WEEK 1: Respiratory Symptoms and Signs Flashcards
Example 1/4
60/M Entrepreneur, Smoker
Breathlessness, Productive cough x 3/12
Wheezing 1/52
Similar problem every winter for over 10 years
Mild symptoms persist throughout the year
What is the diagnosis?
Ex 1 =Chronic Bronchitis/COPD
Example 2/4
20/M Medical Student
Sore Throat, Runny Nose x 2days
Dry and painful cough x 1 day
Fever x 1 day
What is the diagnosis?
Ex 2= Upper Respiratory Tract Infection
Example 3/4
50/M Teacher
Dry cough x 2 weeks
Recently started on treatment for High Blood Pressure (Amlodipine & Enalapril)
What is the diagnosis?
Ex 3= Angiotensin Converting Enzyme (ACE) inhibitor induced cough
They prevent the inbition of Bradykinin which can stimulate the cough mechanoreceptors in the lungs.
Example 4/4
40/F Nurse
Productive cough x 2 months
Weight loss, Fever x 2 months
Blood in sputum x 2days
What is the diagnosis?
Pulmonary TB
The respiratory system has several key functions.
State the principal ones.
The respiratory system has several key functions, the principal ones being to extract oxygen from the external environment and to dispose of carbon dioxide.
Gas exchange is achieved by exposing thin-walled capillaries to the alveolar gas and matching ventilation to blood flow through the pulmonary capillary bed.
The lungs expose a large surface area of body tissue to the external environment in order to achieve gas exchange hence they can be damaged by dusts, gases and infective agents.
Host defense is therefore a key priority for the lung and is achieved by a combination of structural and immunological defenses.
The pulmonary circulation responds readily to increased oxygen demands in exercise and also plays a role in innate immunity: for example, in de-priming neutrophils.
Describe the pathway of the upper respiratory tract.
The upper respiratory tract (URT) is the portion of the respiratory system that includes the nose, nasal cavity, pharynx, and larynx.
Upper respiratory vs lower respiratory tracts
The conduction of air through the nose-nasopharynx-oropharynx-laryngopharynx allows for filtration, warming, water saturation of air from nose to alveoli
Describe the pathway of the lower respiratory tract.
Trachea
Main bronchi (right and left)
Secondary (lobar bronchi)
Tertary (Segmental bronchi)
Bronchioles
Terminal bronchioles
Respiratory bronchioles
Alveolar ducts
Alveoli
Capillaries (surrounding alveoli)
Where does the carina lie?
The trachea lies slightly to the right of the midline and divides at the carina into right and left main bronchi.
The carina lies under the junction of the manubrium sterni and the second right costal cartilage.Strenal angle. T4/T5.
Compare right and left lung.
The right main bronchus is more vertical than the left and inhaled material is therefore more likely to end up in the right lung.
The right main bronchus divides into the upper lobe bronchus and the intermediate bronchus, which further subdivides into the middle and lower lobe bronchi. On the left, the main bronchus divides into upper and lower lobe bronchi only.
Each lobar bronchus further divides into segmental and subsegmental bronchi.
2 Fissures on the right and 1 on the left; resulting in 3 lobes on the right and 2 on the left.
Fissures and lobes determine whether clinical signs are anterior or posterior e.g …
What is pleura?
Describe the 2 types found at the lungs.
State the key inspiratory muscles.
What feature of the lungs does expiration depends on?
Boundaries: Spine, Heart, Mediastinum, Diaphragm
Lung movement facilitated by visceral & parietal pleura.
The pleura is a layer of connective tissue; The visceral pleura covers the surface of the lung, lines the interlobar fissures, and is continuous at the hilum with the parietal pleura, which lines the inside of the hemithorax.
Key inspiratory muscles: Diaphragm, IC muscles
Expiration: passive-elastic recoil
There are about how many divisions between the trachea and the alveoli?
The first 7 divisions are bronchi. Describe bronchi.
The next 16–18 divisions are bronchioles. Describe bronchioles.
What is the function of the ciliated epithelium?
There are approximately how many alveoli in each lung, with a large surface area for gas exchange by diffusion?
What is an Acinus? -
State the 2 types of cells lining the alveoli and their functions.
Phospholipid rich fluid that counteracts alveoli collapse. What is it?
Whatis the function of type I pneumocytes?
There are about 25 divisions between the trachea and the alveoli.
The first 7 divisions are bronchi that have walls consisting of cartilage and smooth muscle, an epithelial lining with cilia and goblet cells, submucosal mucus-secreting glands endocrine cells.
The next 16–18 divisions are bronchioles that have: no cartilage but have a muscular layer, a layer of ciliated cells but very few goblet cells, Clara cells that produce a surfactant-like substance.
The ciliated epithelium is a key defense mechanism as it moves Mucus, which contains macrophages, cell debris, inhaled particles and bacteria, towards the larynx: the ‘mucociliary escalator.’
There are approximately 300 million alveoli in each lung, with a large surface area for gas exchange by diffusion.
Acinus-unit of gas exchange; composed of respiratory bronchiole and clusters of alveoli.
Alveoli lined with Type 1 & 2 epithelial cells/pneumocytes.
Type 2-surfactant-phospholipid rich fluid that counteracts alveoli collapse.
Barrier Maintenance: Type I pneumocytes form the structure of the alveoli. Their primary function is to maintain a barrier that prevents the leakage of fluid and proteins across the alveolar wall into the air spaces. Simultaneously, they allow gases (such as oxygen and carbon dioxide) to freely cross the air-blood barrier 12.
