Courses
Courses for Kids
Free study material
Offline Centres
More
Store Icon
Store
NEET 2022 | Class 12

NEET Important Chapter - Breathing and Exchange of Gases

Get plus subscription and access unlimited live and recorded courses
Breathing and Exchange of Gases

Breathing and Exchange of Gases


Last updated date: 28th Mar 2024
Total views: 204.6k
Views today: 16.78k

This document contains all related materials on the chapter named Breathing and Exchange of Gases as per the NEET syllabus for Biology. It will be fruitful for NEET aspirants who are looking for last-minute revision notes. 


The following document carries all of the important concepts and provides insight into the exam pattern. By going through this document and also solving the problems given in it, one will be able to find out all the answers to the important questions related to the chapter such as what are respiratory organs, how do the exchanges of gases take place, what is the oxygen dissociation curve and what are respiratory disorders associated with the respiratory system?


Important Topics of Breathing and Exchange of Gases

  • Respiratory Organs

  • Mechanism of Breathing

  • Exchange of Gases

  • Transport of Gases

  • Disorders of Respiratory System


Important Concepts

Respiration vs Breathing

Respiration

Breathing

It is a metabolic process in which the living cells of an organism obtain energy (in the form of ATP) by taking in oxygen and liberating carbon dioxide from the oxidation of complex organic substances. 

It is defined as the process which involves the intake of fresh air and removal of foul air.

It is a biochemical process.

It is a physical process.

It is an exothermic process.

It is an endothermic process.

During this process, several enzymes are involved.

No enzymes are involved during this process.

The process of respiration takes place in each and every cell.

The process of breathing occurs in the lungs.


Respiratory Organs

The following table describes the various respiratory organs in different organisms:

Organism

Respiratory Organs

Sponges, Coelenterates and Flat-worms

General body surface

Earthworm

Moist skin

Insects such as cockroach 

Tracheal system

Amphibians such as frogs

Skin and lungs

Fishes, Molluscs, Aquatic arthropods

Gills

Birds and Mammals

Lungs


Human Respiratory System

It is a network of tissues and organs that help the living organism to breathe. The human respiratory system consists of various organs such as the nose, nasal cavity, pharynx, larynx, trachea, lungs, etc.


Respiratory System in Human-beings


Respiratory System

It is divided into two parts:

  • The Conduction Part: It is composed of all of the structures that provide passageways for air to travel into and out of the lungs. It includes the nasal cavity, pharynx, trachea, bronchi and mostly bronchioles.

  • The Exchange Part: It is the site where the diffusion of carbon dioxide and oxygen between blood and atmospheric air takes place.


Mechanism of Breathing

It is defined as the exchange of gases. There are mainly two events that occur during this process.

  • Inspiration: It is defined as the process which involves the intake of oxygen.

  • Expiration: It is defined as the process which involves the elimination of carbon-dioxide.

The muscles and their movement during these events are given below:

                                                         

Muscles and Organs Involved

Inspiration

Expiration

External intercostal muscle

Contract

Relax

Internal intercostal muscles

Relax

Contract

Diaphragm

Contract

Relax

Air pressure inside the lungs

Decreases

Increases

Movement of air

Into the lungs

Out of the lungs

Volume of lungs

Increases

Decreases


Mechanism of Breathing


Respiratory Volume and Capacities

  • Tidal volume: It is defined as the amount of air coming in and going outside the lungs during the normal breathing cycle. Its value is 500ml.

  • Inspiratory reserve volume: It is defined as the maximum amount of air a person can intake after a normal inspiration. Its value is 2500 to 3000 mL.

  • Expiratory reserve volume: It is defined as the maximum amount of air a person can exhale after normal expiration. Its value is 1000 to 1100 mL.

  • Residual volume: It is defined as the amount of air left in the lungs after forceful expiration. Its value is  1100 mL to 1200 mL.

  • Functional Residual Capacity: It is defined as the volume of air that will remain in the lungs after a normal expiration. It can be calculated by ERV+RV.

  • Inspiratory capacity: It is defined as the maximum volume of air that can be inspired after reaching the end of a normal, quiet expiration. It can be calculated by TV+IRV.

  • Expiratory capacity: After normal inspiration, the total volume of air a person can expire is known as expiratory capacity. It can be calculated by TV+ERV.

  • Vital capacity: It is defined as the amount of air a person can expel out of the lung after a maximum inspiration (intake of oxygen into the lungs). It can be calculated by TV+IRV+ERV.

  • Total lung capacity: At the end of forceful inspiration, the total volume of air accommodated in the lungs is called the total lung capacity. It can be calculated by VC+RV.


