Samacheer Class 11 Bio Zoology - Respiration

The airway resistance is low because:
* The diameter of most airways is relatively large.
* For smaller airways there are many in parallel, making their combined diameter large.
* Air has a low viscosity.

• When a person travels from sea level to elevations where the atmospheric pressure and partial pressure of O 2 lowered there is a poor binding of O 2 with haemoglobin leads to acute mountain sickness.
• When the person lives there for a long time the kidney synthesizes the erythropoietin which stimulates the bone marrow to produce more RBCs

Inflammation of the lungs due to infection caused by bacteria or virus is called pneumonia. The symptoms are sputum production, nasal congestion, shortness of breath, sore throat etc. The alveoli get filled with fluid or pus, making is difficult to breathe (lung abscesses).

* The other parts of the respiratory system do the work of passing the air into the lungs only.
* Real respiration takes place between alveoli and blood capillaries.
The diffusion membrane of the alveolus is made up of three layers.
* The thin squamous epithelial cells.
* The endothelium of the alveolar capillaries.
* The basement substance found in between them.
The thin squamous epithelial cells of the alveoli provide space for gaseous exchange

When a person travels quickly from sea level to elevations above 8000 ft, where the atmospheric pressure and partial pressure of oxygen are lowered, the individual responds with symptoms of acute mountain sickness (AMS)- headache, shortness of breath, nausea, and dizziness due to poor binding of O 2 with hemoglobin. When the person moves on a long-term basis to mountains from sea level his body begins to make respiratory and hematopoietic adjustments.
To overcome this situation kidneys accelerate the production of the hormone erythropoietin, which stimulates the bone marrow to produce more RBCs. When a person descends deep into the sea, the pressure in the surrounding water increases which causes the lungs to decrease in volume.
This decrease in volume increases the partial pressure of the gases within the lungs. This effect can be beneficial, because it tends to drive additional oxygen into the circulation, but this benefit also has a risk, the increased pressure can also drive nitrogen gas into the circulation.
This increase in blood nitrogen content can lead to a condition called nitrogen narcosis. When the diver ascends to the surface too quickly a condition called ‘bends’ or decompression sickness occurs and nitrogen comes out of solution while still in the blood-forming bubbles. Small bubbles in the blood are not harmful, but large bubbles can lodge in small capillaries, blocking blood flow or can press on nerve endings.
Decompression sickness is associated with pain in joints and muscles and neurological problems including stroke. The risk of nitrogen narcosis and bends is common in scuba divers. During carbon dioxide poisoning, the demand for oxygen increases. As the 02 level in the blood decreases it leads to suffocation and the skin turns bluish-black.
Part II
11th Bio Zoology Guide Respiration Additional Important Questions and Answers
(1 Mark)
I. Choose The Best Options

a) Toxic substances present in tobacco.
Nicotine tar, carbon monoxide ammonia, arsenic and sulphur dioxide.
b) ill effects
* Carbon monoxide and Nicotine damaged the cardie vascular system.
* The tar damages the gaseous exchange system.
* Nicotine stimulate the heart to beat faster and narrowing the blood vessels results in raised blood pressure and coronary heart diseases.
* Carbon monoxide reduces O 2 Supply.
* Smoking causes lung, stomach, and pancreases and bladder cancer.
* It lowers sperm count in men.

• Smoking can cause lung diseases by damaging the airways and alveoli and results in emphysema and chronic bronchitis.
• These two diseases along with asthma are referred to as a chronic obstructive pulmonary disease.
• When a preson smokes 85% of the smoke released is inhaled by the smoker himself and others in the vicinity called passive smokers are also affected indirectly.

• In the alveoli high PO 2 low PCO 3 Low temperature and less H + Concentration favours the formation of oxyhemoglobin wjiere as in the tissues low PO 2 high PCO 2 high H and high-temperature favoures the dissocation of O 2 from oxyhemoglobin.
• A sigmoid curve is obtained when the percentage saturation of haemoglobin with O 2 is plotted against PO 2.
• This S, Shaped curve has a steep slope for PO 2 valuer between 10 and 50 mm Hg and then flattens between 70 and 100 mm Hg.
• Under normal physiological conditions, every 100 ml of oxygenated blood can deliver about 5 ml of O 2 to the tissues.

