Diversity of respiratory structures

Animals have different respiratory structures depending mainly on the environment they live. So , we can study various type of respiratory structures  in animals. the area where gaseous exchange takes place with the environment is called the respiratory surface. An effective respiratory surface must have the following properties.

•   It must be permeable, and wet so that gases can pass through

•   It must be thin because diffusion is only efficient over the thin surfaces.

•   It should possess a large surface area to allow  sufficient volumes of gases  to be

      exchanged according to the organism’s need.

 •   It should possess a good blood supply.

Diffusion and surface to volume ratio

                      Respiratory gas exchange occurs due to diffusion. In small animals diffusion through

                      body surface is adequate as they are simple and the energy requirement is very low.

                      However, when surface volume ratio decreases, sufficient area is needed for gas

                      exchange and thus respiratory structures with large surface area were developed.

 Respiratory structures in animals

                      •   Body surface   e.g.,   Earthworm, flat worm

                      •   External gills   e.g.,   Polycheate worms, Arenicola tadpole of frog, salamander

                      •   Internal gills    e.g.,   Bony fish, lobster

                      •   Trachea       eg:    Insects, Millipedes, Centipedes

                      •   Book lungs    e.g.,   Spider, scorpion

                      •   Lungs         e.g.,   Human, Reptiles, Birds

  Gross structure of the human respiratory system.

                      •    The gross structure and location of components of human respiratory system -nostrils,

                          nasal cavity, pharynx, larynx, trachea, bronchi, bronchioles, alveolar sacs (lungs)

                   •      The structure of each related with the function should be explained.

                   •      The walls of respiratory passage are lined with ciliated pseudo columnar epithelial cells

                      & goblet cells. (Cartilages are present in larynx, trachea and bronchi)

                   •      Mechanism of ventilation of lungs

                      •    Mechanism of lung ventilation should be explained with the aid of diagrams.

                      •    The role of inter coastal muscles & diaphragm in inspiration & expiration should be

                          explained

                   •    Exchange of gases between blood & air

                   •     Oxygen dissolves in mucous and diffuses across the thin epithelium of alveoli &

                     endothelium    of the capillaries. It passes first into the blood plasma & combines with

                     haemoglobin to form oxyhaemoglobin

                 

                   •    Regulation of respiration

                   •    Regulation of breathing by chemo receptors and respiration control centre in medulla

                         oblongata    .