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Respiratory system: the organ system - class-VII

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The trachea is prevented from collapsing by

  1. Complete cartilaginous rings

  2. Incomplete cartilaginous rings

  3. Bony rings

  4. Chitinous rings


Correct Option: B
Explanation:
  • The trachea is a rigid tube that conducts air from your larynx to your bronchi.
  • The trachea's rigidity is maintained by a series of incomplete cartilaginous rings arranged along its length called C-shaped cartilage rings. Hence, The trachea is prevented from collapsing by Incomplete cartilaginous rings.
So, the correct answer is 'Incomplete cartilaginous rings'.



Which of the following correctly illustrates the passage of oxygen in the respiratory system?

  1. Nostrils--> trachea--> bronchus--> bronchiole--> alveoli

  2. Nostrils--> trachea--> bronchiole--> alveoli

  3. Nostrils--> bronchiole--> alveoli

  4. Nostrils--> alveoli


Correct Option: A
Explanation:
  • The pathway of air through the respiratory system is through 
nasal cavities (or oral cavity) > pharynx > trachea > primary bronchi (right & left) > secondary bronchi > tertiary bronchi > bronchioles > alveoli (site of gas exchange). Hence, Nostrils--> trachea--> bronchus--> bronchiole--> alveoli  is   the passage of oxygen in the respiratory system.
So, the correct answer is 'Nostrils--> trachea--> bronchus--> bronchiole--> alveoli'.

The short tube leading from the nose is

  1. Pharynx

  2. Bronchi

  3. Trachea

  4. Alveoli


Correct Option: A
Explanation:

  • The pharynx, or throat, is the passageway leading from the mouth and nose to the oesophagus and larynx. 
  • The pharynx permits the passage of swallowed solids and liquids into the oesophagus, and conducts air to and from the trachea, or windpipe, during respiration. 
  • The pharynx also connects on either side with the cavity of the middle ear by way of the Eustachian tube and provides for equalization of air pressure on the eardrum membrane, which separates the cavity of the middle ear from the external ear canal. Hence, The short tube leading from the nose is pharynx.
So, the correct answer is 'pharynx'

Diaphragm is 

  1. Dome shaped muscle

  2. Oblique muscle

  3. Round muscle

  4. Elongated muscle


Correct Option: A
Explanation:

  • The diaphragm is a part of the abdominopelvic cavity.
  •  It is located below the thoracic cavity and above the pelvic cavity.
  •  Its dome-shaped roof is the thoracic diaphragm, a thin sheet of muscle under the lungs, and its floor is the pelvic inlet, opening into the pelvis. Hence, the diaphragm is a dome-shaped muscle.
So, the correct answer is 'dome-shaped muscle'.

Air goes from pharynx to.

  1. Trachea

  2. Bronchus

  3. Bronchi

  4. Bronchiole


Correct Option: A
Explanation:

  • The nasal cavity and the mouth meet at the pharynx, or throat, at the back of the nose and mouth. 
  • From there, air quickly enters the second part of your respiratory system, the trachea or windpipe. 
  • The trachea is a tube that delivers air to the lungs, the third and most important part of your respiratory system. Hence, Air goes from the pharynx to. trachea.
So, the correct answer is 'trachea'.

Bronchi divide into

  1. Bronchus

  2. Bronchioles

  3. Alveoli

  4. Air sacs


Correct Option: B
Explanation:

  • The bronchi (or bronchus) are the air passages into the lungs that begin at the end of the trachea. 
  • There are two bronchi, one for each lung. 
  • The bronchus divides into smaller branches known as segmental bronchi, which divide again into bronchioles, Hence, Bronchi divide into bronchioles.
So, the correct answer is 'bronchioles'.

Major part of $CO _2$ is transported to respiratory surface as.

  1. $HCO _3$ ions

  2. $H _2CO _3$

  3. $Hb-CO _2$

  4. Free $CO _2$


Correct Option: A

Respiratory system is derived from.

  1. Endoderm

  2. Mesoderm

  3. Ectoderm

  4. None of the above


Correct Option: A

What is correct about human respiration?