Location
Partial Pressures of Oxygen PO 2
The partial pressure of CO 2 PCO 2
Inspiration
159 mm. Hg
0.3 mm. Hg
Expiration
120 mm. Hg
127 mm. Hg
Alveoli
104 mm. Hg
40 mm. Hg
Pulmonary artery
40 mm. Hg
45 mm.Hg
Pulmonary vein
95 mm. Hg
40 mm. Hg
Oxygenated blood
95 mm. Hg
40 mm. Hg
Deoxygenated blood
40 mm. Hg
45 mm. Hg

The amount of dissolved oxygen is very low in water compared to the amount of oxygen in the air. Hence the rate of breathing in aquatic animals is faster than the terrestrial animals.

Epiglottis is a thin elastic flap at the junction of the nasopharynx and larynx. It prevents the food from entering into the larynx and avoids choking on food.

The lungs are light spongy tissues enclosed in the thoracic cavity surrounded by an air-tight space. It is bound dorsally by the vertebral column and ventrally by the sternum, laterally by the ribs, and on the lower side by the dome-shaped diaphragm.

* The amount of air that moves into the respiratory passage per minute is called minute respiratory volume.
Normal TV = 500 ml
* Normal respiratory rate = 12 times / minute Therefore the minute respiratory volume – 6 litre / minute

The surface area of the respiratory surface is large and richly supplied with blood vessels.
* It is extremely thin and kept moist.
* It is in direct contact with the environment.
* It is permeable to respiratory gases.

• The surface area must be very large and richly supplied with blood vessels.
• Should be extremely thin and kept moist.
• Should be in direct contact with the environment.
• Should be permeable to the respiratory gases.

• Healthy lungs contain large amounts of elastic connective tissue around the alveoli containing elastin which makes the lung tissue elastic.
• People with emphysema and bronchitis have difficulty in exhaling because the enzyme elastase destroys the elastin around the alveoli and reduces the elasticity of the lungs.

• Allergy is caused by allergens, it may be due to dust, pollens some seafood.
• Allergens provoke an inflammatory response. The allergens affect our respiratory tracts and we immediately start sneezing and coughing.

Breathing with a hoarse sound during sleep is caused by the vibration of the soft palate.
Snoring is caused by a partially closed upper airway (nose and throat) which becomes too narrow for enough air to travel through the lungs. This makes the surrounding tissues vibrate and produces the snoring sound.

• The oesophagus and trachea lies in the pharynx During swallowing a thin elastic flap called epiglottis prevent the food from entering in to the larynx.
• If we talk or laugh during swallowing the closing of trachea becomes disturbed and hence the food may enter in to trachea.

• There are more dust and microbes in the air. If we breathe through the mouth there is a possibility of entering these microbes and dust in to the stomach through oesophagus.
• When we breathe through the nose the dust will be filtered by the bristles. The dust particular is trapped by the mucous membrane of the nasal cavity.

• The diffusion membrane of the alveolus is made up of three layers. The thin squamous epithelial cells.
• The endothelium of the alveolar capillaries
• The basement substance found in between them. The thin requamous epithelial cells of alveoli are composed of Type-I and Type-II cells.
• The Type-I cells are very thin so that gases can diffuse rapidly through them. Type-II cells are thicker synthesize and secrete a substance called surfactant.

Some of the inspired air never reaches the gas exchange areas but fills the respiratory passages where exchange of gases does not occur. This air is called dead space. Dead space is not involved in gaseous exchange. It amounts to approximately 150mL.

• Hemoglobin belongs to the class of conjugated protein.
• The iron-containing pigment portion haem constitutes only 4% and the rest colourless protein of the histone class globin.
• The molecular weight of Hb is 68000
• These four Iron atoms can combine with a molecule of oxygen.

If the iron component of the haem is in ferric state in stead of normal ferrous state it is called methaemoglobin. Methaeglobin does not bind with O 2.

Premature Babies have low levels of surfactant in the alveoli may develop the new bom respiratory distress syndrome (NRDS) because the synthesis of surfactants begins only afer the 25th week of gestation.

When there is a shortage of O 2, it is sensed by our brain and sends a message to CNS to correct the imbalance for O 2 demand and trigger us to yawn. Yawning helps us to breath more oxygen to the lungs.

For all the activities of our body energy is needed. This we receive from the food. Oxygen is utilized by the organisms to break down the biomolecules the glucose and to derive energy. Hence Respiration is necessary.

The amount of dissolved oxygen is very low in water compared to the amount of oxygen in the air. So the rate of breathing in aquatic organisms is much faster than land animals.

