This document summarizes key aspects of the respiratory system and respiratory diseases. It begins by describing the major parts of the respiratory system - the airways, lungs, and respiratory muscles. It then details each part of the airways from nose to bronchioles. It discusses diseases like asthma and chronic obstructive pulmonary disease (COPD), outlining their causes, symptoms, classifications, pathophysiology, and treatment approaches. COPD encompasses respiratory failure, bronchitis, and emphysema.

1. Pathophysiology
Unit II
Chapter 2nd

2. RESPIRATORY
SYSTEM

3. INTRODUCTION TO RESPIRATORY SYSTEM
The cells of the human body require a constant stream of oxygen to
stay alive. The respiratory system provides oxygen to the body’s cells
while removing carbon dioxide, a waste product that can be lethal if
allowed to accumulate. There are 3 major parts of the respiratory
system: the airway, the lungs, and the muscles of respiration.

4. The airway, which includes the nose, mouth, pharynx, larynx,
trachea, bronchi, and bronchioles, carries air between the lungs and
the body’s exterior. The lungs act as the functional units of the
respiratory system by passing oxygen into the body and carbon
dioxide out of the body. Finally, the muscles of respiration, including
the diaphragm and intercostal muscles, work together to act as a
pump, pushing air into and out of the lungs during breathing.

6. Nose and Nasal Cavity: The nose and nasal cavity form the main
external opening for the respiratory system and are the first section
of the body’s airway, the respiratory tract through which air moves.
The nose is a structure of the face, made of cartilage, bone, muscle
and skin that supports and protects the anterior portion of the nasal
cavity.

7. Mouth: The mouth is the secondary external opening for the
respiratory tract. Mostly, normal breathing takes place through the
nasal cavity, but the oral cavity can be used as supplement or
replace the nasal cavity’s functions when needed. Because the
pathway of air entering the body from the mouth is shorter than the
pathway for air entering from the nose, the mouth does not warm
and moisturize the air entering the lungs.

8. Pharynx: The pharynx, also known as the throat, is a muscular funnel
that extends from the posterior end of the nasal cavity to the
superior end of the esophagus and larynx. The pharynx is divided
into 3 regions: the nasopharynx, oropharynx, and laryngopharynx.
Larynx: The larynx, also known as the voice box, is a short section of
the airway that connects the laryngopharynx and the trachea. The
larynx is located in the anterior portion of the neck, just inferior to
the hyoid bone and superior to the trachea.

9. Trachea: The trachea connects the larynx to the bronchi and allows
air to pass through the neck and into the thorax. The rings of
cartilage making up the trachea allow it to remain open to air at all
times. The open end of the cartilage rings faces posteriorly toward
the esophagus, allowing the esophagus to expand into the space
occupied by the trachea to accommodate masses of food moving
through the esophagus.

10. Bronchi and Bronchioles: At the inferior end of the trachea, the
airway splits into left and right branches known as the primary
bronchi. The left and right bronchi run into each lung before
branching off into smaller secondary bronchi. The secondary
bronchi carry air into the lobes of the lungs two in the left lung
and three in the right lung.

11. Lungs: The lungs are a pair of large, spongy organs found in the
thorax, lateral to the heart and superior to the diaphragm. Each lung
is surrounded by a pleural membrane that provides the lung with
space to expand as well as a negative pressure space relative to the
body’s exterior. The negative pressure allows the lungs to passively fill
fill with air as they relax.

12. Muscles of Respiration
Surrounding the lungs are sets of muscles that are able to cause air
to be inhaled or exhaled from the lungs. The principal muscle of
respiration in the human body is the diaphragm, a thin sheet of
skeletal muscle that forms the floor of the thorax.

13. Physiology of the Respiratory System
Pulmonary Ventilation: Pulmonary ventilation is the process of
moving air into and out of the lungs to facilitate gas exchange.
The respiratory system uses both a negative pressure system and
the contraction of muscles to achieve pulmonary ventilation.

14. External Respiration: External respiration is the exchange of gases
between the air filling the alveoli and the blood in the capillaries
surrounding the walls of the alveoli. Air entering the lungs from the
atmosphere has a higher partial pressure of oxygen and a lower
partial pressure of carbon dioxide than does the blood in the
capillaries.

