Respiratory System Honor

Science & Health

Requirements

1. What are the structures that form the respiratory system? Illustrate and describe the main functions of each one.

   Answer: Upper airways: nasal cavities (filter, warm, humidify the air), pharynx (common passage for air/food), larynx (vocal cords, speech, closure of the glottis during swallowing). Lower airways: trachea (cartilaginous tube, conducts air), bronchi (2 branches to the lungs), bronchioles (fine branches), alveoli (sacs where gas exchange occurs). — The epiglottis is a crucial structure that covers the glottis during swallowing, preventing food from entering the trachea — when one 'chokes', it is because a piece of food got past the epiglottis, activating the cough reflex to expel it.

2. Are the right and left lungs the same? What is the anatomical difference between them?

   Answer: The lungs are NOT identical. The right lung is larger and has 3 lobes (upper, middle and lower), separated by two fissures (oblique and horizontal). The left lung is smaller and has only 2 lobes (upper and lower), separated by an oblique fissure, with the 'cardiac notch' leaving room for the heart, which occupies the left half of the thorax. — The 'cardiac notch' of the left lung is the anatomical depression where the heart sits — the cardiac apex points to the left and downward, which is why the left side of the lung is more compressed.

3. What are the 2 main gases in our body? What is gas exchange? Describe the airways conducting air up to the moment of gas exchange.

   Answer: The two main gases are oxygen (O₂), which enters the body, and carbon dioxide (CO₂), which leaves. Gas exchange (hematosis) is the diffusion of gases between the pulmonary alveoli and the blood capillaries: O₂ passes from the air in the alveoli into the blood and CO₂ passes from the blood into the air, which will be exhaled. The conducting airways up to the moment of gas exchange (the air's path): 1) Nasal cavities (and mouth) — filter, warm and humidify the air; 2) Pharynx — common passage for air and food; 3) Larynx — contains the vocal cords and the glottis; 4) Trachea — a cartilaginous tube that conducts the air; 5) Bronchi — two branches, one for each lung; 6) Bronchioles — increasingly fine ramifications; 7) Pulmonary alveoli — sacs where gas exchange finally occurs. — Diffusion occurs by a concentration gradient — oxygen is more concentrated in the alveoli than in the venous blood, so it passes naturally; CO₂ is more concentrated in the venous blood, so it leaves. The physical principle of Henry's Law applied to human physiology.

4. What is an alveolus and what is its function? Through drawings or figures, illustrate an alveolus demonstrating the moment of gas exchange.

   Answer: Alveoli are small rounded sacs (about 300 million in an adult) located at the ends of the bronchioles, forming a structure similar to clusters of grapes. Their function is gas exchange: very thin walls (1 cell thick) lined by blood capillaries allow the O₂ from the air to pass into the blood and the CO₂ from the blood to pass into the air. — The total area of the 300 million alveoli combined is equivalent to a tennis court (~70 m²) — this immense optimized surface concentrated in the lungs is what allows rapid oxygenation of the entire blood supply in just 1 minute.

5. What is the main function of ciliated cells, with mobile cilia?

   Answer: The ciliated cells, present in the epithelium of the airways (trachea, bronchi, bronchioles), have mobile cilia that beat in a coordinated sweeping motion, expelling the mucus with trapped particles (dust, bacteria, fungi, pollen) toward the pharynx, where it will be swallowed or spat out. — The mucociliary apparatus is so efficient that an entire layer of mucus travels toward the pharynx at approximately 1 cm per minute — smokers have their cilia paralyzed by nicotine, which is why they develop a 'smoker's cough' upon waking (without cilia the mucus accumulates).

6. What is the relationship between cellular respiration and pulmonary respiration?

   Answer: Pulmonary respiration is the exchange of gases in the lungs (the entry of O₂ and the exit of CO₂ from the body). Cellular respiration occurs in the mitochondria of the cells: O₂ is used to 'burn' glucose, producing energy (ATP), CO₂ and water. — Each cell produces about 37 million ATP molecules per day through cellular respiration — the human brain alone consumes 20% of the oxygen we breathe, although it is only 2% of body weight, due to its very high metabolic rate.