  1. About $90\%$ of $CO _2$ is carried by haemoglobin as carbaminohaemoglobin

  2. Neural signals from pneumotaxic centre of pons can increase duration of inspiration

  3. Workers in grinding and store breaking industries may suffer from lung fibrosis

  4. Cigarette smoking leads to inflammation of bronchi


Correct Option: B

Which is not function of 'conductiing part' of respiratory system?

  1. Clears the air from foreign particles

  2. Humidifies the air

  3. Brings the air to body temperature

  4. It is site for diffusion of oxygen and carbon dioxide

  5. Transports air to alveoli


Correct Option: D

Choose the correct statements with regard to human respiration:
(a) Inspiration is faciliated by contraction of phrenic and internal intercostal muscles
(b) Healthy human can inhale or exhale about $2000-3000$ml of air/min
(c) Functional residual capacity represents the volume of left out air in lungs after expiration
(d) Total lung capacity is the total volume of air that would be accomodated in the lunds after forced inspiration.

  1. a, c

  2. b, d

  3. c, d

  4. a, b


Correct Option: C

Respiratory quotient for three different substrates was calculated and tubulated as shown here.

Substrate R.Q.
XYZ 0.911.3

Identify X, Y and Z and select the correct option regarding them.

  1. X - Protein, Y - Fats, Z - Glucose

  2. X - Glucose, Y - Protein, Z - Organic acid

  3. X - Protein, Y - Glucose, Z - Organic acid

  4. X - Organic acid, Y - Protein, Z - Fats


Correct Option: C
Explanation:

Respiratory quotient if the protein is 0.8-0.9

For glucose- 1
For  organic acids -1.3
So, the correct option is 'X - Protein, Y - glucose, Z - organic acids'.

The exchange of respiratory gases with the blood occurs at.

  1. Secondary bronchi

  2. Alveolar duct

  3. Alveolar wall

  4. Nasal chambers


Correct Option: C

In lungs, a respiratory bronchiole divides to form.

  1. Alveolar ducts

  2. Alveolar sacs

  3. Alveoli

  4. Terminal bronchioles


Correct Option: A

Which is the end part of pulmonary or lung division and place of gaseous exchange?

  1. Bronchiole

  2. Alveolus

  3. Air chamber

  4. Trachiole


Correct Option: B

Oxygen and carbon dioxide concentration in the alveolar air is respectively.

  1. $16\%$ and $4\%$

  2. $19.8\%$ and $4.6\%$

  3. $21\%$ and $4\%$

  4. $13.1\%$ and $5.3\%$


Correct Option: D

Inner/alveolar surface area of human lungs is?

  1. $1m^2$

  2. $10m^2$

  3. $100m^2$

  4. $1000m^2$


Correct Option: C

Approximate normal composition of alveolar air is?

  1. $14\% O _2, 6\% CO _2, 80\% N _2$

  2. $16\% O _2, 3\% CO _2, 81\% N _2$

  3. $21\% O _2, 2\% CO _2, 77\% N _2$

  4. $10\% O _2, 8\% CO _2, 82\% N _2$


Correct Option: A

What is correct?

  1. Pulmonary ventilation is equal to alveolar ventilation

  2. Alveolar ventilation is less than pulmonary ventilation

  3. Alveolar ventilation is more than pulmonary ventilation

  4. The two are variable


Correct Option: B

Complete and balance the following equation $Na _2HPO _4+X\rightarrow Y+NaH _2PO _4$.

  1. $X=NaHCO _3, Y=NaCl$

  2. $X=NaHCO _3, Y=H _2CO _3$

  3. $X=H _2CO _3, Y=NaH _2CO _3$

  4. $X=H _2CO _3, Y=NaHCO _3$


Correct Option: D

The partial pressure of oxygen in the alveoli of lungs is?

  1. Less than that of $CO _2$

  2. Equal to that in blood

  3. More than that in the blood

  4. Less than that in the blood


Correct Option: C

Choose the correct answer from the alternatives given.
What are the tiny clusters of chambers for diffusion of gases in lungs?

