ectotherms 6 Flashcards
What is the purpose of a circulatory system?
When complexity increases diffusion is insufficient to supply an organism with all its needs so a circulatory system is used to deliver nutrients and allow a higher metabolic rate to be maintained
What is the difference between an open and closed circulatory system?
A closed circulatory system can generate increased pressure and therefore is more efficient
What are the three types of heart?
An extrinsic muscle pump which is a thickening of the blood vessel which pushes blood through
A pulsatile heart which contracts to form a pulse to push the blood around
A chambered heart which beats generating a pressure wave
What is the difference between afferent and efferent?
Afferent is coming towards the central body (heart) and efferent is going away from the central body
What are the different types of circulatory system?
A single circulation (two chambered heart) as in fish where blood is first delivered to the gills where it is oxygenated and it is then taken to the body capillaries
A divided circulation with a separate track for the pulmonary and systemic circuit
How does the hag fish heart work?
It uses a caudal heart which is an extrinsic muscle pump depend on the animal moving, this is inefficient and not capable of generating a large amount of pressure
Consequently the hagfish has several within its single circulatory system
What is a conus arteriosus?
A shark uses a two chambered heart however it also contains a conus arteriosus to dampen down the pressure wave sent to the gills to prevent them getting damaged
Teleosts have a similar structure known as a bulbus arteriosus
What is the difference between a volume pump and a pressure pump?
A volume pump has a low heart rate but a high stroke volume while a pressure pump has a high rate and a low stroke volume (lots of blood, low O2)
What are three key strategies for a divided circulation?
An amphibian uses a three chambered heart where there is a circuit to the lungs and skin and one to the systemic circulation with a heart containing two atria and a single ventricle causing blood mixing
Most reptiles use a circulatory system where there is two atria, two ventricles with an incomplete septum, they also contain a left and right aortic arch which allows control of the blood away from the gills when air breathing
The crocodilian system also has a four chambered heart, but also contains a left and right aortic arch and a panizzas foramen which blocks blood flow allowing oxygenated blood to bypass the lungs underwater
How can turtles regulate their circulatory system?
When they dive their lungs are compressed which prevents blood flow to the lungs due to high vascular resistance
