Tag: respiratory system of human

Questions Related to respiratory system of human

Inspiration is initiated by the contraction of?

zoology respiratory system of human mechanism of respiration respiratory cycle breathing and exchange of gas

  1. External intercostal muscles

  2. Internal intercostal muscles

  3. Diaphragm

  4. Both a and b

Show answer
Correct Option: C

Read the following sentences carefully and select the incorrect one.

zoology respiratory system of human mechanism of respiration respiratory cycle breathing and exchange of gas

  1. During expiration, $pO _2$ of expired air is more than alveolar air but less than atmospheric air

  2. During expiration, $pO _2$ of expired air is less than $pCO _2$ of alveolar air but more than $pCO _2$ of atmospheric air

  3. Sum of partial pressure of all gases at sea level is $760 mm Hg$

  4. The partial pressure of $O _2$ and $CO _2$$ in the systemic veins is same as that in pulomonary vein.

Show answer
Correct Option: A
Explanation:

Sum of the partial pressure of all gases is 760 mm of Hg.

The partial pressure of oxygen and carbon dioxide is same in systematic vein since they are continuous.
During expiration, $pO _2$ of experience air is less than $pCO _2$ of alveolar air but less than atmospheric air as the atmosphere has a high concentration of oxygen.
During expiration, $pO _2$ of expired air is less than alveolar air and atmospheric air.
So the correct answer is 'During expiration $pO _2$ of expired air is more than alveolar air but less than atmospheric air'.

Oxygen in expired air

zoology respiratory system of human mechanism of respiration respiratory cycle breathing and exchange of gas

  1. 10%

  2. 16%

  3. 19%

  4. 4%

Show answer
Correct Option: B
Explanation:

The amount gases in exhaled air are 4% to 5% by volume more carbon dioxide and 4% to 5% by volume less oxygen than was inhaled. This expired air typically composed of: 78.04% nitrogen; 13.6% - 16% oxygen; 4% - 5.3% carbon dioxide; 1% other gases.

Expiration involves

zoology respiratory system of human mechanism of respiration respiratory cycle breathing and exchange of gas

  1. Relaxation of diaphragm and intercostal muscles

  2. Contraction of diaphragm and intercostal muscles

  3. Contraction of diaphragm muscles

  4. Contraction of intercostal muscles

Show answer
Correct Option: A
Explanation:

When the diaphragm relaxes, air is exhaled by elastic recoil of the lung and the tissues lining the thoracic cavity in conjunction with the abdominal muscles which act as an antagonist paired with the diaphragm's contraction. The internal intercostals assist in expiration by pulling the ribcage down.

Which one of the following statement is correct?

zoology respiratory system of human mechanism of respiration respiratory cycle breathing and exchange of gas

  1. Chest expands because air enters into the lungs.

  2. Air enters into the lungs because chest expands.

  3. The muscles of the diaphragm contracts because air enters into the lungs.

  4. All of the above statements are correct.

Show answer
Correct Option: B
Explanation:

When we breathe in, or inhale, the diaphragm contracts (tightens) and moves downward. This increases the space in the chest cavity, into which the lungs expand. The intercostal muscles between the ribs also help enlarge the chest cavity. They contract to pull the rib cage both upward and outward when we inhale. As the lungs expand, air is sucked in through the nose or mouth. The air travels down the windpipe and into the lungs. After passing through the bronchial tubes, the air finally reaches and enters the alveoli (air sacs).

About 30% of CO$ _2$ is transported as 

zoology respiratory system of human mechanism of respiration respiratory cycle breathing and exchange of gas

  1. Carbamino compounds

  2. Bicarbonates of Na and K

  3. Carboxyhaemoglobin

  4. Oxyhaemoglobin

Show answer
Correct Option: A
Explanation:

Carbon dioxide can bind to plasma proteins or can enter red blood cells and bind to hemoglobin. This form transports about 10 percent of the carbon dioxide. When carbon dioxide binds to hemoglobin, a molecule called carbaminohemoglobin is formed. Binding of carbon dioxide to hemoglobin is reversible. Therefore, when it reaches the lungs, the carbon dioxide can freely dissociate from the hemoglobin and be expelled from the body. About 30% of CO$ _2$ is transported as carbamino haemoglobin. 

Therefore, the correct answer is option A.

The tissue respiration refers to 

zoology respiratory system of human mechanism of respiration respiratory cycle breathing and exchange of gas

  1. Inspiration

  2. External respiration

  3. Internal respiration

  4. Expiration

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Correct Option: C
Explanation:

Internal respiration refers to gas exchange across the respiratory membrane in the metabolizing tissues. External respiration refers to gas exchange across the respiratory membrane in the lungs. Pulmonary ventilation is the process by which oxygen enters and carbon dioxide exits the alveoli. Respiration is the process by which oxygen and carbon dioxide diffuse in and out of the blood. 

If the CO$ _2$ concentration in the blood increases, the breathing shall 

zoology respiratory system of human mechanism of respiration respiratory cycle breathing and exchange of gas

  1. Increase

  2. Decrease

  3. Affected

  4. Stop

Show answer
Correct Option: A
Explanation:

What most people don’t know is that it is, in fact, the level of CO$ _2$ rather than oxygen that usually drives breathing rate. Your body’s ability to detect specific concentrations of CO$ _2$ is extremely sensitive. If the level of CO$ _2$ in your blood increases by a mere 10%, your rate of breathing will double. The answer comes from the way CO$ _2$ is transported. Instead of being bound to hemoglobin, the CO$ _2$ mostly just dissolves in your blood. When the CO$ _2$ dissolves, it combines with the water in your blood to form carbonic acid. As this acid builds up, it dramatically decreases the pH of your blood, throwing it out of balance. Your brainstem detects this pH change, and speeds up your breathing rate in order to to get rid of the extra CO$ _2$. 

Therefore, the correct answer is option A.

Which of the following sequences is correct to initiate inspiration? 
(i)    The contraction of external intercostal muscles raises the ribs and sternum
(ii)   Volume of thorax increases in the dorso-ventral axis 
(iii)  Intrapulmonary pressure decreases 
(iv)  Diaphragm contraction 
(v)   Air rushes into lungs 
(vi)   Volume of thorax increases in the anterior-posterior axis 

zoology respiratory system of human mechanism of respiration respiratory cycle breathing and exchange of gas

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

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

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

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

Show answer
Correct Option: C
Explanation:

The correct sequence of events in the initiation of respiration is:
(i)    The contraction of external intercostal muscles raises the ribs and sternum
(ii)    The volume of thorax increases in the dorsoventral axis
(iv)    Diaphragm contraction
(vi)    The volume of thorax increases in the anterior-posterior axis
(iii)    Intrapulmonary pressure decreases

(v)    Air rushes into lungs
So, the correct answer is '(i),(ii),(iv),(vi),(iii),(v)'.

The ventilation movements of the lungs in mammals are governed by

zoology respiratory system of human mechanism of respiration respiratory cycle breathing and exchange of gas

  1. muscular walls of lung

  2. diaphragm

  3. costal muscles

  4. both (b) and (c).

Show answer
Correct Option: D
Explanation:
The relaxation and contraction of the diaphragm and the movement of the costal muscles present in the thorax of an individual are responsible for the ventilation movements of the lungs that facilitate respiration.
So, the correct answer is 'both (b) and (c)'.