1ST TERM

[admin]

TOPIC OF THE LESSON: RESPIRATORY SYSTEM
BEHAVIOURAL OBJECTIVES: BY THE END OF THE LESSON, LEARNERS SHOULD BE ABLE TO:
i. Define respiration
ii. Mention the two phases in respiration
iii. State the types of respiratory system
iv. Explain the human respiratory system
REFERENCE: MODERN BIOLOGY FOR S.S.CE by SAROJINI T. RANALINGAN

CONTENT: RESPIRATORY SYSTEM
Respiration is a process carried out by all living organisms. It is the process through which food materials/nutrients are utilized to release energy. Therefore respiration is a process which occurs in a biological system in which glucose is broken down by certain enzyme controlled reactions to release energy.
C6H12O6 + 6O2 6CO2 + 6H2O + Energy
The reaction above is an overall general equation of respiration in all living organisms.

There are two phases/stages in respiration:
i. External respiration (breathing)
a. Inhalation - breathing in of air or oxygen
b. Exhalation - breathing out of air & oxygen

ii. Tissue respiration (internal respiration): this is the conversion of organic food materials into energy within the cells. This is an oxidation process i.e. food materials are oxidized to release energy, water and carbon dioxide. Carbon dioxide and water are regarded as waste products of respiration.

iii. Tissue respiration can also be referred to as cellular respiration. It involves two processes:
(a) The glycolysis which is the breaking down of glucose to release pyruvic acid in the cytoplasm of the cell.
(b) The Krebb's or TCA cycle which is a cyclic process which occurs in the mitochondria of the cell to release a large amount of energy.

CHARACTERISTICS OF RESPIRATORY SURFACE
i. Must be moist
ii. Respiratory surface must be supplied with adequate medium of transportation e.g. blood
iii. It must make diffusion easier
iv. It must have a large surface area for adequate diffusion of gases.
v. It must be semi-permeable
vi. It must be vascular (well supplied with capillaries of other network of transport of materials).

EVALUATION:
a. What is respiration
b. Describe the stages in respiration

ASSIGNMENT:
Describe the mechanism of inhalation





BEHAVIOURAL OBJECTIVES: BY THE END OF THE LESSON, LEARNERS SHOULD BE ABLE TO:
State the types of respiratory systems and explain their process of respiration

CONTENT: TYPES OF RESPIRATORY SYSTEMS
By respiration we mean all structures and organs are involved in the process of respiration. The respiratory system of each group of organism has to do with the complexity, the size and the type of environment where the organism lives.
Respiratory systems include the following:

i. Simple diffusion in unicellular organs e.g Amoeba, paramecium. The amount of oxygen in water is much more high than inside the body of these animals. Therefore oxygen gains entrance in all parts of the body. Also the concentration of carbon dioxide in the body is much more higher in the surrounding water, therefore, the carbon dioxide diffuses freely through the cell membrane to the surrounding water. These unicellular organisms have large surface area to volume ratio. As a result, the process of respiration is by simple diffusion through the body surface.

ii. Tracheal system in insects: insects such as mosquito, cockroach, grass hopper, respire through a tracheal system. This system by compression and relaxation of the body to expel and inhale air for respiration. Oxygen take in are dissolved in the body fluid at the end of the tracheoles where it enters the various cells. Carbon dioxide diffuses from the cells diffuse in the body fluid into the trachea and finally comes out through the spiracles.

iii. Gills in fishes: fish respire with the help of the gills. They are arranged in the gill chamber closed up by the operculum. Oxygen in the water taken in diffuses into the gill chamber into the gill filament while carbon dioxide diffuses out of the body into the water.
The gill filaments contain the gaseous exchange surfaces. Each filament is made up of a series of transverse plates which is held together along one of the edges. These plates serve to increase the surface area of the gill filament.

iv. Gills and Lungs in amphibians (toad & frog): the young toads are called tadpoles. Tadpole uses external gill at the early stage of development while advanced tadpole uses internal gills.
Adult toads and frogs use lungs and skin for respiration. This is why they can survive both on land and in water. This is because it has a large surface area and a thin covering. The skin is well vascularized with cutaneous secretion from the mucus gland. Therefore oxygen can diffuse in both on land and in water. Oxygen dissolved in water diffuses into the body and carbon dioxide diffuses out by simple diffusion

EVALUATION:
i. List the features that make the gills of bony fishes efficient gaseous exchange structures.
ii. Describe respiration the unicellular organisms

ASSIGNMENT:
Explain the mechanism of exhalation






BEHAVIOURAL OBJECTIVES: BY THE END OF THE LESSON, LEARNERS SHOULD BE ABLE TO:
a. Describe the structure of respiration in mammals
b. List the structures involved in breathing in mammals

CONTENT: RESPIRATORY SYSTEM OF A MAN
The respiratory system of a man include the nasal passages or nostrils, the pharynx, the larynx or voice box, the trachea or wind pipe, the bronchus, the bronchioles ad the alveoli.
The nostrils lead to the posterior portion of the mouth cavity called the pharynx which leads to the voice box or larynx which leads to the wind pipe or trachea. The trachea branches into two bronchi (singular bronchus), the air tubes enter the lungs. The smaller are tubes are called bronchioles which end up in thin walled, hollow air sacs or alveoli (sing. Alveolus). Alveoli form the gaseous exchange surface, the trachea and bronchi are lined with ciliated cells which also secrete mucus. Dust and germs in the air are trapped in the mucus and swept up to the throat away from the lungs, by ciliary action. These eventually get into the gullet during swallowing. The lung is a pair of reddish, elastic organ located within the thoracic cavity of a mammal.

EVALUATION:
i. Describe the structure of respiratory system in mammals
ii. List the features involved in breathing

ASSIGNMENT:
State the process of inspiration and expiration in man and state the composition of inhaled and exhaled air.

[admin]

REVISION