Tag: transport of respiratory gases

Questions Related to transport of respiratory gases

In response to $CO {2}$ and $H^{+}$ concentration, the chemosensitive area and, receptors associated with aortic arch and carotic artery, send necessary signals for remedial action to ______________.

  1. Pneumotaxic centre

  2. Apneustic centre

  3. Respiratory rhythm centre

  4. Both A and B


Correct Option: A

Listed below are four respiratory capacities (i-iv) and four jumbled respiratory volumes of a normal human adult.

Respiratory volumes and capacities Volume of air
(i)    Residual volume  2500 mL
(ii)   Vital capacity   3500 mL
(iii) Inspiratory reserve volume 1200 mL
 (iv) Inspiratory capacity  4500 mL

Which one of the following is the correct matching of two capacities and volumes?

  1. (ii) 2500 mL, (iii) 4500 mL

  2. (iii) 1200 mL, (iv) 2500 mL

  3. (iv)3500mL, (i) 1200 mL

  4. (i) 4500 mL; (ii) 3500 mL


Correct Option: C
Explanation:

Respiratory volumes and capacities Volume of air

Residual volume 1200 mL Vital capacity 4500 mL
Inspiratory reserve volume 2500 mL Inspiratory capacity 3500 mL.

Rate of breathing is controlled mainly by ________________.

  1. $CO _{2}$ level in blood

  2. pH in blood

  3. $O _{2}$ level in blood

  4. $O _{2}$ level and pH in blood.


Correct Option: A
Explanation:

Rate of breathing is mainly controlled by $CO _2$ level in the blood. Excess $CO _2$ decrease the pH of the blood and it mainly stimulate the respiratory centre of the brain (i.e., Medulla oblongata) and increase the inspiratory and expiratory signals to the respiratory muscles.

Rate of breathing is controlled mainly by

  1. $CO _2$ level in blood

  2. pH in blood

  3. $O _2$ level in blood

  4. $O _2$ level and pH in blood


Correct Option: A
Explanation:

The rate of breathing is controlled mainly by CO$ _2$ level in blood. The partial pressure of carbon dioxide (PCO$ _2$) controls the respiratory rate. The respiratory centre measures the levels of carbon dioxide, oxygen and acidosis in the arterial blood and sends message accordingly. If the carbon dioxide levels in the blood increases, the rate and depth of breathing increases.

Thus, the correct answer is 'CO$ _2$ level in blood.'

Which of the following is not a stimulus for breathing?

  1. Rising $CO _2$ levels

  2. Rising blood pressure

  3. Arterial $pO _2$ below $60$mm of Hg

  4. Change in pH of arterial blood


Correct Option: A
Explanation:

An increased concentration of carbon dioxide is the strongest stimulus to breathe more deeply and more frequently. When the carbon dioxide concentration in the blood is low, the brain decreases the frequency and depth of breath.

So the correct answer is 'Rising CO2 levels'.

Types of chemoreceptors involved in respiration regulation is

  1. Central chemoreceptors

  2. Peripheral chemoreceptors

  3. Spinal chemoreceptors

  4. Both A and B


Correct Option: D
Explanation:
Central and peripheral chemoreceptors involve in the regulation of respiration. They detect reduction and elevation in the concentration level of oxygen, carbon dioxide and pH in the body.
So the correct answer is 'Both A and B'.

In response to a decrease in blood pH, the respiratory center sends nervous impulses to

  1. Increase breathing rate

  2. Decrease breathing rate

  3. Increase heart beat

  4. None of th above


Correct Option: A
Explanation:
Respiratory centre is located in the medulla oblongata and pons. They control the rate and depth of respiratory movements of the diaphragm. The increase in CO$ _2$ level in the blood lowers the pH of the blood which in response cause respiratory center to send impulses to breath fast and increase breathing rate.
So the correct answer is 'Increase breathing rate'.

Central chemoreceptors are found in

  1. Pons

  2. Medulla

  3. Spinal cord

  4. Cerebrum


Correct Option: B
Explanation:
Central chemoreceptors are located on the ventrolateral medullary surface in the central nervous system. There receptors act to detect the changes in pH of their environment by detecting alteration in the concentration of O$ _2$ and CO$ _2$ of nearby cerebrospinal fluid. The decrease in CO$ _2$ causes the blood to become more acidic while it's increase makes the blood alkaline
So, the correct answer is 'Medulla'.

Central chemoreceptors are sensitive to the

  1. pH of their environment

  2. Level of oxygen

  3. High blood pressure

  4. Level of sugar in blood


Correct Option: A
Explanation:
Central chemoreceptors are located on the ventrolateral medullary surface in the central nervous system. There receptors act to detect the changes in pH of their environment by detecting alteration in the concentration of O$ _2$ and CO$ _2$ of nearby cerebrospinal fluid. The decrease in CO$ _2$ causes the blood to become more acidic while it's increase makes the blood alkaline.
So, the correct answer is 'pH of their environment'.

In a $PCR$, which of the following components is not required?

  1. Nucleotide precursors

  2. A primer containing $3'-OH'$

  3. DNA helicase to separate the strands

  4. DNA polymerase to catalyse the reaction


Correct Option: A
Explanation:

A common laboratory technique used to make many copies (millions or billions) of a particular region of DNA is called Polymerase Chain Reaction(PCR). It requires a primer, DNA helicases, DNA polymerases, etc.,

So, the correct option is ‘ Nucleotide precursors’.