circulatory systems Flashcards
describe the need for exchange transport systems in animals
- small SA:V
- large size so distances too far for diffusion alone to be efficient
- high metabolic demand due to high level of activity which requires more gas exchange for aerobic respiration
what is a single circulatory system?
blood passes through the heart once in a complete circuit
what is a double circulatory system?
blood passes through the heart twice in one complete circuit
what is the advantage of a double circulatory system?
- higher pressure
- faster flow maintained
- can change the pressure in specific regions
what is an open circulatory system?
blood is not always enclosed in vessels and is pumped through a cavity, coming into direct contact with tissues and cells
what is a closed circulatory system?
blood is enclosed in vessels and does not come into direct contact with tissues and cells
what are the advantages of a closed circulatory system?
high pressure and fast blood flow
what are the 3 components which make up a circulatory system?
- a circulatory fluid, (blood)
- a set of tubes, (blood vessels)
- a muscular pump (the heart)
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 single circulatory systems heart composed of and what is blood flow like?
One atrium and one ventricle
- slow
- low pressure
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.
suggest why the mammalian system is called a complete double circulation but amphibian is partial? (3 marks)
- mammals have 2 ventricles separated into oxygenated and deoxygenated blood
- blood passes through the heart twice
suggest why a partial double circulation system would be less effective at supplying body tissues with oxygen (3 marks)
- deoxygenated and oxygenated blood are not separated
- distance for oxygen to travel is further
- blood pressure and flow decreases
