Tag: mechanism of respiration in animals

Questions Related to mechanism of respiration in animals

Which of the following changes occur in diaphragm and intercostal muscles when expiration of air takes place? 

evs respiration in living organisms respiration in human beings respiration and associated structures respiration in humans mechanism of respiration in animals human lungs respiratory organs in humans

  1. Internal intercostal muscles relax and diaphragm contracts

  2. External intercostal muscles and diaphragm relaxes

  3. Internal intercostal muscles contract and diaphragm relax

  4. External intercostal muscles and diaphragm contract

Show answer
Correct Option: C
Explanation:
  • When the internal intercostal muscles contract and diaphragm relax, the ribs move .downward and inward and the diaphragm becomes convex {dome shaped), 
  • thus decreasing the volume of the thoracic cavity and increasing the pressure inside as compared to the atmospheric pressure outside. This will cause the air to move out (expiration).

Read the given statements and select the correct option.


Statement 1 : Mammals can eat while breathing. 

Statement 2 : Mammals have negative-pressure breathing.

evs respiration in living organisms respiration in human beings respiration and associated structures respiration in humans mechanism of respiration in animals human lungs respiratory organs in humans

  1. Both statements 1 and 2 are Correct.

  2. Statement 1 is correct but statement 2 is incorrect.

  3. Statement 1 is incorrect but statement 2 is correct.

  4. Both statements 1 and 2 are incorrect.

Show answer
Correct Option: A
Explanation:
Mammals like humans along with birds and reptiles have negative pressure breathing. They use their mouths for both eating and breathing. Breathing requires pressure gradient. Mammals create pressure gradient using their diaphragm. The high volume and low pressure in the lung cavity results in the air to be sucked in. They cannot swallow and breathe at once. However, it is possible for them to eat while breathing.
Thus, the correct answer is option (A).

Given below is a list of different steps (i-vi) involved in respiration.
(i) Utilisation of $O _2$ by the cells for catabolic reactions
(ii) Transport of gases by the blood
(iii) Pulmonary ventilation by which atmospheric air is drawn in and $CO _2$ is released out
(iv) Release of resultant $CO _2$
(v) Diffusion of $O _2$ and $CO _2$ between blood and tissues
(vi) Diffusion of gases ($O _2$ and $CO _2$) across alveolar tissues.
Select an option which has correct sequence of all the steps.

evs respiration in living organisms respiration in human beings respiration and associated structures respiration in humans mechanism of respiration in animals human lungs respiratory organs in humans

  1. (iii), (vi), (ii), (v), (i), (iv)

  2. (iii), (vi), (i), (v), (ii), (iv)

  3. (iv), (ii), (v), (iii), (i), (vi)

  4. (iv), (vi), (ii), (v), (i), (iii)

Show answer
Correct Option: A
Explanation:

While respiration atmospheric air is drawn in a carbon dioxide is released out, diffusion of gases takes place in the alveolar tissue which is then carried by blood, then diffusion of gases take place between blood and tissues, oxygen is utilized by cells for catabolic reactions, and the resultant carbon dioxide is released from the body.

So, the correct option is '(iii), (vi), (ii), (v), (i), (iv)'.

Consider the following statements each with two blanks. 
(i)    Diaphragm contracts to help in __(1)   while the contraction of abdominal muscles helps in (2). 
(ii). Vital capacity of trained athletes is _(3)__ than that of non-athletes while the vital capacity of non-smokers is (4) than that of smokers. 
(iii) Alveolar P$O {2}$ is  _(5)  than the venous P$O {2}$ while arterial P$O _{2}$ is __(6)_ than the alveolar P$O _{2}$.
Which of the following options gives the correct fill ups for the respective blanks numbers from (1) to (6) in the above statements?

evs respiration in living organisms respiration in human beings respiration and associated structures respiration in humans mechanism of respiration in animals human lungs respiratory organs in humans

  1. (1)-expiration, (2)-inspiration (5)-higher, (6)-lower

  2. (3)-higher, (4)-lower, (5)-lower, (6)-higher

  3. (1)-inspiration, (2)-forced expiration, (3)-higher, (4)-higher

  4. (1)-expiration, (2)-forced expiration, (5)-higher, (6)-lower

Show answer
Correct Option: C
Explanation:

  (i) Diaphragm contracts to help in (1) inspiration while the contraction of abdominal muscles helps in (2) forced expiration.

(ii) Vital capacity of trained athletes is (3) higher than that of non-athletes while the vital capacity of non-smokers is (4) higher than that of smokers.

(iii) Alveolar PO2 is (5) higher than the venous PO2 while arterial PO2 is (6) lower than the alveolar PO2.

So, the correct answer is '(1)-inspiration, (2)-forced expiration, (3)-higher, (4)-higher'.