         Respiratory Volume and Capacities


Exchange of Gases

Alveoli is the main site for the exchange of gases. It takes place via diffusion, which is a process that involves the movement of molecules (gas molecules in case of breathing) from higher concentration to lower concentration or higher partial pressure to lower partial pressure. The process of breathing is based upon this principle only.


Gaseous Exchange Between the Alveoli and Blood



Exchange of Gases Between Blood and Tissues


Transport of Gases

The transport of gases (oxygen and carbon dioxide) is done via the blood which is a fluid connective tissue.

  • Oxygen-transport: Approximately 97% of oxygen is transported by RBCs in the blood. The remaining (3%) amount of oxygen is carried in a dissolved state through the plasma. 

  • The binding of oxygen with the haemoglobin (respiratory pigment) is associated with certain factors, such as partial pressure of oxygen and carbon dioxide, hydrogen ions concentration and temperature.

  • The graph in which the percentage saturation of haemoglobin is plotted against the partial pressure of oxygen is called the oxygen dissociation curve. 

  • The curve is sigmoid in nature. 

  • This curve is mainly used to study the effect of various factors on the binding of oxygen with the haemoglobin.


Oxygen - Haemoglobin Dissociation Curve


  • Carbon-dioxide transport Approximately 20-25% of carbon dioxide is transported by RBCs, whereas 70% of it is carried as bicarbonate. Nearly 7 % of carbon dioxide is carried in a dissolved state through plasma.


Carbon-dioxide Transport


Disorders of the Respiratory System

The following table describes the disorders associated with the respiratory system:

Respiratory disorder

Description

Asthma

It occurs due to the inflammation of the bronchi and bronchioles. During this disorder, an excess amount of mucus is secreted on the wall of the respiratory tract which may clog bronchi and bronchioles.

Emphysema**

It is a chronic respiratory disorder. During this disorder, there is damage to the alveolar walls due to which the respiratory surface is greatly reduced.

In this disease, exhalation becomes very difficult. There is no permanent cure for the disease as there is irreversible distension and loss of elasticity of the alveoli of the lungs.

Occupational Respiratory Disorders

In certain industries, especially those which are involved in grinding or stone-breaking, so much dust is produced that the defence system of the body cannot fully cope with the situation. Long-term exposure can give rise to inflammation leading to the proliferation of fibrous tissues, which is known as fibrosis. It can thus cause serious lung damage. An example includes silicosis and asbestosis.

Bronchitis

It is the inflammation of bronchi that is mainly caused by infection, cigarette smoking or exposure to air pollutants

Mountain Sickness

This condition is characterised by the ill effects of hypoxia, which is the shortage of oxygen in the tissues at high altitudes. 


Solved Examples from the Chapter

1. The oxygen-haemoglobin dissociation curve shows the right shift in case of high 

  1. High pCO2

  2. High pO2

  3. Low pCO2

  4. Less H+ concentration

Ans: The correct answer is “A”.


The right shift in the oxygen dissociation curve is related to the dissociation of oxyhaemoglobin which occurs when there is low pO2, high pCO2, high H+ concentration and higher temperature exists in the alveoli.


Key point to remember- Right shift = oxyhaemoglobin dissociation


2. What is vital capacity? Describe its significance.

Ans: Vital capacity is defined as the amount of air a person can expel out of the lung after a maximum inspiration(intake of oxygen into the lungs). The value of VC in an average adult human is 3-5 litres. The formula for the vital capacity is VC - TV+IRV+ERV.


It increases the intake of fresh air to its maximum possible amount as well as helps in getting rid of foul air that is full of carbon dioxide in a single stroke. Hence, it increases the amount of gaseous exchange.


As we know, the greater the amount of oxygen, the greater will be the oxidation of respiratory substrate which in turn provides the greater ATP which in the end results in an energetic organism.


Key point to remember VC= TV+IRV+ERV


3. What is chloride shift?


Ans: During the transport of carbon dioxide, the bicarbonate content in RBC becomes much higher in comparison to the plasma (fluid component of blood). The movement of bicarbonate ions from RBC to plasma disturbs the ionic balance, which is restored by chloride ions that diffuse from plasma to the RBC. This movement of chloride ions to restore the ionic balance is called chloride shift or Hamburger’s phenomenon.


Key point to remember: Movement of chloride ions takes place to restore the ionic balance.


Solved Problems of Previous Year Questions

1. Although much CO2 is carried in blood, yet blood does not become acidic, because

  1. It is absorbed by leukocytes

  2. Blood buffer play an important role in carbon-dioxide transport

  3. It combines with water to form H2CO3 which is neutralised by Na2CO3.

  4. It is continuously diffused through tissues & is not allowed to accumulate.    

Ans: The correct answer is “B”.


pH is defined as the concentration of H+ ions. The scale that is used to measure the pH is called the pH scale. The pH of blood is 7.4.  

