Q: How is oxygen and carbon dioxide transported in human body?

\$\bullet\$ The oxygen and carbon dioxide transported in the human body are as follows: \$\bullet\$ The oxygen enters into the blood from the lungs and carbon dioxide is expelled out from the blood into the lungs.\$\bullet\$ Blood is responsible for the transportation of gases.\$\bullet\$ Oxygen is carried by the blood and transported into the cells.\$\bullet\$ The carbon dioxide is carried away from the cells.

Question 1

How is oxygen and carbon dioxide transported in human body?

Accepted Answer

$\bullet$  The oxygen and carbon dioxide transported in the human body are as follows: $\bullet$  The oxygen enters into the blood from the lungs and carbon dioxide is expelled out from the blood into the lungs.$\bullet$  Blood is responsible for the transportation of gases.$\bullet$  Oxygen is carried by the blood and transported into the cells.$\bullet$  The carbon dioxide is carried away from the cells.

Question 2

Describe the mechanism of respiration in man.

Accepted Answer

Mechanism of respiration in man takes place in two phases, namely inspiration and expiration. Inspiration is the process of inhaling air into the lungs. During inspiration, the muscles of diaphragm contract and the diaphragm moves downward. This results in the increase in the volume of the chest cavity, The air pressure inside the chest cavity decreases. The oxygenated air present outside the body being at high-pressure flow rapidly into the lungs. In the lungs, oxygenated air reaches the alveoli. Alveoli are thin walled and are surrounded by a network of blood capillaries. The oxygen passes through the walls of the alveoli into the blood present in blood capillaries. The oxygen is then supplied to all the tissues of the body. From the tissues, the waste product, carbon dioxide is absorbed by blood and carried to the alveoli of lungs for expiration. Expiration is the process of exhaling air from lungs. During expiration, the muscles of diaphragm relax and diaphragm moves upward. This results in the decrease in the volume of the chest cavity. The air pressure inside the chest cavity increases. This pushes out carbon dioxide outside the body.

Question 3

Explain the mechanism of breathing with the help of labelled diagram involving both stages-inspiration and expiration.

Accepted Answer

The action of breathing in and out is due to changes of pressure within the thorax, in comparison with the outside. This action is also known as external respiration. When we inhale the intercostal muscles (between the ribs) and diaphragm contract to expand the chest cavity. The diaphragm flattens and moves downwards and the intercostal muscles move the rib cage upwards and out.Inspiration : This increase in size decreases the internal air pressure and so air from the outside (at a now higher pressure that inside the thorax) rushes into the lungs to equalise the pressures.Expiration : When we exhale the diaphragm and intercostal muscles relax and return to their resting positions. This reduces the size of the thoracic cavity, thereby increasing the pressure and forcing air out of the lungs.

Question 4

What is respiration? Explain the process of respiration in human beings. (Figure not required)

Accepted Answer

Respiration: The process of releasing energy by the oxidation of food is known as respiration. The process of respiration involves intake of oxygenated air into the cells for breaking the food and releasing energy.Mechanism of respiration:i. Air is drawn into the body through the nostrils. ii. The air from the nasal cavity passes to the pharynx, which leads to the trachea, through a slit called glottis.iii. The trachea runs down the neck and divides into two bronchi, which lead into the lungs and further divide into smaller bronchioles. The smallest bronchioles terminate into alveoli. iv. The walls of the alveoli are thin and covered by blood capillaries to facilitate the exchange of gases in the lungs.v. In the alveoli, the exchange of gases takes place, CO$_2$ from the blood is replaced with O$_2$ and CO$_2$ is removed out of the body.vi. In humans, for the process of respiration, air is drawn into the lungs by the process of breathing.When an individual inhales, the diaphragm moves down, and the chest cavity expands and the oxygen rich air is drawn into the lungs. When the individual exhales, the diaphragm relaxes and the chest cavity moves back to its relaxed position and the carbon dioxide rich air is expelled out of the body.

Question 5

(a) Draw a labelled diagram of human respiratory system.(b) Explain the transportation of oxygen and carbon dioxide in human beings.

Accepted Answer

Exchange of gases takes place between the alveoli of lungs and the surrounding blood capillaries.  The two main gases exchanged are oxygen and carbon-dioxide. Oxygen is absorbed by the blood capillaries from the lungs alveoli by diffusion while carbon dioxide is absorbed by the lungs alveoli from blood capillaries by diffusion. Transport of oxygen and carbon dioxide occurs with the help of respiratory pigment called hemoglobin. Haemoglobin, the iron-containing respiratory pigment is a red coloured pigment of blood, which has a very high affinity for oxygen. Haemoglobin though is purple coloured but oxyhemoglobin is of bright red colour. Oxygen is transported from lungs to the body cells in the form of oxyhemoglobin. Carbon dioxide is transported from the body cell to the lungs in the forms of carboxyhemoglobin, carbonic acid, bicarbonates of sodium and potassium.