  1. Pleura

  2. Alveolar sacs

  3. Bronchioles

  4. Lobes


Correct Option: B
Explanation:

The pleura are membranes that secrete a lubricating fluid, which allows free movement of the lungs against the chest wall while breathing. The alveolar sacs are sacs of many alveoli (clusters of chambers), that help exchange oxygen and carbon dioxide in the lungs. The bronchioles are the passageways by which air passes through the nose or mouth to the alveoli (air sacs) of the lungs. Each lobe of the lung has the same physiologic function, bringing oxygen into the bloodstream and removing carbon dioxide. So, the correct option is 'alveolar sacs'.

What is the approximate normal composition of alveolar air? 

  1. 14% oxygen, 6% carbon dioxide, 80% nitrogen

  2. 21 % oxygen, 2% carbon dioxide, 77% nitrogen

  3. 16% oxygen, 3% carbon dioxide, 81 % nitrogen

  4. 10% oxygen, 8% carbon dioxide, 82% nitrogen


Correct Option: A
Explanation:

The air present inside the alveoli or the alveolar air usually has a higher amount of oxygen than carbon dioxide. The approximate composition of alveolar air under normal condition is 14% oxygen, 6% carbon dioxide, and 80% nitrogen.

So, the correct answer is '14% oxygen, 6% carbon dioxide, 80% nitrogen'.


Membrane separating air in pulmonary alveoli from blood capillaries.

  1. Alveolar epithelium

  2. Cardiac epithelium

  3. Endothelium of blood capillaries

  4. Both $'1'$ and $'3'$


Correct Option: A
Explanation:
Here option (D) is the correct answer as-
Outermost Layer Of pulmonary alveolitis alveolar epithelium while that of blood capillaries is endothelium. Thus, both alveolar epithelium and endothelium of blood capillaries separate air in pulmonary alveoli from blood capillaries.

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

  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


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.

  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.


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.

  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)


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?

  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


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.

  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)$CO _{2}$


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

  1. External intercostal muscles

  2. Internal intercostal muscles

  3. Diaphgram

  4. Vertebral column


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

  1. Internal Intercostal muscles

  2. Diaphragm

  3. Lungs

  4. All of above


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

  1. Costal muscle and diaphragm

  2. Costal muscle

  3. Diaphragm

  4. Wall of the lungs


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

  1. Intercostal muscle

  2. Food in air tract

  3. Diapharagm

  4. Inadequate oxygne in environment


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?

  1. The trachea and alveoli

  2. Larynx and bronchi

  3. Ribs and intercostal muscles

  4. Intercostal muscles and diaphragm


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.

The exhaled air mainly contains

  1. Oxygen

  2. Carbon dioxide

  3. Nitrogen

  4. None of the above


Correct Option: B
Explanation:

Exhalation is a process to breath out.carbon dioxide is a waste product in the body that release out during exhalation, it is also saturated with water vapor.

So the correct answer is "carbon dioxide".

Rita breathes out on a mirror and finds water droplets on it. This activity helps to conclude the fact that

  1. Inhalation is faster than exhalation

  2. Water vapour is released during breathing

  3. Exhalation is faster than inhalation

  4. Both A and B


Correct Option: B
Explanation:

Carbon dioxide is released in the process of exhalation in large amount.$CO _2$ dissolves in water and can easily and reversibly form compounds such as carbonic acid and bicarbonates. when it is released out, it is saturated with water vapour and this is the reason for water droplets in the mirror.

So the correct answer is 'water vapour is released during breathing'.

Forced deep breathing during rest for some time is followed by temporary stoppage of breathing because of.

  1. Little $CO _2$ in blood

  2. High $CO _2$ content in blood

  3. High oxygen content in blood

  4. Little oxygen content in blood


Correct Option: A

To generate pressure gradients for faciliatating expiration and inspiration, the human body uses the intercostal muscles and.

  1. Alveolar sacs

  2. Bronchi

  3. Primary, secondary and tertiary bronchioles

  4. Diaphragm

  5. Wind pipe


Correct Option: D

Increase in $CO _2$ concentration shall cause.