   

The main buffering system present in the blood is bicarbonate (which is formed during CO2 transport in the blood). It exists in equilibrium with carbonic acid which in turn can be converted to CO2 and water.


Tricks to solve easily: Buffering system in the blood maintain an ideal pH of the blood.


2. Name the chronic respiratory disorder caused mainly by cigarette smoking

  1. Respiratory Alkalosis

  2. Respiratory Acidosis

  3. Asthma

  4. Emphysema

  

Ans: The correct answer is “D”. 


Emphysema is a chronic respiratory disorder. During this disorder, there is damage  

caused to the alveolar walls due to which the respiratory surface is greatly reduced.


In this disease, exhalation becomes very difficult. There is no cure for this disease  

because there is irreversible distension and loss of elasticity of the alveoli of the   

lungs.


Tricks to solve Cigarette smoking easily leads to emphysema.


3. Lungs are made up of air-filled sacs, the alveoli. They do not collapse even after  forceful expiration, because of :

  1. Residual Volume

  2. Inspiratory Reserve Volume

  3. Tidal Volume

  4. Expiratory Reserve Volume

 

Ans:  The correct answer is “A”.


Residual Volume (RV) is defined as the volume of air remaining inside the lungs even after a forcible expiration. This is the main reason why alveoli do not collapse even after  

forceful expiration.


Tricks to solve easily: RR, where first R= residual volume and second R= Remaining air in the lungs.


Practice Questions

1. Find out the incorrect statement related to allergies

  1. Allergy causing agents are known as allergens

  2. The use of drugs like antihistamine, adrenaline and steroids quickly reduces  symptoms.

  3. IgE antibody is related to allergy

  4. During allergy there is dilation of bronchioles causing difficulty in breathing.

Ans: The correct answer is “D”.


During allergies such as asthma, there is the constriction of bronchioles that decreases the flow of air in the airways which results in difficulty in breathing.  Allergy is defined as the hypersensitivity of any individual to certain foreign particles such as drugs, pollens etc. which are called allergens.

 

Symptoms include itching, running nose, watery eyes, difficulty in breathing etc. It    

involves certain kinds of chemicals such as histamine, serotonin and antibodies such as  

IgE. Some forms of the allergy include hayfever, asthma etc. The use of certain kinds of drugs such as antihistamines, steroids etc. quickly reduces the symptoms.


2. What are the characteristics of the respiratory surface?

Ans: A respiratory surface is defined as the area where the exchange of gas takes place. It includes lungs, gills, trachea, etc. The characteristics feature of respiratory surface are as follows:

  • It must have a large surface area.

  • It must be thin so that it can make direct contact with the blood capillaries.

  • It must be moist.

All the characteristics  that are described above are responsible for making the process  of exchange of gases(carbon dioxide and oxygen) smooth and efficient.

 

Conclusion

This article contains all important information as per the requirement of students who are preparing for the NEET and can be really helpful for a quick and effective revision. It includes all the important concepts and topics from Biology NCERT books, and questions from previous years’ NEET exam  NEET mock test as well. 


Make sure to try the practice question on your own to test your knowledge and to get desired outputs. 

See More
NEET 2024 Important Dates

NEET 2024 Important Dates

View All Dates
NEET 2024 exam date and revised schedule have been announced by the NTA. NEET 2024 will now be conducted on 5 May 2024, and the exam registration starts on 9 February 2024 and closes on 9 March 2024. You can check the complete schedule on our site. Furthermore, you can check NEET 2024 dates for application, admit card, exam, answer key, result, counselling, etc along with other relevant information.
See More
View All Dates
NEET Information

NEET Information

Application Form
Eligibility Criteria
Reservation Policy
Admit Card
NTA has announced the NEET 2024 application form release date on the official website https://neet.nta.nic.in/. The NEET 2024 Application Form is available on the official website for online registration from 9 February 2024 to 9 March 2024. Besides the NEET 2024 application form release date, learn about the application process, steps to fill out the form, how to submit it, the exam date sheet, etc online. Check our website for more details.
NEET 2024 applicants should be aware of the eligibility criteria before applying for the exam. NTA has released all the relevant information on the official website, i.e. https://neet.nta.nic.in/. NEET 2024 aspirants should have passed Class 12th or any other equivalent qualifying examination in 2023, or 2022, or students appearing in the Class 12th final exam in 2024 can also apply. For further details, visit our website.
As per the union government’s norms, NTA has released the NEET 2024 reservation criteria for different candidates’ categories (SC/ST/OBC/PwD), All India Quota, State Government Quota, Deemed Universities, and more. You can check more details on the Vedantu website.
NEET 2024 Admit Card will be released by the NTA in the 4th week of April 2024. Candidates can download the NEET admit card and hall ticket from the NEET official website i.e. https://neet.nta.nic.in/. For more details on the NEET admit card 2024, candidates can check Vedantu's official website.
NEET 2024 Study Material