7. Explain how the circulatory and respiratory systems are closely linked.

   Answer: The two systems work in partnership: the respiratory one captures O₂ and eliminates CO₂ in the lungs; the circulatory one transports O₂ (bound to hemoglobin) to each cell of the body and returns CO₂ to the lungs. — Pulmonary circulation takes only 4-8 seconds for a complete loop through the lungs — during this brief transit the blood is 100% oxygenated and CO₂ is eliminated, an efficiency made possible by the enormous surface of the alveoli.

8. What is the importance of hemoglobin and iron for the oxygenation of the body?

   Answer: Hemoglobin is the protein of the red blood cells responsible for transporting oxygen (O₂) and carbon dioxide (CO₂) in the blood. Each hemoglobin molecule contains 4 heme groups, with one iron atom in each. — Each red blood cell contains about 270 million hemoglobin molecules — a total capacity to transport more than 1 billion O₂ molecules per cell, an efficiency that sustains the life of highly metabolically active tissues such as the brain and muscles.

9. Describe in detail the movements of inhalation and exhalation. What is the importance of the diaphragm muscle for these movements?

   Answer: Inhalation (an ACTIVE movement): the diaphragm contracts and descends (flattens); the external intercostal muscles contract and raise/spread the ribs; the volume of the rib cage increases; the pressure inside the lungs drops below atmospheric pressure and air enters, filling the lungs. Exhalation (at rest it is PASSIVE): the diaphragm relaxes and rises (dome shape); the intercostal muscles relax and the ribs descend; the thoracic volume decreases; the internal pressure of the lungs becomes greater than atmospheric and air leaves. Importance of the diaphragm muscle: it is the main muscle of respiration — it sits between the thorax and the abdomen and is responsible for most of the ventilation. By contracting and descending, it increases the thoracic volume and creates the negative pressure that pulls air in; by relaxing and rising, it helps expel the air. Without the work of the diaphragm, normal breathing does not happen efficiently. — The phrenic nerve, which controls the diaphragm, exits the spinal cord between C3-C5 — hence the clinical mnemonic 'C3, C4, C5 keep the diaphragm alive' used by doctors to remember that injuries above C3 are immediately fatal.

10. Which organ of the central nervous system controls breathing? Why?

    Answer: The medulla oblongata, located in the brainstem, controls breathing in an involuntary and automatic way. It has the 'respiratory center' that detects the level of CO₂ in the blood (via chemoreceptors) and adjusts the respiratory rate. — The 'Hering-Breuer reflex' protects the lungs from over-inflation — receptors in the walls of the bronchi sense the stretching and send a signal to the medulla to begin exhalation, a mechanism discovered in 1868 by two German physiologists.

11. What is the normal respiratory rate of the following:
    • Newborns
    • Children
    • Adults

    Answer: 1) Newborns: 30 to 60 breaths per minute (BPM). 2) Children: it varies with age — babies 24 to 40 BPM, ages 1 to 3 years 22 to 34 BPM, ages 4 to 12 years 18 to 30 BPM. 3) Adults: 12 to 20 BPM (in the elderly, 14 to 20 BPM). Above these values it is called tachypnea and below it bradypnea; the measurement should be taken with the patient at rest, without their noticing, since observation alters the rhythm. — The respiratory rate is considered the most neglected vital sign by health professionals — studies show that changes in it appear 12-24 hours before clinical deterioration, being crucial for the early detection of sepsis and respiratory failure.

12. Define the following terms about respiratory alterations:
    • Eupnea
    • Tachypnea
    • Bradypnea
    • Dyspnea
    • Orthopnea
    • Apnea

    Answer: 1) Eupnea: normal breathing, with a regular and calm rhythm. 2) Tachypnea: accelerated breathing (above 20 BPM in an adult). 3) Bradypnea: slow breathing (below 12 BPM in an adult). 4) Dyspnea: difficulty or discomfort in breathing, with a sensation of shortness of breath. 5) Orthopnea: difficulty breathing when the person is lying down, which improves on sitting or standing up (common in cardiac and pulmonary problems). 6) Apnea: a stoppage or absence of breathing for a period of time. — Orthopnea is a classic sign of left-sided heart failure — when the person lies down, the blood returns to the heart and congests the lungs; sitting up reduces this return and relieves the dyspnea, the type of patient who sleeps with several pillows.

