"عسى أن تكون علما ينتفع به" Natural defenses of respiratory system Mucocilliary apparatus Goblet cell

1. Upper Respiratory System
Defenses

2. Upper Respiratory System Defenses
Upper respiratory system protection is protected through two
mechanisms:
1. Cough
2. Mucociliary apparatus

3. Cough

4. Definition
 Cough is a sudden, often repetitive, spasmodic contraction of
the thoracic cavity, resulting in violent release of air from the
lungs, and usually accompanied by a distinctive sound.
 Coughing is an action the body takes to get rid of substances
that irritates the air passages.
 Coughing can happen voluntarily as well as involuntarily.

5. Causes Of Cough
1. Cough is usually initiated to clear a buildup of phlegm in the
trachea as air may move through this passage at up to 480
km/h during a contraction.
2. Coughing can be triggered by a bolus of food going down the
trachea instead of the esophagus, due to a failure of the
epiglottis, although this may result in choking instead.

6. Cont. …
3. The frequent or chronic coughing usually indicates the
presence of a disease.
– Provided the patient is a non-smoker and has a normal chest X-ray, the
cause of chronic cough in 93% of all patients is due to asthma, reflux
(heartburn) or post-nasal drip.
4. Other causes of chronic cough include chronic bronchitis and
medications such as ACE inhibitors.

7. Cough Reflex
The cough reflex consists of 5 components:
1. Cough receptor
They are the key to cough, particularly in pathological cases,
they are either:
 Extraothoracic receptors:
• Nose, oropharynx or larynx
 Intrathoracic receptors:
• They are rapidly adapting irritant receptors in epithelium of
lower trachea and large central bronchi
 Other location:
• Diaphragm and stomach

8. Cont. …
2. Afferent nerves
Trigeminal, glossopharnygeal, superior laryngeal and vagus
nerve.
3. Cough center in the brain stem
4. Efferent nerves
Recurrent laryngeal, vagus, corticospinal tract and peripheral
nerves.
5. Effector muscle
Thoraco-abdominal muscles

9. Cont. …
The reflex begins with deep inspiration, followed by glottic
closure, diaphragmatic relaxation, and thoracic and abdominal
expiratory muscle contraction.

10. Types Of Cough
1. Dry – nonproductive – irritative cough
 May be caused by mechanical, chemical, thermal, or
inflammatory stimuli.
 Alteration of surface epithelium of major airway, exposed
to irritant receptors, which become sensitized and cause
cough.

11. Cont. …
2. Productive cough
Accumulation of secretions may can be due to one of the
following:
1. Excessive production
2. Altered physical properties
3. Deficient clearance

12. Causes Of Cough
1. Post nasal drip
2. Common cold or influenza
3. Pneumonia and bronchitis
4. Gastroesophageal reflux disease
5. Cough variant asthma
6. Drugs like beta blockers, ACE inhibitors
7. Fungal infections

13. Cont. …
7. Environmental pollutants, such as cigarette smoke, dust, or
smog, can also cause a cough.
– In the case of cigarette smokers, the nicotine present in the smoke
paralyzes the hairs (cilia) that regularly flush mucus from the
respiratory system. The mucus then builds up, forcing the body to
remove it by coughing.
8. Chronic conditions, such as asthma, chronic bronchitis,
emphysema, and cystic fibrosis, are characterized in part by a
cough.

14. Diagnosis
1. Medical history
• Information regarding the duration of the cough.
• What other symptoms may accompany it.
• What environmental factors may influence it.
2. The appearance of the sputum will also help determine what
type of infection, if any, may be involved. The doctor may
even observe the sputum microscopically for the presence of
bacteria and white blood cells.
3. Chest x rays may help indicate the presence and extent of
such infections as pneumonia or tuberculosis.

15. Complications
I. Acute complications
1. Cough Syncope, fainting spells when coughs are prolonged
and forceful due to decreased blood flow to the brain
secondary to raised intrathoracic pressure due to cough.
2. Inability to sleep.
3. Cough induced vomiting.
4. Chest pain due to muscular strain of incessant coughing
5. In severe cases, prolonged coughing can cause fatigue
fractures of lower ribs and costochondritis, an
inflammation of the connective tissue between the
breastbone and the ribs.

16. Cont. …
II. Chronic complications
1. Abdominal or pelvic hernias
2. In women with prolapsed uterus cough can cause
cough micturition which can be a major social
nuisance
3. Cough defecation can also be noted.

