Regulation of Respiration & Respiratory Disorders | Biology Class 11 - NEET PDF Download

Regulation of Respiration

• Human beings have ability to maintain and moderate the rate of respiration to fulfill the demand of body tissues by neural system.
• Respiratory rhythm centre is located in medulla region of hind brain. Pneumotaxic centre in pons moderate the function of respiratory rhythm centre.
• Chemo-sensitive area near rhythm centre is highly sensitive to C and H+ ions that ultimately control the respiratory rate. Oxygen do not play major role in controlling rate of respiration.

Functions of Respiration:

1. Energy production

2. Maintenance of acid-base balance.

3. Maintenance of temperature

4. Return of blood and lymph.

5. Mountain Sickness is the condition characterised by the ill effect of hypoxia (shortage of oxygen) in the tissues at high altitude commonly to person going to high altitude for the first time.

Symptoms of Hypoxia:

• Loss of appetite, nausea, and vomiting occurs due to expansion of gases in digestive system.
• Breathlessness occurs because of pulmonary oedema.
• Headache, depression, disorientation, lack of sleep, weakness and fatigue.

Respiratory Disorders 

(a) Bronchitis : It is the inflammation of the bronchi, which is characterised by hypertophy and hyperplasia of seromucous gland and goblet cells lining the bronchi. The symptom is regular coughing, with thick greenish yellow sputum that indicates the underlying infection, resulting into excessive secretion of mucous. It may also be caused by cigarette smoking and exposure to air pollutants like carbon monoxide.

Prevention and Cure : Avoiding exposure to the cause, i.e. smoke, chemicals and pollutants, can prevent Bronchitis. The underlying infection of the disease is treated with suitable antibiotics. Bronochodilator drugs (for widening the constriction of bronchial passage by relaxing the smooth muscles) provide symptomatic relief.

(b) Bronchial Asthma : This is characterised by the spasm of the smooth muscles present in the walls of the bronchiole. It is generally caused due to the hypersensitivity of the bronchiole to the foreign substances present in the air passing through it. The symptoms of the disease may be coughing, or difficulty in breathing mainly during expiration. The mucous membranes on the wall of the air passage start secreting excess amount of mucous, which may clog the bronchi, as well as bronchiole.

Prevention and Cure :It is an allergic disease hence, avoiding exposure to the foreign substance or allergens is the best preventive measure. In case the patient is sensitive to a very few number of allergens, the hyposensitisation (by exposing small doses of the specific allergen) is the other preventive measure. Treatment of the disease includes antibiotic therapy for removing the infection and use of bronchodilator drugs, as well as inhalers for symptomatic relief.

(c) Emphysema : It is an inflation or abnormal distension of the bronchiole or alveolar sac, which results into the loss of elasticity of these parts. As a result the alevolar sac remains filled with air even after expiration and ultimately, the lung size increases. The reason for such a condition can be assigned to cigarette smoking and chronic bronchitis.

Prevention and Cure : Emphysema is a chronic obstructive disease of lung, causing irreversible distension and loss of elasticity of alveoli. Hence, it can't be cured permanently. However treatment may retard the progression of the disease. Its treatment is also symptomatic Bronchodilaors, antibiotics and oxygen therapy are used. This disease is preventable if chronic exposure to smoke (cigarette and others) an pollutant is avoided.

(d) Pneumonia : It is an acute infection or inflammation of the alveoli of the lung. This disease is caused mainly due to infection of the bacterias (streptococcus pneumoniae). Sometimes, other bacteria of fungi, protozoan viruses and mycoplasma may also be responsible, infants, elderly persons and immuno compromised individuals are susceptible to it. In this disease, most of the air space of the alveloar sac is occupied by the fluid with dead WBC. Uptake of oxygen is adversely affected in the inflammed alveoli, as a result of which, the oxygen level of the blood falls.

Prevention and Cure : Since infection is the main cause of pneumonia, use of antibiotics to remove the infection cures it. Patient may require symptomatic treatment like bronchodilator drugs. In case of immuno compromised individuals, the disease can be prevented by proper and timely vaccination.

(e) Occupational Lung Disease : It is caused because of the exposure to potentially harmful substances, such as gas, fumes of dusts present in the environment where a person works, silicosis and asbestosis are the common examples, which occur due to chronic exposure of silica and asbestos dust in the mining industry. It is characterised by fibrosis (proliferation of fibrous connective tissue) of upper part of lung, causing inflammation.

