Gaseous Exchange Short Answers - 2

·         Effect of Smoking on Teeth:

Smoking is responsible for:

1- The weakening and staining of teeth.

2- It can lead to plaque.

3- Tooth loss is 2 to 3 times higher in smokers than in non-smokers.

·         Pneumonia Symptoms:

The infection of lungs in which causative organisms enter the alveoli, break the lung tissues and area becomes filled with fluid and pus is called pneumonia. 
Symptoms: Cold followed by a high fever, shivering, cough with sputum production, shortness of breath, patient’s skin color may change to dusky or purplish due to poor oxygenation of blood.

·         Arteriosclerosis:

Hardening of blood vessels is called arteriosclerosis.  
Cause: The chemicals present in smoke increase the production of blood platelets. When platelets are more than the normal numbers, they make the blood viscous and it can lead to arteriosclerosis.

·         Stomata vs Lenticels:

Stomata are the living pores formed by the turgor pressure in guard cells while lenticels are the dead pores formed in the bark (when young stem turns into mature stem).

Stomata are present in leaves and young stems while lenticels are present in mature stems and mature roots.

Stomata are not raised while lenticels are the raised pores.
Stomata open during day time and close during night time while lenticels remain open all the time.

·         Respiratory Centre:

The point in medulla oblongata of the brain which controls the rate of breathing is called respiratory Centre.

Significance/Role: It is sensitive to the concentration of carbon dioxide in the blood. Greater than normal concentration of carbon dioxide in blood as a result of increased cellular respiration by muscle cells stimulates the respiratory Centre of brain which sends messages to rib muscles and diaphragm to increase rate of breathing so that excess carbon dioxide present in blood can be removed out of the body. Thus during exercise, breathing rate may increase up to 30-40 times per minute.

·         Bad Effects of Smoking:

1- Tobacco smoke contains 4,000 different chemicals and about 50 carcinogens.

2- Smoking can lead to lung cancer.

3- It can also cause various other cancers of the body e.g. in kidney, oral cavity, larynx, breast and pancreas etc.

4- Chemicals in smoke can cause emphysema and other respiratory disorders.

5- Carbon monoxide in tobacco smoke lessens oxygen carrying capacity of hemoglobin.

6- It leads to increase in number of platelets leading to arteriosclerosis.

7- Smoking can cause greater risk of developing infections in lungs e.g. tuberculosis.

8- Smoking is also responsible for weakening and staining of teeth and tooth loss.

·         Acute vs Chronic Bronchitis:

1- Acute bronchitis occurs for less time span while chronic bronchitis occurs for longer time span.

2- Acute bronchitis usually lasts about two weeks while chronic bronchitis lasts for 3 months to two years.

3- In acute bronchitis, patients recover with no permanent damage to bronchi or bronchioles while in chronic bronchitis, the bronchi develop chronic inflammation leading to permanent damage.

·         Nostrils:

A pair of openings through which air moves into or out of the nasal cavity is termed as nostrils. There are two types of nostrils:

1- External Nostrils: Openings through which nasal cavity opens to the outside.

2- Internal Nostrils: Openings through which nasal cavity opens to the pharynx.

·         Glottis vs Epiglottis:

Glottis: The narrow opening at the floor of pharynx which leads into the larynx is called glottis. The air goes from the pharynx into the larynx through glottis.

Epiglottis: The flap of cartilage which guards the glottis (opening) is called epiglottis. It closes the glottis when food is being swallowed.

·         Gaseous exchange in Roots:

The gases are found in the soil surrounding the roots which can diffuse in or out of the roots.

Young Roots: In young roots, gases diffuse in and out of the general surface.

Mature Roots: The surface of mature roots is covered by bark and is thus impervious to gases or water. However there are certain pores called lenticels which allow the air to pass through them.