  1. Slower and shallower breathing

  2. Slower and deeper breathing

  3. Faster and deeper breathing

  4. No effect on breathing


Correct Option: C

Which one of the following is a possibility for most of us in regard to breathing, by making a conscious effort?

  1. One can breathe out air totally without oxygen.

  2. One can breathe out air through Eustachian tube by closing both nose and mouth.

  3. One can consciously breathe in and breathe out by moving the diaphragm alone, without moving the ribs at all.

  4. The lungs can be made fully empty by forcefully breathing out all air from them.


Correct Option: B
Explanation:

During breathing, 20% oxygen is taken in and 15% oxygen is exhaled out. Movement of diaphragm is very important during breathing process. Ribs will also move in and out with the diaphragm. It is not possible to breathe by moving the diaphragm along without moving ribs. Even after forceful exhalation, lungs are never fully emptied. Residual volume, that is minimum amount of air in lungs always remain at all times. Eustachian tube connects middle ear cavity with nasopharynx and hence, one can breathe out air through it by closing both nose and mouth.

Thus, the correct answer is option B.

Read the following statements:
(A) Nasal chamber opens into nasopharynx which is a portion of pharynx
(B) Larynx produces sound during inspiration as well as expiration
(C) During swallowing gullet can be covered by a thin elastic cartilagenous flap called epiglottis
(D) Trachea is get divided at the level of the 6th thoracic vertebra into right and left primary bronchi.
(E) The braching network of bronchi, bronchioles and alveoli comprise the lungs.
How many statements are not correct-

  1. 2

  2. 3

  3. 4

  4. 1


Correct Option: A
Explanation:

A)Nasal chamber opens into nasopharynx which is a portion of pharynx – True because It also connects the nasal system of air chambers and the upper end of the trachea. The opening of the mouth into the pharynx is the oropharynx, and the nasal opening is the nasopharynx. The eustachian tube from the middle ear opens into the pharynx on each side.

B)Larynx produces sound during inspiration as well as expiration – True, because, the larynx commonly called the voice box, is an organ in the top of the neck of tetrapods involved in breathing, producing sound. They have skeletal muscle, cartilage of the upper larynx collapses inward during inhalation, causing airway obstruction, results in the creation of sounds.

C)During swallowing, gullet can be covered by a thin elastic cartilaginous flap called Epiglottis – false, because, the epiglottis is a flap in the throat that keeps food from entering the windpipe and the lungs. The flap is made of elastic cartilage covered with a mucous membrane, attached to the entrance of the larynx. It projects obliquely upwards behind the tongue and the hyoid bone, pointing dorsally.

D) The trachea is get divided at the level of 6th thoracic vertebra into right and left primary bronchi – False, because The trachea, commonly called the windpipe, is the main airway to the lungs It divides into the right and left bronchi at the level of the fifth thoracic vertebra, channeling air to the right or left lung.

E)The branching network of bronchi, bronchioles, and alveoli comprise the lungs – True.

So, the correct option is ‘2’.

During inspiration muscles of diaphragm

  1. Contracts

  2. Expands

  3. No effect

  4. Coiled like string


Correct Option: A
Explanation:

During inhalation, the diaphragm contracts, thus enlarging the thoracic cavity. This reduces intra-thoracic pressure: enlarging the cavity creates suction that draws air into the lungs. 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.

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

  1. External intercostal muscles relax and diaphragm contracts

  2. External intercostal muscles contracts and diaphragm relaxes

  3. External intercostal muscles and diaphragm relaxes

  4. External intercostal muscles and diaphragm contracts


Correct Option: A

The respiratory centre leading to faster breathing is on account of ________________.

  1. Venous blood entering the respiratory centre

  2. Arterial blood entering respiratory

  3. Venous blood leaving the respiratory centre

  4. Arterial blood leaving the respiratory centre


Correct Option: A
Explanation:

The medulla oblongata is the primary respiratory control centre. Its main function is to send signals to the muscles that control respiration to cause breathing to occur. The respiratory control centre increase respiratory rate on the account of decrease in blood pH, as the oxygenated blood through veins enter the system, decrease in $CO _2$ levels, increased respiratory rate.

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