Question 6

Differentiate between.Inspiration and expiration.

Accepted Answer

INSPIRATION:a)The act of drawing air into the lungs.b)Rib cages move forward and upward.c) Contraction of external intercostals muscles and relaxations and internal intercostals muscles occur.d) Increase in volume of the thoracic cavity.e)Diaphragm contracts and becomes flattened.f)Increase in volume of the thoracic cavity.g) Air pressure in lungs is less than atmospheric pressure.EXPIRATION.a)Expulsion of air from the lungs.b)Rib cages move downward and inward.c)Relaxations of external intercostals muscles and Contraction of internal intercostals muscles occure) Diaphragm relaxes and becomes original dome-shaped.f) The decrease in the volume of the thoracic cavity.g) Air pressure in lungs is higher than atmospheric pressure.

Question 7

Which of the following factors is not favourable for the formation of oxyhaemoglobin?

Accepted Answer

Following are the four factors that are responsible for the oxyhaemoglobin in alveoli:$pO_2$:The greater the partial pressure of the oxygen causes the binding of hemoglobin with the oxygen efficiently.$Temperature$: The normal temperature favors the binding of hemoglobin with oxygen. The high temperature is responsible for the dissociation of the oxygen from haemoglobin.$pCO_2$: The large amount of the carbon dioxide decreases the formation of the oxyhaemoglobin. The carbon dioxide has more affinity for haemoglobin than with the oxygen.$H^+$: The increase in  the hydrogen ion concentration or decrease in pH causes the increases in the dissociation of haemoglobin.Thus, a high $pCO_2$ is not favourable for the formation of oxyhaemoglobin.So, the correct answer is (D).

Question 8

Arrange the following in the order of increasing volume.(1) Tidal volume(2) Residual volume(3) Expiratory reserve volume(4) Vital capacity

Accepted Answer

Tidal Volume is the normal volume of air displaced between normal inhalation and exhalation when extra effort is not applied. It is approx 500ml.Residual volume is a lung volume which represents the amount of air left in the lungs after a forced exhalation. It is 1.1 litres.Expiratory reserve volume is the additional amount of air that can be expired from the lungs by determined effort after normal expiration. It is 0.7 litres.Vital Capacity is the greatest volume of air that can be expelled from the lungs after taking the deepest possible breath. It is approx 4.6 litres.Hence option B is correct.

Question 9

Which of the following is correct for oxygen transport ?

Accepted Answer

For purposes of discussing oxygen transport by the blood, we will consider blood to be composed of two phases: plasma and red blood cells (RBCs). Oxygen is carried in the blood in two forms: (1) dissolved in plasma and RBC water (about 2% of the total) and (2) reversibly bound to hemoglobin (about 98% of the total). At physiological PO2, only a small amount of oxygen is dissolved in plasma since oxygen has such a low solubility. At elevated PO2 (breathing 100 % oxygen or during hyperbaric oxygenation), however, the physically dissolved form of oxygen can become significant. Henry's law states that the amount of oxygen dissolved in plasma is directly proportional to PO2: [O2] = &#945; PO2, where &#945; = 0.003 ml O2 (100 ml plasma)&#8722;1 mm Hg&#8722;1. Thus, at a PO2 of 100 mm Hg (a typical value for arterial blood), 100 ml of plasma contains 0.3 ml O2 (or 0.3 vol%).Some of the carbon dioxide is transported dissolved in the plasma. Some carbon dioxide is transported as carbaminohemoglobin. However, most carbon dioxide is transported as bicarbonate. As blood flows through the tissues, carbon dioxide diffuses into red blood cells, where it is converted into bicarbonate.Carbon dioxide is transported in the blood from the tissue to the lungs in three ways:1(i) dissolved in a solution; (ii) buffered with water as carbonic acid; (iii) bound to proteins, particularly hemoglobin. Approximately 75% of carbon dioxide transport in the red blood cell and 25% in the plasma. The relatively small amount in plasma attributable to a lack of carbonic anhydrase plasma so an association with water is slow; plasma plays little role in buffering and combination with plasma proteins is poor.So, the correct answer is 'Both B and C'.

Question 10

During respiration, exchange of gases take place in

Accepted Answer

Alveoli are the air sacs of the lungs. They have thin walls surrounded by blood capillaries (another layer of simple squamous epithelium). Gas exchange occurs in the alveoli. During inhalation, oxygen gas is in higher concentration in the alveoli than in the blood and so it diffuses into the blood through this thin layer of cells.During exhalation, carbon dioxide is in higher concentration in the blood than in the alveoli and so it diffuses into the alveoli through this thin layer of cells.So, the correct answer is option B.