NEET 2024 Study Material

View NEET Syllabus in Detail
Download full syllabus
Download full syllabus
View NEET Syllabus in Detail
NEET 2024 Study Material

NEET 2024 Study Material

View all study material for NEET
All
Physics
Chemistry
Biology
See All
NEET Question Papers

NEET Question Papers

NEET 2024 Book Solutions and PDF Download

NEET 2024 Book Solutions and PDF Download

View all NEET Important Books
Biology
NCERT Book for Class 12 Biology
Physics
NCERT Book for Class 12 Physics
Chemistry
NCERT Book for Class 12 Chemistry
Physics
H. C. Verma Solutions
See All
NEET 2024 Mock Tests

NEET 2024 Mock Tests

View all mock tests
NEET 2024 free online mock test series for exam preparation are available on the Vedantu website for free download. Practising these mock test papers of Physics, Chemistry and Biology prepared by expert teachers at Vedantu will help you to boost your confidence to face the NEET 2024 examination without any worries. The NEET test series for Physics, Chemistry and Biology that is based on the latest syllabus of NEET and also the Previous Year Question Papers.
See More
NEET 2024 Cut Off

NEET 2024 Cut Off

NEET Cut Off
NTA is responsible for the release of the NEET 2024 cut off score. The qualifying percentile score might remain the same for different categories. According to the latest trends, the expected cut-off mark for NEET 2024 is 50% for general category candidates, 45% for physically challenged candidates, and 40% for candidates from reserved categories. For the general category, NEET qualifying marks for 2024 ranged from 715-117 general category, while for OBC/SC/ST categories, they ranged from 116-93 for OBC, 116-93 for SC and 116-93 for ST category.
See More
NEET 2024 Results

NEET 2024 Results

The NEET 2024 result will be published by NTA on https://neet.nta.nic.in/ in the form of a scorecard on 14 June 2024. The scorecard will include the roll number, application number, candidate's personal details, and the percentile, marks, and rank of the candidate. Only those candidates who achieve the NEET cut-off will be considered qualified for the exam.
See More
Rank List
Counselling
Marks and Rank
NEET 2024 state rank lists will be released by the Medical Counselling Committee (MCC) for admissions to the 85% state quota and to all seats in private medical and dental colleges. NEET 2024 state rank lists are based on the marks obtained in medical entrance exams. Candidates can check the NEET 2024 state rank list on the official website or our site.
The Medical Counselling Committee (MCC) will conduct NEET 2024 counselling at www.mcc.nic.in. There will be two rounds of counselling for admission under 15% All India Quota (AIQ), deemed and central universities, AIIMS, JIPMER, ESIC, and AFMC. A mop-up round of NEET counselling will be conducted excluding 15% AIQ seats, while the dates of NEET counselling for 85% state quota seats will be announced by the respective state authorities.
As per the union government’s norms, NTA has released the NEET 2024 reservation criteria for different candidates’ categories (SC/ST/OBC/PwD), All India Quota, State Government Quota, Deemed Universities, and more. Previously, the Indian Government has provided NEET reservations to OBC (27%) and EWS (10%) candidates under All India Quota (AIQ). You can check more details on the Vedantu website.
NEET 2024 Top Colleges

NEET 2024 Top Colleges

View all NEET 2024 Top Colleges
Want to know which Engineering colleges in India accept the NEET 2024 scores for admission to Engineering? Find the list of Engineering colleges accepting NEET scores in India, compiled by Vedantu. 1990 Colleges are accepting NEET Score. It includes 706 Medical, 323 Dental, 914 AYUSH, and 47 BVSc & AH colleges. Also find more details on Fees, Ranking, Admission, and Placement.
See More
question-image

FAQs on NEET Important Chapter - Breathing and Exchange of Gases

FAQ

1. In the Neet exam how many questions were asked from the chapter Breathing and Exchange of Gases?

This particular chapter belongs to the unit human physiology. On average 2-3 questions have been asked from this chapter in the last few years.

2. What is the weightage of the chapter Breathing and Exchange of Gases?

The weightage of this chapter is around 2% according to the analysis of the last 8 years of the NEET exam.

3. What are the important topics of the chapter Breathing and Exchange of Gases?

Although it is one of the most important chapters in terms of the NEET exam, some of the important topics from where the questions are generally asked are the mechanism of breathing, respiratory volume and capacities, transport and exchange of gases, respiratory disorders, etc.