transport systems Flashcards
why do larger organisms need a transport system
-diffusion is insufficient for their exchange needs because
-SA: vol is too small
-large in size
-high metabolic activity
what are the features of a good transport system
-fluid medium to carry nutrients, oxygen
-pump
-specialised exchange surfaces
-tubes/vessels
-two circuits
what does the term single circulatory system mean
blood passes through the heart once
what are the limitations of the single circulatory system
• Blood pressure drops as blood passes through capillaries in the gills
• Blood flows slowly to the body because of the low blood pressure
• The rate of delivery of oxygen and nutrients to respiring tissues and removal of carbon dioxide and urea is limited
why is the single circulatory system sufficient for fish
• Fish are not as metabolically active as mammals and do not maintain their body temperature so require less energy, a single circulatory systems is therefore sufficient for their needs
what is a double circulatory system
blood passes through heart two times per circuit
heart- body - heart- lungs
what are the advantages of a double circulatory system
systemic and pulmonary circulation have different pressure = heart can increase pressure = rapid delivery
what is systemic circulation
what is pulmonary circulation
-carries blood from heart to all other body parts and back again
-short loop from the heart to the lungs and back again
why do mammals and birds need a double circulatory system
-high metabolic activity
-maintain their body temp so large amount of energy required and so rapid oxygen supply
what is an open circulatory system
where blood circulated through the body cavity bathing all cells directly
-movement of blood can be assisted by action of body muscles or pumping organ
-insects
what are the disadvantages of an open circulatory system
• Blood pressure is low, slow blood flow
Open circulation of a locust
Heart
• Slow delivery of oxygen and nutrients
• Slow removal of carbon dioxide and waste
• Body movements affect circulation of blood
what is a closed circulatory system
what are the advantages
-blood always enclosed in vessels
• High pressure, rapid blood flow
• Rapid delivery of oxygen and nutrients
• Rapid removal of carbon dioxide and waste
• Transport of blood is independent of body movements