15. Internal Respiration: Internal respiration is the exchange of gases
between the blood in capillaries and the tissues of the body.
Capillary blood has a higher partial pressure of oxygen and a lower
partial pressure of carbon dioxide than the tissues through which it
passes.

16. ASTHMA
Asthma is a chronic inflammatory disorder of the airways
associated with variable (usually reversible) airflow
obstruction and enhanced bronchial hyper responsiveness to
a variety of stimuli.

18. Causes
Asthma is characterized by excessive sensitivity of the lungs
to various stimuli. There is increasing evidence to suggest
genetics play an important role in the etiology of the
disease.

19. Physiological factors that may trigger or increase asthma symptoms
include:
• Viral upper respiratory infections.
• Heavy exercise.
• Untreated conditions such as rhinitis, sinusitis, and
gastroesophageal reflux (GERD).

20. • Drugs: NSAIDS such as aspirin.
• Ibuprofen, acetaminophen, naproxen sodium and Ketoprophen;
statin drugs (cholesterol reducing medications) and other
antiinflammatory drugs.
• Stress and strong emotions.
• Menstrual cycle/hormone changes.

21. Based upon causes, the asthma is divided into two types:
a. Intrinsic asthma: Usually develop beyond age 40 and have
many causes other than exposure to allergens.
b. Extrinsic asthma: Most commonly develop in childhood and
caused by exposure to definite allergens.

22. Classification of Asthma
Current classification of asthma is based on clinical severity. This
allows asthma sufferers and clinicians to better manage treatment
choices and clinical outcomes.
1. Mild Intermittent Asthma: It occurs in people with daytime
symptoms that occur no more frequently than twice a week and
night-time symptoms that occur no more than twice a month. These
people are usually asymptomatic with normal Peak Expiratory Flow
Rate between exacerbations.

23. 2. Mild Persistent Asthma: It is characterized by daytime symptoms
that occur more than twice a week but less than once a day with
night-time symptoms more frequent than twice a month. These
people are asymptomatic but have abnormal pulmonary function
tests.

24. 3. Moderate Persistent Asthma: It occurs in people who have daytime
symptoms every day and night-time symptoms more than once a
week. Exacerbations limit their activity and occur at least twice a
week, and may last for several days.
4. Severe Persistent Asthma: It is characterized by continual daytime
symptoms and frequent night-time symptoms. They experience
limited physical activity and exacerbations are frequent.

25. Pathophysiology
1. Increased production of thick tenacious mucus with impaired
mucocilary function.
2. Mucosal swelling due to increased vascular permeability and
vascular congestion.
3. Bronchial smooth muscle contraction
4. These changes cause bronchial hyper responsiveness and
obstruction. Airway obstruction increases resistance to air flow and
decreases flow rates, including expiratory flow.

26. Symptoms
• Coughing, especially at night, during exercise or when laughing.
• Shortness of breath.
• Chest tightness.
• Wheezing (a whistling or squeaky sound in chest when breathe,
especially while exhaling).

27. Prevention and Treatment
Prevention of exposure to known triggers is warranted.
Hyposensitization may be beneficial if the asthma has an allergic
mechanism, in such cases:
• Identify and avoid asthma triggers.
• Identify and treat attacks early and monitor breathing.
• Other measures include dust free house.
• Intake of selective type of food

28. CHRONIC OBSTRUCTIVE AIRWAYS DISEASES
Chronic Obstructive Airways Diseases (COPD) is a lung disease that
includes —
1. Respiratory failure
2. 2. Bronchitis
3. 3. Emphysema

29. Respiratory Failure
Respiratory failure is inadequate gas exchange by the respiratory
system, with the result that levels of arterial oxygen, carbon dioxide
or both cannot be maintained within their normal ranges. A drop in
blood oxygenation is known as hypoxemia; a rise in arterial carbon
dioxide levels is called hypercapnia.

30. Causes Common causes of type I (hypoxemic) respiratory failure
include the following:
• COPD
• Pneumonia
• Pulmonary edema
• Pulmonary fibrosis
• Asthma
• Pneumothorax
• Pulmonary embolism
• Pulmonary arterial hypertension

31. Common causes of type II (hypercapnic) respiratory failure include the
following:
• COPD
• Severe asthma
• Drug overdose, poisonings
• Myasthenia gravis
• Polyneuropathy
• Poliomyelitis
• Primary muscle disorders
• Porphyria
• Cervical cordotomy

32. Symptoms
• Marked CO2 excess can cause headaches and, in time, a
semiconscious state, restlessness, anxiety, confusion, seizures, or
even coma.
• Low blood oxygen causes bluish coloration in skin, fingertips and
lips.
• Tachycardia and cardiac arrhythmias may result from hypoxaemia
and acidosis.

