Circulatory Systems Flashcards
Explain the 3 reasons why there is a need for transport systems in multicellular animals.
1) Size: due to several cell layers, and the oxygen and nutrients diffusing in being used by the outer cell layers, there is an increased distance from the oxygen and nutrients to the cells requiring them
2) Surface area to volume ratio: multicellular organisms have small surface areas for their large volumes, therefore it is not large enough to supply all nutrients needed by inner cells
3) Levels of activity: active animals require more oxygen for respiration
Explain what is meant by mass transport.
- Where everything all moves together in one direction.
- this includes cells, plasma, dissolved substances in the blood
- is opposite to diffusion, where molecules move around individually, -mass transport is a much faster way of transporting materials
- driving force of mass transport is pressure
What are the 3 basic components which make up both types of circulatory system?
- a circulatory fluid, (blood)
- a set of tubes, (blood vessels)
- a muscular pump (the heart)
What is an open circulatory system?
-where blood isn’t enclosed in blood vessels all the time, instead it flows freely through the body cavity
Explain how an open circulatory system works in an insect.
- there is not a separate blood system and lymph system, so circulatory fluid is called haemolymph
- haemolymph doesn’t carry gases, as gas exchange happens in tracheal system. It transports food and nitrogenous waste products
- only one vessel is present, the dorsal vessel, which acts as the heart in the abdominal region, pumping the haemolymph forward into the head and thorax, acting as the aorta, then returns to heart via ostia.
Explain some disadvantages to an open circulatory system
- although haemolymph circulates, it is not possible to maintain a step diffusion gradient so exchange of materials isn’t very efficient
- delivery of haemolymph is not tailored to meet specific needs within animals body; can’t be diverted to particular tissues
- need a large haemolymph volume
What is a closed circulatory system?
-where blood is enclosed inside blood vessels, and there is a separate lymphatic system
Explain how a closed circulatory system works in animals
1) heart pumps blood into arteries, which branch off into millions of capillaries
2) substances like oxygen and glucose diffuse from the blood in the capillaries into the body cells, but blood stays inside its vessels
3) veins take blood back to the heart
What are some advantages to a closed circulatory system?
- greater efficiency in transporting circulatory fluids to tissues and cells
- only a small volume of blood is required compared to in an open circulatory system
What is a single circulatory system?
-blood only passes through the heart once, for each complete circuit of the body
Where is a single circulatory system commonly found?
In fish, the heart pumps blood through the gills (to pick up oxygen) and then onto the rest of the body (to deliver the oxygen) without an extra boost from the heart, in a single circuit
What is a single circulatory systems heart composed of and what is blood flow like?
- One atrium and one ventricle
- blood at low pressure and flow is slow
What is a double circulatory system?
-blood passes through the heart twice for each complete circuit of the body
Explain what the 2 separate circuits found in a double circulatory system are.
- Pulmonary circuit: carries deoxygenated blood from the right side of the heart to the lungs to pick up oxygen and offload carbon dioxide then return the oxygenated blood to the left side of the heart
- Systemic circuit: carries oxygenated blood from left side of heart to body tissues where gas exchange takes place. Deoxygenated blood then taken back to right side of heart.
Explain some advantages of a double circulatory system.
- blood flow is quick due to blood pressure created by heart
- heart can increase pressure of blood flowing to body tissues without increasing pressure of blood to same extent to the lungs