Prevention and Cure : Almost all the occupational lung disease, express symptoms after chronic exposure, i.e. 10-15 years or even more. Not only this, disease like silicosis and asbestosis are incurable. Hence, the person likely to be exposed to such irritants, should adopt all possible preventive measures. These measures include :

(i) Minimising the exposure of harmful dust at the work place.

(ii) Workers should be well informed about the harm of the exposure to such dusts.

(iii) Use of protective gears and clothing by the workers at the work place.

(iv) Regular health check up.

(v) Holiday from duty at short intervals for the workers in such areas.

The patient may be provided with symptomatic treatment, like bronchodilators and antibiotic treatment, like bronchodialors and antibiotics to remove underlying secondary infection.

(f) Decompression Sickness : During deep sea diving the diver inhales gases at an increased pressure in depth, as a result the nitrogen also gets dissolved in the blood. When the diver comes back to the surface, where the pressure has again decreased, the dissolved nitrogen start getting released from blood in the form of Bubbles which cause a number of problems, example air embolism infarction due to blocked vessel etc.

Some Terms Related to Respiration

1. Eupnoea :- It is the state of normal breathing. In man rate of normal breathing is 12-16 per minute. In infants rate of breathing is 44 per minute. Rate of breathing is slowest while sleeping.

2. Bradypnoea or Hyponea :- It is the state of slow breathing.

3. Tachypnoea or hypernea :- It is the state of fast breathing.

4. Apnoea - It is the state of stoppage of breathing temporarily.

5. Dyspnoea - It is the state of discomfort due to difficulty in breathing.

6. Asphyxia - It is the state of suffocation due to high CO₂ concn or low O₂ concn.

7. Anoxia - It is the lack of O₂ supply to tissues.

8. Hypocapnoea - It is the state of reduced CO₂ concn in blood.

9. Hypercapnoea - It is the state of increased CO₂ cocn in blood.

Old NCERT Syllabus
SPECIAL POINTS

1. Anatomical dead space :- Amount of air which is inhaled but never reaches the alveoli. (It remain in the conduction zone, which extends from external nostrils to terminal branchiole) This air does not take part in exchange of gases. It is 150 ml in volume.

2. Pathological dead space :- If due to disease of circulatory origin the air is filling in the alveolis but the blood circulation or perfusion in the capillaries of wall of alveoli is absent or low then this air also gets wasted as there is no blood present to whome it may oxygenate. This amount of air is pathological dead space.

In a normal person this is zero.

Total dead space = Anatomical dead space + Pathological dead space.

3. Alveolar perfusion :- The amount of blood that enters the walls of the alveoli via capillaries to participate in exchange of gases. This is denoted as 'Q'.

4. Physiological shunt :- Not entire amount of blood which enters the lungs via pulmonary arteries actually reaches in the walls of alveoli. 2% of the total blood actually never passes through the walls of alveoli, instead it enters the venule side from arteriole side via the conduction zone in lungs. So this blood never gets oxygenated.

This is shunted blood (2% of total) this means that only 98% of the blood which enters the lungs actually gets oxygenated. This phenomenon of By pass of alveoli by 2% of total blood is called as physiological shunt.

It is normally present in all human beings.

5. Pathological shunt :- If due to presence of some respiratory disease, alveolis do not get filled up with air and remain collapse, then the blood which passes through the walls of these alveoli does not gets oxygenated.

This portion of blood is called pathological shunt.

So greater is the pathological shunt, greater will be the amount of blood which fails to get oxygenated as it passes through lungs.

This pathological shunt is zero in lungs of normal human beings.

Total shunt = Physiological shunt + Pathological shunt

6. Nostrils, nasal passage, pharynx bronchus are called accessory respiratory organs.These organs do not participate in gaseous exchange but only provide space for incoming and outgoing air Lungs are basic or main respiratory organs.

7. One molecule of haemoglobin combine with four molecules of carbon mono oxide gas to form carboxyhaemoglobin. Its colour is cherry red.

8. One molecule of haemoglobin has 4 Fe++ ions metal. Only one Ion of iron metal is present in myoglobin.

9. In normal conditions - frogs show 35% - Cutaneous respiration 9% - Buccopharyngeal respiration 56% - Pulmonary respiration

10. In frog, respiration rate is 80/ minute.

11. In frog, sternohyal & mylohyal (petrohyal) muscles are related with the process of respiration.

12. Ludwig first explained gaseous exchange in blood.