (pushed
into) into this sac so that it forms two layers: one adheres to
the lung & the other to the wall of the thoracic cavity.

40. The visceral pleura
This is adherent to the lung, covering each lobe &
passing into the fissures that separate them.
The parietal pleura
This is adherent to the inside of the chest wall & the
thoracic surface of the diaphragm. It is not attached to other
structures in the mediastinum & is continuous with the
visceral pleura round the edges of the hilum.

41. The pleural cavity
This is only a potential space & contains no air. In
health, the two layers of pleura are separated by a thin film of
serous fluid (pleural fluid), which allows them to glide over
each other, preventing friction between them during breathing.
The serous fluid is secreted by the epithelial cells of the
membrane. The double membrane arrangement of the pleura is
similar to the serous pericardium of the heart

42. Interior of the lungs
The lungs are composed of the
Bronchi and
Smaller air passages,
Alveoli,
Connective tissue,
Blood vessels, lymph vessels & nerves,
all embedded in an elastic connective tissue matrix. Each
lobe is made up of a large number of lobules.

43. Pulmonary blood supply

45. 6. Bronchi & bronchioles
The two primary bronchi are
formed when the trachea
divides, at about the level of
the 5th thoracic vertebra

46. The right bronchus
This is wider, shorter & more vertical than the left bronchus & is
therefore more likely to become obstructed by an inhaled foreign
body. It is approximately 2.5 cm long. After entering the right lung
at the hilum it divides into three branches, one to each lobe. Each
branch then subdivides into numeroussmaller branches.
The left bronchus
This is about 5 cm long and is narrower than the right. After
entering the lung at the hilum it divides into two branches, one to
each lobe. Each branch then subdivides into progressively smaller
airways within the lung substance.

47. Functions
Control of air entry
Warming and humidifying
Support and patency
Removal of particulate matter
Cough reflex.
Respiratory bronchioles and alveoli

48. Respiration
The term respiration means the exchange of gases between
body cells & the environment. This involves two main processes:
Breathing (pulmonary ventilation)
This is movement of air into and out of the lungs.
Exchange of gases
This takes place:
in the lungs: external respiration
in the tissues: internal respiration.

49. Breathing
Breathing supplies O2 to the alveoli, & eliminates CO2.
Muscles of breathing: Expansion of the chest during inspiration
occurs as a result of muscular activity, partly voluntary & partly
involuntary. The main muscles used in normal quiet breathing are the
external intercostal muscles & the diaphragm.
Intercostal muscles: There are 11 pairs of intercostal muscles that
occupy the spaces between the 12 pairs of ribs. They are arranged in
2 layers, the external & internal intercostal muscles

50. The intercostal muscles & the bones of
the thorax

51. The external intercostal muscles
These extend downwards & forwards from the lower border of the
rib above to the upper border of the rib below. They are involved in
inspiration.
The internal intercostal muscles
These extend downwards & backwards from the lower border of the
rib above to the upper border of the rib below, crossing the external
intercostal muscle fibres at right angles. The internal intercostals are
used when exhalation becomes active, as in exercise.

52. Diaphragm
Dome-shaped muscular structure separating the thoracic & abdominal
cavities.
It forms the floor of the thoracic cavity & the roof of the abdominal
cavity & consists of a central tendon from which muscle fibres radiate
to be attached to the lower ribs and sternum and to the vertebral
column by two crura.
When the muscle of the diaphragm is relaxed, the central tendon is
at the level of the 8th thoracic vertebra.
When it contracts, its muscle fibres shorten & the central tendon is
pulled downwards to the level of the 9th thoracic vertebra,
lengthening the thoracic cavity.
The diaphragm is supplied by the phrenic nerves.

53. A. Muscles involved in respiration (accessory muscles labelled in bold).
B, C. Changes in chest volume.

54. Cycle of breathing
The average respiratory rate is 12 to 15 breaths per
minute. Each breath consists of three phases:
Inspiration: contraction of the external intercostal muscles &
diaphragm expands the thorax. inspiration is active, as it needs
energy for muscle contraction. (lasts about 2 seconds)
Expiration: Relaxation of the external intercostal muscles & the
diaphragm results in downward & inward movement of the
ribcage. This process is passive as it does not require the
expenditure of energy. (lasts about 3 seconds)
Pause.

55. Lung volumes and capacities:
In normal quiet breathing there are about 15
complete respiratory cycles per minute.
The lungs & the air passages are never empty
and, as the exchange of gases takes place only
across the walls of the alveolar ducts and
alveoli, the remaining capacity of the
respiratory passages is called the anatomical
dead space (about 150 ml).

56. Lung volumes and capacities. IRV: inspiratory reserve volume; IC:
inspiratory capacity; FRC: functional residual capacity; ERV: expiratory
reserve volume; RV: residual volume; VC: vital capacity; TLC: total lung
capacity.

57. Tidal volume (TV)
This is the amount of air passing into & out of the lungs during
each cycle of breathing (about 500 ml at rest).
Inspiratory reserve volume (IRV)
This is the extra volume of air that can be inhaled into the lungs
during maximal inspiration, i.e. over and above normal TV.
Inspiratory capacity (IC)
This is the amount of air that can be inspired with maximum
effort. It consists of the tidal volume (500 ml) plus the
inspiratory reserve volume.

58. Functional residual capacity (FRC)
This is the amount of air remaining in the air passages & alveoli at
the end of quiet expiration.
Expiratory reserve volume (ERV)
This is the largest volume of air which can be expelled from the
lungs during maximal expiration.
Residual volume (RV)
This cannot be directly measured but is the volume of air
remaining in the lungs after forced expiration.

59. Vital capacity (VC)
This is the maximum volume of air which can be moved
into and out of the lungs:
Total lung capacity (TLC)
This is the maximum amount of air the lungs can hold.
•Adult of average build, it is normally around 6 litres.
•Total lung capacity represents the sum of the vital capacity
and the residual volume

60.  Air enters your lungs through a system of pipes called the bronchi.
 The alveoli are where the important work of gas exchange takes place
between the air and your blood. Covering each alveolus is a whole
network of little blood vessel called capillaries,
 It is important that the air in the alveoli and the blood in the capillaries
are very close together, so that oxygen and carbon dioxide can move (or
diffuse) between them.
 When you breathe in, air comes down the trachea and through the
bronchi into the alveoli.
 This fresh air has lots of oxygen in it, and some of this oxygen will travel
across the walls of the alveoli into your blood stream.
 Travelling in the opposite direction is carbon dioxide, which crosses from
the blood in the capillaries into the air in the alveoli and is then breathed
out.
 In this way, you bring in to your body the oxygen that you need to live,
and get rid of the waste product carbon dioxide.

61. H
o
wL
u
n
g
swork?
Branch of
Pulmonary vein
Branch of
Pulmonary
artery
Bronchiole Terminal
Bronchiole
Respiratory Bronchiole
Capillary beds
Alveoli

62. Breathing
 Lungs are sealed in
pleural membranes
inside the chest cavity.
 At the bottom of the
cavity is a large, flat
muscle known as the
diaphragm.

63. Breathing
 During inhalation, the
diaphragm contracts and the
rib cage rises up.
 This expands the volume of
the chest cavity.
 The chest cavity is sealed, so
this creates a partial vacuum
inside the cavity.
 Atmospheric pressure fills
the lungs as air rushes into
the breathing passages.

64. Breathing
 Often exhaling is a passive
event.
 When the rib cage lowers and
the diaphragm relaxes,
pressure in the chest cavity is
greater than atmospheric
pressure.
 Air is pushed out of the lungs.
Exhalation
Rib cage
lowers
Air Exhaled