4.Respiration-contdact as resonators of the sound waves. They vibrate and produce sound.

Larynx

Vocal Cords

e) Trachea or Wind Pipe: - The larynx opens into a long tube called trachea or wind pipe. The trachea externally has a number of C shaped cartilaginous rings. These rings give stability and flexibility to the trachea. They also prevent the collapse of the wind pipe when there is no air in it.

The trachea divides ,in front of esophagus. into two branches called BRONCHI. These bronchi enter the lungs on their respective sides. They divide into a number of branches in the lungs. The branches are called BRONCHIOLES.

f) Lungs: - There are two lungs in the thoracic cavity. They lie in the rib cage which gives them protection.

Each lung is enclosed in a double walled sac called PLEURA. Internally the lung has a number of thin walled air sacs called ALVEOLI.

The walls of alveoli are richly supplied with blood vessels. There are about 300 million alveoli in each lung. Gaseous exchange takes place in the alveoli. The total surface area inside the alveoli is about 400 –800 square feet

. Animate:Blue – entering-Red going out.The blue gradually changes to red before going out of the blood vessels.

In man the blood is associated with respiration. The red blood cells contain a respiratory pigment known as HAEMOGLOBIN. Haemoglobin is the vehicle that transports gases in and out of lungs.

How does respiration take place? What are the processes involved?

There are mainly four processes.They are . . . . . . . 1) Breathing 2) Gaseous transport3) Tissue respiration4) Cellular respiration

Let us examine the processes individually.

1) BREATHING : - Breathing involves INHALATION or INSPIRATION and EXHALATION or EXPIRATION. During inhalation we breath in air. Thus oxygen in the air is taken into the lungs.

2) During exhalation we breath out air. Thus carbon dioxide is expelled from lungs.

3) GASEOUS TRANSPORT: - The oxygen in the air is absorbed by the blood vessels present in the alveoli of lungs. This oxygen attaches to hemoglobin by weak bonds and now the hemoglobin is called oxyhaemoglobin. Blood carries it to different parts of the body from the lungs.

The carbon dioxide from tissues forms a bond with hemoglobin. This compound is known as carbamino-haemoglobin.This compound from different parts of the body is carried to the lungs by blood . In the lungs the CO2 detaches from hemoglobin and is expelled into the cavity of lungs. It is subsequently expelled out of the body during expiration.

4) TISSUE RESPIRATION : - The blood vessels end as capillaries in tissues. The oxygen carried by blood from lungs easily diffuses through the capillaries into tissues and CO2 is picked up by haemoglobin to be taken lungs.

5) CELLULAR RESPIRATION : -. The oxygen is utilized to produce energy from glucose in mitochondria of the cells. The production of energy involves a number of biochemical processes.

What is the mechanism of Respiration?

The mechanism of respiration involves two stages.1) INHALATION or INSPIRATION and

2) EXHALATION or EXPIRATION

1) Inspiration: - During the stage of inhalation the muscles of the thoracic cavity contract. Due to this contraction the thoracic cavity expands. The diaphragm is lowered. This results in reduced air pressure in lungs in comparison to the external air pressure. The air rushes in to the lungs through nostrils, trachea, bronchi, bronchioles and finally the alveoli.

Expiration:- The muscles of thoracic cavity come back to natural position. The diaphragm also comes back to its natural position. The air pressure in the lungs increases than the pressure outside. Air rushes out of the lungs and expelled through bronchi, trachea and nostrils. Both inhalation and exhalation are involuntary events.

Animate1. Show thoracic cavity in normal position.2. Show expansion of thoracic cavity.3. Show lowering of diaphragm.4. Show air entering lungs into the capillaries and carbon dioxide diffuses

out of the capillaries. Exchange of gases has taken place.5. Show the thoracic cavity going back to normal position.6. Diaphragm in normal position.7. Air rushing out of lungs shows the thoracic cavity going back to normal

position.8. Diaphragm in normal position.

9. Air rushing out of lungs

What is the composition of inhaled and exhaled air?The following chart gives us the composition of inhaled and exhaled air.S.no Inhaled exhaled1. Nitrogen – 79% 79%2. Oxygen - 21% 17%3. Carbon dioxide – 0.03% 4%4. Water Vapor - varies saturated

The air we breathe in is containing more oxygen than the air we breathe out. About 5 to 6% of oxygen in air we breath in is absorbed. The air we breathe out contains more of carbon dioxide than that in the air we breathe in.

