Akankwatsa Cv Dickson

1. THE PARTS AND FUNCTIONS OF
HUMAN RESPIRATORY SYTEM

2. * It is the system, consisting of tubes and is
responsible for the exchange of gases in
Humans by filtering incoming air
and transporting it into the microscopic
alveoli where gases are exchanged
THE HUMAN RESPIRATORY SYSTEM

3. THE HUMAN RESPIRATORY SYSTEM

4. The organs of the
“Respiratory Tract”
can be divided into two groups
“STRUCTURALLY”
** The Upper Respiratory Tract ** The Lower Respiratory Tract
* Nose
* Nasal cavity
* Sinuses
* Pharynx
* Larynx
* Trachea
* Bronchial Tree
* Lungs

5. THE HUMAN RESPIRATORY SYSTEM

6. The organs of the
“Respiratory Tract”
can be divided into two groups
“FUNCTIONALLY”
** The Conducting Portion
- system of interconnecting
cavities and tubes that
conduct air into the lungs
** The Respiratory Portion
- system where the exchange of
respiratory gases occurs
* Nose
* Pharynx
* Larynx
* Trachea
* Bronchi
* Respiratory
bronchioles
* Alveolar Ducts
* Alveoli

7. THE HUMAN RESPIRATORY SYSTEM
I. N O S E
A. N a s a l C a v i t y
B. P a r a n a s a l S i n u s e s
II. P H A R Y N X
III. L A R Y N X
A. E p I g i o t t i s
B. V o c a l C o r d s
IV. T R A C H E A
v. B R O N C H I
A. B r o n c h i a l T r e e
VI. L U N G S
A. L o b e s o f t h e L u n g s
B. P l e u r a l C a v i t i e s
C. A l v e o l i

8. THE NOSE

9. * It provides an entrance for air in which air is
filtered by coarse hairs inside the nostrils.
* It has 2 portions : the external and internal
* The external portion is supported by a framework
of bone and cartilage covered with skin and
lined with mucous membrane.
* The internal portion is a large cavity in the skull,
THE NOSE

10. The Nasal Cavity

11. * Interior area of the nose; lined with a sticky mucous
membrane and contains tiny, surface hairs,
cilia. divided medially by the nasal septum.
* Nasal conchae divide the cavity into passageways
that are lined with mucous membrane,
and help increase the surface area available
to warm and filter incoming air.
•Particles trapped in the mucus are carried to the
pharynx by ciliary action, swallowed,
The Nasal Cavity

12. Paranasal Sinuses

13. * Sinuses are air-filled spaces
within the maxillary, frontal, ethmoid,
and sphenoid bones of the skull.
* These spaces open to the nasal cavity
and are lined with mucus membrane
that is continuous with that lining the nasal
cavity.
* The sinuses reduce the weight of the skull
and serve as a resonant chamber to affect
the quality of the voice.
Paranasal Sinuses

14. THE PHARYNX

15. * The “throat” is a funnel shaped tube that lies posterior
to the nasal cavity, oral cavity and larynx;
and anteriorly to the cervical vertebra.
* It is composed of:
Nasopharynx – uppermost portion
Oropharynx – middle portion
Laryngopharynx – lowermost portion
* It is a common passageway for air and food and it
provides a resonating chamber for speech sounds
THE PHARYNX

16. * It is an enlargement in the airway
superior to the trachea and inferior to the pharynx.
* It helps keep particles from entering the trachea
and also houses the vocal cords.
* It is composed of a framework of muscles
and cartilage bound by elastic tissue
THE LARYNX

17. * It is a large leaf-shaped piece of cartilage.
* A flap of cartilage that prevents food from
entering the trachea (or windpipe).
* During swallowing, there is elevation of the larynx
The Epiglottis

18. * Inside the larynx, 2 pairs of folds of muscle and
connective tissues covered with mucous
membrane make up the vocal cords.
a. The upper pair is the false vocal cords.
b. The lower pair is the true vocal cords.
c. Changing tension on the vocal cords controls pitch,
while increasing the loudness depends upon
increasing the force of air vibrating the vocal cords.
The Vocal Cords

19. * During normal breathing,
the vocal cords are relaxed and the
glottis is a triangular slit.
* During swallowing,
the false vocal cords and epiglottis
close off the glottis.
The Vocal Cords

20. THE TRACHEA

21. * It is a tubular passageway for air, located anterior
to the esophagus
* It extends from the larynx to the 5th
thoracic vertebra
where it divides into the right and left bronchi.
THE TRACHEA

22. THE TRACHEA

23. * The inner wall of the trachea is lined with
ciliated mucous membrane with many
goblet cells that serve to trap incoming particles.
* The tracheal wall is supported by
20 incomplete cartilaginous rings.
THE TRACHEA

