الفصل 2: التنفس وتبادل الغاز

Chapter 2: Respiration & Gas Exchange

• This chapter discusses respiration and gas exchange in living organisms.
• The chapter is divided into sections, including:
  • Introduction
  • Cellular Respiration
  • Plant Respiration
  • Animal Respiration
  • Chapter Questions

Learning Objectives

• Students will be able to define cellular respiration.
• Students will be able to explain the four stages of glucose oxidation in cellular respiration.
• Students will be able to compare photosynthesis and respiration in plants.
• Students will be able to explain the mechanics of gas exchange in plants.
• Students will be able to define stomata and lenticels, and compare them.
• Students will be able to compare external and internal respiration.
• Students will be able to explain the concept of aerobic cellular respiration.
• Students will be able to explain the mechanics of respiration in animals.
• Students will be able to define pulmonary (alveolar) respiration.
• Students will be able to explain the concept of cutaneous respiration in vertebrates.
• Students will be able to explain the mechanics of respiration in birds.
• Students will be able to list the parts of the human respiratory system.
• Students will be able to explain the function of each part of the human respiratory system.
• Students will be able to explain the mechanism of inhalation and exhalation in humans.
• Students will be able to describe the structure of alveoli in the lungs.
• Students will be able to explain the process of gas exchange in the blood.

Introduction (1-2)

• Early organisms obtained energy from glucose through glycolysis.
• Glycolysis splits glucose into two molecules of pyruvic acid, releasing some energy.
• Most cells use glycolysis to produce energy.
• Early organisms likely cycled between photosynthesis and glycolysis.
• Glycolysis releases less than 0.1% of the energy stored in glucose produced during photosynthesis.

Cellular Respiration (2-2)

• Cellular respiration is a process requiring oxygen, producing carbon dioxide.
• Complete breakdown of glucose into carbon dioxide, water, and energy.
• Cellular respiration involves enzymatic processes.
• External Respiration is the exchange of gases between the blood and the external environment.
• Internal Respiration is the gas exchange between the blood and the body's cells.
• The process involves multiple steps (glycolysis, preparatory reaction, citric acid cycle, electron transport chain).
• Cellular respiration produces ATP, a crucial energy source for life.

Respiration in Plants (3-2)

• Plants lack specialized respiratory organs but exchange gases through their tissues.
• Gases enter and exit through stomata (and lenticels in woody stems).
• Oxygen diffuses into plant cells and carbon dioxide diffuses out.
• During the day, photosynthesis and respiration both occur, with photosynthesis generally exceeding respiration.
• At night, only respiration occurs.

Respiration in Animals (4-2)

• Animals require oxygen for metabolic processes to remove carbon dioxide.
• Various methods of gas exchange exist (e.g., body wall, gills, lungs).
• External Respiration in animals involves gas exchange between the respiratory surface and the blood.
• Internal Respiration in animals involves gas exchange between the blood and the body's cells.
• Animals use various respiratory systems based on their environment.

Mechanisms of Respiration

• Different organisms have different respiratory mechanisms.
• Simple diffusion is used for gas exchange in single-celled organisms.
• More complex organisms have specialized respiratory systems with moist surfaces for gas exchange.
• Types of Systems include:
  • Cutaneous respiration
  • Gills
  • Tracheal systems
  • Lungs

Respiration in Invertebrates

• Cutaneous - Skin respiration. This allows for gas exchange in flat or thin-bodied invertebrates.
• Gills are used by aquatic animals.
• Tracheal systems are the respiratory structures of many terrestrial arthropods (insects).

Respiration in Vertebrates

• Cutaneous respiration is used by some vertebrates (e.g., amphibians).
• Gills are the primary respiratory system for many aquatic vertebrates.
• Lungs form in vertebrates to support respiration on land.

Ventilation in Amphibians, Reptiles, Birds, and Mammals

• Amphibians, reptiles, birds, and mammals demonstrate different ventilation strategies.
• Ventilation in each class allows for gas exchange in their respiratory systems.
• Key differences in structures and mechanisms are described.

Gas Exchange

• Gases move according to diffusion gradients (high pressure to low pressure).
• Gaseous exchange in the lungs follows physical principles of diffusion.
• Gas exchange involves a moist surface for diffusion across cell membranes.
• Differences in gas pressures drive the exchange of oxygen and carbon dioxide.

Gas Transport in the Blood

• Haemoglobin is the primary oxygen-carrying pigment in blood; it combines with oxygen to form oxyhemoglobin (a reversible reaction)
• Some carbon dioxide is carried dissolved in the blood plasma.
• The rest of the CO2 combines with water to form carbonic acid, which then dissociates into hydrogen and bicarbonate ions.

Other Important Concepts

• Breathing and gas exchange are critical for life.
• Various respiratory structures and mechanisms exist in different organisms to facilitate these processes.