Gas Exchange: These flat and thin cells cover approximately 95% of the alveolar surface. Their thinness facilitates rapid diffusion of gases between the alveoli and capillaries. During inspiration and expiration, their flat extensions overlap, aiding in efficient gas exchange 1.
Regeneration: Interestingly, type I pneumocytes cannot replicate when exposed to toxicity. However, they have a backup plan! If damaged, type II pneumocytes differentiate into type I cells to compensate for the injury
Describe the blood supply to the lung and venous drainage.
The lungs are supplied with deoxygenated blood by the paired pulmonary arteries. Once the blood has received oxygenation, it leaves the lungs via four pulmonary veins (two for each lung).
The bronchi, lung roots, visceral pleura and supporting lung tissues require an extra nutritive blood supply. This is delivered by the bronchial arteries, which arise from the descending aorta.
The bronchial veins provide venous drainage. The right bronchial vein drains into the azygos vein, whilst the left drains into the accessory hemiazygos vein.
The venous drainage to the left atrium follows the interlobular septa.
State the 2 types of fibers that are found in the alveolar walls and their functions.
Healthy alveolar walls contain a fine network of elastin and collagen fibers.
Elastin fibers allow the lung to be easily distended at physiological lung volumes.
Collagen fibers cause increasing stiffness at full inflation, to avoid overinflation.
Elastin fibers in alveolar walls maintain small airway patency.
What is emphysema?
Describe what happens in emphysema.
Emphysema is a chronic and progressive respiratory disease that falls under the umbrella term of chronic obstructive pulmonary disease (COPD).
It is characterized by the gradual destruction of the air sacs (alveoli) in the lungs and the accompanying loss of lung elasticity. Emphysema, along with chronic bronchitis, is a major contributing factor to COPD.
In emphysema, there is loss of alveolar walls, which leaves the small airways unsupported, resulting in their collapse on expiration. This causes air trapping and limits expiration.
What is lung compliance?
Lung compliance: a measure of the lung’s ability to stretch and expand.
Low compliance = stiff lung; extra work is required to bring in normal air volume; e.g thick balloon; seen in lung fibrosis
High compliance = pliable lung, with low elastic recoil; the elastic tissue is damaged by enzymes, resulting in difficulty exhaling air e.g., grocery bag/emphysema
What is the difference between elasticity and compliance?
Elasticity:
Definition: Elasticity refers to the ability of a material to return to its original shape and size after deformation or stretching.
In the Lungs: In the respiratory system, lung elasticity is a crucial property. The lung tissue, particularly the alveoli and surrounding connective tissue, possesses elasticity.
During inhalation, the lungs stretch, and elastic recoil occurs during exhalation.
This elasticity aids in the passive recoil of the lungs and chest wall, allowing them to return to their resting state after each breath.
Clinical Significance: Reduced lung elasticity, as seen in conditions like emphysema, can lead to a loss of the lungs’ natural recoil, making exhalation more difficult and contributing to symptoms like shortness of breath.
Compliance:
Definition: Compliance refers to the ease with which a structure can be stretched or distended. It is the reciprocal of stiffness.
In the Lungs: Lung compliance specifically refers to the ease with which the lungs can expand.
High compliance means the lungs can easily expand, while low compliance indicates that the lungs are stiff and resistant to expansion.
Compliance is influenced by the elastic properties of the lung tissue, the surface tension of the alveoli, and the flexibility of the chest wall.
Clinical Significance: Reduced lung compliance is associated with conditions like fibrosis, where lung tissue becomes stiff and less distensible. This can result in difficulty in fully expanding the lungs during inhalation.
CONTROL OF BREATHING
Where are respiratory motor neurons found?
State the 4 main control stations for respiratory systemm and their inputs.
Ventilation is controlled by a combination of neurogenic and chemical factors, however voluntary control through Cortical (volitional) and limbic (emotional) influences can override the automatic control of breathing.
Respiratory motor neurons are found in the medulla oblongata and are the origin of the respiratory cycle, modulated by multiple inputs;
*pH & PaCO2 -Central chemoreceptors
*Hypoxemia -carotid bodies
*Mechanical load -muscle spindles
*Stretch, inhaled toxins, interstitial disease- Vagal sensory fibers.
In healthy individuals, what is the main driver for respiration?
Sensitivity to this may be lost in chronic obstructive pulmonary disease: In these patients, what is the chief stimulus to respiratory drive?
State 2 factors that can depress the respiratory center.
In healthy individuals the main driver for respiration is the arterial pH, which is due to a rise in PaCO2, which increases [H+] in cerebrospinal fluid.
Sensitivity to this may be lost in chronic obstructive pulmonary disease: In these patients, hypoxemia is the chief stimulus to respiratory drive; oxygen treatment may therefore reduce respiratory drive and lead to a further rise in PaCO2.
The respiratory center is depressed by severe hypoxemia and sedatives (e.g. opiates).
Outline the COMMON RESPIRATORY SYMPTOMS.
Cough
Sputum
Hemoptysis
Dyspnea
Wheeze
Chest Pain
Hoarseness,
Constitutional symptoms
What is a cough?
State the purpose of a cough.
Outline the triggers of a cough.
Explosive expiration against a closed glottis
Purpose: clearance of foreign bodies & secretions from the airways.
Triggers
*Exogenous: Smoke, Dust, Foreign Bodies, Fumes
*Endogenous: Secretions, Gastric contents, specific pathologies (next slides)