24. BRONCHI

25. * The Bronchi are the two main air passages
into the lungs.
* They are composed of the:
** “Right Primary Bronchus”
- leading to the right lung.
** “Left Primary Bronchus”
- leading to the left lung.
BRONCHI

26. The Bronchial Tree

27. * The bronchial tree consists of branched tubes
leading from the trachea to the alveoli.
* The bronchial tree begins with the two
primary bronchi, each leading to a lung.
* The branches of the bronchial tree from the trachea
are right and left primary bronchi;
these further subdivide until bronchioles
give rise to alveolar ducts which terminate in alveoli.
* It is through the thin epithelial cells of the alveoli
that gas exchange between the blood and air occurs.
The Bronchial Tree

28. THE LUNGS

29. •The paired soft, spongy, cone-shaped lungs,
separated medially by the mediastinum and are
enclosed by the diaphragm and thoracic cage.
•2 layers of serous membrane, collectively known as
pleural membrane, enclose and protect each lung.
** Parietal Pleura
- outer layer attached to the thoracic cavity
** Visceral Pleura
- inner layer covering the lung itself
THE LUNGS

30. * The two organs that extract oxygen from
inhaled air and expel carbon dioxide
in exhaled air.
* This is the main and primary organ of the
Respiratory System.
* The bronchus and large blood vessels enter each lung.
THE LUNGS

31. Lobes of the Lungs

32. * The right lung has three lobes.
* The left lung has two lobes.
* Each lobe is composed of lobules
that contain air passages, alveoli, nerves,
blood vessels, lymphatic vessels,
and connective tissues.
Lobes of the Lungs

33. The Pleural Cavities

34. * A layer of serous membrane, between the
visceral pleura and the parietal pleura.
* It contains a lubricating fluid secreted by the
membranes that prevents friction between the
membranes and allows their easy movement
on one another during breathing.
The Pleural Cavities

35. The Alveoli

36. * They are cup-shaped out pouching lined
by epithelium and supported by a thin elastic
basement membrane.
•With that you can imagine having bunch of grapes
with each grape indicating and alveolus.
* Alveolar sacs are 2 or more alveoli that
share a common opening.
* This is where the primary exchange of gases occur.
The Alveoli

37. Physiology of respiratory
system
The nose
The major functions of nasal breathing are:
to heat and moisten the air
 to remove particulate matter.
About 10 000 L of air are inhaled daily. The relatively
low flow rates and turbulence of inspired air are ideal for
particle deposition, and few particles greater than 10
microns pass through the nose. Deposited particles are
removed from the nasal mucosa within 15 minutes,
compared with 60-120 days from the alveolus.

38. Cont…
• Nasal secretion contains many protective
proteins in the form of IgA antibodies,
lysozyme and interferon. In addition, the
cilia of the nasal epithelium move the
mucous gel layer rapidly back to the
oropharynx where it is swallowed.

39. Breathing
• Lung ventilation can be considered in two
parts:
the mechanical process of inspiration and
expiration
the control of respiration to a level
appropriate for the
metabolic needs.

40. Mechanical process
• Inspiration is an active process and results from the
descent of the diaphragm and movement of the ribs
upwards and outwards under the influence of the inter-
costal muscles.
• In healthy individuals at rest, inspiration is almost
entirely due to contraction of the diaphragm. Respiratory
muscles are similar to other skeletal muscles but are
less prone to fatigue

41. Cont…
• Expiration follows passively as a result of
gradual relaxation of the intercostal
muscles, allowing the lungs to collapse
under the influence of their own elastic
forces.
• Inspiration against increased resistance
may require the use of the accessory
muscles of ventilation, such as the
sternomastoid and scalene muscles.

42. Forced expiration is also accomplished with the aid of
accessory muscles, chiefly those of the abdominal wall, which
help to push up the diaphragm.
The lungs have an inherent elastic property that causes them
to tend to collapse away from the thoracic wall, generating a
negative pressure within the pleural space.
The strength of this retractive force relates to the volume of the
lung; thus, at higher lung volumes the lung is stretched more,
and a greater negative intrapleural press-ure is generated.

43. • Lung compliance is a measure of the
relationship between this retractive force
and lung volume.
• It is defined as the change in lung volume
brought about by unit change in
transpulmonary (intrapleural) pressure
and is measured in litres per kilopascal
(L/kPa). At the end of a quiet expiration,
the retractive force exerted by the lungs is
balanced by the tendency of the thoracic
wall to spring outwards

44. Cont…
• At this point, respiratory muscles are
resting and the volume of air in the lung is
known as the functional residual capacity
(FRC).

45. The control of respiration
• Coordinated respiratory movements result from rhyth-
mical discharges arising in an anatomically ill-defined
group of interconnected neurones in the reticular sub-
stance of the brainstem, known as the respiratory
centre.
• Motor discharges from the respiratory centre travel
via the phrenic and intercostal nerves to the
respiratory musculature.