33. Complications
• Pulmonary fibrosis.
• Collapsed lung (pneumothorax).
• Blood clots.
• Infections.
• Abnormal lung function.
• Memory, cognitive and emotional
problems.

34. Treatment
• Antibiotics to prevent and treat respiratory infections.
• Bi-level positive airway pressure (BiPAP).
• Bronchodilators, like anticholinergics, such as tiotropium or β-
agonists, such as Albuterol.
• Continuous positive airway pressure (CPAP).
• Inhaled steroid medications to decrease inflammation.
• Lung transplant, in rare cases.

35. Bronchitis
Bronchitis is an inflammation of the lining of the bronchial tubes, the
airways that connect the trachea (windpipe) to the lungs. Bronchitis is
more specifically when the lining of the bronchial tubes becomes
inflamed or infected. People with bronchitis breathe less air and
oxygen into their lungs; they also have heavy mucus or phlegm
forming in their airways.

36. [I] Acute Bronchitis
Acute bronchitis is swelling and inflammation of the main air
passages to the lungs. This swelling narrows the airways, making
it harder to breath and causing other symptoms, such as a
cough.

37. Causes
Acute bronchitis almost always follows a cold or flu-like infection. The
infection is caused by viruses (influenza, parainfluenza, respiratory
syncitial virus, rhinovirus and adenovirus). At first, it affects nose,
sinuses, and throat. Then it spreads to the airways leading to lungs.
Sometimes, bacteria (Mycoplasma, Streptococcus, Bordetella,
Moraxella, Haemophilus and Chlamydia pneumoniae) also infect the
airways.

38. Symptoms
• Chest discomfort.
• Cough that produces mucus; it may be clear or yellow green.
• Fatigue.
• Fever, usually low grade.
• Shortness of breath that gets worse with activity.
• Wheezing, in people with asthma.

39. Diagnosis
In acute bronchitis, coughing usually lasts between 10 to 20 days.
There are no specific tests for acute bronchitis. Certain tests may be
required if there is recurrent or persistent cough that may suggest
asthma or chronic bronchitis.

40. Treatment of acute bronchitis involves:
• Getting adequate rest and fluid intake.
• Use of analgesic and antipyretic medications to relieve muscle
aches, pains, headaches, and to reduce fever.
• Use of cough suppressants for a dry cough, but not for a
productive cough.
• Use of expectorants for productive cough, to help clear the airways
of mucus.
• Stopping smoking and avoidance of other airborne irritants.

41. (II) Chronic Bronchitis
Chronic bronchitis is a long-term, often irreversible respiratory
illness. It is a chronic inflammatory condition in the lungs that
causes the respiratory passages to be swollen and irritation
increases the mucus production and damages the lungs.

42. Causes
Bronchitis is considered "chronic" if symptoms continue for three
months or longer. Bronchitis caused by allergies can also be
classified as chronic bronchitis. There are many causes of chronic
bronchitis, but the main cause is cigarette smoke. Many other
inhaled irritants (for example, smog, industrial pollutants, toxic gases
gases in the environment or workplace and solvents) can also result
in chronic bronchitis.

43. Pathophysiology
The disease is caused by an interaction between noxious inhaled
agents and host factors, such as genetic predisposition or respiratory
infections which cause injury or irritation to the respiratory epithelium
of the walls and lumen of the bronchi and bronchioles. Chronic
inflammation, edema, temporary bronchospasm, and increased
production of mucus by goblet cells are the result. As a consequence,
airflow into and out of the lungs is reduced, sometimes to a dramatic
degree.

44. Symptoms
• Bluish skin due to lack of oxygen (cyanosis).
• Breathing difficulty including wheezing and shortness of breath.
• Cough and sputum production are the most common symptoms;
they usually last for at least 3 months and occur daily.

45. Treatment
The goal of therapy for chronic bronchitis is to relieve symptoms,
prevent complications and slow the progression of the disease.
Quitting smoking is the most important and most successful
treatment for chronic bronchitis, since continuing to use tobacco
will only further damage the lungs.