transport systems

cells of alll living organisms need a constant supply of reactants for _

metabolism eg oxygen and glucose to cells for respiration and also remove waste products

why do large organisms need a transport system?

they are made up of many layers of cells meaning that the time taken for substances such a glucose and oxygen to diffuse to every cell in the body would be too long. Diffusion distances are too great and large organisms often have high energy requirements so delivery of reactants from metabolism needs to happen quickly. exchange surfaces are connected to a mass transport system to solve this ploblem

examples of mass transport systems

1. digestive system is connected to the circulatory system

2. The lungs are connected to the circulatory system

The need for transport systems depends on what

size

surface area to volume ratio

level of metabolism activity, e.g. digestion and respiration

define mass transport

The bulk movement of gases or liquids in One Direction usually via a system of vessels and tubes

what do mass transport systems help with?

1. to bring substances quickly from one exchange site to another

2. to maintain diffusion gradients at exchange sites and between cells and their fluid surroundings

3. to ensure effective cell activity by supplying reactants and removing waste products.

The two types of circulatory systems and the key features of each

open:

organisms with a low metabolic rate

organisms with a large surface area to volume ratio

so sufficient diffusion rate between blood and cells of oxygen and carbon dioxide

closed:

organisms with a high metabolic rate

organism with a small surface area to volume ratio

so overcomes the limitations of relying on diffusion of substances

as generates higher pressure so blood travels faster and more efficient of delivery of substances

describe the circulatory system of mammals

double closed circulatory system as the blood travels around the body in two separate circuits known as a pulmonary in systematic circulation

pulmonary vs systemic circulation

pulmonary circulation move blood between a heart and the lungs to pick up oxygen and remove carbon dioxideand systematic circulation move blood between the heart and the rest of the body to deliver oxygen and nutrients