The air we breathe out is saturated with water vapor. Due to Breathing about 400 Cm3 of water is lost daily as water vapor from our body.

Gas Exchange in Tissues: - In the tissue various metabolic reactions produce carbon dioxide. The blood supplies oxygen to the parts where the concentration of carbon dioxide is high. Difference in concentrations The exchange of gases is dependent on different concentration of gases. This is called as Tissue Respiration.

The oxygen in tissues is utilized by the cells to produce energy from glucose. The energy production involves oxidation of food (i.e., glucose) inside mitochondria. This is called Cellular respiration.

The Journey of oxygen: Nostrils-Trachea-Bronchioles-Lung cavity-Alveoli-Blood capillaries-Blood vesels-Tissue-Cells-Mitochondria

What is the capacity of lungs? How much air can they accommodate?

A normal person can take in 500ml of air. This is called as TIDAL VOLUME. The rate of respiration is calculated by the volume of air breathed in a minute. This is called Rate of VENTILATION.

Rate of Ventilation = Tidal Volume X Frequency of inspiration.The rate of ventilation varies depending on activity. The rate increases during heavy work.The volume of air that we breathe out is about 4500ml. This is known as TIDAL VOLUME.

Do we expel all the air from our lungs with maximum effort?

No. The lung retains 1500ml of air even if we put maximum effort to expell it. The retained air is called RESIDUAL AIR.

Inspiration of air with maximum effort can take in about 3000ml more than the tidal volume of air. The additional volume of air is called Inspiratory reserve volume (IRV).

The expiratory reserve volume is the air expelled out in addition to normal by maximum effort. The volume is about 1000ml of air. This additional volume is Expiratory reserve volume (ERV).

How do we calculate Vital Capacity?

The vital capacity is calculated by adding tidal volume to IRV and ERV i.e. 500 + 3000+ 1000ml = 4500ml

The Total Lung Capacity includes the vital capacity and Residual air.4500 + 1500 = 6000ml

Let us examine an important disease of respiratory system. This disease is known as EMPHYSEMA.

Emphysema is a disease that affects the smokers. In a smoker the walls of alveoli get broken. Due to this event the absorbing surface area inside lungs is reduced. Less oxygen is absorbed. The heart in this situation is forced to supply more blood to tissues.The change in rate of heart beat can lead to a heart stroke and death.

Dear students smoking is highly injurious to health. Keep away from this unhealthy habit. Live long with energy and enthusiasm.

As we have studied photosynthesis and respiration both being processes of energy production let us compare the processes to find similarities and differences.

Comparison of Photosynthesis and Respiration

We have studied Photosynthesis and Respiration. Did you find any similarities? Are there any differences?

The table that follows shows us the differences or similarities.

Photo Synthesis Respiration1. Occurs only in plants. 1. Occurs in all living organisms.2. Sun light is essential 2. Not depending on sunlight. Occurs

day and night.3. A plant can survive without photosynthesis for two to three days.

3. No organism can survive without respiration even for few minutes.

4. Only few cells specially those in the leaves perform Photosynthesis.

4. All cells of the organism take part in respiration.

5. Photosynthesis is performed in chloroplasts in the presence of sunlight.

5. Aerobic respiration is performed in cytoplasm and mitochondria of cells. It is not dependent on sun light.

6. Raw materials are carbon dioxide and water.

6. Raw materials are organic carbon dioxide and oxygen.

7. Oxygen is liberated. 7. Oxygen is utilized.8. Carbon dioxide is utilized. 8. Carbon dioxide is liberated.9. Adds on weight. 9. Decreases the weight of organism10. Converts the energy from sun rays i.e., radiant energy into chemical energy.

10. Releases chemical and potential energy to be used by many other processes.

11. Produces ATP by use of light energy.

11. Produces ATP by oxidation of glucose.

12. NADP is reduced to NADPH2

using hydrogen and water molecules.12. NADH2 is formed from hydrogen of carbohydrates.

13. ATP & NADHH2 are used for synthesis of organic compounds.

13. NADH2 and ATP are available for cellular activities.

14. Anabolic process. 14. Catabolic process.15.

The ultimate aim of these two processes is production of ATP though the processes are different and raw materials different.

This episode concludes the study on respiration. In the next episode we shall examine the transport system.