Tag: gas exchange in humans

Questions Related to gas exchange in humans

Choose the correct answer from the alternatives given.
In human lungs, gas exchange occurs at the

zoology gas exchange and smoking gas exchange gas exchange in humans respiratory system in humans

  1. two bronchi

  2. alveolar sacs

  3. pleural sacs

  4. both (b) and (c)

Show answer
Correct Option: B
Explanation:

In humans, gas exchange occurs in the lungs between the alveoli and the capillaries located on the walls of the alveoli. The inhaled oxygen moves from the alveoli to the blood in the capillaries, and carbon dioxide moves from the blood in the capillaries to the air in the alveoli. So, the correct option is 'alveolar sacs'.

State whether the following statements are true or false.
Gas exchanges continue uninterrupted in lungs even after a forceful expiration.

zoology gas exchange and smoking gas exchange gas exchange in humans respiratory system in humans

  1. True

  2. False

Show answer
Correct Option: A
Explanation:

Even after the most forcible expiration possible some amount of air remains in the lungs. This is known as the residual volume and is about 1200 ml. This keeps the alveoli open as some air is always present inside the lung alveoli even during expiration. So, the correct option is 'true'.

Choose the correct answer from the alternatives given.
Simple squamous non-ciliated epithelium is found in

zoology gas exchange and smoking gas exchange gas exchange in humans respiratory system in humans

  1. alveoli

  2. bronchi

  3. bronchioles

  4. trachea

Show answer
Correct Option: A
Explanation:

Simple squamous non-ciliated epithelia are found in capillaries, alveoli, and other tissues where rapid diffusion is required. Cells are flat with flattened and oblong nuclei. It is also called pavement epithelium due to its tile-like appearance. The bronchi are lined by ciliated, pseudostratified columnar epithelium and bronchioles are lined by simple cuboidal epithelium. So, the correct option is 'alveoli'.

Lungs are enclosed in

zoology gas exchange and smoking gas exchange gas exchange in humans respiratory system in humans

  1. Perichondrium

  2. Pericardium

  3. Pleural membrane

  4. Peritoneum

Show answer
Correct Option: C
Explanation:

Each lung is enclosed by a double-layered serous membrane, called the pleura. The visceral pleura is firmly attached to the surface of the lung. At the hilum, the visceral pleura is continuous with the parietal pleura that lines the wall of the thorax.

So, the option is 'Pleural membrane'.

Consider the following statements each with one or two blanks.
(i)    Left lung has _(1) lobes and right lung has (2) lobes.
(ii)   Prawn respires with (3) and insects with (4).
(iii) Amount of air inhaled and exhaled with maximum effort is referred to as the (5) of the lungs.
Fill up the above blanks by selecting the correct option.

zoology gas exchange and smoking gas exchange gas exchange in humans respiratory system in humans

  1. (1) - three, (2) - two, (3) - gills (4)-tracheae

  2. (1) - two, (2) - three, (5) - vital capacity

  3. (3) - gills, (4) - tracheae, (5) - tidal volume

  4. (3) - tracheae, (4) - gills, (5) - tidal volume

Show answer
Correct Option: B
Explanation:

Prawn respires with gills (Branchial respiration) and insects respire by tracheae (Tracheal respiration).

Mammalian lungs have an enormous number of minute alveoli (air sac);This is to allow

zoology gas exchange and smoking gas exchange gas exchange in humans respiratory system in humans

  1. more surface area for diffusion of gases

  2. more space for increasing the volume of inspired air

  3. more nerve supply to keep the lungs working

  4. more spongy texture for keeping lung in proper shape.

Show answer
Correct Option: A
Explanation:

The number of alveoli in the human lungs has been estimated to be approximately 300 million. This enormous number of alveoli are meant to increase surface area of lungs for diffusion of gases.

Rings of .................... present in trachea, bronchi and bronchioles prevent their collapse when air is not passing through them.

zoology gas exchange and smoking gas exchange gas exchange in humans respiratory system in humans

  1. Cartilage

  2. Collagen

  3. Bone

  4. None of the above.

Show answer
Correct Option: A
Explanation:

In humans, trachea is a straight tube extending up to the mid-thoracic cavity, which divides at the level of 5th thoracic vertebra into a right and left primary bronchi. Each bronchi undergoes repeated divisions to form the secondary and tertiary bronchi and bronchioles ending up in very thin terminal bronchioles. The tracheae, primary, secondary and tertiary bronchi, and initial bronchioles are supported by incomplete cartilaginous rings.

In respiration, air passes through

zoology gas exchange and smoking gas exchange gas exchange in humans respiratory system in humans

  1. $Pharynx \rightarrow nasal :cavity \rightarrow larynx \rightarrow trachea \rightarrow bronchi \rightarrow bronchioles$

  2. $Nasal :cavity\rightarrow Pharynx\rightarrow larynx \rightarrow trachea \rightarrow bronchi\rightarrow bronchioles$

  3. $Larynx \rightarrow nasal :cavity\rightarrow Pharynx\rightarrow trachea$

  4. $Larynx \rightarrow pharynx \rightarrow trachea \rightarrow lungs$

Show answer
Correct Option: B
Explanation:

Nasal cavity open into pharynx which is common passage for transfer of food and air. Pharynx leads to larynx which is also called the voice box. Tracheae carry air to lungs and branch into left and right bronchus for entering left and right lungs. Inside lungs each bronchus divides and subdivides into terminal bronchioles.

In humans the alveoli are the functioning units of external respiration.

zoology gas exchange and smoking gas exchange gas exchange in humans respiratory system in humans

  1. True

  2. False

Show answer
Correct Option: A
Explanation:
  • Alveoli are an important part of the respiratory system whose function is to exchange oxygen and carbon dioxide molecules to and from the bloodstream. 
  • Alveoli are tiny, balloon-shaped air sacs present at the very end of the respiratory tree and are arranged in clusters throughout the lungs.
  • A typical pair of human lungs contain about 480 million alveoli. Hence, In humans, the alveoli are the functioning units of external respiration.
So, the correct answer is 'True'.

Where does exchange of gases ($O _2$ and $CO _2$) take place in our lungs?

zoology gas exchange and smoking gas exchange gas exchange in humans respiratory system in humans

  1. Pleura

  2. Bronchi

  3. Alveoli

  4. Trachea

Show answer
Correct Option: C
Explanation:

The primary function of the respiratory system is to exchange oxygen and carbon dioxide. Inhaled oxygen enters the lungs and reaches the alveoli. The layers of cells lining the alveoli and the surrounding capillaries are each only one cell thick and are in very close contact with each other. This barrier between air and blood averages about 1 micron  in thickness. Oxygen passes quickly through this air-blood barrier into the blood in the capillaries. Similarly, carbon dioxide passes from the blood into the alveoli and is then exhaled.

So the correct option is 'alveoli'.