Breathing and Exchange of Gases Test 18

The larynx (voice box) is located between the pharynx and the trachea. It has a framework of cartilage that protrudes in the front of the neck and sometimes is referred to as Adam's apple. The arytenoid cartilage are paired hyaline cartilage present just above cricoid cartilage in the dorsal surface of larynx.

Haemoglobin is a red coloured iron containing pigment present in the RBCs. Oxygen can bind with haemoglobin in a reversible manner to form oxyhaemoglobin. Each haemoglobin molecule can carry a maximum of four molecules of oxygen. Binding of oxygen with haemoglobin is primarily related to partial pressure of oxygen. Partial pressure of carbon dioxide, hydrogen ion concentration (pH) and temperature are the other factors, which can affect this binding.

Blood is the medium of transport for oxygen and carbon dioxide. About 97 per cent of oxygen is transported by RBCs in the blood. The remaining 3 per cent of oxygen is carried in a dissolved state through the plasma. Nearly 20-25 per cent of carbon dioxide is transported by RBCs (carbaminohemoglobin), whereas 70 per cent of it is carried as bicarbonate (formed by dissociation of carbonic acid). About 7 per cent of $$CO_2$$ is carried in a dissolved state through plasma.

Concentration of carbonic acid does not increase in blood due to presence of Na$$^+$$. The bicarbonate buffering system of blood is an important buffer system in the acid-base homeostasis of living things, including humans. In plasma, by phosphate buffers, the alkaline phosphates combines with carbonic acid (H$$_2$$CO$$_3$$) and forms sodium bi carbonate.

Solution:

• Correct answer is option B

• Explanation for the correct option

• Vocal cord presents in the top area of the larynx. The larynx is considerably larger in the male than in the female. 
• Hence, the Adam's apple is much more prominent in the male. At the upper end of the larynx are the vocal cords, which serve in the production of speech's .The vocal cord modulates the flow of air from the lungs and into it.

RBCs contain a very high concentration of the enzyme, carbonic anhydrase and minute quantities of the same is present in the plasma too. This enzyme facilitates the production of carbonic acid from carbon dioxide and water. It also catalyzes the dissociation of carbonic acid into bicarbonate ions and protons.

Solution:

• Correct answer is option C 

• Explanation for the correct option

• The thyroid cartilage is the largest among the nine cartilages in the larynx. 
• The larynx is considerably larger in the male than in the female; hence, the Adam's apple is much more prominent in the male.
• It is secondary sexual characters are features that help in distinguishing the male and the female body from each other. 
• Adam’s apple is basically the bony part of the thyroid cartilage present in the human.

RBCs contain a very high concentration of the enzyme, carbonic anhydrase and minute quantities of the same is present in the plasma too. This enzyme facilitates the reaction between carbon dioxide and water to form carbonic acid and its dissociation into bicarbonate ions and protons.

Solution:

• Correct answer is option A

• Explanation for the correct option

• During normal breathing, the volume of air inspired or expired is known as tidal volume. Its value is approximately 500 ml.
• Vital capacity is defined as the maximum volume of air a person can breathe in after a forceful expiration or the maximum volume of air a person can breathe out after a forceful inspiration. This includes expiratory reserve volume, tidal volume and inspiratory reserve volume. Depending on the age, sex and height of the individual, its value varies from 3400 ml to 4800 ml.
• Inspiratory reserve volume is defined as the additional or extra volume of air, a person can inspire by forceful inspiration. This volume averages 2500 ml to 3000 ml.
• Expiratory reserve volume is defined as the additional or extra volume of air, a person expires by forceful expiration. This volume averages 1000 ml to 1100 ml.

In higher vertebrates like mammals (example rabbit, humans etc.), trachea is a straight tube, which divides into a right and left primary bronchi. Each bronchi undergoes repeated divisions to form the secondary and tertiary bronchi and bronchioles ending up in very thin terminal bronchioles. The tracheae, primary, secondary and tertiary bronchi and initial bronchioles are supported by incomplete cartilaginous rings. Each terminal bronchiole gives rise to a number of very thin, irregular walled and vascularised bag-like structures called as alveoli. Alveoli and alveolar ducts or terminal bronchioles are the primary sites of exchange of gases.