RESPIRATORY SYSTEM; INTRODUCTION, DIVISIONS, DIFFERENCES, EQUATION, TYPES, CHARACTERISTICS AND MECHANISMS

RESPIRATORY SYSTEM
Welcome back to class once again. I hope we are fully prepared to learn because we will be learning about a new topic called the Respiratory System.
The respiratory system are systems concerned with respiration in living organisms. These are forms organisms respond to their environment through respiration. Many organisms have different ways by which they respire. Respiration is the process by which food substances are broken down and oxidized in the living cells of organisms to release energy while carbon (IV) oxide and water vapour are released as waste products.
Respiration is divided into two namely
1. External Respiration: It is the intake of oxygen from the air and removal of carbon (IV) oxide from the body to the atmosphere. Its called gaseous exchange.
2. Internal Respiration: It is the process of breaking down sugar by a series of enzymes- controlled reactions to release energy in the form of ATP (Adenosine Triphosphate). This usually occur in the cell or tissue.
Table used to show the differences between Respiration and Photosynthesis
RESPIRATION PHOTOSYNTHESIS
Occurs in all living cells only occurs in cells with chlorophyll
Heat is liberated Heat is absorbed
Oxygen is used Oxygen is liberated
Sugar is used Sugar is synthesized
Water is a by- product Water is a raw material
Catabolic process involved Anabolic process involved
TABLE 1.1

The chemical equation for the above process is given as
1. C6H12 + 6O2 ————— 6CO2 + 6H20 + ENERGY (RESPIRATION)
2. 6CO2 + 6H20+ ENERGY ———C6H12O6 + 6O2 (PHOTOSYNTHESIS)

From the above simplified chemical equation, we can deduce the fact that respiration is actually the reverse of photosynthesis.

The following organisms and their respiratory structures are outlined below

Unicellular organisms; Body surface by diffusion
Earthworm; Moist skin or Cell Membrane
Hydra and Flatworms; Cell membrane by diffusion
Fishes; Gills
Certain arthropods and Insects; Tracheal Lube
Arachnids; Book Lungs
Amphibians; Gills, skin, mouth, and lungs
Mammals and Birds; Lungs
Plants; Lenticels and Stomata

CHARACTERISTICS OF RESPIRATORY SURFACES

IN ANIMALS
1. They have flat surface to increase/ Volume
2. Possesses large surface area for gaseous exchange
3. Moist surface to permit gases to diffuse in solution
4. Thin cell wall covering to permit permeability of dissolved gases
5. Rich supply of food
6. Highly vascularized lungs and internal gills.

IN PLANTS
1. Possesses thin walls
2. Possess moist surface
3. Possess large surface area
4. Possess permeable surface.

MECHANISMS OF RESPIRATORY SYSTEMS
Higher Animals, E.g., Man.
Inhalation in man occurs in the following sequence
1. Intercoastal muscles contract, pulling the ribs outward and upwards.
2. Diaphragm contracts and become flattened.
3. Both contractions result in the increase in the chest cavity and decrease in the pressure within the cavity.
4. Air containing oxygen therefore rushes in from the atmosphere through the nose, trachea, and bronchus and fills the alveoli. Thus gaseous exchange takes place between the blood in the capillaries and in the alveoli.
5. Air from the outside rushes in through the nose and fills the alveoli thus gaseous exchange takes place between the blood in the capillaries and the air in the alveoli

EXHALATION IN MAN

EXHALATION OR USUALLY KNOWN AS BREATHING OUT OCCUR IN THE FOLLOWING PRECEPT
1. THE INTERCOSTAL MUSCLES RELAX
2. The ribs are lowered
3. Diaphragm relaxes and returns to its dome shape
4. The chest cavity decreases and pressure in it increases
5. Air rich in carbon (IV) Oxide then rushes out from the lungs to the atmosphere through the nose.

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