46. Cont…
• The pressures of oxygen and carbon dioxide in arterial
blood are closely controlled. In a typical normal adult at
rest:
• The pulmonary blood flow of 5 L/min carries
11 mmol/min (250 mL/min) of oxygen from the lungs
to the tissues.
• Ventilation at about 6 L/min carries 9 mmol/min
(200 mL/min) of carbon dioxide out of the body.

47. Cont…
• The normal pressure of oxygen in arterial
blood (Pao2) is between 11 and 13 kPa (83
and 98 mmHg).
• ■ The normal pressure of carbon dioxide
in arterial
blood (Paco2) is 4.8-6.0 kPa (36-45 mmHg).

48. Airflow
• Movement of air through the airways
results from a difference between the
pressure in the alveoli and the
atmospheric pressure; alveolar pressure is
positive in expiration and negative in
inspiration.
• During quiet breathing the pleural
pressure is sub-atmospheric throughout
the breathing cycle.

49. Cont…
• With vigorous expiratory efforts (e.g.
cough), the central airways are
compressed by positive pleural pressures
exceeding 10 kPa, but the airways do not
close completely because the driving
pressure for expiratory flow (alveolar
pressure) is also increased.
• Alveolar pressure (PALV) is equal to the
pleural pressure (Ppi) plus the elastic
recoil pressure (PEi) of the lung.

50. Cont…
• When there is no airflow (i.e. during a
pause in breathing) the tendency of the
lungs to collapse (the positive recoil
pressure) is exactly balanced by an
equivalent negative pleural pressure.
• As air flows from the alveoli towards the
mouth there is a gradual loss of pressure
owing to flow resistance

51. The airways of the
lungs
•
• From the trachea to the periphery, the
airways become smaller in size (although
greater in number). The cross-sectional
area available for airflow increases as the
total number of airways increases.

52. Cont…
• The flow of air is greatest in the trachea
and slows progressively towards the
periphery (as the velocity of airflow
depends on the ratio of flow to cross-
sectional area). In the terminal airways,
gas flow occurs solely by diffusion. The
resistance to airflow is very low (0.1-0.2
kPa/L in a normal tracheobronchial tree),
steadily increasing from the small to the
large airways.

53. Cont…
• Airways expand as lung volume is
increased, and at full inspiration (total lung
capacity, TLC) they are 30-40% larger in
calibre than at full expiration (residual
volume, RV). In chronic obstructive
pulmonary disease (COPD) the small
airways are narrowed and this can be
partially compensated by breathing at a
larger lung volume.

54. • In forced expiration, the driving pressure raises both the
alveolar pressure and the intrapleural pressure. Between
the alveolus and the mouth, there is a point where the
airway pressure equals the intrapleural pressure, and the
airway collapses.
• However, this collapse is temporary, as the transient
occlu-sion of the airway results in an increase in
pressure behind it (i.e. upstream) and this raises the
intra-airway pressure so that the airways open and flow
is restored.
• The airways thus tend to vibrate at this point of 'dynamic
collapse'.

55. Cont…
• The elastic recoil pressure of the lungs
decreases with decreasing lung volume and the
'collapse point' moves upstream (i.e. towards the
smaller airways .
• Where there is pathological loss of recoil
pressure (as in chronic obstructive pulmonary
disease, COPD), the 'collapse point' starts even
further upstream and causes expiratory flow
limitation.
• The measurement of the forced expiratory
volume in 1 second (FEVj) is a useful clinical

56. Cont…
• To compensate, these patients often
'purse their lips' in order to increase airway
pressure so that their peripheral airways
do not collapse.
• On inspiration, the intrapleural pressure is
always less than the intraluminal pressure
within the intrathoracic airways, so there is
no limitation to airflow with increasing
effort. Inspiratory flow is limited only by the
power of the inspiratory muscles.

57. Cont…
• The measure of the volume that can be forced in from
the residual volume in 1 second (FIVj) will always be
greater than that which can be forced out from TLC in 1
second (FEV,). Thus, the ratio of FEVj to FIV] is below 1.
The only exception to this occurs when there is
significant obstruction to the airways outside the thorax,
such as with a tumour mass in the upper part of the
trachea.
• Under these circumstances expiratory airway narrowing
is prevented by the tracheal resistance (a situation
similar to pursing the lips) and expiratory airflow
becomes more effort-dependen

58. Cont…
• During forced inspiration this same
resistance causes such negative
intraluminal pressure that the trachea is
compressed by the surrounding
atmospheric pressure. Inspiratory flow
thus becomes less effort-dependent, and
the ratio of FEVj to FIVj becomes greater
than 1. This phenomenon, and the
characteristic flow-volume loop, is used to
diagnose extrathoracic airways

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