Complete the following sentence by selecting the correct option.
The breathing rhythm is generated in the (i) and is influenced by variation in levels of (ii)_ in the blood.

evs respiration in living organisms respiration in human beings respiration and associated structures respiration in humans mechanism of respiration in animals human lungs respiratory organs in humans

  1. (i)medulla 

    (ii)$CO _{2}$

  2. (i)medulla 

    (ii)$O _{2}$

  3. (i)frontal lobe 

    (ii)$CO _{2}$ and $O _{2}$

  4. (i)frontal lobe 

    (ii)$CO _{2}$

Show answer
Correct Option: A
Explanation:
The basic rhythm of respiration is generated mainly in the dorsal respiratory group in the medulla. Changes in blood carbon dioxide are believed to stimulate the neurons in the chemosensitive area which affect the rhythm centre. $CO _{2}$ acts by forming carbonic acid which dissociates into H+and $HCO _{3}^{-}$. H+ has a direct effect on this. Oxygen does not have a significant direct effect on rhythm centre.
So the correct answer is 'A'.

The most important muscular structure in respiratory system of rabbit is

evs respiration in living organisms respiration in human beings respiration and associated structures respiration in humans mechanism of respiration in animals human lungs respiratory organs in humans

  1. External intercostal muscles

  2. Internal intercostal muscles

  3. Diaphgram

  4. Vertebral column

Show answer
Correct Option: C
Explanation:

The diaphragm is the dome-shaped sheet of muscle and tendon that serves as the main muscle of respiration and plays a vital role in the breathing process. The diaphragm separates the thoracic cavity containing the heart and lungs, from the abdominal cavity and performs an important function in respiration: as the diaphragm contracts, the volume of the thoracic cavity increases and air is drawn into the lungs.

Thoracic cavity is enlarged by contraction of

evs respiration in living organisms respiration in human beings respiration and associated structures respiration in humans mechanism of respiration in animals human lungs respiratory organs in humans

  1. Internal Intercostal muscles

  2. Diaphragm

  3. Lungs

  4. All of above

Show answer
Correct Option: B
Explanation:

The diaphragm functions in breathing. During inhalation, the diaphragm contracts and moves in the inferior direction, thus enlarging the volume of the thoracic cavity (the external intercostal muscles also participate in this enlargement). This reduces intra-thoracic pressure.

Lungs ventilation movements is due to

evs respiration in living organisms respiration in human beings respiration and associated structures respiration in humans mechanism of respiration in animals human lungs respiratory organs in humans

  1. Costal muscle and diaphragm

  2. Costal muscle

  3. Diaphragm

  4. Wall of the lungs

Show answer
Correct Option: A
Explanation:

Breathing involves two stages, inspiration during which atmospheric air is drawn in and expiration by which the alveolar air is released out. The movement of air into and out of the lungs is carried out by creating a pressure gradient between the lungs and the atmosphere. Inspiration can occur if the pressure within the lungs (intra-pulmonary pressure) is less than the atmospheric pressure, i.e., there is a negative pressure in the lungs with respect to atmospheric pressure. Similarly, expiration takes place when the intra-pulmonary pressure is higher than the atmospheric pressure. The diaphragm and a specialised set of muscles external and internal intercostals between the ribs, help in generation of such gradients.

Therefore, the correct answer is option A.

Hiccough (hiccup) is due to activity of

evs respiration in living organisms respiration in human beings respiration and associated structures respiration in humans mechanism of respiration in animals human lungs respiratory organs in humans

  1. Intercostal muscle

  2. Food in air tract

  3. Diapharagm

  4. Inadequate oxygne in environment

Show answer
Correct Option: C
Explanation:
  • A hiccup is an involuntary contraction of the diaphragm involving a reflex arc, that may repeat several times per minute. 
  • Once triggered, the reflex causes a strong contraction of the diaphragm followed by about 0.25 seconds later by closure of the vocal cords, which results in the classic "hic" sound. 
  • Hiccups may occur individually, or they may occur in bouts. 

Which of the following structures are responsible for breathing process?

evs respiration in living organisms respiration in human beings respiration and associated structures respiration in humans mechanism of respiration in animals human lungs respiratory organs in humans

  1. The trachea and alveoli

  2. Larynx and bronchi

  3. Ribs and intercostal muscles

  4. Intercostal muscles and diaphragm

Show answer
Correct Option: D
Explanation:

Breathing or pulmonary ventilation is a process where the nasal and oral cavities inhaled the air and enter into the lungs through the pharynx, larynx and trachea. Air is also exhaled through the same pathway. While larynx, pharynx and trachea are involved the changes to the volume and air pressure in the lungs trigger  breathing. During the process of  inhalation, the diaphragm and external intercostal muscles contract thereby elevating the rib cage. With the increase in the volume of the lungs, air pressure drops letting the air rush in. Similarly, during exhalation, the muscles relax letting the lungs become smaller, which raises the air pressure and helps to expel the air.