Chapter 5 - Life processes - Respiration

 Click here to go to Home Page

Chapter 5 -Respiration

Respiration: The process by which the food gets oxidised and releases energy for performing various life processes is called respiration.

Types

1. Aerobic respiration - The respiration which takes place in the presence of oxygen is called aerobic respiration. In this process glucose gets completely oxidised to release carbondioxide, water and large amount of energy.

             (In cytoplasm)

Glucose ----------- Pyruvate + Energy 

               

            (In mitochondria)

Pyruvate -----------> Carbondioxide + Water + Energy(38 ATP)

ATP = Adenosine Triphosphate

2. Anaerobic respiration - The respiration which takes place in the absence of oxygen is called anaerobic respiration. Here glucose is oxidised incompletely and release small amount of energy.

a) Anaerobic respiration in yeast 

Yeast cell incompletely breaks down the glucose into ethanol and carbondioxide in absence of oxygen.

            (In cytoplasm)                             (Absence of oxygen in Yeast)

Glucose ----------------> 2 Pyruvate + Energy ---------------------> Ethanol + Carbondioxide + Energy

b) Anaerobic respiration in muscles

Anaerobic respiration occurs in human muscles during vigorous exercise. Here glucose is eventually metabolised to form lactic acid due to which fatigue and muscle cramps occur in muscles.

                                                                (Lack of oxygen)

Glucose --------------> Pyruvate + Energy --------------> Lactic Acid + Energy


Difference between Aerobic and Anaerobic respiration

Aerobic respiration                                            Anaerobic respiration

1. Occurs in presence of oxygen                    1. Occurs in absence of oxygen

2. Complete oxidation of food takes               2. Incomplete oxidation of food takes place

    place

3. Large amount of energy is produced            3. Less amount of energy is released

4. Begins in cytoplasm and continues               4. Occurs only in cytoplasm

   in the mitochondria

Respiration in Plants

The process of respiration in plants involves the exchange of respiratory gases i.e oxygen and carbondioxide from the environment.

In leaves

Gaseous exchange in leaves takes place through stomata present in the lower epidermis.

During daytime: 1) Photosynthesis occurs . 2) Carbondioxide gases are absorbed and oxygen is released through diffusion.

During night time: 1) No photosynthesis occurs       2) Carbondioxide is released through diffusion.

In roots

Exchange of gases in roots also takes place through diffusion process from air between the soils.

In stems

In woody plants, gaseous exchange occurs through small pores found on the stems called as lenticels.

Respiration in Terrestrial Organisms

1. Lungs (in mammals, birds, reptiles)

  • Internal paired sacs with highly folded inner walls (alveoli in mammals; parabronchi in birds).

2. Tracheal System (in insects)

  • Network of tubes (tracheae) opening to the outside through spiracles, branching into tracheoles reaching body cells.

3. Skin (in some amphibians and earthworms)

  • Thin, moist, and richly supplied with blood vessels for cutaneous respiration.

2. Major Components

Component

Structure & Function

Nose/Nasal Cavity

• External nostrils with hairs filter dust.
• Mucous membranes warm and moisten incoming air.

Pharynx (Throat)

• Common passage for air and food; leads to the larynx and oesophagus.

Larynx (Voice Box)

• Contains vocal cords; produces sound when air passes between them.
• Epiglottis prevents food from entering airways.

Trachea (Windpipe)

• A wide tube supported by C‑shaped cartilage rings; conducts air to bronchi.

Bronchi & Bronchioles

• Two primary bronchi (left and right) branch from trachea.
• Further divide into smaller bronchioles, ensuring air reaches all lung regions.

Alveoli

• Tiny air sacs (~300 million total) at bronchiole ends.
• Surrounded by capillaries; site of gas exchange.

Lungs

• Paired organs within the thoracic cavity.
• Right lung has three lobes; left lung has two lobes (to accommodate the heart).

Diaphragm

• Dome‑shaped muscle separating thoracic and abdominal cavities.
• Main muscle of respiration; contracts and relaxes to change thoracic volume.

Intercostal Muscles

• External and internal muscles between ribs.
• Aid in expanding and compressing the rib cage during breathing.

3. Mechanism of Breathing

  1. Inhalation (Inspiration)

    • Diaphragm contracts (moves down) → external intercostal muscles contract → rib cage lifts upward and outward → thoracic cavity volume increases → lung pressure drops below atmospheric pressure → air flows in.

  2. Exhalation (Expiration)

    • Diaphragm relaxes (moves up) → external intercostal muscles relax (internal intercostals may contract for forced exhalation) → rib cage moves downward and inward → thoracic cavity volume decreases → lung pressure rises above atmospheric pressure → air is expelled.

4. Gas Exchange

  • Location: Alveolar walls and capillary walls (both one cell thick).

  • Process:

    • O₂ diffuses from alveolar air (high partial pressure) into blood (low partial pressure).

    • CO₂ diffuses from blood (high partial pressure) into alveolar air (low partial pressure).


Respiratory Pigment Haemoglobin

Haemoglobin is the respiratory pigment found in the blood of human beings.

Comments

Post a Comment

Popular posts from this blog

Class X - Artificial Intelligence / Information Technology CBSE Notes by JAINAL ABEDIN

Click here for Science Notes Content: Part A Unit I – Communication Skills Session I - Methods and Types of Communication  Session II -  Feedback in Communication Session III -  Effective Communication Session IV- Basic Writing Skills I Session V- Basic Writing Skills II Session VI- Basic Writing Skills III Unit II- Self Management Skills Session 1: Self Management Skills – Stress Management Session 2: Self-Awareness Session 3: Self-Motivation Session 4: Self-Regulation – Goal Setting Session 5: TimeManagement Part B Unit I - Introduction to AI Session I - Foundational Concept of AI Session V - Bioethics Framework Unit VII - Advance Python  Session I- Jupyter Notes and Other Python Development Platforms Session II - Python Basics in a New Flavour Session III: Python Conditionals and Loops
Read more

Class X Science Notes

                                                         Class X                                                               Science     Contents Chapter 1 - Chemical reactions and equations ( Home Assignment ) Chapter 2:  Acids, Bases and Salts Chapter 3: Metals and Non-Metals Chapter 4: Carbon and Its Compounds Chapter 5:Life Processes-  Nutrition , Respiration , Transportation , Excretion  -      ( Home Assignment questions  - Life Processes) Chapter 6:  Control and Coordination Chapter 7: How Do Organisms Reproduce Chapter 8: Heredity Chapter 9:...
Read more

Chapter 5 - Life Processes - Nutrition

Click here to go to Home Page Chapter 5 Life Processes Life Processes :- Life processes are the basic activities and functions that are essential for an organism to stay alive. These include processes like nutrition , respiration , transportation , excretion , growth , reproduction , and response to stimuli . All living organisms carry out these processes to maintain and sustain life.   Nutrition :- It is the process by which an organism obtains nutrients from food and utilizes them to obtain energy, for building and repairing its tissues. Modes of Nutrition 1. Autotrophic nutrition 2. Heterotrophic nutrition Autotrophic nutrition - The mode of nutrition in which organisms produces their food by themselves such as green plants, green algae, etc is known as autotrophic mode of nutrition. Photosynthesis The process by which green plants prepare their food by themselves with the help of carbon dioxide, sunlight and water in presence of chlorophyll known as photosyn...
Read more