The goblet cells present in the mucus membrane secrete mucus, a slimy material rich in glycoprotein. Microorganisms and dust particles attach to the mucus films and are carried upwards to pass down the gullet during swallowing.

Some of the inspired air never reaches the gas exchange areas but fills the respiratory passages where the exchange of gases does not occur. This air is called dead space. Dead space is not involved in gaseous exchange. It amounts to approximately 150mL.

He is suffering from a dust allergy. As he entered in a polluted area he started sneezing and coughing. The allergens in that place affecting his respiratory tracts and provoked inflammatory response prolonged allergy leads to Asthma.

Long exposure to sand particles can give rise to inflammation leading to fibrosis. She must be hospitalized and have to give medication like anti-coagulation the imatinib. that fight against the disease.
(5 marks)
V. Essay Questions

• It helps in the exchange of O 2 and CO 2 between the atmosphere and the blood.
• It maintains homeostatic regulation of body pH.
• It protects us from inhaled pathogens and pollutants.
• It maintains the vocal cords for normal communication.
• It removes the heat produced during cellular respiration through breathing.

• The trachea is semiflexible tube supported by cartilaginous rings.
• It starts from the pharynx and ends in the lungs there it divides into right and left primary bronchi.
• With in the lungs the bronchi divided repeatedly into secondary and tertiary bronchi.
• That further divides into terminal bronchioles and respiratory bronchioles.
• Bronchi have ‘c’ shaped curved cartilage plates.
• This plate helps in preventing collapsing as the air pressure changes during breathing.
• There is no cartilaginous stingray the brarichioles,
• The rigidity of the bronchioles prevents them from collapsing.

Inspiration occurs if the pressure inside the lungs is less than the atmospheric pressure.
Inspiration:
* There is a contraction of diaphragm muscles and external intercostal muscles which pulls the ribs and sternum upwards and downwards and increases the volume of the thoracic chamber in the dorsoventral axis.
* Hence the pulmonary pressure is less than the atmospheric pressure.
* This forces the fresh air from outside to enter the air passages into the lungs to equalize the pressure.
Expiration:
* Expiration takes place when the pressure within the lungs is higher than the atmospheric pressure.
* Relaxation of the diaphragm leads to its original dome-shaped nature.
* The internal intercostal muscles contract pulling the ribs downward reducing the thoracic volume and pulmonary volume.
* Thin results in an increase in the intrapulmonary pressure slightly above the atmospheric pressure causing the expulsion of air from the lungs.

• The lungs are light spongy tissue.
• It is enclosed inthe thoracic cavity surrounded by an air-tight space.
• The thoracic cavity is bound dorsally by the ventral column and ventrally by the sternum. laterally by the ribs and on the lower side by the dome-shaped diaphragm.
• The lungs are covered by a double walled pleural membrane and the plural cavity is filled with pleural fluid which reduces friction.
• The trachea is a semi-flexible tube supported by cartilaginous rings which extends upto the 5th thoracic vertebra.
• It divides into right and left bronchi and enters in to the lungs. There it divides further many times and ends in alveoli.

Molecular oxygen is carried in blood in two ways: bound to haemoglobin within the red blood cells and dissolved in plasma. Oxygen is poorly soluble in water, so only 3% of the oxygen is transported in the dissolved form. 97% of oxygen binds with haemoglobin in a reversible manner to form oxyhaemoglobin (Hb0 2 ). The rate at which haemoglobin binds with O 2 is regulated by the partial pressure of O 2.
Each haemoglobin carries maximum of four molecules of oxygen. In the alveoli high pO 2, low pCO 2, low temperature and less H+ concentration, favours the formation of oxyhaemoglobin, whereas in the tissues low p02, high pCO 2, high H+ and high temperature favours the dissociation of oxygen from oxyhaemoglobin.
A sigmoid curve (S-shaped) is obtained when percentage saturation of haemoglobin with oxygen is plotted against pO 2. This curve is called oxygen haemoglobin dissociation curve. This S-shaped curve has a steep slope for pO 2 values between 10 and 50 mm Hg and then flattens between 70 and 100 mm Hg. Under normal physiological conditions, every 100 mL of oxygenated blood can deliver about 5 mL of O 2 to the tissues.

