BIOLOGY: Week 1

CHAPTER 1 – TRANSPORT

1.2 IMPORTANCE OF TRANSPORT SYSTEM

Living organisms need to exchange  substances like oxygen, food, carbon dioxide and other waste products with their environment to grow.

The size of an organism affects the diffusion rate of substances in and out of its body

Unicellular organisms like amoeba sp. and paramecium sp. obtain these substances through diffusion. This is because they are small in size and have large total surface area per volume.

*the smaller the size, the bigger the total surface area per volume!

Multicellular organisms like humans, animals and plants cannot just rely upon diffusion because :-

·         --> The body size is too large for simple substances to simply diffuse

·         --> Total surface area / volume is too small

·         --> The skin is too thick and the cells are located too far in the body.

             

To overcome these problems, we need special transport systems for cellular requirements.

In humans and animals, we have blood circulatory system

In plants, there’s vascular system

1.2 THE CICULATORY SYSTEM

•          Delivers nutrients and oxygen to body cells
•          Carries waste products away from the cells
•          Protects body from infection

MAJOR COMPONENTS

1) BLOOD                                             2) HEART                                    3) BLOOD VESSEL

• PLASMA                                                                                             --> ARTERIES
• BLOOD CELLS                                                                                   -->CAPILLARIES
• PLATELETS                                                                                        --> VEINS

BLOOD AND HAEMOLYMPH

HUMANS AND ANIMALS --> has blood as the medium of transport

INVERTEBRATES (INSECTS) ---> Has haemolymph as the medium of transport.

                                                        Haemolymph is a blood-like nutritive fluid which fills the                                                         entire body cavity (haemocoel)

FUNCTIONS OF BLOOD

FUNCTIONS OF HAEMOLYMPH

Haemolymph transport water, inorganic salts, and organic compounds

Unlike blood, haemolymph does not transport respiratory gases

BUT in insects, respiratory gases are transported via the TRACHEAL SYSTEM