17. Treatment
Treatment of a cough generally involves addressing the condition
causing it.
 An acute infection such as pneumonia may require
antibiotics.
 An asthma-induced cough may be treated with the use of
bronchodilators, or an antihistamine may be administered in
the case of an allergy.

18. Cont. …
 Some physicians prefer not to suppress a productive cough,
since cough aids the body in clearing respiratory system of
infective agents and irritants.
 However, cough medicines may be given if the patient cannot
rest because of the cough or if the cough is not productive, as
is the case with most coughs associated with colds or flu.

19. 1- Cough Suppressants
 The use of cough suppressants as a symptomatic treatment is
appropriate when there is nonproductive cough.
 Cough suppressants have either central or peripheral action
on the cough reflex or a combination of both:

20. Cont. …
CENTRALLY ACTING cough suppressants increase the threshold
of the cough center to the incoming stimuli by inhibiting the
capsaicin-induced sensory nerve by depolarization of the vagus
nerve
e.g. Codeine, pholcodine and dextromethorphan
Major adverse effects of these drugs were; sedation, respiratory
depression and constipation

21. Cont. …
PERIPHERALLY ACTING cough suppressants decreases the
sensitivity of the receptors in the respiratory tract.
They are classified into two types:
1. Demulcents
 Include glycerol, honey, lemon, and sucrose syrup
 They act indirectly by providing a protective coating over
the sensory receptors in the pharyngeal wall, but have little
or no effect on those in the lungs.

22. Cont. …
2.Local anesthetic
 Include lidocaine and menthol
 They act indirectly on the sensory receptors
 Lidocaine is used a s a cough suppressant in:
 Bronchoscopy under mild sedation
 Chronic nonspecific cough
Major adverse effect of these drugs is the loss of the protective
pulmonary reflexes and bronchospasm.

23. 2- Expectorants
Expectorants increase the volume of secretions in the respiratory
tract through a reflex irritant effect on bronchial mucosa, thus,
this fluid have a demulcent effect on the respiratory mucosa and
facilitate their removal by the ciliary action and coughing.

24. 3- Antihistamines
Antihistamines are used in cough preparations for:
1. Reduce the cholinergic nerve transmission, thus blocking the
afferent pathway.
2. Suppress cough as a result of sedative action.
3. Reduce nasal secretion and postnasal drips.

25. 4- Mucolytics
They alter the structure of the mucus in order to decrease its
viscosity, thus facilitating its removal by the ciliary action.

26. Mucocilliary Appartatus

27. Mucocilliary Appartatus
The Mucocilliary escalator is consisted of
1. Ciliated cells lining the airway
2. The secretory cells
3. Secretions (mucus)

28. 1- Cilia
 The entire surface of the respiratory passages is lined with
ciliated epithelium.
 In the nasal cavity and the lower respiratory airways, the cilia
beat in a whip-like motion (10-20/second) which moves a
layer of mucus at a rate of 1 cm/min.

29. Cont. …
 Cilia develop at their tip fine claws with which they can grasp
the mucus blanket when they beat forward, whereas on the
return to the upright position they glide past the mucus
blanket.
 The continuous beating causes the coast of mucus to flow
slowly toward the pharynx.
 Then the mucus and its entrapped particles are either
swallowed or coughed to the exterior.

31. 2- The Secretory Cells
A. Goblet Cells
 Goblet cells are glandular simple columnar epithelial cells
whose sole function is to secrete mucus.
 They form mucus in their endoplasmic reticulum and store it
as droplets in their apical part, then they discharge it as a bulk.
 They are found scattered among the epithelial lining of many
organs, especially the intestinal and respiratory tracts.

32. 2- The Secretory Cells
B. Submucus Gland
 They are found in large bronchi along with goblet cells.
 They are connected to the bronchial surface by long narrow
ducts.

33. 2- The Secretory Cells
C. Clara Cells
 They are secretory cells found in small bronchioles. Although
their secretory products are unknown but they are involved in
the detoxification of foreign compounds.

34. Mucous

35. Mucous
 Mucus secretion is composed of water and glycoprotein.
 It is consisted of 2 layers;
1. Periciliary fluid:
1. It lies over the cilia
2. It is 5 µm thick.
3. It allows the cilia to move freely with only the top of the
cilia contact the overlying mucus.
2. Gel layers:
1. It lies over the periciliary fluid layer.
2. It is 5-10 µm thickness that exists as a discontinuous
blanket (islets of mucus)

36. Cont. …
Functions of mucus:
1. Keep the lining epithelium moist.
2. Traps particles from the inspired air and prevents it from
reaching the alveoli.