13. Study the following respiratory diseases and tell, about each one, how it occurs / is acquired, transmission (if applicable), treatment and prevention:
    • Asthma
    • Tuberculosis
    • Pneumonia
    • Flu / upper respiratory tract infections
    • Pulmonary emphysema
    • Pulmonary thromboembolism
    • Pneumoconioses
    • Cystic fibrosis

    Answer: 1) Asthma: chronic inflammation of the bronchi with an allergic/genetic basis, which causes attacks of shortness of breath, wheezing and coughing; it is not transmissible; treatment with bronchodilators and inhaled corticosteroids; prevention by avoiding the triggers (dust, mites, smoke, cold). 2) Tuberculosis: an infection caused by the bacterium Mycobacterium tuberculosis (Koch's bacillus); transmitted by respiratory droplets (coughing, sneezing, speaking) from a sick person; treatment with antibiotics for about 6 months; prevention by the BCG vaccine, good ventilation and early diagnosis. 3) Pneumonia: an infection of the pulmonary alveoli by bacteria, viruses or fungi; it can be transmissible depending on the agent; treatment with antibiotics or antivirals; prevention by the pneumococcal and flu vaccines and good hygiene habits. 4) Flu / upper airway infections: caused by viruses (Influenza and others); transmitted by droplets and contact; symptomatic treatment and antivirals in indicated cases; prevention by the annual vaccine, hand washing and avoiding crowds. 5) Pulmonary emphysema: a chronic disease (COPD) in which the alveoli are destroyed and lose elasticity, usually due to cigarettes; it is not transmissible; treatment with bronchodilators, oxygen therapy and smoking cessation; prevention by not smoking and avoiding pollutants. 6) Pulmonary thromboembolism: the obstruction of a lung artery by a clot (thrombus) coming from the veins, usually from the legs; it is not transmissible; treatment with anticoagulants; prevention by moving around on long trips and treating thrombosis risk factors. 7) Pneumoconioses: diseases caused by the prolonged inhalation of mineral dust at work (silicosis from silica, asbestosis from asbestos); they are not transmissible; supportive treatment of the symptoms (the injury is irreversible); prevention with protective equipment and dust control in the work environment. 8) Cystic fibrosis: a genetic and hereditary disease that makes the mucus thick, obstructing the lungs and pancreas; it is not transmissible; treatment with respiratory physiotherapy, antibiotics, digestive enzymes and specific medications; there is no prevention, but genetic counseling helps with family planning. — The BCG vaccine, mandatory in the SUS since 1976, protects against severe forms of tuberculosis in children (TB meningitis) — it does not prevent pulmonary tuberculosis, but reduces infant mortality by 80% according to data from the PNI (National Immunization Program).

14. Research the effects of cigarettes on the respiratory system. Present your results in one of the following ways:
    • Written report, at least 500 words
    • Oral presentation, at least 5 minutes
    • Display of posters and banners
    • Poem or song

    Answer: Effects of cigarettes: paralyzes the respiratory cilia → smoker's cough; inflames the bronchi → chronic bronchitis; destroys the alveoli → emphysema; causes lung cancer (90% of cases related to smoking); reduces lung capacity; increases respiratory infections. — Cigarette tar adheres to the alveoli forming dark plaques visible in autopsies — over 20 years of smoking, a smoker's lung takes on a grayish-black coloration, compared to the light pink of a healthy lung.

15. Do research in your region or state comparing the air quality indices. How can these indices be improved? What can you do to improve them?

    Answer: Main air quality indicators: CO (carbon monoxide), NO₂ (nitrogen dioxide), SO₂ (sulfur dioxide), O₃ (ozone), PM10 and PM2.5 (particulate matter). Sources: industries, vehicles, fires. — Particulate Matter (PM2.5) is the most dangerous pollutant because its microscopic particles (smaller than 2.5 μm) cross the alveoli and enter the bloodstream directly — the WHO estimates 4.2 million deaths/year from air pollution.