* 7-10% of CO 2 is transported in a dissolved form in the plasma.
* 20-25% of dissolved CO 2 is bound and carried in the RBCs as carbamino haemoglobin.
CO 2 + H 6 ⇌ H 6 CO 2
* About 70% of CO 2 is transported as bicarbonate ions.
* At the tisoues the PCO 2 is high due to catabolism and diffuses in the blood to form HCO – 3 and H +
* When CO 2 diffuses into RBCs it combines with water forming carbonic acid catalyzed by carbonic anhydrase.
* Carbonic acid is dissociated into hydrogen and bicarbonate.
* Every 100 ml of deoxygenated blood delivers 4ml CO 2 to the alveoli for elimination.

• Medulla oblongata is a repiratory regulation centre.
• The pneumotaxic centre present in the pons varoli is the respiratory rhythm centre.
• The chemosensitive area found close to the rhythm centre is highly sensitive to CO 2 and H +
• H + are eliminated out by respiratory process.
• Receptiors associated with the aortic arch and carotid artery send signals to the rhythm centre for remedial action.

The respiratory system is affected by environmental occupational personal and social factors.
Following are some of the respiratory disorders:
Asthma: It is characterized by narrowing and inflammation of bronchi and bronchioles and difficulty in breathing.
Causes: Allergens like dust drugs pollen grains, certain food items like fish.
Emphysema: It is chronic breathlessness. It is caused by gradual breakdown of the thin wall of the alveoli decreasing the total surface area of a gaseous exchange.
Causes: The widening of the alveoli is called Emphysema.
Cigarette smoking reduces the respiratory surface of the alveolar walls.
Bronchitis: It is the inflammation of the bronchi.
Causes: Pollution smoke ciagratte smoking.
Symptoms: Cough shortness of breath sputum in the lungs.
Pneumonia: It is the inflammation of the lungs.
Causes: Bacteria and virus
Symptoms
* Sputum production Nasal congestion, Shortness of breath sore throat.
* Tuberculosis
Causes
* Tuberculosis is caused by mycobacterium tubercular.
* Infection mainly occurs in the lungs and bones.
Symptoms
Collection of fluid between the lungs and the chest wall is the main complication of this

• It increases the heartbeat rate.
• It narrows the blood vessels results in raised blood pressure and leads to coronary heart diseases.
• Smoking can cause lung diseases by damaging the airways and alveoli and results in emphysema and chronic bronchitis.

ORGANISMS
RESPIRATORY ORGANS
1. Sponges, Coelenterates
Body surface
2. Earth worm
The moist skin
3. Insects
Trachea
4. Aquatic Arthropods mollusca
Gills
5. Fishes
Gills
6. Amphibians, Reptiles Aves mammals
Lungs
7. Frog
Lungs, Moist skin

Steps involved in respiration are
* The exchange of air between the atmosphere and the lungs.
* The exchange of O 2 and CO 2 between the lungs and the blood.
* Transport of O 2 and CO 2 by the blood.
* Exchange of gases between the blood and the cells.
* Intake of O 2 by the cells for various activities and release of CO 2

Disorders
Symptoms
1. Pulmonary Embolism
Blood clot occurs in the lung
2. Bronchitis
Inflammation of the lining of your bronchial tubes
3. Asthma
Swelling and narrowing of air ways and there is excess secretion of mucus.
4. Lung cancer
Smoking causes cancer
5. Pneumonia
Inflammation of lungs affecting alveoli
6. Pulmonary edema
fluid accumulation of the tissue and air spaces of lung.
7. Emphysema
Shortness of breath due to widening of alveoli
8. Atelectasis
Alveoliand lungs get deflated
9. Tuberculosis
It affects lungs and bones and effasion (fluid accumulation in the lungs)
10. Pleurisy
Pleura becomes inflammed

* When a person travels from sea level to elevations above 8000 ft there is a poor binding of O 2 with haemoglobin.
* There is a symptom of headache shortness of breath nausea and dizziness develop. (Acute mountain sickness)
* To overcome this situation kidneys accelerate the production of the hormone erythropoietin which stimulates the synthesis of RBCs.
II. Inthedeepsea
* When a person descends deep in to the sea the pressure in the water increases which causes the lungs to decrease in volume.
* There is an increased nitrogen level in the blood lead to nitrogen narcosis.
* When the diver ascends to the surface a condition called decompression sickness occurs. As nitrogen comes out of solution while still in the blood-forming bubbles.
* The large bubbles can block the blood flowor can press on the nerve ending. This also causes pain in joints, muscles and causes neurological problems.